Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/kernel/ptrace.c |
| 3 | * |
| 4 | * (C) Copyright 1999 Linus Torvalds |
| 5 | * |
| 6 | * Common interfaces for "ptrace()" which we do not want |
| 7 | * to continually duplicate across every architecture. |
| 8 | */ |
| 9 | |
Randy.Dunlap | c59ede7 | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 10 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <linux/module.h> |
| 12 | #include <linux/sched.h> |
| 13 | #include <linux/errno.h> |
| 14 | #include <linux/mm.h> |
| 15 | #include <linux/highmem.h> |
| 16 | #include <linux/pagemap.h> |
| 17 | #include <linux/smp_lock.h> |
| 18 | #include <linux/ptrace.h> |
| 19 | #include <linux/security.h> |
Jesper Juhl | 7ed20e1 | 2005-05-01 08:59:14 -0700 | [diff] [blame] | 20 | #include <linux/signal.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | |
| 22 | #include <asm/pgtable.h> |
| 23 | #include <asm/uaccess.h> |
| 24 | |
| 25 | /* |
| 26 | * ptrace a task: make the debugger its new parent and |
| 27 | * move it to the ptrace list. |
| 28 | * |
| 29 | * Must be called with the tasklist lock write-held. |
| 30 | */ |
Ingo Molnar | 36c8b58 | 2006-07-03 00:25:41 -0700 | [diff] [blame] | 31 | void __ptrace_link(struct task_struct *child, struct task_struct *new_parent) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 32 | { |
Eric Sesterhenn | 524223c | 2006-04-02 13:43:40 +0200 | [diff] [blame] | 33 | BUG_ON(!list_empty(&child->ptrace_list)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 34 | if (child->parent == new_parent) |
| 35 | return; |
| 36 | list_add(&child->ptrace_list, &child->parent->ptrace_children); |
Oleg Nesterov | 9b678ec | 2006-03-28 16:11:05 -0800 | [diff] [blame] | 37 | remove_parent(child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | child->parent = new_parent; |
Oleg Nesterov | 9b678ec | 2006-03-28 16:11:05 -0800 | [diff] [blame] | 39 | add_parent(child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 40 | } |
| 41 | |
| 42 | /* |
| 43 | * Turn a tracing stop into a normal stop now, since with no tracer there |
| 44 | * would be no way to wake it up with SIGCONT or SIGKILL. If there was a |
| 45 | * signal sent that would resume the child, but didn't because it was in |
| 46 | * TASK_TRACED, resume it now. |
| 47 | * Requires that irqs be disabled. |
| 48 | */ |
Ingo Molnar | 36c8b58 | 2006-07-03 00:25:41 -0700 | [diff] [blame] | 49 | void ptrace_untrace(struct task_struct *child) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 50 | { |
| 51 | spin_lock(&child->sighand->siglock); |
| 52 | if (child->state == TASK_TRACED) { |
| 53 | if (child->signal->flags & SIGNAL_STOP_STOPPED) { |
| 54 | child->state = TASK_STOPPED; |
| 55 | } else { |
| 56 | signal_wake_up(child, 1); |
| 57 | } |
| 58 | } |
| 59 | spin_unlock(&child->sighand->siglock); |
| 60 | } |
| 61 | |
| 62 | /* |
| 63 | * unptrace a task: move it back to its original parent and |
| 64 | * remove it from the ptrace list. |
| 65 | * |
| 66 | * Must be called with the tasklist lock write-held. |
| 67 | */ |
Ingo Molnar | 36c8b58 | 2006-07-03 00:25:41 -0700 | [diff] [blame] | 68 | void __ptrace_unlink(struct task_struct *child) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | { |
Oleg Nesterov | 5ecfbae | 2006-02-15 22:50:10 +0300 | [diff] [blame] | 70 | BUG_ON(!child->ptrace); |
