TOMOYO Linux Cross Reference
Linux/kernel/seccomp.c

   // SPDX-License-Identifier: GPL-2.0
   /*
    * linux/kernel/seccomp.c
    *
    * Copyright 2004-2005  Andrea Arcangeli <andrea@cpushare.com>
    *
    * Copyright (C) 2012 Google, Inc.
    * Will Drewry <wad@chromium.org>
    *
   * This defines a simple but solid secure-computing facility.
   *
   * Mode 1 uses a fixed list of allowed system calls.
   * Mode 2 allows user-defined system call filters in the form
   *        of Berkeley Packet Filters/Linux Socket Filters.
   */
  #define pr_fmt(fmt) "seccomp: " fmt
  
  #include <linux/refcount.h>
  #include <linux/audit.h>
  #include <linux/compat.h>
  #include <linux/coredump.h>
  #include <linux/kmemleak.h>
  #include <linux/nospec.h>
  #include <linux/prctl.h>
  #include <linux/sched.h>
  #include <linux/sched/task_stack.h>
  #include <linux/seccomp.h>
  #include <linux/slab.h>
  #include <linux/syscalls.h>
  #include <linux/sysctl.h>
  
  /* Not exposed in headers: strictly internal use only. */
  #define SECCOMP_MODE_DEAD       (SECCOMP_MODE_FILTER + 1)
  
  #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
  #include <asm/syscall.h>
  #endif
  
  #ifdef CONFIG_SECCOMP_FILTER
  #include <linux/file.h>
  #include <linux/filter.h>
  #include <linux/pid.h>
  #include <linux/ptrace.h>
  #include <linux/capability.h>
  #include <linux/uaccess.h>
  #include <linux/anon_inodes.h>
  #include <linux/lockdep.h>
  
  /*
   * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
   * wrong direction flag in the ioctl number. This is the broken one,
   * which the kernel needs to keep supporting until all userspaces stop
   * using the wrong command number.
   */
  #define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR  SECCOMP_IOR(2, __u64)
  
  enum notify_state {
          SECCOMP_NOTIFY_INIT,
          SECCOMP_NOTIFY_SENT,
          SECCOMP_NOTIFY_REPLIED,
  };
  
  struct seccomp_knotif {
          /* The struct pid of the task whose filter triggered the notification */
          struct task_struct *task;
  
          /* The "cookie" for this request; this is unique for this filter. */
          u64 id;
  
          /*
           * The seccomp data. This pointer is valid the entire time this
           * notification is active, since it comes from __seccomp_filter which
           * eclipses the entire lifecycle here.
           */
          const struct seccomp_data *data;
  
          /*
           * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
           * struct seccomp_knotif is created and starts out in INIT. Once the
           * handler reads the notification off of an FD, it transitions to SENT.
           * If a signal is received the state transitions back to INIT and
           * another message is sent. When the userspace handler replies, state
           * transitions to REPLIED.
           */
          enum notify_state state;
  
          /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
          int error;
          long val;
          u32 flags;
  
          /*
           * Signals when this has changed states, such as the listener
           * dying, a new seccomp addfd message, or changing to REPLIED
           */
          struct completion ready;
  
          struct list_head list;
  
         /* outstanding addfd requests */
         struct list_head addfd;
 };
 
 /**
  * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
  *
  * @file: A reference to the file to install in the other task
  * @fd: The fd number to install it at. If the fd number is -1, it means the
  *      installing process should allocate the fd as normal.
  * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
  *         is allowed.
  * @ioctl_flags: The flags used for the seccomp_addfd ioctl.
  * @setfd: whether or not SECCOMP_ADDFD_FLAG_SETFD was set during notify_addfd
  * @ret: The return value of the installing process. It is set to the fd num
  *       upon success (>= 0).
  * @completion: Indicates that the installing process has completed fd
  *              installation, or gone away (either due to successful
  *              reply, or signal)
  * @list: list_head for chaining seccomp_kaddfd together.
  *
  */
 struct seccomp_kaddfd {
         struct file *file;
         int fd;
         unsigned int flags;
         __u32 ioctl_flags;
 
         union {
                 bool setfd;
                 /* To only be set on reply */
                 int ret;
         };
         struct completion completion;
         struct list_head list;
 };
 
 /**
  * struct notification - container for seccomp userspace notifications. Since
  * most seccomp filters will not have notification listeners attached and this
  * structure is fairly large, we store the notification-specific stuff in a
  * separate structure.
  *
  * @requests: A semaphore that users of this notification can wait on for
  *            changes. Actual reads and writes are still controlled with
  *            filter->notify_lock.
  * @flags: A set of SECCOMP_USER_NOTIF_FD_* flags.
  * @next_id: The id of the next request.
  * @notifications: A list of struct seccomp_knotif elements.
  */
 
 struct notification {
         atomic_t requests;
         u32 flags;
         u64 next_id;
         struct list_head notifications;
 };
 
 #ifdef SECCOMP_ARCH_NATIVE
 /**
  * struct action_cache - per-filter cache of seccomp actions per
  * arch/syscall pair
  *
  * @allow_native: A bitmap where each bit represents whether the
  *                filter will always allow the syscall, for the
  *                native architecture.
  * @allow_compat: A bitmap where each bit represents whether the
  *                filter will always allow the syscall, for the
  *                compat architecture.
  */
 struct action_cache {
         DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
 #ifdef SECCOMP_ARCH_COMPAT
         DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
 #endif
 };
 #else
 struct action_cache { };
 
 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
                                              const struct seccomp_data *sd)
 {
         return false;
 }
 
 static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
 {
 }
 #endif /* SECCOMP_ARCH_NATIVE */
 
 /**
  * struct seccomp_filter - container for seccomp BPF programs
  *
  * @refs: Reference count to manage the object lifetime.
  *        A filter's reference count is incremented for each directly
  *        attached task, once for the dependent filter, and if
  *        requested for the user notifier. When @refs reaches zero,
  *        the filter can be freed.
  * @users: A filter's @users count is incremented for each directly
  *         attached task (filter installation, fork(), thread_sync),
  *         and once for the dependent filter (tracked in filter->prev).
  *         When it reaches zero it indicates that no direct or indirect
  *         users of that filter exist. No new tasks can get associated with
  *         this filter after reaching 0. The @users count is always smaller
  *         or equal to @refs. Hence, reaching 0 for @users does not mean
  *         the filter can be freed.
  * @cache: cache of arch/syscall mappings to actions
  * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
  * @wait_killable_recv: Put notifying process in killable state once the
  *                      notification is received by the userspace listener.
  * @prev: points to a previously installed, or inherited, filter
  * @prog: the BPF program to evaluate
  * @notif: the struct that holds all notification related information
  * @notify_lock: A lock for all notification-related accesses.
  * @wqh: A wait queue for poll if a notifier is in use.
  *
  * seccomp_filter objects are organized in a tree linked via the @prev
  * pointer.  For any task, it appears to be a singly-linked list starting
  * with current->seccomp.filter, the most recently attached or inherited filter.
  * However, multiple filters may share a @prev node, by way of fork(), which
  * results in a unidirectional tree existing in memory.  This is similar to
  * how namespaces work.
  *
  * seccomp_filter objects should never be modified after being attached
  * to a task_struct (other than @refs).
  */
 struct seccomp_filter {
         refcount_t refs;
         refcount_t users;
         bool log;
         bool wait_killable_recv;
         struct action_cache cache;
         struct seccomp_filter *prev;
         struct bpf_prog *prog;
         struct notification *notif;
         struct mutex notify_lock;
         wait_queue_head_t wqh;
 };
 
 /* Limit any path through the tree to 256KB worth of instructions. */
 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
 
 /*
  * Endianness is explicitly ignored and left for BPF program authors to manage
  * as per the specific architecture.
  */
 static void populate_seccomp_data(struct seccomp_data *sd)
 {
         /*
          * Instead of using current_pt_reg(), we're already doing the work
          * to safely fetch "current", so just use "task" everywhere below.
          */
         struct task_struct *task = current;
         struct pt_regs *regs = task_pt_regs(task);
         unsigned long args[6];
 
         sd->nr = syscall_get_nr(task, regs);
         sd->arch = syscall_get_arch(task);
         syscall_get_arguments(task, regs, args);
         sd->args[0] = args[0];
         sd->args[1] = args[1];
         sd->args[2] = args[2];
         sd->args[3] = args[3];
         sd->args[4] = args[4];
         sd->args[5] = args[5];
         sd->instruction_pointer = KSTK_EIP(task);
 }
 
