1 // SPDX-License-Identifier: GPL-2.0+ 1 // SPDX-License-Identifier: GPL-2.0+
2 /* 2 /*
3 * Restartable sequences system call 3 * Restartable sequences system call
4 * 4 *
5 * Copyright (C) 2015, Google, Inc., 5 * Copyright (C) 2015, Google, Inc.,
6 * Paul Turner <pjt@google.com> and Andrew Hun 6 * Paul Turner <pjt@google.com> and Andrew Hunter <ahh@google.com>
7 * Copyright (C) 2015-2018, EfficiOS Inc., 7 * Copyright (C) 2015-2018, EfficiOS Inc.,
8 * Mathieu Desnoyers <mathieu.desnoyers@effici 8 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
9 */ 9 */
10 10
11 #include <linux/sched.h> 11 #include <linux/sched.h>
12 #include <linux/uaccess.h> 12 #include <linux/uaccess.h>
13 #include <linux/syscalls.h> 13 #include <linux/syscalls.h>
14 #include <linux/rseq.h> 14 #include <linux/rseq.h>
15 #include <linux/types.h> 15 #include <linux/types.h>
16 #include <asm/ptrace.h> 16 #include <asm/ptrace.h>
17 17
18 #define CREATE_TRACE_POINTS 18 #define CREATE_TRACE_POINTS
19 #include <trace/events/rseq.h> 19 #include <trace/events/rseq.h>
20 20
21 /* The original rseq structure size (including 21 /* The original rseq structure size (including padding) is 32 bytes. */
22 #define ORIG_RSEQ_SIZE 32 22 #define ORIG_RSEQ_SIZE 32
23 23
24 #define RSEQ_CS_NO_RESTART_FLAGS (RSEQ_CS_FLAG 24 #define RSEQ_CS_NO_RESTART_FLAGS (RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT | \
25 RSEQ_CS_FLAG 25 RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL | \
26 RSEQ_CS_FLAG 26 RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE)
27 27
28 /* 28 /*
29 * 29 *
30 * Restartable sequences are a lightweight int 30 * Restartable sequences are a lightweight interface that allows
31 * user-level code to be executed atomically r 31 * user-level code to be executed atomically relative to scheduler
32 * preemption and signal delivery. Typically u 32 * preemption and signal delivery. Typically used for implementing
33 * per-cpu operations. 33 * per-cpu operations.
34 * 34 *
35 * It allows user-space to perform update oper 35 * It allows user-space to perform update operations on per-cpu data
36 * without requiring heavy-weight atomic opera 36 * without requiring heavy-weight atomic operations.
37 * 37 *
38 * Detailed algorithm of rseq user-space assem 38 * Detailed algorithm of rseq user-space assembly sequences:
39 * 39 *
40 * init(rseq_cs) 40 * init(rseq_cs)
41 * cpu = TLS->rseq::cpu_id 41 * cpu = TLS->rseq::cpu_id_start
42 * [1] TLS->rseq::rseq_cs = rs 42 * [1] TLS->rseq::rseq_cs = rseq_cs
43 * [start_ip] ----------------------- 43 * [start_ip] ----------------------------
44 * [2] if (cpu != TLS->rseq::c 44 * [2] if (cpu != TLS->rseq::cpu_id)
45 * goto abort_ip; 45 * goto abort_ip;
46 * [3] <last_instruction_in_cs 46 * [3] <last_instruction_in_cs>
47 * [post_commit_ip] ----------------------- 47 * [post_commit_ip] ----------------------------
48 * 48 *
49 * The address of jump target abort_ip must 49 * The address of jump target abort_ip must be outside the critical
50 * region, i.e.: 50 * region, i.e.:
51 * 51 *
52 * [abort_ip] < [start_ip] || [abort_ip] 52 * [abort_ip] < [start_ip] || [abort_ip] >= [post_commit_ip]
53 * 53 *
54 * Steps [2]-[3] (inclusive) need to be a se 54 * Steps [2]-[3] (inclusive) need to be a sequence of instructions in
55 * userspace that can handle being interrupt 55 * userspace that can handle being interrupted between any of those
56 * instructions, and then resumed to the abo 56 * instructions, and then resumed to the abort_ip.
