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Side by Side Diff: sandbox/linux/suid/sandbox.c

Issue 236083002: Linux sandbox: style cleanup for setuid sandbox. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: Also fix header inclusions. Ohh goodness. Created 6 years, 8 months ago
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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 // http://code.google.com/p/chromium/wiki/LinuxSUIDSandbox 5 // http://code.google.com/p/chromium/wiki/LinuxSUIDSandbox
6 6
7 #include "common/sandbox.h" 7 #include "sandbox/linux/suid/common/sandbox.h"
8 8
9 #define _GNU_SOURCE 9 #define _GNU_SOURCE
10 #include <asm/unistd.h> 10 #include <asm/unistd.h>
11 #include <errno.h> 11 #include <errno.h>
12 #include <fcntl.h> 12 #include <fcntl.h>
13 #include <limits.h> 13 #include <limits.h>
14 #include <sched.h> 14 #include <sched.h>
15 #include <signal.h> 15 #include <signal.h>
16 #include <stdarg.h> 16 #include <stdarg.h>
17 #include <stdbool.h> 17 #include <stdbool.h>
18 #include <stdint.h> 18 #include <stdint.h>
19 #include <stdio.h> 19 #include <stdio.h>
20 #include <stdlib.h> 20 #include <stdlib.h>
21 #include <string.h> 21 #include <string.h>
22 #include <sys/prctl.h> 22 #include <sys/prctl.h>
23 #include <sys/resource.h> 23 #include <sys/resource.h>
24 #include <sys/socket.h> 24 #include <sys/socket.h>
25 #include <sys/stat.h> 25 #include <sys/stat.h>
26 #include <sys/time.h> 26 #include <sys/time.h>
27 #include <sys/types.h> 27 #include <sys/types.h>
28 #include <sys/vfs.h> 28 #include <sys/vfs.h>
29 #include <sys/wait.h> 29 #include <sys/wait.h>
30 #include <unistd.h> 30 #include <unistd.h>
31 31
32 #include "linux_util.h" 32 #include "sandbox/linux/suid/common/suid_unsafe_environment_variables.h"
33 #include "process_util.h" 33 #include "sandbox/linux/suid/linux_util.h"
34 #include "common/suid_unsafe_environment_variables.h" 34 #include "sandbox/linux/suid/process_util.h"
35 35
36 #if !defined(CLONE_NEWPID) 36 #if !defined(CLONE_NEWPID)
37 #define CLONE_NEWPID 0x20000000 37 #define CLONE_NEWPID 0x20000000
38 #endif 38 #endif
39 #if !defined(CLONE_NEWNET) 39 #if !defined(CLONE_NEWNET)
40 #define CLONE_NEWNET 0x40000000 40 #define CLONE_NEWNET 0x40000000
41 #endif 41 #endif
42 42
43 static bool DropRoot(); 43 static bool DropRoot();
44 44
45 #define HANDLE_EINTR(x) TEMP_FAILURE_RETRY(x) 45 #define HANDLE_EINTR(x) TEMP_FAILURE_RETRY(x)
46 46
47 static void FatalError(const char *msg, ...) 47 static void FatalError(const char* msg, ...)
