Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 1 | /* Copyright (c) 2011 The Chromium OS Authors. All rights reserved. |
| 2 | * Use of this source code is governed by a BSD-style license that can be |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 3 | * found in the LICENSE file. |
| 4 | */ |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 5 | |
| 6 | #define _BSD_SOURCE |
| 7 | #define _GNU_SOURCE |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 8 | #include <ctype.h> |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 9 | #include <errno.h> |
| 10 | #include <grp.h> |
| 11 | #include <inttypes.h> |
Will Drewry | fe4a372 | 2011-09-16 14:50:50 -0500 | [diff] [blame] | 12 | #include <limits.h> |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 13 | #include <linux/capability.h> |
| 14 | #include <linux/securebits.h> |
| 15 | #include <pwd.h> |
| 16 | #include <sched.h> |
| 17 | #include <signal.h> |
Will Drewry | 2f54b6a | 2011-09-16 13:45:31 -0500 | [diff] [blame] | 18 | #include <stdarg.h> |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 19 | #include <stdio.h> |
| 20 | #include <stdlib.h> |
| 21 | #include <string.h> |
| 22 | #include <syscall.h> |
| 23 | #include <sys/capability.h> |
| 24 | #include <sys/mount.h> |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 25 | #include <sys/param.h> |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 26 | #include <sys/prctl.h> |
| 27 | #include <sys/wait.h> |
| 28 | #include <syslog.h> |
| 29 | #include <unistd.h> |
| 30 | |
| 31 | #include "libminijail.h" |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 32 | #include "libsyscalls.h" |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 33 | #include "libminijail-private.h" |
| 34 | |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 35 | /* Until these are reliably available in linux/prctl.h */ |
| 36 | #ifndef PR_SET_SECCOMP_FILTER |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 37 | # define PR_SECCOMP_FILTER_SYSCALL 0 |
| 38 | # define PR_SECCOMP_FILTER_EVENT 1 |
| 39 | # define PR_GET_SECCOMP_FILTER 35 |
| 40 | # define PR_SET_SECCOMP_FILTER 36 |
| 41 | # define PR_CLEAR_SECCOMP_FILTER 37 |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 42 | #endif |
| 43 | |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 44 | #define die(_msg, ...) do { \ |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 45 | syslog(LOG_ERR, "libminijail: " _msg, ## __VA_ARGS__); \ |
| 46 | abort(); \ |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 47 | } while (0) |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 48 | |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 49 | #define pdie(_msg, ...) \ |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 50 | die(_msg ": %s", ## __VA_ARGS__, strerror(errno)) |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 51 | |
| 52 | #define warn(_msg, ...) \ |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 53 | syslog(LOG_WARNING, "libminijail: " _msg, ## __VA_ARGS__) |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 54 | |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 55 | struct seccomp_filter { |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 56 | int nr; |
| 57 | char *filter; |
| 58 | struct seccomp_filter *next, *prev; |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 59 | }; |
| 60 | |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 61 | struct binding { |
| 62 | char *src; |
| 63 | char *dest; |
| 64 | int writeable; |
| 65 | struct binding *next; |
| 66 | }; |
| 67 | |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 68 | struct minijail { |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 69 | struct { |
| 70 | int uid:1; |
| 71 | int gid:1; |
| 72 | int caps:1; |
| 73 | int vfs:1; |
| 74 | int pids:1; |
| 75 | int seccomp:1; |
| 76 | int readonly:1; |
| 77 | int usergroups:1; |
| 78 | int ptrace:1; |
| 79 | int seccomp_filter:1; |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 80 | int chroot:1; |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 81 | } flags; |
| 82 | uid_t uid; |
| 83 | gid_t gid; |
| 84 | gid_t usergid; |
| 85 | char *user; |
| 86 | uint64_t caps; |
| 87 | pid_t initpid; |
| 88 | int filter_count; |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 89 | int binding_count; |
| 90 | char *chrootdir; |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 91 | struct seccomp_filter *filters; |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 92 | struct binding *bindings_head; |
| 93 | struct binding *bindings_tail; |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 94 | }; |
| 95 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 96 | struct minijail *minijail_new(void) |
| 97 | { |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 98 | return calloc(1, sizeof(struct minijail)); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 99 | } |
| 100 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 101 | void minijail_change_uid(struct minijail *j, uid_t uid) |
| 102 | { |
| 103 | if (uid == 0) |
| 104 | die("useless change to uid 0"); |
| 105 | j->uid = uid; |
| 106 | j->flags.uid = 1; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 107 | } |
| 108 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 109 | void minijail_change_gid(struct minijail *j, gid_t gid) |