| 71 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 72 | child->ptrace = 0; |
| 73 | if (!list_empty(&child->ptrace_list)) { |
| 74 | list_del_init(&child->ptrace_list); |
Oleg Nesterov | 9b678ec | 2006-03-28 16:11:05 -0800 | [diff] [blame] | 75 | remove_parent(child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 76 | child->parent = child->real_parent; |
Oleg Nesterov | 9b678ec | 2006-03-28 16:11:05 -0800 | [diff] [blame] | 77 | add_parent(child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 78 | } |
| 79 | |
Roland McGrath | e57a505 | 2006-04-12 16:30:20 -0700 | [diff] [blame] | 80 | if (child->state == TASK_TRACED) |
| 81 | ptrace_untrace(child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 82 | } |
| 83 | |
| 84 | /* |
| 85 | * Check that we have indeed attached to the thing.. |
| 86 | */ |
| 87 | int ptrace_check_attach(struct task_struct *child, int kill) |
| 88 | { |
| 89 | int ret = -ESRCH; |
| 90 | |
| 91 | /* |
| 92 | * We take the read lock around doing both checks to close a |
| 93 | * possible race where someone else was tracing our child and |
| 94 | * detached between these two checks. After this locked check, |
| 95 | * we are sure that this is our traced child and that can only |
| 96 | * be changed by us so it's not changing right after this. |
| 97 | */ |
| 98 | read_lock(&tasklist_lock); |
| 99 | if ((child->ptrace & PT_PTRACED) && child->parent == current && |
| 100 | (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) |
| 101 | && child->signal != NULL) { |
| 102 | ret = 0; |
| 103 | spin_lock_irq(&child->sighand->siglock); |
| 104 | if (child->state == TASK_STOPPED) { |
| 105 | child->state = TASK_TRACED; |
| 106 | } else if (child->state != TASK_TRACED && !kill) { |
| 107 | ret = -ESRCH; |
| 108 | } |
| 109 | spin_unlock_irq(&child->sighand->siglock); |
| 110 | } |
| 111 | read_unlock(&tasklist_lock); |
| 112 | |
| 113 | if (!ret && !kill) { |
| 114 | wait_task_inactive(child); |
| 115 | } |
| 116 | |
| 117 | /* All systems go.. */ |
| 118 | return ret; |
| 119 | } |
| 120 | |
Miklos Szeredi | ab8d11b | 2005-09-06 15:18:24 -0700 | [diff] [blame] | 121 | static int may_attach(struct task_struct *task) |
| 122 | { |
Eric W. Biederman | df26c40 | 2006-06-26 00:25:59 -0700 | [diff] [blame] | 123 | /* May we inspect the given task? |
| 124 | * This check is used both for attaching with ptrace |
| 125 | * and for allowing access to sensitive information in /proc. |
| 126 | * |
| 127 | * ptrace_attach denies several cases that /proc allows |
| 128 | * because setting up the necessary parent/child relationship |
| 129 | * or halting the specified task is impossible. |
| 130 | */ |
| 131 | int dumpable = 0; |
| 132 | /* Don't let security modules deny introspection */ |
| 133 | if (task == current) |
| 134 | return 0; |
Miklos Szeredi | ab8d11b | 2005-09-06 15:18:24 -0700 | [diff] [blame] | 135 | if (((current->uid != task->euid) || |
| 136 | (current->uid != task->suid) || |
| 137 | (current->uid != task->uid) || |
| 138 | (current->gid != task->egid) || |
| 139 | (current->gid != task->sgid) || |
| 140 | (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) |
| 141 | return -EPERM; |
| 142 | smp_rmb(); |
Eric W. Biederman | df26c40 | 2006-06-26 00:25:59 -0700 | [diff] [blame] | 143 | if (task->mm) |
| 144 | dumpable = task->mm->dumpable; |
| 145 | if (!dumpable && !capable(CAP_SYS_PTRACE)) |