57 * 57 *
58 * 1. Userspace stores the address of the s 58 * 1. Userspace stores the address of the struct rseq_cs assembly
59 * block descriptor into the rseq_cs fie 59 * block descriptor into the rseq_cs field of the registered
60 * struct rseq TLS area. This update is 60 * struct rseq TLS area. This update is performed through a single
61 * store within the inline assembly inst 61 * store within the inline assembly instruction sequence.
62 * [start_ip] 62 * [start_ip]
63 * 63 *
64 * 2. Userspace tests to check whether the 64 * 2. Userspace tests to check whether the current cpu_id field match
65 * the cpu number loaded before start_ip 65 * the cpu number loaded before start_ip, branching to abort_ip
66 * in case of a mismatch. 66 * in case of a mismatch.
67 * 67 *
68 * If the sequence is preempted or inter 68 * If the sequence is preempted or interrupted by a signal
69 * at or after start_ip and before post_ 69 * at or after start_ip and before post_commit_ip, then the kernel
70 * clears TLS->__rseq_abi::rseq_cs, and 70 * clears TLS->__rseq_abi::rseq_cs, and sets the user-space return
71 * ip to abort_ip before returning to us 71 * ip to abort_ip before returning to user-space, so the preempted
72 * execution resumes at abort_ip. 72 * execution resumes at abort_ip.
73 * 73 *
74 * 3. Userspace critical section final inst 74 * 3. Userspace critical section final instruction before
75 * post_commit_ip is the commit. The cri 75 * post_commit_ip is the commit. The critical section is
76 * self-terminating. 76 * self-terminating.
77 * [post_commit_ip] 77 * [post_commit_ip]
78 * 78 *
79 * 4. <success> 79 * 4. <success>
80 * 80 *
81 * On failure at [2], or if interrupted by p 81 * On failure at [2], or if interrupted by preempt or signal delivery
82 * between [1] and [3]: 82 * between [1] and [3]:
83 * 83 *
84 * [abort_ip] 84 * [abort_ip]
85 * F1. <failure> 85 * F1. <failure>
86 */ 86 */
87 87
88 static int rseq_update_cpu_node_id(struct task 88 static int rseq_update_cpu_node_id(struct task_struct *t)
89 { 89 {
90 struct rseq __user *rseq = t->rseq; 90 struct rseq __user *rseq = t->rseq;
91 u32 cpu_id = raw_smp_processor_id(); 91 u32 cpu_id = raw_smp_processor_id();
92 u32 node_id = cpu_to_node(cpu_id); 92 u32 node_id = cpu_to_node(cpu_id);
93 u32 mm_cid = task_mm_cid(t); 93 u32 mm_cid = task_mm_cid(t);
94 94
95 WARN_ON_ONCE((int) mm_cid < 0); 95 WARN_ON_ONCE((int) mm_cid < 0);
96 if (!user_write_access_begin(rseq, t-> 96 if (!user_write_access_begin(rseq, t->rseq_len))
97 goto efault; 97 goto efault;
98 unsafe_put_user(cpu_id, &rseq->cpu_id_ 98 unsafe_put_user(cpu_id, &rseq->cpu_id_start, efault_end);
99 unsafe_put_user(cpu_id, &rseq->cpu_id, 99 unsafe_put_user(cpu_id, &rseq->cpu_id, efault_end);
100 unsafe_put_user(node_id, &rseq->node_i 100 unsafe_put_user(node_id, &rseq->node_id, efault_end);
101 unsafe_put_user(mm_cid, &rseq->mm_cid, 101 unsafe_put_user(mm_cid, &rseq->mm_cid, efault_end);
102 /* 102 /*
103 * Additional feature fields added aft 103 * Additional feature fields added after ORIG_RSEQ_SIZE
104 * need to be conditionally updated on 104 * need to be conditionally updated only if
105 * t->rseq_len != ORIG_RSEQ_SIZE. 105 * t->rseq_len != ORIG_RSEQ_SIZE.