| 110 | { |
| 111 | if (gid == 0) |
| 112 | die("useless change to gid 0"); |
| 113 | j->gid = gid; |
| 114 | j->flags.gid = 1; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 115 | } |
| 116 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 117 | int minijail_change_user(struct minijail *j, const char *user) |
| 118 | { |
| 119 | char *buf = NULL; |
| 120 | struct passwd pw; |
| 121 | struct passwd *ppw = NULL; |
| 122 | ssize_t sz = sysconf(_SC_GETPW_R_SIZE_MAX); |
| 123 | if (sz == -1) |
| 124 | sz = 65536; /* your guess is as good as mine... */ |
Elly Jones | eb300c5 | 2011-09-22 14:35:43 -0400 | [diff] [blame] | 125 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 126 | /* sysconf(_SC_GETPW_R_SIZE_MAX), under glibc, is documented to return |
| 127 | * the maximum needed size of the buffer, so we don't have to search. |
| 128 | */ |
| 129 | buf = malloc(sz); |
| 130 | if (!buf) |
| 131 | return -ENOMEM; |
| 132 | getpwnam_r(user, &pw, buf, sz, &ppw); |
| 133 | free(buf); |
| 134 | if (!ppw) |
| 135 | return -errno; |
| 136 | minijail_change_uid(j, ppw->pw_uid); |
| 137 | j->user = strdup(user); |
| 138 | if (!j->user) |
| 139 | return -ENOMEM; |
| 140 | j->usergid = ppw->pw_gid; |
| 141 | return 0; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 142 | } |
| 143 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 144 | int minijail_change_group(struct minijail *j, const char *group) |
| 145 | { |
| 146 | char *buf = NULL; |
| 147 | struct group gr; |
| 148 | struct group *pgr = NULL; |
| 149 | ssize_t sz = sysconf(_SC_GETGR_R_SIZE_MAX); |
| 150 | if (sz == -1) |
| 151 | sz = 65536; /* and mine is as good as yours, really */ |
Elly Jones | eb300c5 | 2011-09-22 14:35:43 -0400 | [diff] [blame] | 152 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 153 | /* sysconf(_SC_GETGR_R_SIZE_MAX), under glibc, is documented to return |
| 154 | * the maximum needed size of the buffer, so we don't have to search. |
| 155 | */ |
| 156 | buf = malloc(sz); |
| 157 | if (!buf) |
| 158 | return -ENOMEM; |
| 159 | getgrnam_r(group, &gr, buf, sz, &pgr); |
| 160 | free(buf); |
| 161 | if (!pgr) |
| 162 | return -errno; |
| 163 | minijail_change_gid(j, pgr->gr_gid); |
| 164 | return 0; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 165 | } |
| 166 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 167 | void minijail_use_seccomp(struct minijail *j) |
| 168 | { |
| 169 | j->flags.seccomp = 1; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 170 | } |
| 171 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 172 | void minijail_use_seccomp_filter(struct minijail *j) |
| 173 | { |
| 174 | j->flags.seccomp_filter = 1; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 175 | } |
| 176 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 177 | void minijail_use_caps(struct minijail *j, uint64_t capmask) |
| 178 | { |
| 179 | j->caps = capmask; |
| 180 | j->flags.caps = 1; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 181 | } |
| 182 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 183 | void minijail_namespace_vfs(struct minijail *j) |
| 184 | { |
| 185 | j->flags.vfs = 1; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 186 | } |
| 187 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 188 | void minijail_namespace_pids(struct minijail *j) |
| 189 | { |
| 190 | j->flags.pids = 1; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 191 | } |
| 192 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 193 | void minijail_remount_readonly(struct minijail *j) |
| 194 | { |
| 195 | j->flags.vfs = 1; |
| 196 | j->flags.readonly = 1; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 197 | } |
| 198 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 199 | void minijail_inherit_usergroups(struct minijail *j) |
| 200 | { |
| 201 | j->flags.usergroups = 1; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 202 | } |
| 203 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 204 | void minijail_disable_ptrace(struct minijail *j) |
| 205 | { |
| 206 | j->flags.ptrace = 1; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 207 | } |
| 208 | |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 209 | int minijail_enter_chroot(struct minijail *j, const char *dir) { |
| 210 | if (j->chrootdir) |
| 211 | return -EINVAL; |
| 212 | j->chrootdir = strdup(dir); |
| 213 | if (!j->chrootdir) |
| 214 | return -ENOMEM; |
| 215 | j->flags.chroot = 1; |
| 216 | return 0; |
| 217 | } |
| 218 | |
| 219 | int minijail_bind(struct minijail *j, const char *src, const char *dest, |
| 220 | int writeable) { |
| 221 | struct binding *b; |
| 222 | |
| 223 | if (*dest != '/') |
| 224 | return -EINVAL; |
| 225 | b = calloc(1, sizeof(*b)); |
| 226 | if (!b) |
| 227 | return -ENOMEM; |
| 228 | b->dest = strdup(dest); |
| 229 | if (!b->dest) |
| 230 | goto error; |
| 231 | b->src = strdup(src); |
| 232 | if (!b->src) |
| 233 | goto error; |
| 234 | b->writeable = writeable; |
| 235 | |
| 236 | syslog(LOG_INFO, "libminijail: bind %s -> %s", src, dest); |
| 237 | |
| 238 | /* Force vfs namespacing so the bind mounts don't leak out into the |
| 239 | * containing vfs namespace. |
| 240 | */ |
| 241 | minijail_namespace_vfs(j); |
| 242 | |
| 243 | if (j->bindings_tail) |