48 __attribute__((noreturn, format(printf, 1, 2))); 48 __attribute__((noreturn, format(printf, 1, 2)));
49 49
50 static void FatalError(const char *msg, ...) { 50 static void FatalError(const char* msg, ...) {
51 va_list ap; 51 va_list ap;
52 va_start(ap, msg); 52 va_start(ap, msg);
53 53
54 vfprintf(stderr, msg, ap); 54 vfprintf(stderr, msg, ap);
55 fprintf(stderr, ": %s\n", strerror(errno)); 55 fprintf(stderr, ": %s\n", strerror(errno));
56 fflush(stderr); 56 fflush(stderr);
57 va_end(ap); 57 va_end(ap);
58 _exit(1); 58 _exit(1);
59 } 59 }
60 60
(...skipping 17 matching lines...) Expand all
78 #define SAFE_DIR "/proc/self/fdinfo" 78 #define SAFE_DIR "/proc/self/fdinfo"
79 #define SAFE_DIR2 "/proc/self/fd" 79 #define SAFE_DIR2 "/proc/self/fd"
80 80
81 static bool SpawnChrootHelper() { 81 static bool SpawnChrootHelper() {
82 int sv[2]; 82 int sv[2];
83 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) == -1) { 83 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) == -1) {
84 perror("socketpair"); 84 perror("socketpair");
85 return false; 85 return false;
86 } 86 }
87 87
88 char *safedir = NULL; 88 char* safedir = NULL;
89 struct stat sdir_stat; 89 struct stat sdir_stat;
90 if (!stat(SAFE_DIR, &sdir_stat) && S_ISDIR(sdir_stat.st_mode)) 90 if (!stat(SAFE_DIR, &sdir_stat) && S_ISDIR(sdir_stat.st_mode)) {
91 safedir = SAFE_DIR; 91 safedir = SAFE_DIR;
92 else 92 } else if (!stat(SAFE_DIR2, &sdir_stat) && S_ISDIR(sdir_stat.st_mode)) {
93 if (!stat(SAFE_DIR2, &sdir_stat) && S_ISDIR(sdir_stat.st_mode)) 93 safedir = SAFE_DIR2;
94 safedir = SAFE_DIR2; 94 } else {
95 else { 95 fprintf(stderr, "Could not find %s\n", SAFE_DIR2);
96 fprintf(stderr, "Could not find %s\n", SAFE_DIR2); 96 return false;
97 return false; 97 }
98 }
99 98
100 const pid_t pid = syscall( 99 const pid_t pid = syscall(__NR_clone, CLONE_FS | SIGCHLD, 0, 0, 0);
101 __NR_clone, CLONE_FS | SIGCHLD, 0, 0, 0);
102 100
103 if (pid == -1) { 101 if (pid == -1) {
104 perror("clone"); 102 perror("clone");
105 close(sv[0]); 103 close(sv[0]);
106 close(sv[1]); 104 close(sv[1]);
107 return false; 105 return false;
108 } 106 }
109 107
110 if (pid == 0) { 108 if (pid == 0) {
111 // We share our files structure with an untrusted process. As a security in 109 // We share our files structure with an untrusted process. As a security in
(...skipping 95 matching lines...) Expand 10 before | Expand all | Expand 10 after
207 // Don't "Core" on SIGABRT. SIGABRT is sent by the Chrome OS session manager 205 // Don't "Core" on SIGABRT. SIGABRT is sent by the Chrome OS session manager
208 // when things are hanging. 206 // when things are hanging.
209 // Here, the current process is going to waitid() and _exit(), so there is no 207 // Here, the current process is going to waitid() and _exit(), so there is no
210 // point in generating a crash report. The child process is the one 208 // point in generating a crash report. The child process is the one
211 // blocking us. 209 // blocking us.
212 if (signal(SIGABRT, ExitWithErrorSignalHandler) == SIG_ERR) { 210 if (signal(SIGABRT, ExitWithErrorSignalHandler) == SIG_ERR) {
213 FatalError("Failed to change signal handler"); 211 FatalError("Failed to change signal handler");
214 } 212 }
215 213
216 int wait_ret = 214 int wait_ret =
217 HANDLE_EINTR(waitid(P_PID, child_pid, &reaped_child_info, WEXITED)); 215 HANDLE_EINTR(waitid(P_PID, child_pid, &reaped_child_info, WEXITED));
218 216
219 if (!wait_ret && reaped_child_info.si_pid == child_pid) { 217 if (!wait_ret && reaped_child_info.si_pid == child_pid) {
220 if (reaped_child_info.si_code == CLD_EXITED) { 218 if (reaped_child_info.si_code == CLD_EXITED) {
221 exit_code = reaped_child_info.si_status; 219 exit_code = reaped_child_info.si_status;
222 } else { 220 } else {
223 // Exit with code 0 if the child got signaled. 221 // Exit with code 0 if the child got signaled.
224 exit_code = 0; 222 exit_code = 0;
225 } 223 }
226 } 224 }
227 _exit(exit_code); 225 _exit(exit_code);
228 } 226 }
229 227
230 static bool MoveToNewNamespaces() { 228 static bool MoveToNewNamespaces() {
231 // These are the sets of flags which we'll try, in order. 229 // These are the sets of flags which we'll try, in order.