106 */ 106 */
107 user_write_access_end(); 107 user_write_access_end();
108 trace_rseq_update(t); 108 trace_rseq_update(t);
109 return 0; 109 return 0;
110 110
111 efault_end: 111 efault_end:
112 user_write_access_end(); 112 user_write_access_end();
113 efault: 113 efault:
114 return -EFAULT; 114 return -EFAULT;
115 } 115 }
116 116
117 static int rseq_reset_rseq_cpu_node_id(struct 117 static int rseq_reset_rseq_cpu_node_id(struct task_struct *t)
118 { 118 {
119 u32 cpu_id_start = 0, cpu_id = RSEQ_CP 119 u32 cpu_id_start = 0, cpu_id = RSEQ_CPU_ID_UNINITIALIZED, node_id = 0,
120 mm_cid = 0; 120 mm_cid = 0;
121 121
122 /* 122 /*
123 * Reset cpu_id_start to its initial s 123 * Reset cpu_id_start to its initial state (0).
124 */ 124 */
125 if (put_user(cpu_id_start, &t->rseq->c 125 if (put_user(cpu_id_start, &t->rseq->cpu_id_start))
126 return -EFAULT; 126 return -EFAULT;
127 /* 127 /*
128 * Reset cpu_id to RSEQ_CPU_ID_UNINITI 128 * Reset cpu_id to RSEQ_CPU_ID_UNINITIALIZED, so any user coming
129 * in after unregistration can figure 129 * in after unregistration can figure out that rseq needs to be
130 * registered again. 130 * registered again.
131 */ 131 */
132 if (put_user(cpu_id, &t->rseq->cpu_id) 132 if (put_user(cpu_id, &t->rseq->cpu_id))
133 return -EFAULT; 133 return -EFAULT;
134 /* 134 /*
135 * Reset node_id to its initial state 135 * Reset node_id to its initial state (0).
136 */ 136 */
137 if (put_user(node_id, &t->rseq->node_i 137 if (put_user(node_id, &t->rseq->node_id))
138 return -EFAULT; 138 return -EFAULT;
139 /* 139 /*
140 * Reset mm_cid to its initial state ( 140 * Reset mm_cid to its initial state (0).
141 */ 141 */
142 if (put_user(mm_cid, &t->rseq->mm_cid) 142 if (put_user(mm_cid, &t->rseq->mm_cid))
143 return -EFAULT; 143 return -EFAULT;
144 /* 144 /*
145 * Additional feature fields added aft 145 * Additional feature fields added after ORIG_RSEQ_SIZE
146 * need to be conditionally reset only 146 * need to be conditionally reset only if
147 * t->rseq_len != ORIG_RSEQ_SIZE. 147 * t->rseq_len != ORIG_RSEQ_SIZE.
148 */ 148 */
149 return 0; 149 return 0;
150 } 150 }
151 151
152 static int rseq_get_rseq_cs(struct task_struct 152 static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs)
153 { 153 {
154 struct rseq_cs __user *urseq_cs; 154 struct rseq_cs __user *urseq_cs;
155 u64 ptr; 155 u64 ptr;
156 u32 __user *usig; 156 u32 __user *usig;
157 u32 sig; 157 u32 sig;
158 int ret; 158 int ret;
159 159
160 #ifdef CONFIG_64BIT 160 #ifdef CONFIG_64BIT
161 if (get_user(ptr, &t->rseq->rseq_cs)) 161 if (get_user(ptr, &t->rseq->rseq_cs))
162 return -EFAULT; 162 return -EFAULT;
163 #else 163 #else
164 if (copy_from_user(&ptr, &t->rseq->rse 164 if (copy_from_user(&ptr, &t->rseq->rseq_cs, sizeof(ptr)))
165 return -EFAULT; 165 return -EFAULT;
166 #endif 166 #endif
167 if (!ptr) { 167 if (!ptr) {
168 memset(rseq_cs, 0, sizeof(*rse 168 memset(rseq_cs, 0, sizeof(*rseq_cs));
169 return 0; 169 return 0;
170 } 170 }
171 if (ptr >= TASK_SIZE) 171 if (ptr >= TASK_SIZE)
172 return -EINVAL; 172 return -EINVAL;
173 urseq_cs = (struct rseq_cs __user *)(u 173 urseq_cs = (struct rseq_cs __user *)(unsigned long)ptr;
174 if (copy_from_user(rseq_cs, urseq_cs, 174 if (copy_from_user(rseq_cs, urseq_cs, sizeof(*rseq_cs)))
