1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * net/core/netclassid_cgroup.c Classid Cgroupfs Handling
4 *
5 * Authors: Thomas Graf <tgraf@suug.ch>
6 */
7
8 #include <linux/slab.h>
9 #include <linux/cgroup.h>
10 #include <linux/fdtable.h>
11 #include <linux/sched/task.h>
12
13 #include <net/cls_cgroup.h>
14 #include <net/sock.h>
15
16 static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
17 {
18 return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
19 }
20
21 struct cgroup_cls_state *task_cls_state(struct task_struct *p)
22 {
23 return css_cls_state(task_css_check(p, net_cls_cgrp_id,
24 rcu_read_lock_bh_held()));
25 }
26 EXPORT_SYMBOL_GPL(task_cls_state);
27
28 static struct cgroup_subsys_state *
29 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
30 {
31 struct cgroup_cls_state *cs;
32
33 cs = kzalloc(sizeof(*cs), GFP_KERNEL);
34 if (!cs)
35 return ERR_PTR(-ENOMEM);
36
37 return &cs->css;
38 }
39
40 static int cgrp_css_online(struct cgroup_subsys_state *css)
41 {
42 struct cgroup_cls_state *cs = css_cls_state(css);
43 struct cgroup_cls_state *parent = css_cls_state(css->parent);
44
45 if (parent)
46 cs->classid = parent->classid;
47
48 return 0;
49 }
50
51 static void cgrp_css_free(struct cgroup_subsys_state *css)
52 {
53 kfree(css_cls_state(css));
54 }
55
56 /*
57 * To avoid freezing of sockets creation for tasks with big number of threads
58 * and opened sockets lets release file_lock every 1000 iterated descriptors.
59 * New sockets will already have been created with new classid.
60 */
61
62 struct update_classid_context {
63 u32 classid;
64 unsigned int batch;
65 };
66
67 #define UPDATE_CLASSID_BATCH 1000
68
69 static int update_classid_sock(const void *v, struct file *file, unsigned int n)
70 {
71 struct update_classid_context *ctx = (void *)v;
72 struct socket *sock = sock_from_file(file);
73
74 if (sock)
75 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data, ctx->classid);
76 if (--ctx->batch == 0) {
77 ctx->batch = UPDATE_CLASSID_BATCH;
78 return n + 1;
79 }
80 return 0;
81 }
82
83 static void update_classid_task(struct task_struct *p, u32 classid)
84 {
85 struct update_classid_context ctx = {
86 .classid = classid,
87 .batch = UPDATE_CLASSID_BATCH
88 };
89 unsigned int fd = 0;
90
91 /* Only update the leader task, when many threads in this task,
92 * so it can avoid the useless traversal.
93 */
94 if (p != p->group_leader)
95 return;
96
97 do {
98 task_lock(p);
99 fd = iterate_fd(p->files, fd, update_classid_sock, &ctx);
100 task_unlock(p);
101 cond_resched();
102 } while (fd);
103 }
104
105 static void cgrp_attach(struct cgroup_taskset *tset)
106 {
107 struct cgroup_subsys_state *css;
108 struct task_struct *p;
109
110 cgroup_taskset_for_each(p, css, tset) {
111 update_classid_task(p, css_cls_state(css)->classid);
112 }
113 }
114
115 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
116 {
117 return css_cls_state(css)->classid;
118 }
119
120 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
121 u64 value)
122 {
123 struct cgroup_cls_state *cs = css_cls_state(css);
124 struct css_task_iter it;
125 struct task_struct *p;
126
127 cs->classid = (u32)value;
128
129 css_task_iter_start(css, 0, &it);
130 while ((p = css_task_iter_next(&it)))
131 update_classid_task(p, cs->classid);
132 css_task_iter_end(&it);
133
134 return 0;
135 }
136
137 static struct cftype ss_files[] = {
138 {
139 .name = "classid",
140 .read_u64 = read_classid,
141 .write_u64 = write_classid,
142 },
143 { } /* terminate */
144 };
145
146 struct cgroup_subsys net_cls_cgrp_subsys = {
147 .css_alloc = cgrp_css_alloc,
148 .css_online = cgrp_css_online,
149 .css_free = cgrp_css_free,
150 .attach = cgrp_attach,
151 .legacy_cftypes = ss_files,
152 };
153
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