 /**
  *      seccomp_check_filter - verify seccomp filter code
  *      @filter: filter to verify
  *      @flen: length of filter
  *
  * Takes a previously checked filter (by bpf_check_classic) and
  * redirects all filter code that loads struct sk_buff data
  * and related data through seccomp_bpf_load.  It also
  * enforces length and alignment checking of those loads.
  *
  * Returns 0 if the rule set is legal or -EINVAL if not.
  */
 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
 {
         int pc;
         for (pc = 0; pc < flen; pc++) {
                 struct sock_filter *ftest = &filter[pc];
                 u16 code = ftest->code;
                 u32 k = ftest->k;
 
                 switch (code) {
                 case BPF_LD | BPF_W | BPF_ABS:
                         ftest->code = BPF_LDX | BPF_W | BPF_ABS;
                         /* 32-bit aligned and not out of bounds. */
                         if (k >= sizeof(struct seccomp_data) || k & 3)
                                 return -EINVAL;
                         continue;
                 case BPF_LD | BPF_W | BPF_LEN:
                         ftest->code = BPF_LD | BPF_IMM;
                         ftest->k = sizeof(struct seccomp_data);
                         continue;
                 case BPF_LDX | BPF_W | BPF_LEN:
                         ftest->code = BPF_LDX | BPF_IMM;
                         ftest->k = sizeof(struct seccomp_data);
                         continue;
                 /* Explicitly include allowed calls. */
                 case BPF_RET | BPF_K:
                 case BPF_RET | BPF_A:
                 case BPF_ALU | BPF_ADD | BPF_K:
                 case BPF_ALU | BPF_ADD | BPF_X:
                 case BPF_ALU | BPF_SUB | BPF_K:
                 case BPF_ALU | BPF_SUB | BPF_X:
                 case BPF_ALU | BPF_MUL | BPF_K:
                 case BPF_ALU | BPF_MUL | BPF_X:
                 case BPF_ALU | BPF_DIV | BPF_K:
                 case BPF_ALU | BPF_DIV | BPF_X:
                 case BPF_ALU | BPF_AND | BPF_K:
                 case BPF_ALU | BPF_AND | BPF_X:
                 case BPF_ALU | BPF_OR | BPF_K:
                 case BPF_ALU | BPF_OR | BPF_X:
                 case BPF_ALU | BPF_XOR | BPF_K:
                 case BPF_ALU | BPF_XOR | BPF_X:
                 case BPF_ALU | BPF_LSH | BPF_K:
                 case BPF_ALU | BPF_LSH | BPF_X:
                 case BPF_ALU | BPF_RSH | BPF_K:
                 case BPF_ALU | BPF_RSH | BPF_X:
                 case BPF_ALU | BPF_NEG:
                 case BPF_LD | BPF_IMM:
                 case BPF_LDX | BPF_IMM:
                 case BPF_MISC | BPF_TAX:
                 case BPF_MISC | BPF_TXA:
                 case BPF_LD | BPF_MEM:
                 case BPF_LDX | BPF_MEM:
                 case BPF_ST:
                 case BPF_STX:
                 case BPF_JMP | BPF_JA:
                 case BPF_JMP | BPF_JEQ | BPF_K:
                 case BPF_JMP | BPF_JEQ | BPF_X:
                 case BPF_JMP | BPF_JGE | BPF_K:
                 case BPF_JMP | BPF_JGE | BPF_X:
                 case BPF_JMP | BPF_JGT | BPF_K:
                 case BPF_JMP | BPF_JGT | BPF_X:
                 case BPF_JMP | BPF_JSET | BPF_K:
                 case BPF_JMP | BPF_JSET | BPF_X:
                         continue;
                 default:
                         return -EINVAL;
                 }
         }
         return 0;
 }
 
 #ifdef SECCOMP_ARCH_NATIVE
 static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
                                                     size_t bitmap_size,
                                                     int syscall_nr)
 {
         if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
                 return false;
         syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
 
         return test_bit(syscall_nr, bitmap);
 }
 
 /**
  * seccomp_cache_check_allow - lookup seccomp cache
  * @sfilter: The seccomp filter
  * @sd: The seccomp data to lookup the cache with
  *
  * Returns true if the seccomp_data is cached and allowed.
  */
 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
                                              const struct seccomp_data *sd)
 {
         int syscall_nr = sd->nr;
         const struct action_cache *cache = &sfilter->cache;
 
 #ifndef SECCOMP_ARCH_COMPAT
         /* A native-only architecture doesn't need to check sd->arch. */
         return seccomp_cache_check_allow_bitmap(cache->allow_native,
                                                 SECCOMP_ARCH_NATIVE_NR,
                                                 syscall_nr);
 #else
         if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
                 return seccomp_cache_check_allow_bitmap(cache->allow_native,
                                                         SECCOMP_ARCH_NATIVE_NR,
                                                         syscall_nr);
         if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
                 return seccomp_cache_check_allow_bitmap(cache->allow_compat,
                                                         SECCOMP_ARCH_COMPAT_NR,
                                                         syscall_nr);
 #endif /* SECCOMP_ARCH_COMPAT */
 
         WARN_ON_ONCE(true);
         return false;
 }
 #endif /* SECCOMP_ARCH_NATIVE */
 
 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
 /**
  * seccomp_run_filters - evaluates all seccomp filters against @sd
  * @sd: optional seccomp data to be passed to filters
  * @match: stores struct seccomp_filter that resulted in the return value,
  *         unless filter returned SECCOMP_RET_ALLOW, in which case it will
  *         be unchanged.
  *
  * Returns valid seccomp BPF response codes.
  */
 static u32 seccomp_run_filters(const struct seccomp_data *sd,
                                struct seccomp_filter **match)
 {
         u32 ret = SECCOMP_RET_ALLOW;
         /* Make sure cross-thread synced filter points somewhere sane. */
         struct seccomp_filter *f =
                         READ_ONCE(current->seccomp.filter);
 
         /* Ensure unexpected behavior doesn't result in failing open. */
         if (WARN_ON(f == NULL))
                 return SECCOMP_RET_KILL_PROCESS;
 
         if (seccomp_cache_check_allow(f, sd))
                 return SECCOMP_RET_ALLOW;
 
         /*
          * All filters in the list are evaluated and the lowest BPF return
          * value always takes priority (ignoring the DATA).
          */
         for (; f; f = f->prev) {
                 u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
 
                 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
                         ret = cur_ret;
                         *match = f;
                 }
         }
         return ret;
 }
 #endif /* CONFIG_SECCOMP_FILTER */
 
 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
 {
         assert_spin_locked(&current->sighand->siglock);
 
         if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
                 return false;
 
         return true;
 }
 
 void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
 
 static inline void seccomp_assign_mode(struct task_struct *task,
                                        unsigned long seccomp_mode,
                                        unsigned long flags)
 {
         assert_spin_locked(&task->sighand->siglock);
 
         task->seccomp.mode = seccomp_mode;
         /*
          * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
          * filter) is set.
          */
         smp_mb__before_atomic();
         /* Assume default seccomp processes want spec flaw mitigation. */
         if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
                 arch_seccomp_spec_mitigate(task);
         set_task_syscall_work(task, SECCOMP);
 }
 
 #ifdef CONFIG_SECCOMP_FILTER
 /* Returns 1 if the parent is an ancestor of the child. */
 static int is_ancestor(struct seccomp_filter *parent,
                        struct seccomp_filter *child)
 {
         /* NULL is the root ancestor. */
         if (parent == NULL)
                 return 1;
         for (; child; child = child->prev)
                 if (child == parent)
                         return 1;
         return 0;
 }
 
 /**
  * seccomp_can_sync_threads: checks if all threads can be synchronized
  *
  * Expects sighand and cred_guard_mutex locks to be held.
  *
  * Returns 0 on success, -ve on error, or the pid of a thread which was
  * either not in the correct seccomp mode or did not have an ancestral
  * seccomp filter.
  */
 static inline pid_t seccomp_can_sync_threads(void)
 {
         struct task_struct *thread, *caller;
 
         BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
         assert_spin_locked(&current->sighand->siglock);
 
         /* Validate all threads being eligible for synchronization. */
         caller = current;
         for_each_thread(caller, thread) {
                 pid_t failed;
 
                 /* Skip current, since it is initiating the sync. */
                 if (thread == caller)
                         continue;
                 /* Skip exited threads. */
                 if (thread->flags & PF_EXITING)
                         continue;
 
                 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
                     (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
                      is_ancestor(thread->seccomp.filter,
                                  caller->seccomp.filter)))
                         continue;
 
                 /* Return the first thread that cannot be synchronized. */
                 failed = task_pid_vnr(thread);
                 /* If the pid cannot be resolved, then return -ESRCH */
                 if (WARN_ON(failed == 0))
                         failed = -ESRCH;
                 return failed;
         }
 
         return 0;
 }
 
 static inline void seccomp_filter_free(struct seccomp_filter *filter)
 {
         if (filter) {
                 bpf_prog_destroy(filter->prog);
                 kfree(filter);
         }
 }
 
 static void __seccomp_filter_orphan(struct seccomp_filter *orig)
 {
         while (orig && refcount_dec_and_test(&orig->users)) {
                 if (waitqueue_active(&orig->wqh))
                         wake_up_poll(&orig->wqh, EPOLLHUP);
                 orig = orig->prev;
         }
 }
 
 static void __put_seccomp_filter(struct seccomp_filter *orig)
 {
         /* Clean up single-reference branches iteratively. */
         while (orig && refcount_dec_and_test(&orig->refs)) {
                 struct seccomp_filter *freeme = orig;
                 orig = orig->prev;
                 seccomp_filter_free(freeme);
         }
 }
 
 static void __seccomp_filter_release(struct seccomp_filter *orig)
 {
         /* Notify about any unused filters in the task's former filter tree. */
         __seccomp_filter_orphan(orig);
         /* Finally drop all references to the task's former tree. */
         __put_seccomp_filter(orig);
 }
 