175 return -EFAULT; 175 return -EFAULT;
176 176
177 if (rseq_cs->start_ip >= TASK_SIZE || 177 if (rseq_cs->start_ip >= TASK_SIZE ||
178 rseq_cs->start_ip + rseq_cs->post_ 178 rseq_cs->start_ip + rseq_cs->post_commit_offset >= TASK_SIZE ||
179 rseq_cs->abort_ip >= TASK_SIZE || 179 rseq_cs->abort_ip >= TASK_SIZE ||
180 rseq_cs->version > 0) 180 rseq_cs->version > 0)
181 return -EINVAL; 181 return -EINVAL;
182 /* Check for overflow. */ 182 /* Check for overflow. */
183 if (rseq_cs->start_ip + rseq_cs->post_ 183 if (rseq_cs->start_ip + rseq_cs->post_commit_offset < rseq_cs->start_ip)
184 return -EINVAL; 184 return -EINVAL;
185 /* Ensure that abort_ip is not in the 185 /* Ensure that abort_ip is not in the critical section. */
186 if (rseq_cs->abort_ip - rseq_cs->start 186 if (rseq_cs->abort_ip - rseq_cs->start_ip < rseq_cs->post_commit_offset)
187 return -EINVAL; 187 return -EINVAL;
188 188
189 usig = (u32 __user *)(unsigned long)(r 189 usig = (u32 __user *)(unsigned long)(rseq_cs->abort_ip - sizeof(u32));
190 ret = get_user(sig, usig); 190 ret = get_user(sig, usig);
191 if (ret) 191 if (ret)
192 return ret; 192 return ret;
193 193
194 if (current->rseq_sig != sig) { 194 if (current->rseq_sig != sig) {
195 printk_ratelimited(KERN_WARNIN 195 printk_ratelimited(KERN_WARNING
196 "Possible attack attem 196 "Possible attack attempt. Unexpected rseq signature 0x%x, expecting 0x%x (pid=%d, addr=%p).\n",
197 sig, current->rseq_sig 197 sig, current->rseq_sig, current->pid, usig);
198 return -EINVAL; 198 return -EINVAL;
199 } 199 }
200 return 0; 200 return 0;
201 } 201 }
202 202
203 static bool rseq_warn_flags(const char *str, u 203 static bool rseq_warn_flags(const char *str, u32 flags)
204 { 204 {
205 u32 test_flags; 205 u32 test_flags;
206 206
207 if (!flags) 207 if (!flags)
208 return false; 208 return false;
209 test_flags = flags & RSEQ_CS_NO_RESTAR 209 test_flags = flags & RSEQ_CS_NO_RESTART_FLAGS;
210 if (test_flags) 210 if (test_flags)
211 pr_warn_once("Deprecated flags 211 pr_warn_once("Deprecated flags (%u) in %s ABI structure", test_flags, str);
212 test_flags = flags & ~RSEQ_CS_NO_RESTA 212 test_flags = flags & ~RSEQ_CS_NO_RESTART_FLAGS;
213 if (test_flags) 213 if (test_flags)
214 pr_warn_once("Unknown flags (% 214 pr_warn_once("Unknown flags (%u) in %s ABI structure", test_flags, str);
215 return true; 215 return true;
216 } 216 }
217 217
218 static int rseq_need_restart(struct task_struc 218 static int rseq_need_restart(struct task_struct *t, u32 cs_flags)
219 { 219 {
220 u32 flags, event_mask; 220 u32 flags, event_mask;
221 int ret; 221 int ret;
222 222
223 if (rseq_warn_flags("rseq_cs", cs_flag 223 if (rseq_warn_flags("rseq_cs", cs_flags))
224 return -EINVAL; 224 return -EINVAL;
225 225
226 /* Get thread flags. */ 226 /* Get thread flags. */
227 ret = get_user(flags, &t->rseq->flags) 227 ret = get_user(flags, &t->rseq->flags);
228 if (ret) 228 if (ret)
229 return ret; 229 return ret;
230 230
231 if (rseq_warn_flags("rseq", flags)) 231 if (rseq_warn_flags("rseq", flags))
232 return -EINVAL; 232 return -EINVAL;
233 233
234 /* 234 /*
235 * Load and clear event mask atomicall 235 * Load and clear event mask atomically with respect to
236 * scheduler preemption. 236 * scheduler preemption.