Miklos Szeredi | ab8d11b | 2005-09-06 15:18:24 -0700 | [diff] [blame] | 146 | return -EPERM; |
| 147 | |
| 148 | return security_ptrace(current, task); |
| 149 | } |
| 150 | |
| 151 | int ptrace_may_attach(struct task_struct *task) |
| 152 | { |
| 153 | int err; |
| 154 | task_lock(task); |
| 155 | err = may_attach(task); |
| 156 | task_unlock(task); |
| 157 | return !err; |
| 158 | } |
| 159 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 160 | int ptrace_attach(struct task_struct *task) |
| 161 | { |
| 162 | int retval; |
Linus Torvalds | f5b40e3 | 2006-05-07 10:49:33 -0700 | [diff] [blame] | 163 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 164 | retval = -EPERM; |
| 165 | if (task->pid <= 1) |
Linus Torvalds | f5b40e3 | 2006-05-07 10:49:33 -0700 | [diff] [blame] | 166 | goto out; |
Linus Torvalds | 28d838c | 2005-11-09 11:33:07 -0800 | [diff] [blame] | 167 | if (task->tgid == current->tgid) |
Linus Torvalds | f5b40e3 | 2006-05-07 10:49:33 -0700 | [diff] [blame] | 168 | goto out; |
| 169 | |
Linus Torvalds | f358166 | 2006-05-11 11:08:49 -0700 | [diff] [blame] | 170 | repeat: |
| 171 | /* |
| 172 | * Nasty, nasty. |
| 173 | * |
| 174 | * We want to hold both the task-lock and the |
| 175 | * tasklist_lock for writing at the same time. |
| 176 | * But that's against the rules (tasklist_lock |
| 177 | * is taken for reading by interrupts on other |
| 178 | * cpu's that may have task_lock). |
| 179 | */ |
Linus Torvalds | f5b40e3 | 2006-05-07 10:49:33 -0700 | [diff] [blame] | 180 | task_lock(task); |
Linus Torvalds | f358166 | 2006-05-11 11:08:49 -0700 | [diff] [blame] | 181 | local_irq_disable(); |
| 182 | if (!write_trylock(&tasklist_lock)) { |
| 183 | local_irq_enable(); |
| 184 | task_unlock(task); |
| 185 | do { |
| 186 | cpu_relax(); |
| 187 | } while (!write_can_lock(&tasklist_lock)); |
| 188 | goto repeat; |
| 189 | } |
Linus Torvalds | f5b40e3 | 2006-05-07 10:49:33 -0700 | [diff] [blame] | 190 | |
Eric W. Biederman | df26c40 | 2006-06-26 00:25:59 -0700 | [diff] [blame] | 191 | if (!task->mm) |
| 192 | goto bad; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 193 | /* the same process cannot be attached many times */ |
| 194 | if (task->ptrace & PT_PTRACED) |
| 195 | goto bad; |
Miklos Szeredi | ab8d11b | 2005-09-06 15:18:24 -0700 | [diff] [blame] | 196 | retval = may_attach(task); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 197 | if (retval) |
| 198 | goto bad; |
| 199 | |
| 200 | /* Go */ |
| 201 | task->ptrace |= PT_PTRACED | ((task->real_parent != current) |
| 202 | ? PT_ATTACHED : 0); |
| 203 | if (capable(CAP_SYS_PTRACE)) |
| 204 | task->ptrace |= PT_PTRACE_CAP; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 205 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 206 | __ptrace_link(task, current); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 207 | |
| 208 | force_sig_specific(SIGSTOP, task); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 209 | |
| 210 | bad: |
Linus Torvalds | f5b40e3 | 2006-05-07 10:49:33 -0700 | [diff] [blame] | 211 | write_unlock_irq(&tasklist_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 212 | task_unlock(task); |
Linus Torvalds | f5b40e3 | 2006-05-07 10:49:33 -0700 | [diff] [blame] | 213 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | return retval; |
| 215 | } |
| 216 | |