 /**
  * seccomp_filter_release - Detach the task from its filter tree,
  *                          drop its reference count, and notify
  *                          about unused filters
  *
  * @tsk: task the filter should be released from.
  *
  * This function should only be called when the task is exiting as
  * it detaches it from its filter tree. PF_EXITING has to be set
  * for the task.
  */
 void seccomp_filter_release(struct task_struct *tsk)
 {
         struct seccomp_filter *orig;
 
         if (WARN_ON((tsk->flags & PF_EXITING) == 0))
                 return;
 
         spin_lock_irq(&tsk->sighand->siglock);
         orig = tsk->seccomp.filter;
         /* Detach task from its filter tree. */
         tsk->seccomp.filter = NULL;
         spin_unlock_irq(&tsk->sighand->siglock);
         __seccomp_filter_release(orig);
 }
 
 /**
  * seccomp_sync_threads: sets all threads to use current's filter
  *
  * @flags: SECCOMP_FILTER_FLAG_* flags to set during sync.
  *
  * Expects sighand and cred_guard_mutex locks to be held, and for
  * seccomp_can_sync_threads() to have returned success already
  * without dropping the locks.
  *
  */
 static inline void seccomp_sync_threads(unsigned long flags)
 {
         struct task_struct *thread, *caller;
 
         BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
         assert_spin_locked(&current->sighand->siglock);
 
         /* Synchronize all threads. */
         caller = current;
         for_each_thread(caller, thread) {
                 /* Skip current, since it needs no changes. */
                 if (thread == caller)
                         continue;
 
                 /*
                  * Skip exited threads. seccomp_filter_release could have
                  * been already called for this task.
                  */
                 if (thread->flags & PF_EXITING)
                         continue;
 
                 /* Get a task reference for the new leaf node. */
                 get_seccomp_filter(caller);
 
                 /*
                  * Drop the task reference to the shared ancestor since
                  * current's path will hold a reference.  (This also
                  * allows a put before the assignment.)
                  */
                 __seccomp_filter_release(thread->seccomp.filter);
 
                 /* Make our new filter tree visible. */
                 smp_store_release(&thread->seccomp.filter,
                                   caller->seccomp.filter);
                 atomic_set(&thread->seccomp.filter_count,
                            atomic_read(&caller->seccomp.filter_count));
 
                 /*
                  * Don't let an unprivileged task work around
                  * the no_new_privs restriction by creating
                  * a thread that sets it up, enters seccomp,
                  * then dies.
                  */
                 if (task_no_new_privs(caller))
                         task_set_no_new_privs(thread);
 
                 /*
                  * Opt the other thread into seccomp if needed.
                  * As threads are considered to be trust-realm
                  * equivalent (see ptrace_may_access), it is safe to
                  * allow one thread to transition the other.
                  */
                 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
                         seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
                                             flags);
         }
 }
 
 /**
  * seccomp_prepare_filter: Prepares a seccomp filter for use.
  * @fprog: BPF program to install
  *
  * Returns filter on success or an ERR_PTR on failure.
  */
 static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
 {
         struct seccomp_filter *sfilter;
         int ret;
         const bool save_orig =
 #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
                 true;
 #else
                 false;
 #endif
 
         if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
                 return ERR_PTR(-EINVAL);
 
         BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
 
         /*
          * Installing a seccomp filter requires that the task has
          * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
          * This avoids scenarios where unprivileged tasks can affect the
          * behavior of privileged children.
          */
         if (!task_no_new_privs(current) &&
                         !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
                 return ERR_PTR(-EACCES);
 
         /* Allocate a new seccomp_filter */
         sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
         if (!sfilter)
                 return ERR_PTR(-ENOMEM);
 
         mutex_init(&sfilter->notify_lock);
         ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
                                         seccomp_check_filter, save_orig);
         if (ret < 0) {
                 kfree(sfilter);
                 return ERR_PTR(ret);
         }
 
         refcount_set(&sfilter->refs, 1);
         refcount_set(&sfilter->users, 1);
         init_waitqueue_head(&sfilter->wqh);
 
         return sfilter;
 }
 
 /**
  * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
  * @user_filter: pointer to the user data containing a sock_fprog.
  *
  * Returns 0 on success and non-zero otherwise.
  */
 static struct seccomp_filter *
 seccomp_prepare_user_filter(const char __user *user_filter)
 {
         struct sock_fprog fprog;
         struct seccomp_filter *filter = ERR_PTR(-EFAULT);
 
 #ifdef CONFIG_COMPAT
         if (in_compat_syscall()) {
                 struct compat_sock_fprog fprog32;
                 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
                         goto out;
                 fprog.len = fprog32.len;
                 fprog.filter = compat_ptr(fprog32.filter);
         } else /* falls through to the if below. */
 #endif
         if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
                 goto out;
         filter = seccomp_prepare_filter(&fprog);
 out:
         return filter;
 }
 
 #ifdef SECCOMP_ARCH_NATIVE
 /**
  * seccomp_is_const_allow - check if filter is constant allow with given data
  * @fprog: The BPF programs
  * @sd: The seccomp data to check against, only syscall number and arch
  *      number are considered constant.
  */
 static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
                                    struct seccomp_data *sd)
 {
         unsigned int reg_value = 0;
         unsigned int pc;
         bool op_res;
 
         if (WARN_ON_ONCE(!fprog))
                 return false;
 
         for (pc = 0; pc < fprog->len; pc++) {
                 struct sock_filter *insn = &fprog->filter[pc];
                 u16 code = insn->code;
                 u32 k = insn->k;
 
                 switch (code) {
                 case BPF_LD | BPF_W | BPF_ABS:
                         switch (k) {
                         case offsetof(struct seccomp_data, nr):
                                 reg_value = sd->nr;
                                 break;
                         case offsetof(struct seccomp_data, arch):
                                 reg_value = sd->arch;
                                 break;
                         default:
                                 /* can't optimize (non-constant value load) */
                                 return false;
                         }
                         break;
                 case BPF_RET | BPF_K:
                         /* reached return with constant values only, check allow */
                         return k == SECCOMP_RET_ALLOW;
                 case BPF_JMP | BPF_JA:
                         pc += insn->k;
                         break;
                 case BPF_JMP | BPF_JEQ | BPF_K:
                 case BPF_JMP | BPF_JGE | BPF_K:
                 case BPF_JMP | BPF_JGT | BPF_K:
                 case BPF_JMP | BPF_JSET | BPF_K:
                         switch (BPF_OP(code)) {
                         case BPF_JEQ:
                                 op_res = reg_value == k;
                                 break;
                         case BPF_JGE:
                                 op_res = reg_value >= k;
                                 break;
                         case BPF_JGT:
                                 op_res = reg_value > k;
                                 break;
                         case BPF_JSET:
                                 op_res = !!(reg_value & k);
                                 break;
                         default:
                                 /* can't optimize (unknown jump) */
                                 return false;
                         }
 
                         pc += op_res ? insn->jt : insn->jf;
                         break;
                 case BPF_ALU | BPF_AND | BPF_K:
                         reg_value &= k;
                         break;
                 default:
                         /* can't optimize (unknown insn) */
                         return false;
                 }
         }
 
         /* ran off the end of the filter?! */
         WARN_ON(1);
         return false;
 }
 
 static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
                                          void *bitmap, const void *bitmap_prev,
                                          size_t bitmap_size, int arch)
 {
         struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
         struct seccomp_data sd;
         int nr;
 
         if (bitmap_prev) {
                 /* The new filter must be as restrictive as the last. */
                 bitmap_copy(bitmap, bitmap_prev, bitmap_size);
         } else {
                 /* Before any filters, all syscalls are always allowed. */
                 bitmap_fill(bitmap, bitmap_size);
         }
 
         for (nr = 0; nr < bitmap_size; nr++) {
                 /* No bitmap change: not a cacheable action. */
                 if (!test_bit(nr, bitmap))
                         continue;
 
                 sd.nr = nr;
                 sd.arch = arch;
 
                 /* No bitmap change: continue to always allow. */
                 if (seccomp_is_const_allow(fprog, &sd))
                         continue;
 
                 /*
                  * Not a cacheable action: always run filters.
                  * atomic clear_bit() not needed, filter not visible yet.
                  */
                 __clear_bit(nr, bitmap);
         }
 }
 
 /**
  * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
  * @sfilter: The seccomp filter
  *
  * Returns 0 if successful or -errno if error occurred.
  */
 static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
 {
         struct action_cache *cache = &sfilter->cache;
         const struct action_cache *cache_prev =
                 sfilter->prev ? &sfilter->prev->cache : NULL;
 
         seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
                                      cache_prev ? cache_prev->allow_native : NULL,
                                      SECCOMP_ARCH_NATIVE_NR,
                                      SECCOMP_ARCH_NATIVE);
 
 #ifdef SECCOMP_ARCH_COMPAT
         seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
                                      cache_prev ? cache_prev->allow_compat : NULL,
                                      SECCOMP_ARCH_COMPAT_NR,
                                      SECCOMP_ARCH_COMPAT);
 #endif /* SECCOMP_ARCH_COMPAT */
 }
 #endif /* SECCOMP_ARCH_NATIVE */
 
 /**
  * seccomp_attach_filter: validate and attach filter
  * @flags:  flags to change filter behavior
  * @filter: seccomp filter to add to the current process
  *
  * Caller must be holding current->sighand->siglock lock.
  *
  * Returns 0 on success, -ve on error, or
  *   - in TSYNC mode: the pid of a thread which was either not in the correct
  *     seccomp mode or did not have an ancestral seccomp filter
  *   - in NEW_LISTENER mode: the fd of the new listener
  */
 static long seccomp_attach_filter(unsigned int flags,
                                   struct seccomp_filter *filter)
 {
         unsigned long total_insns;
         struct seccomp_filter *walker;
 
         assert_spin_locked(&current->sighand->siglock);
 