| 244 | j->bindings_tail->next = b; |
| 245 | else |
| 246 | j->bindings_head = b; |
| 247 | j->bindings_tail = b; |
| 248 | j->binding_count++; |
| 249 | |
| 250 | return 0; |
| 251 | |
| 252 | error: |
| 253 | free(b->src); |
| 254 | free(b->dest); |
| 255 | free(b); |
| 256 | return -ENOMEM; |
| 257 | } |
| 258 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 259 | int minijail_add_seccomp_filter(struct minijail *j, int nr, const char *filter) |
| 260 | { |
| 261 | struct seccomp_filter *sf; |
| 262 | if (!filter || nr < 0) |
| 263 | return -EINVAL; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 264 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 265 | sf = malloc(sizeof(*sf)); |
| 266 | if (!sf) |
| 267 | return -ENOMEM; |
| 268 | sf->nr = nr; |
| 269 | sf->filter = strndup(filter, MINIJAIL_MAX_SECCOMP_FILTER_LINE); |
| 270 | if (!sf->filter) { |
| 271 | free(sf); |
| 272 | return -ENOMEM; |
| 273 | } |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 274 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 275 | j->filter_count++; |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 276 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 277 | if (!j->filters) { |
| 278 | j->filters = sf; |
| 279 | sf->next = sf; |
| 280 | sf->prev = sf; |
| 281 | return 0; |
| 282 | } |
| 283 | sf->next = j->filters; |
| 284 | sf->prev = j->filters->prev; |
| 285 | sf->prev->next = sf; |
| 286 | j->filters->prev = sf; |
| 287 | return 0; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 288 | } |
| 289 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 290 | int minijail_lookup_syscall(const char *name) |
| 291 | { |
| 292 | const struct syscall_entry *entry = syscall_table; |
| 293 | for (; entry->name && entry->nr >= 0; ++entry) |
| 294 | if (!strcmp(entry->name, name)) |
| 295 | return entry->nr; |
| 296 | return -1; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 297 | } |
| 298 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 299 | static char *strip(char *s) |
| 300 | { |
| 301 | char *end; |
| 302 | while (*s && isblank(*s)) |
| 303 | s++; |
| 304 | end = s + strlen(s) - 1; |
| 305 | while (*end && (isblank(*end) || *end == '\n')) |
| 306 | end--; |
| 307 | *(end + 1) = '\0'; |
| 308 | return s; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 309 | } |
| 310 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 311 | void minijail_parse_seccomp_filters(struct minijail *j, const char *path) |
| 312 | { |
| 313 | FILE *file = fopen(path, "r"); |
| 314 | char line[MINIJAIL_MAX_SECCOMP_FILTER_LINE]; |
| 315 | int count = 1; |
| 316 | if (!file) |
| 317 | pdie("failed to open seccomp filters file"); |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 318 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 319 | /* Format is simple: |
| 320 | * syscall_name<COLON><FILTER STRING>[\n|EOF] |
| 321 | * #...comment... |
| 322 | * <empty line? |
| 323 | */ |
| 324 | while (fgets(line, sizeof(line), file)) { |
| 325 | char *filter = line; |
| 326 | char *name = strsep(&filter, ":"); |
| 327 | char *name_end = NULL; |
| 328 | int nr = -1; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 329 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 330 | if (!name) |
| 331 | die("invalid filter on line %d", count); |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 332 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 333 | name = strip(name); |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 334 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 335 | if (!filter) { |
| 336 | if (strlen(name)) |
| 337 | die("invalid filter on line %d", count); |
| 338 | /* Allow empty lines */ |
| 339 | continue; |
| 340 | } |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 341 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 342 | /* Allow comment lines */ |
| 343 | if (*name == '#') |
| 344 | continue; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 345 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 346 | filter = strip(filter); |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 347 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 348 | /* Take direct syscall numbers */ |
| 349 | nr = strtol(name, &name_end, 0); |
| 350 | /* Or fail-over to using names */ |
| 351 | if (*name_end != '\0') |
| 352 | nr = minijail_lookup_syscall(name); |
| 353 | if (nr < 0) |
| 354 | die("syscall '%s' unknown", name); |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 355 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 356 | if (minijail_add_seccomp_filter(j, nr, filter)) |
| 357 | pdie("failed to add filter for syscall '%s'", name); |
| 358 | } |
| 359 | fclose(file); |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 360 | } |
| 361 | |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 362 | struct marshal_state { |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 363 | size_t available; |
| 364 | size_t total; |
| 365 | char *buf; |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 366 | }; |
| 367 | |
| 368 | static void marshal_state_init(struct marshal_state *state, |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 369 | char *buf, size_t available) |
| 370 | { |
| 371 | state->available = available; |
| 372 | state->buf = buf; |