Oleg Nesterov | d5f70c0 | 2006-06-26 00:26:07 -0700 | [diff] [blame] | 217 | static inline void __ptrace_detach(struct task_struct *child, unsigned int data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 218 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 219 | child->exit_code = data; |
Oleg Nesterov | 5ecfbae | 2006-02-15 22:50:10 +0300 | [diff] [blame] | 220 | /* .. re-parent .. */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 221 | __ptrace_unlink(child); |
| 222 | /* .. and wake it up. */ |
| 223 | if (child->exit_state != EXIT_ZOMBIE) |
| 224 | wake_up_process(child); |
Oleg Nesterov | 5ecfbae | 2006-02-15 22:50:10 +0300 | [diff] [blame] | 225 | } |
| 226 | |
| 227 | int ptrace_detach(struct task_struct *child, unsigned int data) |
| 228 | { |
| 229 | if (!valid_signal(data)) |
| 230 | return -EIO; |
| 231 | |
| 232 | /* Architecture-specific hardware disable .. */ |
| 233 | ptrace_disable(child); |
| 234 | |
| 235 | write_lock_irq(&tasklist_lock); |
Oleg Nesterov | d5f70c0 | 2006-06-26 00:26:07 -0700 | [diff] [blame] | 236 | /* protect against de_thread()->release_task() */ |
Oleg Nesterov | 5ecfbae | 2006-02-15 22:50:10 +0300 | [diff] [blame] | 237 | if (child->ptrace) |
| 238 | __ptrace_detach(child, data); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 239 | write_unlock_irq(&tasklist_lock); |
| 240 | |
| 241 | return 0; |
| 242 | } |
| 243 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 244 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) |
| 245 | { |
| 246 | int copied = 0; |
| 247 | |
| 248 | while (len > 0) { |
| 249 | char buf[128]; |
| 250 | int this_len, retval; |
| 251 | |
| 252 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; |
| 253 | retval = access_process_vm(tsk, src, buf, this_len, 0); |
| 254 | if (!retval) { |
| 255 | if (copied) |
| 256 | break; |
| 257 | return -EIO; |
| 258 | } |
| 259 | if (copy_to_user(dst, buf, retval)) |
| 260 | return -EFAULT; |
| 261 | copied += retval; |
| 262 | src += retval; |
| 263 | dst += retval; |
| 264 | len -= retval; |
| 265 | } |
| 266 | return copied; |
| 267 | } |
| 268 | |
| 269 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) |
| 270 | { |
| 271 | int copied = 0; |
| 272 | |
| 273 | while (len > 0) { |
| 274 | char buf[128]; |
| 275 | int this_len, retval; |
| 276 | |
| 277 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; |
| 278 | if (copy_from_user(buf, src, this_len)) |
| 279 | return -EFAULT; |
| 280 | retval = access_process_vm(tsk, dst, buf, this_len, 1); |
| 281 | if (!retval) { |
| 282 | if (copied) |
| 283 | break; |
| 284 | return -EIO; |
| 285 | } |
| 286 | copied += retval; |
| 287 | src += retval; |
| 288 | dst += retval; |
| 289 | len -= retval; |
| 290 | } |
| 291 | return copied; |
| 292 | } |
| 293 | |
| 294 | static int ptrace_setoptions(struct task_struct *child, long data) |
| 295 | { |
| 296 | child->ptrace &= ~PT_TRACE_MASK; |
| 297 | |
| 298 | if (data & PTRACE_O_TRACESYSGOOD) |
| 299 | child->ptrace |= PT_TRACESYSGOOD; |
| 300 | |
| 301 | if (data & PTRACE_O_TRACEFORK) |
| 302 | child->ptrace |= PT_TRACE_FORK; |
| 303 | |
| 304 | if (data & PTRACE_O_TRACEVFORK) |
| 305 | child->ptrace |= PT_TRACE_VFORK; |
| 306 | |
| 307 | if (data & PTRACE_O_TRACECLONE) |
| 308 | child->ptrace |= PT_TRACE_CLONE; |
| 309 | |
| 310 | if (data & PTRACE_O_TRACEEXEC) |
| 311 | child->ptrace |= PT_TRACE_EXEC; |
| 312 | |
| 313 | if (data & PTRACE_O_TRACEVFORKDONE) |