         /* Validate resulting filter length. */
         total_insns = filter->prog->len;
         for (walker = current->seccomp.filter; walker; walker = walker->prev)
                 total_insns += walker->prog->len + 4;  /* 4 instr penalty */
         if (total_insns > MAX_INSNS_PER_PATH)
                 return -ENOMEM;
 
         /* If thread sync has been requested, check that it is possible. */
         if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
                 int ret;
 
                 ret = seccomp_can_sync_threads();
                 if (ret) {
                         if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
                                 return -ESRCH;
                         else
                                 return ret;
                 }
         }
 
         /* Set log flag, if present. */
         if (flags & SECCOMP_FILTER_FLAG_LOG)
                 filter->log = true;
 
         /* Set wait killable flag, if present. */
         if (flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV)
                 filter->wait_killable_recv = true;
 
         /*
          * If there is an existing filter, make it the prev and don't drop its
          * task reference.
          */
         filter->prev = current->seccomp.filter;
         seccomp_cache_prepare(filter);
         current->seccomp.filter = filter;
         atomic_inc(&current->seccomp.filter_count);
 
         /* Now that the new filter is in place, synchronize to all threads. */
         if (flags & SECCOMP_FILTER_FLAG_TSYNC)
                 seccomp_sync_threads(flags);
 
         return 0;
 }
 
 static void __get_seccomp_filter(struct seccomp_filter *filter)
 {
         refcount_inc(&filter->refs);
 }
 
 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
 void get_seccomp_filter(struct task_struct *tsk)
 {
         struct seccomp_filter *orig = tsk->seccomp.filter;
         if (!orig)
                 return;
         __get_seccomp_filter(orig);
         refcount_inc(&orig->users);
 }
 
 #endif  /* CONFIG_SECCOMP_FILTER */
 
 /* For use with seccomp_actions_logged */
 #define SECCOMP_LOG_KILL_PROCESS        (1 << 0)
 #define SECCOMP_LOG_KILL_THREAD         (1 << 1)
 #define SECCOMP_LOG_TRAP                (1 << 2)
 #define SECCOMP_LOG_ERRNO               (1 << 3)
 #define SECCOMP_LOG_TRACE               (1 << 4)
 #define SECCOMP_LOG_LOG                 (1 << 5)
 #define SECCOMP_LOG_ALLOW               (1 << 6)
 #define SECCOMP_LOG_USER_NOTIF          (1 << 7)
 
 static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
                                     SECCOMP_LOG_KILL_THREAD  |
                                     SECCOMP_LOG_TRAP  |
                                     SECCOMP_LOG_ERRNO |
                                     SECCOMP_LOG_USER_NOTIF |
                                     SECCOMP_LOG_TRACE |
                                     SECCOMP_LOG_LOG;
 
 static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
                                bool requested)
 {
         bool log = false;
 
         switch (action) {
         case SECCOMP_RET_ALLOW:
                 break;
         case SECCOMP_RET_TRAP:
                 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
                 break;
         case SECCOMP_RET_ERRNO:
                 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
                 break;
         case SECCOMP_RET_TRACE:
                 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
                 break;
         case SECCOMP_RET_USER_NOTIF:
                 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
                 break;
         case SECCOMP_RET_LOG:
                 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
                 break;
         case SECCOMP_RET_KILL_THREAD:
                 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
                 break;
         case SECCOMP_RET_KILL_PROCESS:
         default:
                 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
         }
 
         /*
          * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
          * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
          * any action from being logged by removing the action name from the
          * seccomp_actions_logged sysctl.
          */
         if (!log)
                 return;
 
         audit_seccomp(syscall, signr, action);
 }
 
 /*
  * Secure computing mode 1 allows only read/write/exit/sigreturn.
  * To be fully secure this must be combined with rlimit
  * to limit the stack allocations too.
  */
 static const int mode1_syscalls[] = {
         __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
         -1, /* negative terminated */
 };
 
 static void __secure_computing_strict(int this_syscall)
 {
         const int *allowed_syscalls = mode1_syscalls;
 #ifdef CONFIG_COMPAT
         if (in_compat_syscall())
                 allowed_syscalls = get_compat_mode1_syscalls();
 #endif
         do {
                 if (*allowed_syscalls == this_syscall)
                         return;
         } while (*++allowed_syscalls != -1);
 
 #ifdef SECCOMP_DEBUG
         dump_stack();
 #endif
         current->seccomp.mode = SECCOMP_MODE_DEAD;
         seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
         do_exit(SIGKILL);
 }
 
 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
 void secure_computing_strict(int this_syscall)
 {
         int mode = current->seccomp.mode;
 
         if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
             unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
                 return;
 
         if (mode == SECCOMP_MODE_DISABLED)
                 return;
         else if (mode == SECCOMP_MODE_STRICT)
                 __secure_computing_strict(this_syscall);
         else
                 BUG();
 }
 #else
 
 #ifdef CONFIG_SECCOMP_FILTER
 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
 {
         /*
          * Note: overflow is ok here, the id just needs to be unique per
          * filter.
          */
         lockdep_assert_held(&filter->notify_lock);
         return filter->notif->next_id++;
 }
 
 static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_knotif *n)
 {
         int fd;
 
         /*
          * Remove the notification, and reset the list pointers, indicating
          * that it has been handled.
          */
         list_del_init(&addfd->list);
         if (!addfd->setfd)
                 fd = receive_fd(addfd->file, NULL, addfd->flags);
         else
                 fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
         addfd->ret = fd;
 
         if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) {
                 /* If we fail reset and return an error to the notifier */
                 if (fd < 0) {
                         n->state = SECCOMP_NOTIFY_SENT;
                 } else {
                         /* Return the FD we just added */
                         n->flags = 0;
                         n->error = 0;
                         n->val = fd;
                 }
         }
 
         /*
          * Mark the notification as completed. From this point, addfd mem
          * might be invalidated and we can't safely read it anymore.
          */
         complete(&addfd->completion);
 }
 
 static bool should_sleep_killable(struct seccomp_filter *match,
                                   struct seccomp_knotif *n)
 {
         return match->wait_killable_recv && n->state == SECCOMP_NOTIFY_SENT;
 }
 
 static int seccomp_do_user_notification(int this_syscall,
                                         struct seccomp_filter *match,
                                         const struct seccomp_data *sd)
 {
         int err;
         u32 flags = 0;
         long ret = 0;
         struct seccomp_knotif n = {};
         struct seccomp_kaddfd *addfd, *tmp;
 
         mutex_lock(&match->notify_lock);
         err = -ENOSYS;
         if (!match->notif)
                 goto out;
 
         n.task = current;
         n.state = SECCOMP_NOTIFY_INIT;
         n.data = sd;
         n.id = seccomp_next_notify_id(match);
         init_completion(&n.ready);
         list_add_tail(&n.list, &match->notif->notifications);
         INIT_LIST_HEAD(&n.addfd);
 
         atomic_inc(&match->notif->requests);
         if (match->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
                 wake_up_poll_on_current_cpu(&match->wqh, EPOLLIN | EPOLLRDNORM);
         else
                 wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
 
         /*
          * This is where we wait for a reply from userspace.
          */
         do {
                 bool wait_killable = should_sleep_killable(match, &n);
 
                 mutex_unlock(&match->notify_lock);
                 if (wait_killable)
                         err = wait_for_completion_killable(&n.ready);
                 else
                         err = wait_for_completion_interruptible(&n.ready);
                 mutex_lock(&match->notify_lock);
 
                 if (err != 0) {
                         /*
                          * Check to see if the notifcation got picked up and
                          * whether we should switch to wait killable.
                          */
                         if (!wait_killable && should_sleep_killable(match, &n))
                                 continue;
 
                         goto interrupted;
                 }
 
                 addfd = list_first_entry_or_null(&n.addfd,
                                                  struct seccomp_kaddfd, list);
                 /* Check if we were woken up by a addfd message */
                 if (addfd)
                         seccomp_handle_addfd(addfd, &n);
 
         }  while (n.state != SECCOMP_NOTIFY_REPLIED);
 
         ret = n.val;
         err = n.error;
         flags = n.flags;
 
 interrupted:
         /* If there were any pending addfd calls, clear them out */
         list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
                 /* The process went away before we got a chance to handle it */
                 addfd->ret = -ESRCH;
                 list_del_init(&addfd->list);
                 complete(&addfd->completion);
         }
 
         /*
          * Note that it's possible the listener died in between the time when
          * we were notified of a response (or a signal) and when we were able to
          * re-acquire the lock, so only delete from the list if the
          * notification actually exists.
          *
          * Also note that this test is only valid because there's no way to
          * *reattach* to a notifier right now. If one is added, we'll need to
          * keep track of the notif itself and make sure they match here.
          */
         if (match->notif)
                 list_del(&n.list);
 out:
         mutex_unlock(&match->notify_lock);
 
         /* Userspace requests to continue the syscall. */
         if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
                 return 0;
 
         syscall_set_return_value(current, current_pt_regs(),
                                  err, ret);
         return -1;
 }
 