| 373 | state->total = 0; |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 374 | } |
| 375 | |
| 376 | static void marshal_append(struct marshal_state *state, |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 377 | char *src, size_t length) |
| 378 | { |
| 379 | size_t copy_len = MIN(state->available, length); |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 380 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 381 | /* Up to |available| will be written. */ |
| 382 | if (copy_len) { |
| 383 | memcpy(state->buf, src, copy_len); |
| 384 | state->buf += copy_len; |
| 385 | state->available -= copy_len; |
| 386 | } |
| 387 | /* |total| will contain the expected length. */ |
| 388 | state->total += length; |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 389 | } |
| 390 | |
| 391 | static void minijail_marshal_helper(struct marshal_state *state, |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 392 | const struct minijail *j) |
| 393 | { |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 394 | struct binding *b = NULL; |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 395 | marshal_append(state, (char *)j, sizeof(*j)); |
| 396 | if (j->user) |
| 397 | marshal_append(state, j->user, strlen(j->user) + 1); |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 398 | if (j->chrootdir) |
| 399 | marshal_append(state, j->chrootdir, strlen(j->chrootdir) + 1); |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 400 | if (j->flags.seccomp_filter && j->filters) { |
| 401 | struct seccomp_filter *f = j->filters; |
| 402 | do { |
| 403 | marshal_append(state, (char *)&f->nr, sizeof(f->nr)); |
| 404 | marshal_append(state, f->filter, strlen(f->filter) + 1); |
| 405 | f = f->next; |
| 406 | } while (f != j->filters); |
| 407 | } |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 408 | for (b = j->bindings_head; b; b = b->next) { |
| 409 | marshal_append(state, b->src, strlen(b->src) + 1); |
| 410 | marshal_append(state, b->dest, strlen(b->dest) + 1); |
| 411 | marshal_append(state, (char *)&b->writeable, sizeof(b->writeable)); |
| 412 | } |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 413 | } |
| 414 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 415 | size_t minijail_size(const struct minijail *j) |
| 416 | { |
| 417 | struct marshal_state state; |
| 418 | marshal_state_init(&state, NULL, 0); |
| 419 | minijail_marshal_helper(&state, j); |
| 420 | return state.total; |
Will Drewry | 2ddaad0 | 2011-09-16 11:36:08 -0500 | [diff] [blame] | 421 | } |
| 422 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 423 | int minijail_marshal(const struct minijail *j, char *buf, size_t available) |
| 424 | { |
| 425 | struct marshal_state state; |
| 426 | marshal_state_init(&state, buf, available); |
| 427 | minijail_marshal_helper(&state, j); |
| 428 | return (state.total > available); |
Will Drewry | 2ddaad0 | 2011-09-16 11:36:08 -0500 | [diff] [blame] | 429 | } |
| 430 | |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 431 | /* consumebytes: consumes @length bytes from a buffer @buf of length @buflength |
| 432 | * @length Number of bytes to consume |
| 433 | * @buf Buffer to consume from |
| 434 | * @buflength Size of @buf |
| 435 | * |
| 436 | * Returns a pointer to the base of the bytes, or NULL for errors. |
| 437 | */ |
| 438 | static void *consumebytes(size_t length, char **buf, size_t *buflength) { |
| 439 | char *p = *buf; |
| 440 | if (length > *buflength) |
| 441 | return NULL; |
| 442 | *buf += length; |
| 443 | *buflength -= length; |
| 444 | return p; |
| 445 | } |
| 446 | |
| 447 | /* consumestr: consumes a C string from a buffer @buf of length @length |
| 448 | * @buf Buffer to consume |
| 449 | * @length Length of buffer |
| 450 | * |
| 451 | * Returns a pointer to the base of the string, or NULL for errors. |
| 452 | */ |
| 453 | static char *consumestr(char **buf, size_t *buflength) { |
| 454 | size_t len = strnlen(*buf, *buflength); |
| 455 | if (len == *buflength) |
| 456 | /* There's no null-terminator */ |
| 457 | return NULL; |
| 458 | return consumebytes(len + 1, buf, buflength); |
| 459 | } |
| 460 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 461 | int minijail_unmarshal(struct minijail *j, char *serialized, size_t length) |
| 462 | { |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 463 | int i; |
| 464 | int count; |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 465 | if (length < sizeof(*j)) |
| 466 | return -EINVAL; |
| 467 | memcpy((void *)j, serialized, sizeof(*j)); |
| 468 | serialized += sizeof(*j); |
| 469 | length -= sizeof(*j); |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 470 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 471 | if (j->user) { /* stale pointer */ |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 472 | char *user = consumestr(&serialized, &length); |
| 473 | if (!user) |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 474 | return -EINVAL; |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 475 | j->user = strdup(user); |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 476 | } |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 477 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 478 | if (j->flags.seccomp_filter && j->filter_count) { |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 479 | count = j->filter_count; |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 480 | /* Let add_seccomp_filter recompute the value. */ |
