src/core/smack-setup.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright © 2013 Intel Corporation
   4   Authors:
   5         Nathaniel Chen <nathaniel.chen@intel.com>
   6 ***/
   7
   8 #include <dirent.h>
   9 #include <errno.h>
  10 #include <fcntl.h>
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <unistd.h>
  15
  16 #include "alloc-util.h"
  17 #include "dirent-util.h"
  18 #include "fd-util.h"
  19 #include "fileio.h"
  20 #include "log.h"
  21 #include "macro.h"
  22 #include "smack-setup.h"
  23 #include "string-util.h"
  24 #include "util.h"
  25
  26 #if ENABLE_SMACK
  27
  28 static int fdopen_unlocked_at(int dfd, const char *dir, const char *name, int *status, FILE **ret_file) {
  29         int fd, r;
  30         FILE *f;
  31
  32         fd = openat(dfd, name, O_RDONLY|O_CLOEXEC);
  33         if (fd < 0) {
  34                 if (*status == 0)
  35                         *status = -errno;
  36
  37                 return log_warning_errno(errno, "Failed to open \"%s/%s\": %m", dir, name);
  38         }
  39
  40         r = fdopen_unlocked(fd, "r", &f);
  41         if (r < 0) {
  42                 if (*status == 0)
  43                         *status = r;
  44
  45                 safe_close(fd);
  46                 return log_error_errno(r, "Failed to open \"%s/%s\": %m", dir, name);
  47         }
  48
  49         *ret_file = f;
  50         return 0;
  51 }
  52
  53 static int write_access2_rules(const char *srcdir) {
  54         _cleanup_close_ int load2_fd = -1, change_fd = -1;
  55         _cleanup_closedir_ DIR *dir = NULL;
  56         struct dirent *entry;
  57         int dfd = -1, r = 0;
  58
  59         load2_fd = open("/sys/fs/smackfs/load2", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
  60         if (load2_fd < 0)  {
  61                 if (errno != ENOENT)
  62                         log_warning_errno(errno, "Failed to open '/sys/fs/smackfs/load2': %m");
  63                 return -errno; /* negative error */
  64         }
  65
  66         change_fd = open("/sys/fs/smackfs/change-rule", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
  67         if (change_fd < 0)  {
  68                 if (errno != ENOENT)
  69                         log_warning_errno(errno, "Failed to open '/sys/fs/smackfs/change-rule': %m");
  70                 return -errno; /* negative error */
  71         }
  72
  73         /* write rules to load2 or change-rule from every file in the directory */
  74         dir = opendir(srcdir);
  75         if (!dir) {
  76                 if (errno != ENOENT)
  77                         log_warning_errno(errno, "Failed to opendir '%s': %m", srcdir);
  78                 return errno; /* positive on purpose */
  79         }
  80
  81         dfd = dirfd(dir);
  82         assert(dfd >= 0);
  83
  84         FOREACH_DIRENT(entry, dir, return 0) {
  85                 _cleanup_fclose_ FILE *policy = NULL;
  86
  87                 if (!dirent_is_file(entry))
  88                         continue;
  89
  90                 if (fdopen_unlocked_at(dfd, srcdir, entry->d_name, &r, &policy) < 0)
  91                         continue;
  92
  93                 /* load2 write rules in the kernel require a line buffered stream */
  94                 for (;;) {
  95                         _cleanup_free_ char *buf = NULL, *sbj = NULL, *obj = NULL, *acc1 = NULL, *acc2 = NULL;
  96                         int q;
  97
  98                         q = read_line(policy, NAME_MAX, &buf);
  99                         if (q < 0)
 100                                 return log_error_errno(q, "Failed to read line from '%s': %m", entry->d_name);
 101                         if (q == 0)
 102                                 break;
 103
 104                         if (isempty(buf) || strchr(COMMENTS, buf[0]))
 105                                 continue;
 106
 107                         /* if 3 args -> load rule   : subject object access1 */
 108                         /* if 4 args -> change rule : subject object access1 access2 */
 109                         if (sscanf(buf, "%ms %ms %ms %ms", &sbj, &obj, &acc1, &acc2) < 3) {
 110                                 log_error_errno(errno, "Failed to parse rule '%s' in '%s', ignoring.", buf, entry->d_name);
 111                                 continue;
 112                         }
 113
 114                         if (write(isempty(acc2) ? load2_fd : change_fd, buf, strlen(buf)) < 0) {