 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
                             const bool recheck_after_trace)
 {
         u32 filter_ret, action;
         struct seccomp_filter *match = NULL;
         int data;
         struct seccomp_data sd_local;
 
         /*
          * Make sure that any changes to mode from another thread have
          * been seen after SYSCALL_WORK_SECCOMP was seen.
          */
         smp_rmb();
 
         if (!sd) {
                 populate_seccomp_data(&sd_local);
                 sd = &sd_local;
         }
 
         filter_ret = seccomp_run_filters(sd, &match);
         data = filter_ret & SECCOMP_RET_DATA;
         action = filter_ret & SECCOMP_RET_ACTION_FULL;
 
         switch (action) {
         case SECCOMP_RET_ERRNO:
                 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
                 if (data > MAX_ERRNO)
                         data = MAX_ERRNO;
                 syscall_set_return_value(current, current_pt_regs(),
                                          -data, 0);
                 goto skip;
 
         case SECCOMP_RET_TRAP:
                 /* Show the handler the original registers. */
                 syscall_rollback(current, current_pt_regs());
                 /* Let the filter pass back 16 bits of data. */
                 force_sig_seccomp(this_syscall, data, false);
                 goto skip;
 
         case SECCOMP_RET_TRACE:
                 /* We've been put in this state by the ptracer already. */
                 if (recheck_after_trace)
                         return 0;
 
                 /* ENOSYS these calls if there is no tracer attached. */
                 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
                         syscall_set_return_value(current,
                                                  current_pt_regs(),
                                                  -ENOSYS, 0);
                         goto skip;
                 }
 
                 /* Allow the BPF to provide the event message */
                 ptrace_event(PTRACE_EVENT_SECCOMP, data);
                 /*
                  * The delivery of a fatal signal during event
                  * notification may silently skip tracer notification,
                  * which could leave us with a potentially unmodified
                  * syscall that the tracer would have liked to have
                  * changed. Since the process is about to die, we just
                  * force the syscall to be skipped and let the signal
                  * kill the process and correctly handle any tracer exit
                  * notifications.
                  */
                 if (fatal_signal_pending(current))
                         goto skip;
                 /* Check if the tracer forced the syscall to be skipped. */
                 this_syscall = syscall_get_nr(current, current_pt_regs());
                 if (this_syscall < 0)
                         goto skip;
 
                 /*
                  * Recheck the syscall, since it may have changed. This
                  * intentionally uses a NULL struct seccomp_data to force
                  * a reload of all registers. This does not goto skip since
                  * a skip would have already been reported.
                  */
                 if (__seccomp_filter(this_syscall, NULL, true))
                         return -1;
 
                 return 0;
 
         case SECCOMP_RET_USER_NOTIF:
                 if (seccomp_do_user_notification(this_syscall, match, sd))
                         goto skip;
 
                 return 0;
 
         case SECCOMP_RET_LOG:
                 seccomp_log(this_syscall, 0, action, true);
                 return 0;
 
         case SECCOMP_RET_ALLOW:
                 /*
                  * Note that the "match" filter will always be NULL for
                  * this action since SECCOMP_RET_ALLOW is the starting
                  * state in seccomp_run_filters().
                  */
                 return 0;
 
         case SECCOMP_RET_KILL_THREAD:
         case SECCOMP_RET_KILL_PROCESS:
         default:
                 current->seccomp.mode = SECCOMP_MODE_DEAD;
                 seccomp_log(this_syscall, SIGSYS, action, true);
                 /* Dump core only if this is the last remaining thread. */
                 if (action != SECCOMP_RET_KILL_THREAD ||
                     (atomic_read(&current->signal->live) == 1)) {
                         /* Show the original registers in the dump. */
                         syscall_rollback(current, current_pt_regs());
                         /* Trigger a coredump with SIGSYS */
                         force_sig_seccomp(this_syscall, data, true);
                 } else {
                         do_exit(SIGSYS);
                 }
                 return -1; /* skip the syscall go directly to signal handling */
         }
 
         unreachable();
 
 skip:
         seccomp_log(this_syscall, 0, action, match ? match->log : false);
         return -1;
 }
 #else
 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
                             const bool recheck_after_trace)
 {
         BUG();
 
         return -1;
 }
 #endif
 
 int __secure_computing(const struct seccomp_data *sd)
 {
         int mode = current->seccomp.mode;
         int this_syscall;
 
         if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
             unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
                 return 0;
 
         this_syscall = sd ? sd->nr :
                 syscall_get_nr(current, current_pt_regs());
 
         switch (mode) {
         case SECCOMP_MODE_STRICT:
                 __secure_computing_strict(this_syscall);  /* may call do_exit */
                 return 0;
         case SECCOMP_MODE_FILTER:
                 return __seccomp_filter(this_syscall, sd, false);
         /* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
         case SECCOMP_MODE_DEAD:
                 WARN_ON_ONCE(1);
                 do_exit(SIGKILL);
                 return -1;
         default:
                 BUG();
         }
 }
 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
 
 long prctl_get_seccomp(void)
 {
         return current->seccomp.mode;
 }
 
 /**
  * seccomp_set_mode_strict: internal function for setting strict seccomp
  *
  * Once current->seccomp.mode is non-zero, it may not be changed.
  *
  * Returns 0 on success or -EINVAL on failure.
  */
 static long seccomp_set_mode_strict(void)
 {
         const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
         long ret = -EINVAL;
 
         spin_lock_irq(&current->sighand->siglock);
 
         if (!seccomp_may_assign_mode(seccomp_mode))
                 goto out;
 
 #ifdef TIF_NOTSC
         disable_TSC();
 #endif
         seccomp_assign_mode(current, seccomp_mode, 0);
         ret = 0;
 
 out:
         spin_unlock_irq(&current->sighand->siglock);
 
         return ret;
 }
 
 #ifdef CONFIG_SECCOMP_FILTER
 static void seccomp_notify_free(struct seccomp_filter *filter)
 {
         kfree(filter->notif);
         filter->notif = NULL;
 }
 
 static void seccomp_notify_detach(struct seccomp_filter *filter)
 {
         struct seccomp_knotif *knotif;
 
         if (!filter)
                 return;
 
         mutex_lock(&filter->notify_lock);
 
         /*
          * If this file is being closed because e.g. the task who owned it
          * died, let's wake everyone up who was waiting on us.
          */
         list_for_each_entry(knotif, &filter->notif->notifications, list) {
                 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
                         continue;
 
                 knotif->state = SECCOMP_NOTIFY_REPLIED;
                 knotif->error = -ENOSYS;
                 knotif->val = 0;
 
                 /*
                  * We do not need to wake up any pending addfd messages, as
                  * the notifier will do that for us, as this just looks
                  * like a standard reply.
                  */
                 complete(&knotif->ready);
         }
 
         seccomp_notify_free(filter);
         mutex_unlock(&filter->notify_lock);
 }
 
 static int seccomp_notify_release(struct inode *inode, struct file *file)
 {
         struct seccomp_filter *filter = file->private_data;
 
         seccomp_notify_detach(filter);
         __put_seccomp_filter(filter);
         return 0;
 }
 
 /* must be called with notif_lock held */
 static inline struct seccomp_knotif *
 find_notification(struct seccomp_filter *filter, u64 id)
 {
         struct seccomp_knotif *cur;
 
         lockdep_assert_held(&filter->notify_lock);
 
         list_for_each_entry(cur, &filter->notif->notifications, list) {
                 if (cur->id == id)
                         return cur;
         }
 
         return NULL;
 }
 
 static int recv_wake_function(wait_queue_entry_t *wait, unsigned int mode, int sync,
                                   void *key)
 {
         /* Avoid a wakeup if event not interesting for us. */
         if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR | EPOLLHUP)))
                 return 0;
         return autoremove_wake_function(wait, mode, sync, key);
 }
 
 static int recv_wait_event(struct seccomp_filter *filter)
 {
         DEFINE_WAIT_FUNC(wait, recv_wake_function);
         int ret;
 
         if (refcount_read(&filter->users) == 0)
                 return 0;
 
         if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
                 return 0;
 
         for (;;) {
                 ret = prepare_to_wait_event(&filter->wqh, &wait, TASK_INTERRUPTIBLE);
 
                 if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
                         break;
                 if (refcount_read(&filter->users) == 0)
                         break;
 
                 if (ret)
                         return ret;
 
                 schedule();
         }
         finish_wait(&filter->wqh, &wait);
         return 0;
 }
 
 static long seccomp_notify_recv(struct seccomp_filter *filter,
                                 void __user *buf)
 {
         struct seccomp_knotif *knotif = NULL, *cur;
         struct seccomp_notif unotif;
         ssize_t ret;
 
         /* Verify that we're not given garbage to keep struct extensible. */
         ret = check_zeroed_user(buf, sizeof(unotif));
         if (ret < 0)
                 return ret;
         if (!ret)
                 return -EINVAL;
 
         memset(&unotif, 0, sizeof(unotif));
 
         ret = recv_wait_event(filter);
         if (ret < 0)
                 return ret;
 
         mutex_lock(&filter->notify_lock);
         list_for_each_entry(cur, &filter->notif->notifications, list) {
                 if (cur->state == SECCOMP_NOTIFY_INIT) {
                         knotif = cur;
                         break;
                 }
         }
 