| 481 | j->filter_count = 0; |
| 482 | j->filters = NULL; /* Don't follow the stale pointer. */ |
| 483 | for (; count > 0; --count) { |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 484 | int *nr = (int *)consumebytes(sizeof(*nr), &serialized, |
| 485 | &length); |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 486 | char *filter; |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 487 | if (!nr) |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 488 | return -EINVAL; |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 489 | filter = consumestr(&serialized, &length); |
| 490 | if (!filter) |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 491 | return -EINVAL; |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 492 | if (minijail_add_seccomp_filter(j, *nr, filter)) |
| 493 | return -EINVAL; |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 494 | } |
| 495 | } |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 496 | |
| 497 | count = j->binding_count; |
| 498 | j->bindings_head = NULL; |
| 499 | j->bindings_tail = NULL; |
| 500 | j->binding_count = 0; |
| 501 | for (i = 0; i < count; ++i) { |
| 502 | int *writeable; |
| 503 | const char *dest; |
| 504 | const char *src = consumestr(&serialized, &length); |
| 505 | if (!src) |
| 506 | return -EINVAL; |
| 507 | dest = consumestr(&serialized, &length); |
| 508 | if (!dest) |
| 509 | return -EINVAL; |
| 510 | writeable = consumebytes(sizeof(*writeable), &serialized, &length); |
| 511 | if (!writeable) |
| 512 | return -EINVAL; |
| 513 | if (minijail_bind(j, src, dest, *writeable)) |
| 514 | return -EINVAL; |
| 515 | } |
| 516 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 517 | return 0; |
Will Drewry | 2ddaad0 | 2011-09-16 11:36:08 -0500 | [diff] [blame] | 518 | } |
| 519 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 520 | void minijail_preenter(struct minijail *j) |
| 521 | { |
| 522 | /* Strip out options which are minijail_run() only. */ |
| 523 | j->flags.vfs = 0; |
| 524 | j->flags.readonly = 0; |
| 525 | j->flags.pids = 0; |
Will Drewry | fe4a372 | 2011-09-16 14:50:50 -0500 | [diff] [blame] | 526 | } |
| 527 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 528 | void minijail_preexec(struct minijail *j) |
| 529 | { |
| 530 | int vfs = j->flags.vfs; |
| 531 | int readonly = j->flags.readonly; |
| 532 | if (j->user) |
| 533 | free(j->user); |
| 534 | j->user = NULL; |
| 535 | memset(&j->flags, 0, sizeof(j->flags)); |
| 536 | /* Now restore anything we meant to keep. */ |
| 537 | j->flags.vfs = vfs; |
| 538 | j->flags.readonly = readonly; |
| 539 | /* Note, pidns will already have been used before this call. */ |
Will Drewry | 2ddaad0 | 2011-09-16 11:36:08 -0500 | [diff] [blame] | 540 | } |
| 541 | |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 542 | /* bind_one: Applies bindings from @b for @j, recursing as needed. |
| 543 | * @j Minijail these bindings are for |
| 544 | * @b Head of list of bindings |
| 545 | * |
| 546 | * Returns 0 for success. |
| 547 | */ |
| 548 | static int bind_one(const struct minijail *j, struct binding *b) { |
| 549 | int ret = 0; |
| 550 | char *dest = NULL; |
| 551 | int mflags = MS_BIND | (b->writeable ? 0 : MS_RDONLY); |
| 552 | if (ret) |
| 553 | return ret; |
| 554 | /* dest has a leading "/" */ |
| 555 | if (asprintf(&dest, "%s%s", j->chrootdir, b->dest) < 0) |
| 556 | return -ENOMEM; |
| 557 | ret = mount(b->src, dest, NULL, mflags, NULL); |
| 558 | if (ret) |
| 559 | pdie("bind: %s -> %s", b->src, dest); |
| 560 | free(dest); |
| 561 | if (b->next) |
| 562 | return bind_one(j, b->next); |
| 563 | return ret; |
| 564 | } |
| 565 | |
| 566 | static int enter_chroot(const struct minijail *j) { |
| 567 | int ret; |
| 568 | if (j->bindings_head && (ret = bind_one(j, j->bindings_head))) |
| 569 | return ret; |
| 570 | |
| 571 | if (chroot(j->chrootdir)) |
| 572 | return -errno; |
| 573 | |
| 574 | if (chdir("/")) |
| 575 | return -errno; |
| 576 | |
| 577 | return 0; |
| 578 | } |
| 579 | |
| 580 | |
| 581 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 582 | static int remount_readonly(void) |
| 583 | { |
| 584 | const char *kProcPath = "/proc"; |
| 585 | const unsigned int kSafeFlags = MS_NODEV | MS_NOEXEC | MS_NOSUID; |
| 586 | /* Right now, we're holding a reference to our parent's old mount of |
| 587 | * /proc in our namespace, which means using MS_REMOUNT here would |
| 588 | * mutate our parent's mount as well, even though we're in a VFS |
| 589 | * namespace (!). Instead, remove their mount from our namespace |
| 590 | * and make our own. |
| 591 | */ |
| 592 | if (umount(kProcPath)) |
| 593 | return -errno; |
| 594 | if (mount("", kProcPath, "proc", kSafeFlags | MS_RDONLY, "")) |
| 595 | return -errno; |
| 596 | return 0; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 597 | } |
| 598 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 599 | static void drop_caps(const struct minijail *j) |
| 600 | { |
| 601 | cap_t caps = cap_get_proc(); |
| 602 | cap_value_t raise_flag[1]; |
| 603 | unsigned int i; |
| 604 | if (!caps) |
| 605 | die("can't get process caps"); |
| 606 | if (cap_clear_flag(caps, CAP_INHERITABLE)) |