| 314 | child->ptrace |= PT_TRACE_VFORK_DONE; |
| 315 | |
| 316 | if (data & PTRACE_O_TRACEEXIT) |
| 317 | child->ptrace |= PT_TRACE_EXIT; |
| 318 | |
| 319 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; |
| 320 | } |
| 321 | |
| 322 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) |
| 323 | { |
| 324 | siginfo_t lastinfo; |
| 325 | int error = -ESRCH; |
| 326 | |
| 327 | read_lock(&tasklist_lock); |
| 328 | if (likely(child->sighand != NULL)) { |
| 329 | error = -EINVAL; |
| 330 | spin_lock_irq(&child->sighand->siglock); |
| 331 | if (likely(child->last_siginfo != NULL)) { |
| 332 | lastinfo = *child->last_siginfo; |
| 333 | error = 0; |
| 334 | } |
| 335 | spin_unlock_irq(&child->sighand->siglock); |
| 336 | } |
| 337 | read_unlock(&tasklist_lock); |
| 338 | if (!error) |
| 339 | return copy_siginfo_to_user(data, &lastinfo); |
| 340 | return error; |
| 341 | } |
| 342 | |
| 343 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) |
| 344 | { |
| 345 | siginfo_t newinfo; |
| 346 | int error = -ESRCH; |
| 347 | |
| 348 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) |
| 349 | return -EFAULT; |
| 350 | |
| 351 | read_lock(&tasklist_lock); |
| 352 | if (likely(child->sighand != NULL)) { |
| 353 | error = -EINVAL; |
| 354 | spin_lock_irq(&child->sighand->siglock); |
| 355 | if (likely(child->last_siginfo != NULL)) { |
| 356 | *child->last_siginfo = newinfo; |
| 357 | error = 0; |
| 358 | } |
| 359 | spin_unlock_irq(&child->sighand->siglock); |
| 360 | } |
| 361 | read_unlock(&tasklist_lock); |
| 362 | return error; |
| 363 | } |
| 364 | |
| 365 | int ptrace_request(struct task_struct *child, long request, |
| 366 | long addr, long data) |
| 367 | { |
| 368 | int ret = -EIO; |
| 369 | |
| 370 | switch (request) { |
| 371 | #ifdef PTRACE_OLDSETOPTIONS |
| 372 | case PTRACE_OLDSETOPTIONS: |
| 373 | #endif |
| 374 | case PTRACE_SETOPTIONS: |
| 375 | ret = ptrace_setoptions(child, data); |
| 376 | break; |
| 377 | case PTRACE_GETEVENTMSG: |
| 378 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); |
| 379 | break; |
| 380 | case PTRACE_GETSIGINFO: |
| 381 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); |
| 382 | break; |
| 383 | case PTRACE_SETSIGINFO: |
| 384 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); |
| 385 | break; |
| 386 | default: |
| 387 | break; |
| 388 | } |
| 389 | |
| 390 | return ret; |
| 391 | } |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 392 | |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 393 | /** |
| 394 | * ptrace_traceme -- helper for PTRACE_TRACEME |
| 395 | * |
| 396 | * Performs checks and sets PT_PTRACED. |
| 397 | * Should be used by all ptrace implementations for PTRACE_TRACEME. |
| 398 | */ |
| 399 | int ptrace_traceme(void) |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 400 | { |
Linus Torvalds | f5b40e3 | 2006-05-07 10:49:33 -0700 | [diff] [blame] | 401 | int ret = -EPERM; |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 402 | |
| 403 | /* |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 404 | * Are we already being traced? |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 405 | */ |
Linus Torvalds | f5b40e3 | 2006-05-07 10:49:33 -0700 | [diff] [blame] | 406 | task_lock(current); |
| 407 | if (!(current->ptrace & PT_PTRACED)) { |
| 408 | ret = security_ptrace(current->parent, current); |
| 409 | /* |