         /*
          * If we didn't find a notification, it could be that the task was
          * interrupted by a fatal signal between the time we were woken and
          * when we were able to acquire the rw lock.
          */
         if (!knotif) {
                 ret = -ENOENT;
                 goto out;
         }
 
         unotif.id = knotif->id;
         unotif.pid = task_pid_vnr(knotif->task);
         unotif.data = *(knotif->data);
 
         knotif->state = SECCOMP_NOTIFY_SENT;
         wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
         ret = 0;
 out:
         mutex_unlock(&filter->notify_lock);
 
         if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
                 ret = -EFAULT;
 
                 /*
                  * Userspace screwed up. To make sure that we keep this
                  * notification alive, let's reset it back to INIT. It
                  * may have died when we released the lock, so we need to make
                  * sure it's still around.
                  */
                 mutex_lock(&filter->notify_lock);
                 knotif = find_notification(filter, unotif.id);
                 if (knotif) {
                         /* Reset the process to make sure it's not stuck */
                         if (should_sleep_killable(filter, knotif))
                                 complete(&knotif->ready);
                         knotif->state = SECCOMP_NOTIFY_INIT;
                         atomic_inc(&filter->notif->requests);
                         wake_up_poll(&filter->wqh, EPOLLIN | EPOLLRDNORM);
                 }
                 mutex_unlock(&filter->notify_lock);
         }
 
         return ret;
 }
 
 static long seccomp_notify_send(struct seccomp_filter *filter,
                                 void __user *buf)
 {
         struct seccomp_notif_resp resp = {};
         struct seccomp_knotif *knotif;
         long ret;
 
         if (copy_from_user(&resp, buf, sizeof(resp)))
                 return -EFAULT;
 
         if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
                 return -EINVAL;
 
         if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
             (resp.error || resp.val))
                 return -EINVAL;
 
         ret = mutex_lock_interruptible(&filter->notify_lock);
         if (ret < 0)
                 return ret;
 
         knotif = find_notification(filter, resp.id);
         if (!knotif) {
                 ret = -ENOENT;
                 goto out;
         }
 
         /* Allow exactly one reply. */
         if (knotif->state != SECCOMP_NOTIFY_SENT) {
                 ret = -EINPROGRESS;
                 goto out;
         }
 
         ret = 0;
         knotif->state = SECCOMP_NOTIFY_REPLIED;
         knotif->error = resp.error;
         knotif->val = resp.val;
         knotif->flags = resp.flags;
         if (filter->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
                 complete_on_current_cpu(&knotif->ready);
         else
                 complete(&knotif->ready);
 out:
         mutex_unlock(&filter->notify_lock);
         return ret;
 }
 
 static long seccomp_notify_id_valid(struct seccomp_filter *filter,
                                     void __user *buf)
 {
         struct seccomp_knotif *knotif;
         u64 id;
         long ret;
 
         if (copy_from_user(&id, buf, sizeof(id)))
                 return -EFAULT;
 
         ret = mutex_lock_interruptible(&filter->notify_lock);
         if (ret < 0)
                 return ret;
 
         knotif = find_notification(filter, id);
         if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
                 ret = 0;
         else
                 ret = -ENOENT;
 
         mutex_unlock(&filter->notify_lock);
         return ret;
 }
 
 static long seccomp_notify_set_flags(struct seccomp_filter *filter,
                                     unsigned long flags)
 {
         long ret;
 
         if (flags & ~SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
                 return -EINVAL;
 
         ret = mutex_lock_interruptible(&filter->notify_lock);
         if (ret < 0)
                 return ret;
         filter->notif->flags = flags;
         mutex_unlock(&filter->notify_lock);
         return 0;
 }
 
 static long seccomp_notify_addfd(struct seccomp_filter *filter,
                                  struct seccomp_notif_addfd __user *uaddfd,
                                  unsigned int size)
 {
         struct seccomp_notif_addfd addfd;
         struct seccomp_knotif *knotif;
         struct seccomp_kaddfd kaddfd;
         int ret;
 
         BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
         BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
 
         if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
                 return -EINVAL;
 
         ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
         if (ret)
                 return ret;
 
         if (addfd.newfd_flags & ~O_CLOEXEC)
                 return -EINVAL;
 
         if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD | SECCOMP_ADDFD_FLAG_SEND))
                 return -EINVAL;
 
         if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
                 return -EINVAL;
 
         kaddfd.file = fget(addfd.srcfd);
         if (!kaddfd.file)
                 return -EBADF;
 
         kaddfd.ioctl_flags = addfd.flags;
         kaddfd.flags = addfd.newfd_flags;
         kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
         kaddfd.fd = addfd.newfd;
         init_completion(&kaddfd.completion);
 
         ret = mutex_lock_interruptible(&filter->notify_lock);
         if (ret < 0)
                 goto out;
 
         knotif = find_notification(filter, addfd.id);
         if (!knotif) {
                 ret = -ENOENT;
                 goto out_unlock;
         }
 
         /*
          * We do not want to allow for FD injection to occur before the
          * notification has been picked up by a userspace handler, or after
          * the notification has been replied to.
          */
         if (knotif->state != SECCOMP_NOTIFY_SENT) {
                 ret = -EINPROGRESS;
                 goto out_unlock;
         }
 
         if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) {
                 /*
                  * Disallow queuing an atomic addfd + send reply while there are
                  * some addfd requests still to process.
                  *
                  * There is no clear reason to support it and allows us to keep
                  * the loop on the other side straight-forward.
                  */
                 if (!list_empty(&knotif->addfd)) {
                         ret = -EBUSY;
                         goto out_unlock;
                 }
 
                 /* Allow exactly only one reply */
                 knotif->state = SECCOMP_NOTIFY_REPLIED;
         }
 
         list_add(&kaddfd.list, &knotif->addfd);
         complete(&knotif->ready);
         mutex_unlock(&filter->notify_lock);
 
         /* Now we wait for it to be processed or be interrupted */
         ret = wait_for_completion_interruptible(&kaddfd.completion);
         if (ret == 0) {
                 /*
                  * We had a successful completion. The other side has already
                  * removed us from the addfd queue, and
                  * wait_for_completion_interruptible has a memory barrier upon
                  * success that lets us read this value directly without
                  * locking.
                  */
                 ret = kaddfd.ret;
                 goto out;
         }
 
         mutex_lock(&filter->notify_lock);
         /*
          * Even though we were woken up by a signal and not a successful
          * completion, a completion may have happened in the mean time.
          *
          * We need to check again if the addfd request has been handled,
          * and if not, we will remove it from the queue.
          */
         if (list_empty(&kaddfd.list))
                 ret = kaddfd.ret;
         else
                 list_del(&kaddfd.list);
 
 out_unlock:
         mutex_unlock(&filter->notify_lock);
 out:
         fput(kaddfd.file);
 
         return ret;
 }
 
 static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
                                  unsigned long arg)
 {
         struct seccomp_filter *filter = file->private_data;
         void __user *buf = (void __user *)arg;
 
         /* Fixed-size ioctls */
         switch (cmd) {
         case SECCOMP_IOCTL_NOTIF_RECV:
                 return seccomp_notify_recv(filter, buf);
         case SECCOMP_IOCTL_NOTIF_SEND:
                 return seccomp_notify_send(filter, buf);
         case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
         case SECCOMP_IOCTL_NOTIF_ID_VALID:
                 return seccomp_notify_id_valid(filter, buf);
         case SECCOMP_IOCTL_NOTIF_SET_FLAGS:
                 return seccomp_notify_set_flags(filter, arg);
         }
 
         /* Extensible Argument ioctls */
 #define EA_IOCTL(cmd)   ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
         switch (EA_IOCTL(cmd)) {
         case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
                 return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
         default:
                 return -EINVAL;
         }
 }
 
 static __poll_t seccomp_notify_poll(struct file *file,
                                     struct poll_table_struct *poll_tab)
 {
         struct seccomp_filter *filter = file->private_data;
         __poll_t ret = 0;
         struct seccomp_knotif *cur;
 
         poll_wait(file, &filter->wqh, poll_tab);
 
         if (mutex_lock_interruptible(&filter->notify_lock) < 0)
                 return EPOLLERR;
 
         list_for_each_entry(cur, &filter->notif->notifications, list) {
                 if (cur->state == SECCOMP_NOTIFY_INIT)
                         ret |= EPOLLIN | EPOLLRDNORM;
                 if (cur->state == SECCOMP_NOTIFY_SENT)
                         ret |= EPOLLOUT | EPOLLWRNORM;
                 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
                         break;
         }
 
         mutex_unlock(&filter->notify_lock);
 
         if (refcount_read(&filter->users) == 0)
                 ret |= EPOLLHUP;
 
         return ret;
 }
 
 static const struct file_operations seccomp_notify_ops = {
         .poll = seccomp_notify_poll,
         .release = seccomp_notify_release,
         .unlocked_ioctl = seccomp_notify_ioctl,
         .compat_ioctl = seccomp_notify_ioctl,
 };
 
 static struct file *init_listener(struct seccomp_filter *filter)
 {
         struct file *ret;
 
         ret = ERR_PTR(-ENOMEM);
         filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
         if (!filter->notif)
                 goto out;
 
         filter->notif->next_id = get_random_u64();
         INIT_LIST_HEAD(&filter->notif->notifications);
 
         ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
                                  filter, O_RDWR);
         if (IS_ERR(ret))
                 goto out_notif;
 