| 607 | die("can't clear inheritable caps"); |
| 608 | if (cap_clear_flag(caps, CAP_EFFECTIVE)) |
| 609 | die("can't clear effective caps"); |
| 610 | if (cap_clear_flag(caps, CAP_PERMITTED)) |
| 611 | die("can't clear permitted caps"); |
| 612 | for (i = 0; i < sizeof(j->caps) * 8 && cap_valid((int)i); ++i) { |
| 613 | if (i != CAP_SETPCAP && !(j->caps & (1 << i))) |
| 614 | continue; |
| 615 | raise_flag[0] = i; |
| 616 | if (cap_set_flag(caps, CAP_EFFECTIVE, 1, raise_flag, CAP_SET)) |
| 617 | die("can't add effective cap"); |
| 618 | if (cap_set_flag(caps, CAP_PERMITTED, 1, raise_flag, CAP_SET)) |
| 619 | die("can't add permitted cap"); |
| 620 | if (cap_set_flag(caps, CAP_INHERITABLE, 1, raise_flag, CAP_SET)) |
| 621 | die("can't add inheritable cap"); |
| 622 | } |
| 623 | if (cap_set_proc(caps)) |
| 624 | die("can't apply cleaned capset"); |
| 625 | cap_free(caps); |
| 626 | for (i = 0; i < sizeof(j->caps) * 8 && cap_valid((int)i); ++i) { |
| 627 | if (j->caps & (1 << i)) |
| 628 | continue; |
| 629 | if (prctl(PR_CAPBSET_DROP, i)) |
| 630 | pdie("prctl(PR_CAPBSET_DROP)"); |
| 631 | } |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 632 | } |
| 633 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 634 | static int setup_seccomp_filters(const struct minijail *j) |
| 635 | { |
| 636 | const struct seccomp_filter *sf = j->filters; |
| 637 | int ret = 0; |
| 638 | int broaden = 0; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 639 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 640 | /* No filters installed isn't necessarily an error. */ |
| 641 | if (!sf) |
| 642 | return ret; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 643 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 644 | do { |
| 645 | errno = 0; |
| 646 | ret = prctl(PR_SET_SECCOMP_FILTER, PR_SECCOMP_FILTER_SYSCALL, |
| 647 | sf->nr, broaden ? "1" : sf->filter); |
| 648 | if (ret) { |
| 649 | switch (errno) { |
| 650 | case ENOSYS: |
| 651 | /* TODO(wad) make this a config option */ |
| 652 | if (broaden) |
| 653 | die("CONFIG_SECCOMP_FILTER is not" |
| 654 | "supported by your kernel"); |
| 655 | warn("missing CONFIG_FTRACE_SYSCALLS; relaxing" |
| 656 | "the filter for %d", sf->nr); |
| 657 | broaden = 1; |
| 658 | continue; |
| 659 | case E2BIG: |
| 660 | warn("seccomp filter too long: %d", sf->nr); |
| 661 | pdie("filter too long"); |
| 662 | case ENOSPC: |
| 663 | pdie("too many seccomp filters"); |
| 664 | case EPERM: |
| 665 | warn("syscall filter disallowed for %d", |
| 666 | sf->nr); |
| 667 | pdie("failed to install seccomp filter"); |
| 668 | case EINVAL: |
| 669 | warn("seccomp filter or call method is" |
| 670 | " invalid. %d:'%s'", sf->nr, sf->filter); |
| 671 | default: |
| 672 | pdie("failed to install seccomp filter"); |
| 673 | } |
| 674 | } |
| 675 | sf = sf->next; |
| 676 | broaden = 0; |
| 677 | } while (sf != j->filters); |
| 678 | return ret; |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 679 | } |
| 680 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 681 | void minijail_enter(const struct minijail *j) |
| 682 | { |
| 683 | if (j->flags.pids) |
| 684 | die("tried to enter a pid-namespaced jail;" |
| 685 | "try minijail_run()?"); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 686 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 687 | if (j->flags.seccomp_filter && setup_seccomp_filters(j)) |
| 688 | pdie("failed to configure seccomp filters"); |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 689 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 690 | if (j->flags.usergroups && !j->user) |
| 691 | die("usergroup inheritance without username"); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 692 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 693 | /* We can't recover from failures if we've dropped privileges partially, |
| 694 | * so we don't even try. If any of our operations fail, we abort() the |
| 695 | * entire process. |
| 696 | */ |
| 697 | if (j->flags.vfs && unshare(CLONE_NEWNS)) |
| 698 | pdie("unshare"); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 699 | |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 700 | if (j->flags.chroot && enter_chroot(j)) |
| 701 | pdie("chroot"); |
| 702 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 703 | if (j->flags.readonly && remount_readonly()) |
| 704 | pdie("remount"); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 705 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 706 | if (j->flags.caps) { |
| 707 | /* POSIX capabilities are a bit tricky. If we drop our |
| 708 | * capability to change uids, our attempt to use setuid() |
| 709 | * below will fail. Hang on to root caps across setuid(), then |
| 710 | * lock securebits. |
| 711 | */ |
| 712 | if (prctl(PR_SET_KEEPCAPS, 1)) |
| 713 | pdie("prctl(PR_SET_KEEPCAPS)"); |
| 714 | if (prctl |
| 715 | (PR_SET_SECUREBITS, SECURE_ALL_BITS | SECURE_ALL_LOCKS)) |
| 716 | pdie("prctl(PR_SET_SECUREBITS)"); |
| 717 | } |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 718 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 719 | if (j->flags.usergroups) { |
| 720 | if (initgroups(j->user, j->usergid)) |
| 721 | pdie("initgroups"); |
| 722 | } else { |
| 723 | /* Only attempt to clear supplemental groups if we are changing |
| 724 | * users. */ |