237 */ 237 */
238 preempt_disable(); 238 preempt_disable();
239 event_mask = t->rseq_event_mask; 239 event_mask = t->rseq_event_mask;
240 t->rseq_event_mask = 0; 240 t->rseq_event_mask = 0;
241 preempt_enable(); 241 preempt_enable();
242 242
243 return !!event_mask; 243 return !!event_mask;
244 } 244 }
245 245
246 static int clear_rseq_cs(struct task_struct *t 246 static int clear_rseq_cs(struct task_struct *t)
247 { 247 {
248 /* 248 /*
249 * The rseq_cs field is set to NULL on 249 * The rseq_cs field is set to NULL on preemption or signal
250 * delivery on top of rseq assembly bl 250 * delivery on top of rseq assembly block, as well as on top
251 * of code outside of the rseq assembl 251 * of code outside of the rseq assembly block. This performs
252 * a lazy clear of the rseq_cs field. 252 * a lazy clear of the rseq_cs field.
253 * 253 *
254 * Set rseq_cs to NULL. 254 * Set rseq_cs to NULL.
255 */ 255 */
256 #ifdef CONFIG_64BIT 256 #ifdef CONFIG_64BIT
257 return put_user(0UL, &t->rseq->rseq_cs 257 return put_user(0UL, &t->rseq->rseq_cs);
258 #else 258 #else
259 if (clear_user(&t->rseq->rseq_cs, size 259 if (clear_user(&t->rseq->rseq_cs, sizeof(t->rseq->rseq_cs)))
260 return -EFAULT; 260 return -EFAULT;
261 return 0; 261 return 0;
262 #endif 262 #endif
263 } 263 }
264 264
265 /* 265 /*
266 * Unsigned comparison will be true when ip >= 266 * Unsigned comparison will be true when ip >= start_ip, and when
267 * ip < start_ip + post_commit_offset. 267 * ip < start_ip + post_commit_offset.
268 */ 268 */
269 static bool in_rseq_cs(unsigned long ip, struc 269 static bool in_rseq_cs(unsigned long ip, struct rseq_cs *rseq_cs)
270 { 270 {
271 return ip - rseq_cs->start_ip < rseq_c 271 return ip - rseq_cs->start_ip < rseq_cs->post_commit_offset;
272 } 272 }
273 273
274 static int rseq_ip_fixup(struct pt_regs *regs) 274 static int rseq_ip_fixup(struct pt_regs *regs)
275 { 275 {
276 unsigned long ip = instruction_pointer 276 unsigned long ip = instruction_pointer(regs);
277 struct task_struct *t = current; 277 struct task_struct *t = current;
278 struct rseq_cs rseq_cs; 278 struct rseq_cs rseq_cs;
279 int ret; 279 int ret;
280 280
281 ret = rseq_get_rseq_cs(t, &rseq_cs); 281 ret = rseq_get_rseq_cs(t, &rseq_cs);
282 if (ret) 282 if (ret)
283 return ret; 283 return ret;
284 284
285 /* 285 /*
286 * Handle potentially not being within 286 * Handle potentially not being within a critical section.
287 * If not nested over a rseq critical 287 * If not nested over a rseq critical section, restart is useless.
288 * Clear the rseq_cs pointer and retur 288 * Clear the rseq_cs pointer and return.
289 */ 289 */
290 if (!in_rseq_cs(ip, &rseq_cs)) 290 if (!in_rseq_cs(ip, &rseq_cs))
291 return clear_rseq_cs(t); 291 return clear_rseq_cs(t);
292 ret = rseq_need_restart(t, rseq_cs.fla 292 ret = rseq_need_restart(t, rseq_cs.flags);
293 if (ret <= 0) 293 if (ret <= 0)
294 return ret; 294 return ret;
295 ret = clear_rseq_cs(t); 295 ret = clear_rseq_cs(t);
296 if (ret) 296 if (ret)
297 return ret; 297 return ret;
298 trace_rseq_ip_fixup(ip, rseq_cs.start_ 298 trace_rseq_ip_fixup(ip, rseq_cs.start_ip, rseq_cs.post_commit_offset,
299 rseq_cs.abort_ip); 299 rseq_cs.abort_ip);
300 instruction_pointer_set(regs, (unsigne 300 instruction_pointer_set(regs, (unsigned long)rseq_cs.abort_ip);
301 return 0; 301 return 0;
302 } 302 }
303 303
304 /* 304 /*
305 * This resume handler must always be executed 305 * This resume handler must always be executed between any of:
306 * - preemption, 306 * - preemption,
307 * - signal delivery, 307 * - signal delivery,
308 * and return to user-space. 308 * and return to user-space.