| 410 | * Set the ptrace bit in the process ptrace flags. |
| 411 | */ |
| 412 | if (!ret) |
| 413 | current->ptrace |= PT_PTRACED; |
| 414 | } |
| 415 | task_unlock(current); |
| 416 | return ret; |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 417 | } |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 418 | |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 419 | /** |
| 420 | * ptrace_get_task_struct -- grab a task struct reference for ptrace |
| 421 | * @pid: process id to grab a task_struct reference of |
| 422 | * |
| 423 | * This function is a helper for ptrace implementations. It checks |
| 424 | * permissions and then grabs a task struct for use of the actual |
| 425 | * ptrace implementation. |
| 426 | * |
| 427 | * Returns the task_struct for @pid or an ERR_PTR() on failure. |
| 428 | */ |
| 429 | struct task_struct *ptrace_get_task_struct(pid_t pid) |
| 430 | { |
| 431 | struct task_struct *child; |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 432 | |
| 433 | /* |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 434 | * Tracing init is not allowed. |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 435 | */ |
| 436 | if (pid == 1) |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 437 | return ERR_PTR(-EPERM); |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 438 | |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 439 | read_lock(&tasklist_lock); |
| 440 | child = find_task_by_pid(pid); |
| 441 | if (child) |
| 442 | get_task_struct(child); |
| 443 | read_unlock(&tasklist_lock); |
| 444 | if (!child) |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 445 | return ERR_PTR(-ESRCH); |
| 446 | return child; |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 447 | } |
| 448 | |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 449 | #ifndef __ARCH_SYS_PTRACE |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 450 | asmlinkage long sys_ptrace(long request, long pid, long addr, long data) |
| 451 | { |
| 452 | struct task_struct *child; |
| 453 | long ret; |
| 454 | |
| 455 | /* |
| 456 | * This lock_kernel fixes a subtle race with suid exec |
| 457 | */ |
| 458 | lock_kernel(); |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 459 | if (request == PTRACE_TRACEME) { |
| 460 | ret = ptrace_traceme(); |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 461 | goto out; |
Christoph Hellwig | 6b9c7ed | 2006-01-08 01:02:33 -0800 | [diff] [blame] | 462 | } |
| 463 | |
| 464 | child = ptrace_get_task_struct(pid); |
| 465 | if (IS_ERR(child)) { |
| 466 | ret = PTR_ERR(child); |
| 467 | goto out; |
| 468 | } |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 469 | |
| 470 | if (request == PTRACE_ATTACH) { |
| 471 | ret = ptrace_attach(child); |
Christoph Hellwig | 005f18d | 2005-11-13 16:06:33 -0800 | [diff] [blame] | 472 | goto out_put_task_struct; |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 473 | } |
| 474 | |
| 475 | ret = ptrace_check_attach(child, request == PTRACE_KILL); |
| 476 | if (ret < 0) |
| 477 | goto out_put_task_struct; |
| 478 | |
| 479 | ret = arch_ptrace(child, request, addr, data); |
| 480 | if (ret < 0) |
| 481 | goto out_put_task_struct; |
| 482 | |
| 483 | out_put_task_struct: |
| 484 | put_task_struct(child); |
| 485 | out: |
| 486 | unlock_kernel(); |
| 487 | return ret; |
| 488 | } |
| 489 | #endif /* __ARCH_SYS_PTRACE */ |