| 725 | if ((j->uid || j->gid) && setgroups(0, NULL)) |
| 726 | pdie("setgroups"); |
| 727 | } |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 728 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 729 | if (j->flags.gid && setresgid(j->gid, j->gid, j->gid)) |
| 730 | pdie("setresgid"); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 731 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 732 | if (j->flags.uid && setresuid(j->uid, j->uid, j->uid)) |
| 733 | pdie("setresuid"); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 734 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 735 | if (j->flags.caps) |
| 736 | drop_caps(j); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 737 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 738 | /* seccomp has to come last since it cuts off all the other |
| 739 | * privilege-dropping syscalls :) |
| 740 | */ |
| 741 | if (j->flags.seccomp_filter && prctl(PR_SET_SECCOMP, 13)) |
| 742 | pdie("prctl(PR_SET_SECCOMP, 13)"); |
Will Drewry | 32ac9f5 | 2011-08-18 21:36:27 -0500 | [diff] [blame] | 743 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 744 | if (j->flags.seccomp && prctl(PR_SET_SECCOMP, 1)) |
| 745 | pdie("prctl(PR_SET_SECCOMP)"); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 746 | } |
| 747 | |
| 748 | static int init_exitstatus = 0; |
| 749 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 750 | static void init_term(int __attribute__ ((unused)) sig) |
| 751 | { |
| 752 | _exit(init_exitstatus); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 753 | } |
| 754 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 755 | static int init(pid_t rootpid) |
| 756 | { |
| 757 | pid_t pid; |
| 758 | int status; |
| 759 | /* so that we exit with the right status */ |
| 760 | signal(SIGTERM, init_term); |
| 761 | /* TODO(wad) self jail with seccomp_filters here. */ |
| 762 | while ((pid = wait(&status)) > 0) { |
| 763 | /* This loop will only end when either there are no processes |
| 764 | * left inside our pid namespace or we get a signal. |
| 765 | */ |
| 766 | if (pid == rootpid) |
| 767 | init_exitstatus = status; |
| 768 | } |
| 769 | if (!WIFEXITED(init_exitstatus)) |
| 770 | _exit(MINIJAIL_ERR_INIT); |
| 771 | _exit(WEXITSTATUS(init_exitstatus)); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 772 | } |
| 773 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 774 | int minijail_from_fd(int fd, struct minijail *j) |
| 775 | { |
| 776 | size_t sz = 0; |
| 777 | size_t bytes = read(fd, &sz, sizeof(sz)); |
| 778 | char *buf; |
| 779 | int r; |
| 780 | if (sizeof(sz) != bytes) |
| 781 | return -EINVAL; |
| 782 | if (sz > USHRT_MAX) /* Arbitrary sanity check */ |
| 783 | return -E2BIG; |
| 784 | buf = malloc(sz); |
| 785 | if (!buf) |
| 786 | return -ENOMEM; |
| 787 | bytes = read(fd, buf, sz); |
| 788 | if (bytes != sz) { |
| 789 | free(buf); |
| 790 | return -EINVAL; |
| 791 | } |
| 792 | r = minijail_unmarshal(j, buf, sz); |
| 793 | free(buf); |
| 794 | return r; |
Will Drewry | 2f54b6a | 2011-09-16 13:45:31 -0500 | [diff] [blame] | 795 | } |
| 796 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 797 | int minijail_to_fd(struct minijail *j, int fd) |
| 798 | { |
| 799 | char *buf; |
| 800 | size_t sz = minijail_size(j); |
| 801 | ssize_t written; |
| 802 | int r; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 803 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 804 | if (!sz) |
| 805 | return -EINVAL; |
| 806 | buf = malloc(sz); |
| 807 | r = minijail_marshal(j, buf, sz); |
| 808 | if (r) { |
| 809 | free(buf); |
| 810 | return r; |
| 811 | } |
| 812 | /* Sends [size][minijail]. */ |
| 813 | written = write(fd, &sz, sizeof(sz)); |
| 814 | if (written != sizeof(sz)) { |
| 815 | free(buf); |
| 816 | return -EFAULT; |
| 817 | } |
| 818 | written = write(fd, buf, sz); |
| 819 | if (written < 0 || (size_t) written != sz) { |
| 820 | free(buf); |
| 821 | return -EFAULT; |
| 822 | } |
| 823 | free(buf); |
| 824 | return 0; |
Will Drewry | 2f54b6a | 2011-09-16 13:45:31 -0500 | [diff] [blame] | 825 | } |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 826 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 827 | static int setup_preload(void) |
| 828 | { |
| 829 | char *oldenv = getenv(kLdPreloadEnvVar) ? : ""; |
| 830 | char *newenv = malloc(strlen(oldenv) + 2 + strlen(PRELOADPATH)); |
| 831 | if (!newenv) |
| 832 | return -ENOMEM; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 833 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 834 | /* Only insert a separating space if we have something to separate... */ |
| 835 | sprintf(newenv, "%s%s%s", oldenv, strlen(oldenv) ? " " : "", |
| 836 | PRELOADPATH); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 837 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 838 | /* setenv() makes a copy of the string we give it */ |
| 839 | setenv(kLdPreloadEnvVar, newenv, 1); |
| 840 | free(newenv); |
| 841 | return 0; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 842 | } |
| 843 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 844 | static int setup_pipe(int fds[2]) |
| 845 | { |
| 846 | int r = pipe(fds); |
| 847 | char fd_buf[11]; |
| 848 | if (r) |
| 849 | return r; |
| 850 | r = snprintf(fd_buf, sizeof(fd_buf), "%d", fds[0]); |
| 851 | if (r <= 0) |
| 852 | return -EINVAL; |