         /* The file has a reference to it now */
         __get_seccomp_filter(filter);
 
 out_notif:
         if (IS_ERR(ret))
                 seccomp_notify_free(filter);
 out:
         return ret;
 }
 
 /*
  * Does @new_child have a listener while an ancestor also has a listener?
  * If so, we'll want to reject this filter.
  * This only has to be tested for the current process, even in the TSYNC case,
  * because TSYNC installs @child with the same parent on all threads.
  * Note that @new_child is not hooked up to its parent at this point yet, so
  * we use current->seccomp.filter.
  */
 static bool has_duplicate_listener(struct seccomp_filter *new_child)
 {
         struct seccomp_filter *cur;
 
         /* must be protected against concurrent TSYNC */
         lockdep_assert_held(&current->sighand->siglock);
 
         if (!new_child->notif)
                 return false;
         for (cur = current->seccomp.filter; cur; cur = cur->prev) {
                 if (cur->notif)
                         return true;
         }
 
         return false;
 }
 
 /**
  * seccomp_set_mode_filter: internal function for setting seccomp filter
  * @flags:  flags to change filter behavior
  * @filter: struct sock_fprog containing filter
  *
  * This function may be called repeatedly to install additional filters.
  * Every filter successfully installed will be evaluated (in reverse order)
  * for each system call the task makes.
  *
  * Once current->seccomp.mode is non-zero, it may not be changed.
  *
  * Returns 0 on success or -EINVAL on failure.
  */
 static long seccomp_set_mode_filter(unsigned int flags,
                                     const char __user *filter)
 {
         const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
         struct seccomp_filter *prepared = NULL;
         long ret = -EINVAL;
         int listener = -1;
         struct file *listener_f = NULL;
 
         /* Validate flags. */
         if (flags & ~SECCOMP_FILTER_FLAG_MASK)
                 return -EINVAL;
 
         /*
          * In the successful case, NEW_LISTENER returns the new listener fd.
          * But in the failure case, TSYNC returns the thread that died. If you
          * combine these two flags, there's no way to tell whether something
          * succeeded or failed. So, let's disallow this combination if the user
          * has not explicitly requested no errors from TSYNC.
          */
         if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
             (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
             ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
                 return -EINVAL;
 
         /*
          * The SECCOMP_FILTER_FLAG_WAIT_KILLABLE_SENT flag doesn't make sense
          * without the SECCOMP_FILTER_FLAG_NEW_LISTENER flag.
          */
         if ((flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) &&
             ((flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) == 0))
                 return -EINVAL;
 
         /* Prepare the new filter before holding any locks. */
         prepared = seccomp_prepare_user_filter(filter);
         if (IS_ERR(prepared))
                 return PTR_ERR(prepared);
 
         if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
                 listener = get_unused_fd_flags(O_CLOEXEC);
                 if (listener < 0) {
                         ret = listener;
                         goto out_free;
                 }
 
                 listener_f = init_listener(prepared);
                 if (IS_ERR(listener_f)) {
                         put_unused_fd(listener);
                         ret = PTR_ERR(listener_f);
                         goto out_free;
                 }
         }
 
         /*
          * Make sure we cannot change seccomp or nnp state via TSYNC
          * while another thread is in the middle of calling exec.
          */
         if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
             mutex_lock_killable(&current->signal->cred_guard_mutex))
                 goto out_put_fd;
 
         spin_lock_irq(&current->sighand->siglock);
 
         if (!seccomp_may_assign_mode(seccomp_mode))
                 goto out;
 
         if (has_duplicate_listener(prepared)) {
                 ret = -EBUSY;
                 goto out;
         }
 
         ret = seccomp_attach_filter(flags, prepared);
         if (ret)
                 goto out;
         /* Do not free the successfully attached filter. */
         prepared = NULL;
 
         seccomp_assign_mode(current, seccomp_mode, flags);
 out:
         spin_unlock_irq(&current->sighand->siglock);
         if (flags & SECCOMP_FILTER_FLAG_TSYNC)
                 mutex_unlock(&current->signal->cred_guard_mutex);
 out_put_fd:
         if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
                 if (ret) {
                         listener_f->private_data = NULL;
                         fput(listener_f);
                         put_unused_fd(listener);
                         seccomp_notify_detach(prepared);
                 } else {
                         fd_install(listener, listener_f);
                         ret = listener;
                 }
         }
 out_free:
         seccomp_filter_free(prepared);
         return ret;
 }
 #else
 static inline long seccomp_set_mode_filter(unsigned int flags,
                                            const char __user *filter)
 {
         return -EINVAL;
 }
 #endif
 
 static long seccomp_get_action_avail(const char __user *uaction)
 {
         u32 action;
 
         if (copy_from_user(&action, uaction, sizeof(action)))
                 return -EFAULT;
 
         switch (action) {
         case SECCOMP_RET_KILL_PROCESS:
         case SECCOMP_RET_KILL_THREAD:
         case SECCOMP_RET_TRAP:
         case SECCOMP_RET_ERRNO:
         case SECCOMP_RET_USER_NOTIF:
         case SECCOMP_RET_TRACE:
         case SECCOMP_RET_LOG:
         case SECCOMP_RET_ALLOW:
                 break;
         default:
                 return -EOPNOTSUPP;
         }
 
         return 0;
 }
 
 static long seccomp_get_notif_sizes(void __user *usizes)
 {
         struct seccomp_notif_sizes sizes = {
                 .seccomp_notif = sizeof(struct seccomp_notif),
                 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
                 .seccomp_data = sizeof(struct seccomp_data),
         };
 
         if (copy_to_user(usizes, &sizes, sizeof(sizes)))
                 return -EFAULT;
 
         return 0;
 }
 
 /* Common entry point for both prctl and syscall. */
 static long do_seccomp(unsigned int op, unsigned int flags,
                        void __user *uargs)
 {
         switch (op) {
         case SECCOMP_SET_MODE_STRICT:
                 if (flags != 0 || uargs != NULL)
                         return -EINVAL;
                 return seccomp_set_mode_strict();
         case SECCOMP_SET_MODE_FILTER:
                 return seccomp_set_mode_filter(flags, uargs);
         case SECCOMP_GET_ACTION_AVAIL:
                 if (flags != 0)
                         return -EINVAL;
 
                 return seccomp_get_action_avail(uargs);
         case SECCOMP_GET_NOTIF_SIZES:
                 if (flags != 0)
                         return -EINVAL;
 
                 return seccomp_get_notif_sizes(uargs);
         default:
                 return -EINVAL;
         }
 }
 
 SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
                          void __user *, uargs)
 {
         return do_seccomp(op, flags, uargs);
 }
 
 /**
  * prctl_set_seccomp: configures current->seccomp.mode
  * @seccomp_mode: requested mode to use
  * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
  *
  * Returns 0 on success or -EINVAL on failure.
  */
 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
 {
         unsigned int op;
         void __user *uargs;
 
         switch (seccomp_mode) {
         case SECCOMP_MODE_STRICT:
                 op = SECCOMP_SET_MODE_STRICT;
                 /*
                  * Setting strict mode through prctl always ignored filter,
                  * so make sure it is always NULL here to pass the internal
                  * check in do_seccomp().
                  */
                 uargs = NULL;
                 break;
         case SECCOMP_MODE_FILTER:
                 op = SECCOMP_SET_MODE_FILTER;
                 uargs = filter;
                 break;
         default:
                 return -EINVAL;
         }
 
         /* prctl interface doesn't have flags, so they are always zero. */
         return do_seccomp(op, 0, uargs);
 }
 
 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
 static struct seccomp_filter *get_nth_filter(struct task_struct *task,
                                              unsigned long filter_off)
 {
         struct seccomp_filter *orig, *filter;
         unsigned long count;
 
         /*
          * Note: this is only correct because the caller should be the (ptrace)
          * tracer of the task, otherwise lock_task_sighand is needed.
          */
         spin_lock_irq(&task->sighand->siglock);
 
         if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
                 spin_unlock_irq(&task->sighand->siglock);
                 return ERR_PTR(-EINVAL);
         }
 
         orig = task->seccomp.filter;
         __get_seccomp_filter(orig);
         spin_unlock_irq(&task->sighand->siglock);
 
         count = 0;
         for (filter = orig; filter; filter = filter->prev)
                 count++;
 
         if (filter_off >= count) {
                 filter = ERR_PTR(-ENOENT);
                 goto out;
         }
 
         count -= filter_off;
         for (filter = orig; filter && count > 1; filter = filter->prev)
                 count--;
 
         if (WARN_ON(count != 1 || !filter)) {
                 filter = ERR_PTR(-ENOENT);
                 goto out;
         }
 