232 const int kCloneExtraFlags[] = { 230 const int kCloneExtraFlags[] = {CLONE_NEWPID | CLONE_NEWNET, CLONE_NEWPID, };
233 CLONE_NEWPID | CLONE_NEWNET,
234 CLONE_NEWPID,
235 };
236 231
237 // We need to close kZygoteIdFd before the child can continue. We use this 232 // We need to close kZygoteIdFd before the child can continue. We use this
238 // socketpair to tell the child when to continue; 233 // socketpair to tell the child when to continue;
239 int sync_fds[2]; 234 int sync_fds[2];
240 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sync_fds)) { 235 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sync_fds)) {
241 FatalError("Failed to create a socketpair"); 236 FatalError("Failed to create a socketpair");
242 } 237 }
243 238
244 for (size_t i = 0; 239 for (size_t i = 0; i < sizeof(kCloneExtraFlags) / sizeof(kCloneExtraFlags[0]);
245 i < sizeof(kCloneExtraFlags) / sizeof(kCloneExtraFlags[0]);
246 i++) { 240 i++) {
247 pid_t pid = syscall(__NR_clone, SIGCHLD | kCloneExtraFlags[i], 0, 0, 0); 241 pid_t pid = syscall(__NR_clone, SIGCHLD | kCloneExtraFlags[i], 0, 0, 0);
248 const int clone_errno = errno; 242 const int clone_errno = errno;
249 243
250 if (pid > 0) { 244 if (pid > 0) {
251 if (!DropRoot()) { 245 if (!DropRoot()) {
252 FatalError("Could not drop privileges"); 246 FatalError("Could not drop privileges");
253 } else { 247 } else {
254 if (close(sync_fds[0]) || shutdown(sync_fds[1], SHUT_RD)) 248 if (close(sync_fds[0]) || shutdown(sync_fds[1], SHUT_RD))
255 FatalError("Could not close socketpair"); 249 FatalError("Could not close socketpair");
(...skipping 123 matching lines...) Expand 10 before | Expand all | Expand 10 after
379 free(saved_envvar); 373 free(saved_envvar);
380 } 374 }
381 375
382 return true; 376 return true;
383 } 377 }
384 378
385 bool CheckAndExportApiVersion() { 379 bool CheckAndExportApiVersion() {
386 // Check the environment to see if a specific API version was requested. 380 // Check the environment to see if a specific API version was requested.
387 // assume version 0 if none. 381 // assume version 0 if none.
388 long api_number = -1; 382 long api_number = -1;
389 char *api_string = getenv(kSandboxEnvironmentApiRequest); 383 char* api_string = getenv(kSandboxEnvironmentApiRequest);
390 if (!api_string) { 384 if (!api_string) {
391 api_number = 0; 385 api_number = 0;
392 } else { 386 } else {
393 errno = 0; 387 errno = 0;
394 char* endptr = NULL; 388 char* endptr = NULL;
395 api_number = strtol(api_string, &endptr, 10); 389 api_number = strtol(api_string, &endptr, 10);
396 if (!endptr || *endptr || errno != 0) 390 if (!endptr || *endptr || errno != 0)
397 return false; 391 return false;
398 } 392 }
399 393
400 // Warn only for now. 394 // Warn only for now.
401 if (api_number != kSUIDSandboxApiNumber) { 395 if (api_number != kSUIDSandboxApiNumber) {
402 fprintf(stderr, "The setuid sandbox provides API version %ld, " 396 fprintf(
403 "but you need %ld\n" 397 stderr,
404 "Please read " 398 "The setuid sandbox provides API version %ld, "
405 "https://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment." 399 "but you need %ld\n"
406 "\n\n", 400 "Please read "
407 kSUIDSandboxApiNumber, 401 "https://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment."
408 api_number); 402 "\n\n",
403 kSUIDSandboxApiNumber,
404 api_number);
409 } 405 }
410 406
411 // Export our version so that the sandboxed process can verify it did not 407 // Export our version so that the sandboxed process can verify it did not
412 // use an old sandbox. 408 // use an old sandbox.