| 853 | setenv(kFdEnvVar, fd_buf, 1); |
| 854 | return 0; |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 855 | } |
| 856 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 857 | int minijail_run(struct minijail *j, const char *filename, char *const argv[]) |
| 858 | { |
| 859 | unsigned int pidns = j->flags.pids ? CLONE_NEWPID : 0; |
| 860 | char *oldenv, *oldenv_copy = NULL; |
| 861 | pid_t child_pid; |
| 862 | int pipe_fds[2]; |
| 863 | int ret; |
Ben Chan | 541c7e5 | 2011-08-26 14:55:53 -0700 | [diff] [blame] | 864 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 865 | oldenv = getenv(kLdPreloadEnvVar); |
| 866 | if (oldenv) { |
| 867 | oldenv_copy = strdup(oldenv); |
| 868 | if (!oldenv_copy) |
| 869 | return -ENOMEM; |
| 870 | } |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 871 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 872 | if (setup_preload()) |
| 873 | return -EFAULT; |
Will Drewry | 2f54b6a | 2011-09-16 13:45:31 -0500 | [diff] [blame] | 874 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 875 | /* Before we fork(2) and execve(2) the child process, we need to open |
| 876 | * a pipe(2) to send the minijail configuration over. |
| 877 | */ |
| 878 | if (setup_pipe(pipe_fds)) |
| 879 | return -EFAULT; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 880 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 881 | child_pid = syscall(SYS_clone, pidns | SIGCHLD, NULL); |
| 882 | if (child_pid < 0) { |
| 883 | free(oldenv_copy); |
| 884 | return child_pid; |
| 885 | } |
Will Drewry | f89aef5 | 2011-09-16 16:48:57 -0500 | [diff] [blame] | 886 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 887 | if (child_pid) { |
| 888 | /* Restore parent's LD_PRELOAD. */ |
| 889 | if (oldenv_copy) { |
| 890 | setenv(kLdPreloadEnvVar, oldenv_copy, 1); |
| 891 | free(oldenv_copy); |
| 892 | } else { |
| 893 | unsetenv(kLdPreloadEnvVar); |
| 894 | } |
| 895 | unsetenv(kFdEnvVar); |
| 896 | j->initpid = child_pid; |
| 897 | close(pipe_fds[0]); /* read endpoint */ |
| 898 | ret = minijail_to_fd(j, pipe_fds[1]); |
| 899 | close(pipe_fds[1]); /* write endpoint */ |
| 900 | if (ret) { |
| 901 | kill(j->initpid, SIGKILL); |
| 902 | die("failed to send marshalled minijail"); |
| 903 | } |
| 904 | return 0; |
| 905 | } |
| 906 | free(oldenv_copy); |
Ben Chan | 541c7e5 | 2011-08-26 14:55:53 -0700 | [diff] [blame] | 907 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 908 | /* Drop everything that cannot be inherited across execve. */ |
| 909 | minijail_preexec(j); |
| 910 | /* Jail this process and its descendants... */ |
| 911 | minijail_enter(j); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 912 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 913 | if (pidns) { |
| 914 | /* pid namespace: this process will become init inside the new |
| 915 | * namespace, so fork off a child to actually run the program |
| 916 | * (we don't want all programs we might exec to have to know |
| 917 | * how to be init). |
| 918 | */ |
| 919 | child_pid = fork(); |
| 920 | if (child_pid < 0) |
| 921 | _exit(child_pid); |
| 922 | else if (child_pid > 0) |
| 923 | init(child_pid); /* never returns */ |
| 924 | } |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 925 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 926 | /* If we aren't pid-namespaced: |
| 927 | * calling process |
| 928 | * -> execve()-ing process |
| 929 | * If we are: |
| 930 | * calling process |
| 931 | * -> init()-ing process |
| 932 | * -> execve()-ing process |
| 933 | */ |
| 934 | _exit(execve(filename, argv, environ)); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 935 | } |
| 936 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 937 | int minijail_kill(struct minijail *j) |
| 938 | { |
| 939 | int st; |
| 940 | if (kill(j->initpid, SIGTERM)) |
| 941 | return -errno; |
| 942 | if (waitpid(j->initpid, &st, 0) < 0) |
| 943 | return -errno; |
| 944 | return st; |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 945 | } |
| 946 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 947 | int minijail_wait(struct minijail *j) |
| 948 | { |
| 949 | int st; |
| 950 | if (waitpid(j->initpid, &st, 0) < 0) |
| 951 | return -errno; |
| 952 | if (!WIFEXITED(st)) |
| 953 | return MINIJAIL_ERR_JAIL; |
| 954 | return WEXITSTATUS(st); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 955 | } |
| 956 | |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 957 | void minijail_destroy(struct minijail *j) |
| 958 | { |
| 959 | struct seccomp_filter *f = j->filters; |
| 960 | /* Unlink the tail and head */ |
| 961 | if (f) |
| 962 | f->prev->next = NULL; |
| 963 | while (f) { |
| 964 | struct seccomp_filter *next = f->next; |
| 965 | free(f->filter); |
| 966 | free(f); |
| 967 | f = next; |
| 968 | } |
Elly Jones | 51a5b6c | 2011-10-12 19:09:26 -0400 | [diff] [blame^] | 969 | while (j->bindings_head) { |
| 970 | struct binding *b = j->bindings_head; |
| 971 | j->bindings_head = j->bindings_head->next; |
| 972 | free(b->dest); |
| 973 | free(b->src); |
| 974 | free(b); |
| 975 | } |
| 976 | j->bindings_tail = NULL; |
Elly Jones | e1749eb | 2011-10-07 13:54:59 -0400 | [diff] [blame] | 977 | if (j->user) |
| 978 | free(j->user); |
| 979 | free(j); |
Elly Jones | cd7a904 | 2011-07-22 13:56:51 -0400 | [diff] [blame] | 980 | } |