         __get_seccomp_filter(filter);
 
 out:
         __put_seccomp_filter(orig);
         return filter;
 }
 
 long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
                         void __user *data)
 {
         struct seccomp_filter *filter;
         struct sock_fprog_kern *fprog;
         long ret;
 
         if (!capable(CAP_SYS_ADMIN) ||
             current->seccomp.mode != SECCOMP_MODE_DISABLED) {
                 return -EACCES;
         }
 
         filter = get_nth_filter(task, filter_off);
         if (IS_ERR(filter))
                 return PTR_ERR(filter);
 
         fprog = filter->prog->orig_prog;
         if (!fprog) {
                 /* This must be a new non-cBPF filter, since we save
                  * every cBPF filter's orig_prog above when
                  * CONFIG_CHECKPOINT_RESTORE is enabled.
                  */
                 ret = -EMEDIUMTYPE;
                 goto out;
         }
 
         ret = fprog->len;
         if (!data)
                 goto out;
 
         if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
                 ret = -EFAULT;
 
 out:
         __put_seccomp_filter(filter);
         return ret;
 }
 
 long seccomp_get_metadata(struct task_struct *task,
                           unsigned long size, void __user *data)
 {
         long ret;
         struct seccomp_filter *filter;
         struct seccomp_metadata kmd = {};
 
         if (!capable(CAP_SYS_ADMIN) ||
             current->seccomp.mode != SECCOMP_MODE_DISABLED) {
                 return -EACCES;
         }
 
         size = min_t(unsigned long, size, sizeof(kmd));
 
         if (size < sizeof(kmd.filter_off))
                 return -EINVAL;
 
         if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
                 return -EFAULT;
 
         filter = get_nth_filter(task, kmd.filter_off);
         if (IS_ERR(filter))
                 return PTR_ERR(filter);
 
         if (filter->log)
                 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
 
         ret = size;
         if (copy_to_user(data, &kmd, size))
                 ret = -EFAULT;
 
         __put_seccomp_filter(filter);
         return ret;
 }
 #endif
 
 #ifdef CONFIG_SYSCTL
 
 /* Human readable action names for friendly sysctl interaction */
 #define SECCOMP_RET_KILL_PROCESS_NAME   "kill_process"
 #define SECCOMP_RET_KILL_THREAD_NAME    "kill_thread"
 #define SECCOMP_RET_TRAP_NAME           "trap"
 #define SECCOMP_RET_ERRNO_NAME          "errno"
 #define SECCOMP_RET_USER_NOTIF_NAME     "user_notif"
 #define SECCOMP_RET_TRACE_NAME          "trace"
 #define SECCOMP_RET_LOG_NAME            "log"
 #define SECCOMP_RET_ALLOW_NAME          "allow"
 
 static const char seccomp_actions_avail[] =
                                 SECCOMP_RET_KILL_PROCESS_NAME   " "
                                 SECCOMP_RET_KILL_THREAD_NAME    " "
                                 SECCOMP_RET_TRAP_NAME           " "
                                 SECCOMP_RET_ERRNO_NAME          " "
                                 SECCOMP_RET_USER_NOTIF_NAME     " "
                                 SECCOMP_RET_TRACE_NAME          " "
                                 SECCOMP_RET_LOG_NAME            " "
                                 SECCOMP_RET_ALLOW_NAME;
 
 struct seccomp_log_name {
         u32             log;
         const char      *name;
 };
 
 static const struct seccomp_log_name seccomp_log_names[] = {
         { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
         { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
         { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
         { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
         { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
         { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
         { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
         { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
         { }
 };
 
 static bool seccomp_names_from_actions_logged(char *names, size_t size,
                                               u32 actions_logged,
                                               const char *sep)
 {
         const struct seccomp_log_name *cur;
         bool append_sep = false;
 
         for (cur = seccomp_log_names; cur->name && size; cur++) {
                 ssize_t ret;
 
                 if (!(actions_logged & cur->log))
                         continue;
 
                 if (append_sep) {
                         ret = strscpy(names, sep, size);
                         if (ret < 0)
                                 return false;
 
                         names += ret;
                         size -= ret;
                 } else
                         append_sep = true;
 
                 ret = strscpy(names, cur->name, size);
                 if (ret < 0)
                         return false;
 
                 names += ret;
                 size -= ret;
         }
 
         return true;
 }
 
 static bool seccomp_action_logged_from_name(u32 *action_logged,
                                             const char *name)
 {
         const struct seccomp_log_name *cur;
 
         for (cur = seccomp_log_names; cur->name; cur++) {
                 if (!strcmp(cur->name, name)) {
                         *action_logged = cur->log;
                         return true;
                 }
         }
 
         return false;
 }
 
 static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
 {
         char *name;
 
         *actions_logged = 0;
         while ((name = strsep(&names, " ")) && *name) {
                 u32 action_logged = 0;
 
                 if (!seccomp_action_logged_from_name(&action_logged, name))
                         return false;
 
                 *actions_logged |= action_logged;
         }
 
         return true;
 }
 
 static int read_actions_logged(const struct ctl_table *ro_table, void *buffer,
                                size_t *lenp, loff_t *ppos)
 {
         char names[sizeof(seccomp_actions_avail)];
         struct ctl_table table;
 
         memset(names, 0, sizeof(names));
 
         if (!seccomp_names_from_actions_logged(names, sizeof(names),
                                                seccomp_actions_logged, " "))
                 return -EINVAL;
 
         table = *ro_table;
         table.data = names;
         table.maxlen = sizeof(names);
         return proc_dostring(&table, 0, buffer, lenp, ppos);
 }
 
 static int write_actions_logged(const struct ctl_table *ro_table, void *buffer,
                                 size_t *lenp, loff_t *ppos, u32 *actions_logged)
 {
         char names[sizeof(seccomp_actions_avail)];
         struct ctl_table table;
         int ret;
 
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
         memset(names, 0, sizeof(names));
 
         table = *ro_table;
         table.data = names;
         table.maxlen = sizeof(names);
         ret = proc_dostring(&table, 1, buffer, lenp, ppos);
         if (ret)
                 return ret;
 
         if (!seccomp_actions_logged_from_names(actions_logged, table.data))
                 return -EINVAL;
 
         if (*actions_logged & SECCOMP_LOG_ALLOW)
                 return -EINVAL;
 
         seccomp_actions_logged = *actions_logged;
         return 0;
 }
 
 static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
                                  int ret)
 {
         char names[sizeof(seccomp_actions_avail)];
         char old_names[sizeof(seccomp_actions_avail)];
         const char *new = names;
         const char *old = old_names;
 
         if (!audit_enabled)
                 return;
 
         memset(names, 0, sizeof(names));
         memset(old_names, 0, sizeof(old_names));
 
         if (ret)
                 new = "?";
         else if (!actions_logged)
                 new = "(none)";
         else if (!seccomp_names_from_actions_logged(names, sizeof(names),
                                                     actions_logged, ","))
                 new = "?";
 
         if (!old_actions_logged)
                 old = "(none)";
         else if (!seccomp_names_from_actions_logged(old_names,
                                                     sizeof(old_names),
                                                     old_actions_logged, ","))
                 old = "?";
 
         return audit_seccomp_actions_logged(new, old, !ret);
 }
 
 static int seccomp_actions_logged_handler(const struct ctl_table *ro_table, int write,
                                           void *buffer, size_t *lenp,
                                           loff_t *ppos)
 {
         int ret;
 
         if (write) {
                 u32 actions_logged = 0;
                 u32 old_actions_logged = seccomp_actions_logged;
 
                 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
                                            &actions_logged);
                 audit_actions_logged(actions_logged, old_actions_logged, ret);
         } else
                 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
 
         return ret;
 }
 
 static struct ctl_table seccomp_sysctl_table[] = {
         {
                 .procname       = "actions_avail",
                 .data           = (void *) &seccomp_actions_avail,
                 .maxlen         = sizeof(seccomp_actions_avail),
                 .mode           = 0444,
                 .proc_handler   = proc_dostring,
         },
         {
                 .procname       = "actions_logged",
                 .mode           = 0644,
                 .proc_handler   = seccomp_actions_logged_handler,
         },
 };
 
 static int __init seccomp_sysctl_init(void)
 {
         register_sysctl_init("kernel/seccomp", seccomp_sysctl_table);
         return 0;
 }
 
 device_initcall(seccomp_sysctl_init)
 
 #endif /* CONFIG_SYSCTL */
 
 #ifdef CONFIG_SECCOMP_CACHE_DEBUG
 /* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
 static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
                                         const void *bitmap, size_t bitmap_size)
 {
         int nr;
 
         for (nr = 0; nr < bitmap_size; nr++) {
                 bool cached = test_bit(nr, bitmap);
                 char *status = cached ? "ALLOW" : "FILTER";
 
                 seq_printf(m, "%s %d %s\n", name, nr, status);
         }
 }
 
 int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
                            struct pid *pid, struct task_struct *task)
 {
         struct seccomp_filter *f;
         unsigned long flags;
 
         /*
          * We don't want some sandboxed process to know what their seccomp
          * filters consist of.
          */
         if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
                 return -EACCES;
 
         if (!lock_task_sighand(task, &flags))
                 return -ESRCH;
 
         f = READ_ONCE(task->seccomp.filter);
         if (!f) {
                 unlock_task_sighand(task, &flags);
                 return 0;
         }
 
         /* prevent filter from being freed while we are printing it */
         __get_seccomp_filter(f);
         unlock_task_sighand(task, &flags);
 
         proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
                                     f->cache.allow_native,
                                     SECCOMP_ARCH_NATIVE_NR);
 
 #ifdef SECCOMP_ARCH_COMPAT
         proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
                                     f->cache.allow_compat,
                                     SECCOMP_ARCH_COMPAT_NR);
 #endif /* SECCOMP_ARCH_COMPAT */
 
         __put_seccomp_filter(f);
         return 0;
 }
 #endif /* CONFIG_SECCOMP_CACHE_DEBUG */
 

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