413 char version_string[64]; 409 char version_string[64];
414 snprintf(version_string, sizeof(version_string), "%ld", 410 snprintf(
415 kSUIDSandboxApiNumber); 411 version_string, sizeof(version_string), "%ld", kSUIDSandboxApiNumber);
416 if (setenv(kSandboxEnvironmentApiProvides, version_string, 1)) { 412 if (setenv(kSandboxEnvironmentApiProvides, version_string, 1)) {
417 perror("setenv"); 413 perror("setenv");
418 return false; 414 return false;
419 } 415 }
420 416
421 return true; 417 return true;
422 } 418 }
423 419
424 int main(int argc, char **argv) { 420 int main(int argc, char** argv) {
425 if (argc <= 1) { 421 if (argc <= 1) {
426 if (argc <= 0) { 422 if (argc <= 0) {
427 return 1; 423 return 1;
428 } 424 }
429 425
430 fprintf(stderr, "Usage: %s <renderer process> <args...>\n", argv[0]); 426 fprintf(stderr, "Usage: %s <renderer process> <args...>\n", argv[0]);
431 return 1; 427 return 1;
432 } 428 }
433 429
434 // Allow someone to query our API version 430 // Allow someone to query our API version
(...skipping 34 matching lines...) Expand 10 before | Expand all | Expand 10 after
469 char* endptr = NULL; 465 char* endptr = NULL;
470 long score; 466 long score;
471 errno = 0; 467 errno = 0;
472 unsigned long pid_ul = strtoul(argv[2], &endptr, 10); 468 unsigned long pid_ul = strtoul(argv[2], &endptr, 10);
473 if (pid_ul == ULONG_MAX || !endptr || *endptr || errno != 0) 469 if (pid_ul == ULONG_MAX || !endptr || *endptr || errno != 0)
474 return 1; 470 return 1;
475 pid_t pid = pid_ul; 471 pid_t pid = pid_ul;
476 endptr = NULL; 472 endptr = NULL;
477 errno = 0; 473 errno = 0;
478 score = strtol(argv[3], &endptr, 10); 474 score = strtol(argv[3], &endptr, 10);
479 if (score == LONG_MAX || score == LONG_MIN || 475 if (score == LONG_MAX || score == LONG_MIN || !endptr || *endptr ||
480 !endptr || *endptr || errno != 0) 476 errno != 0) {
481 return 1; 477 return 1;
478 }
482 return AdjustOOMScore(pid, score); 479 return AdjustOOMScore(pid, score);
483 } 480 }
484 481
485 // Protect the core setuid sandbox functionality with an API version 482 // Protect the core setuid sandbox functionality with an API version
486 if (!CheckAndExportApiVersion()) { 483 if (!CheckAndExportApiVersion()) {
487 return 1; 484 return 1;
488 } 485 }
489 486
490 if (geteuid() != 0) { 487 if (geteuid() != 0) {
491 fprintf(stderr, 488 fprintf(stderr,
492 "The setuid sandbox is not running as root. Common causes:\n" 489 "The setuid sandbox is not running as root. Common causes:\n"
493 " * An unprivileged process using ptrace on it, like a debugger.\n" 490 " * An unprivileged process using ptrace on it, like a debugger.\n"
494 " * A parent process set prctl(PR_SET_NO_NEW_PRIVS, ...)\n"); 491 " * A parent process set prctl(PR_SET_NO_NEW_PRIVS, ...)\n");
495 } 492 }
496 493
497 if (!MoveToNewNamespaces()) 494 if (!MoveToNewNamespaces())
498 return 1; 495 return 1;
499 if (!SpawnChrootHelper()) 496 if (!SpawnChrootHelper())
500 return 1; 497 return 1;
501 if (!DropRoot()) 498 if (!DropRoot())
502 return 1; 499 return 1;
503 if (!SetupChildEnvironment()) 500 if (!SetupChildEnvironment())
504 return 1; 501 return 1;
505 502
506 execv(argv[1], &argv[1]); 503 execv(argv[1], &argv[1]);
507 FatalError("execv failed"); 504 FatalError("execv failed");
508 505
509 return 1; 506 return 1;
510 } 507 }
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