309 * 309 *
310 * This is how we can ensure that the entire r 310 * This is how we can ensure that the entire rseq critical section
311 * will issue the commit instruction only if e 311 * will issue the commit instruction only if executed atomically with
312 * respect to other threads scheduled on the s 312 * respect to other threads scheduled on the same CPU, and with respect
313 * to signal handlers. 313 * to signal handlers.
314 */ 314 */
315 void __rseq_handle_notify_resume(struct ksigna 315 void __rseq_handle_notify_resume(struct ksignal *ksig, struct pt_regs *regs)
316 { 316 {
317 struct task_struct *t = current; 317 struct task_struct *t = current;
318 int ret, sig; 318 int ret, sig;
319 319
320 if (unlikely(t->flags & PF_EXITING)) 320 if (unlikely(t->flags & PF_EXITING))
321 return; 321 return;
322 322
323 /* 323 /*
324 * regs is NULL if and only if the cal 324 * regs is NULL if and only if the caller is in a syscall path. Skip
325 * fixup and leave rseq_cs as is so th 325 * fixup and leave rseq_cs as is so that rseq_sycall() will detect and
326 * kill a misbehaving userspace on deb 326 * kill a misbehaving userspace on debug kernels.
327 */ 327 */
328 if (regs) { 328 if (regs) {
329 ret = rseq_ip_fixup(regs); 329 ret = rseq_ip_fixup(regs);
330 if (unlikely(ret < 0)) 330 if (unlikely(ret < 0))
331 goto error; 331 goto error;
332 } 332 }
333 if (unlikely(rseq_update_cpu_node_id(t 333 if (unlikely(rseq_update_cpu_node_id(t)))
334 goto error; 334 goto error;
335 return; 335 return;
336 336
337 error: 337 error:
338 sig = ksig ? ksig->sig : 0; 338 sig = ksig ? ksig->sig : 0;
339 force_sigsegv(sig); 339 force_sigsegv(sig);
340 } 340 }
341 341
342 #ifdef CONFIG_DEBUG_RSEQ 342 #ifdef CONFIG_DEBUG_RSEQ
343 343
344 /* 344 /*
345 * Terminate the process if a syscall is issue 345 * Terminate the process if a syscall is issued within a restartable
346 * sequence. 346 * sequence.
347 */ 347 */
348 void rseq_syscall(struct pt_regs *regs) 348 void rseq_syscall(struct pt_regs *regs)
349 { 349 {
350 unsigned long ip = instruction_pointer 350 unsigned long ip = instruction_pointer(regs);
351 struct task_struct *t = current; 351 struct task_struct *t = current;
352 struct rseq_cs rseq_cs; 352 struct rseq_cs rseq_cs;
353 353
354 if (!t->rseq) 354 if (!t->rseq)
355 return; 355 return;
356 if (rseq_get_rseq_cs(t, &rseq_cs) || i 356 if (rseq_get_rseq_cs(t, &rseq_cs) || in_rseq_cs(ip, &rseq_cs))
357 force_sig(SIGSEGV); 357 force_sig(SIGSEGV);
358 } 358 }
359 359
360 #endif 360 #endif
361 361
362 /* 362 /*
363 * sys_rseq - setup restartable sequences for 363 * sys_rseq - setup restartable sequences for caller thread.
364 */ 364 */
365 SYSCALL_DEFINE4(rseq, struct rseq __user *, rs 365 SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len,
366 int, flags, u32, sig) 366 int, flags, u32, sig)
367 { 367 {
368 int ret; 368 int ret;
369 369
370 if (flags & RSEQ_FLAG_UNREGISTER) { 370 if (flags & RSEQ_FLAG_UNREGISTER) {
371 if (flags & ~RSEQ_FLAG_UNREGIS 371 if (flags & ~RSEQ_FLAG_UNREGISTER)
372 return -EINVAL; 372 return -EINVAL;
373 /* Unregister rseq for current 373 /* Unregister rseq for current thread. */
374 if (current->rseq != rseq || ! 374 if (current->rseq != rseq || !current->rseq)
375 return -EINVAL; 375 return -EINVAL;
376 if (rseq_len != current->rseq_ 376 if (rseq_len != current->rseq_len)
377 return -EINVAL; 377 return -EINVAL;
378 if (current->rseq_sig != sig) 378 if (current->rseq_sig != sig)
379 return -EPERM; 379 return -EPERM;
380 ret = rseq_reset_rseq_cpu_node 380 ret = rseq_reset_rseq_cpu_node_id(current);
381 if (ret) 381 if (ret)
382 return ret; 382 return ret;
383 current->rseq = NULL; 383 current->rseq = NULL;
384 current->rseq_sig = 0; 384 current->rseq_sig = 0;
385 current->rseq_len = 0; 385 current->rseq_len = 0;
386 return 0; 386 return 0;
387 } 387 }
388 388
389 if (unlikely(flags)) 389 if (unlikely(flags))
390 return -EINVAL; 390 return -EINVAL;
391 391
392 if (current->rseq) { 392 if (current->rseq) {
393 /* 393 /*
394 * If rseq is already register 394 * If rseq is already registered, check whether
395 * the provided address differ 395 * the provided address differs from the prior
396 * one. 396 * one.
397 */ 397 */
398 if (current->rseq != rseq || r 398 if (current->rseq != rseq || rseq_len != current->rseq_len)
399 return -EINVAL; 399 return -EINVAL;
400 if (current->rseq_sig != sig) 400 if (current->rseq_sig != sig)
401 return -EPERM; 401 return -EPERM;
402 /* Already registered. */ 402 /* Already registered. */
403 return -EBUSY; 403 return -EBUSY;
404 } 404 }
405 405
406 /* 406 /*
407 * If there was no rseq previously reg 407 * If there was no rseq previously registered, ensure the provided rseq
408 * is properly aligned, as communcated 408 * is properly aligned, as communcated to user-space through the ELF
409 * auxiliary vector AT_RSEQ_ALIGN. If 409 * auxiliary vector AT_RSEQ_ALIGN. If rseq_len is the original rseq
410 * size, the required alignment is the 410 * size, the required alignment is the original struct rseq alignment.
411 * 411 *
412 * In order to be valid, rseq_len is e 412 * In order to be valid, rseq_len is either the original rseq size, or
413 * large enough to contain all support 413 * large enough to contain all supported fields, as communicated to
414 * user-space through the ELF auxiliar 414 * user-space through the ELF auxiliary vector AT_RSEQ_FEATURE_SIZE.
415 */ 415 */
416 if (rseq_len < ORIG_RSEQ_SIZE || 416 if (rseq_len < ORIG_RSEQ_SIZE ||
417 (rseq_len == ORIG_RSEQ_SIZE && !IS 417 (rseq_len == ORIG_RSEQ_SIZE && !IS_ALIGNED((unsigned long)rseq, ORIG_RSEQ_SIZE)) ||
418 (rseq_len != ORIG_RSEQ_SIZE && (!I 418 (rseq_len != ORIG_RSEQ_SIZE && (!IS_ALIGNED((unsigned long)rseq, __alignof__(*rseq)) ||
419 rs 419 rseq_len < offsetof(struct rseq, end))))
420 return -EINVAL; 420 return -EINVAL;
421 if (!access_ok(rseq, rseq_len)) 421 if (!access_ok(rseq, rseq_len))
422 return -EFAULT; 422 return -EFAULT;
423 current->rseq = rseq; 423 current->rseq = rseq;
424 current->rseq_len = rseq_len; 424 current->rseq_len = rseq_len;
425 current->rseq_sig = sig; 425 current->rseq_sig = sig;
426 /* 426 /*
427 * If rseq was previously inactive, an 427 * If rseq was previously inactive, and has just been
428 * registered, ensure the cpu_id_start 428 * registered, ensure the cpu_id_start and cpu_id fields
429 * are updated before returning to use 429 * are updated before returning to user-space.
430 */ 430 */
431 rseq_set_notify_resume(current); 431 rseq_set_notify_resume(current);
432 432
433 return 0; 433 return 0;
434 } 434 }
435 435
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