 115                                 if (r == 0)
 116                                         r = -errno;
 117                                 log_error_errno(errno, "Failed to write '%s' to '%s' in '%s': %m",
 118                                                 buf, isempty(acc2) ? "/sys/fs/smackfs/load2" : "/sys/fs/smackfs/change-rule", entry->d_name);
 119                         }
 120                 }
 121         }
 122
 123         return r;
 124 }
 125
 126 static int write_cipso2_rules(const char *srcdir) {
 127         _cleanup_close_ int cipso2_fd = -1;
 128         _cleanup_closedir_ DIR *dir = NULL;
 129         struct dirent *entry;
 130         int dfd = -1, r = 0;
 131
 132         cipso2_fd = open("/sys/fs/smackfs/cipso2", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 133         if (cipso2_fd < 0)  {
 134                 if (errno != ENOENT)
 135                         log_warning_errno(errno, "Failed to open '/sys/fs/smackfs/cipso2': %m");
 136                 return -errno; /* negative error */
 137         }
 138
 139         /* write rules to cipso2 from every file in the directory */
 140         dir = opendir(srcdir);
 141         if (!dir) {
 142                 if (errno != ENOENT)
 143                         log_warning_errno(errno, "Failed to opendir '%s': %m", srcdir);
 144                 return errno; /* positive on purpose */
 145         }
 146
 147         dfd = dirfd(dir);
 148         assert(dfd >= 0);
 149
 150         FOREACH_DIRENT(entry, dir, return 0) {
 151                 _cleanup_fclose_ FILE *policy = NULL;
 152
 153                 if (!dirent_is_file(entry))
 154                         continue;
 155
 156                 if (fdopen_unlocked_at(dfd, srcdir, entry->d_name, &r, &policy) < 0)
 157                         continue;
 158
 159                 /* cipso2 write rules in the kernel require a line buffered stream */
 160                 for (;;) {
 161                         _cleanup_free_ char *buf = NULL;
 162                         int q;
 163
 164                         q = read_line(policy, NAME_MAX, &buf);
 165                         if (q < 0)
 166                                 return log_error_errno(q, "Failed to read line from '%s': %m", entry->d_name);
 167                         if (q == 0)
 168                                 break;
 169
 170                         if (isempty(buf) || strchr(COMMENTS, buf[0]))
 171                                 continue;
 172
 173                         if (write(cipso2_fd, buf, strlen(buf)) < 0) {
 174                                 if (r == 0)
 175                                         r = -errno;
 176                                 log_error_errno(errno, "Failed to write '%s' to '/sys/fs/smackfs/cipso2' in '%s': %m",
 177                                                 buf, entry->d_name);
 178                                 break;
 179                         }
 180                 }
 181         }
 182
 183         return r;
 184 }
 185
 186 static int write_netlabel_rules(const char *srcdir) {
 187         _cleanup_fclose_ FILE *dst = NULL;
 188         _cleanup_closedir_ DIR *dir = NULL;
 189         struct dirent *entry;
 190         int dfd = -1, r = 0;
 191
 192         dst = fopen("/sys/fs/smackfs/netlabel", "we");
 193         if (!dst)  {
 194                 if (errno != ENOENT)
 195                         log_warning_errno(errno, "Failed to open /sys/fs/smackfs/netlabel: %m");
 196                 return -errno; /* negative error */
 197         }
 198
 199         /* write rules to dst from every file in the directory */
 200         dir = opendir(srcdir);
 201         if (!dir) {
 202                 if (errno != ENOENT)
 203                         log_warning_errno(errno, "Failed to opendir %s: %m", srcdir);
 204                 return errno; /* positive on purpose */
 205         }
 206
 207         dfd = dirfd(dir);
 208         assert(dfd >= 0);
 209
 210         FOREACH_DIRENT(entry, dir, return 0) {
 211                 _cleanup_fclose_ FILE *policy = NULL;
 212
 213                 if (fdopen_unlocked_at(dfd, srcdir, entry->d_name, &r, &policy) < 0)
 214                         continue;
 215
 216                 /* load2 write rules in the kernel require a line buffered stream */
 217                 for (;;) {
 218                         _cleanup_free_ char *buf = NULL;
 219                         int q;
 220
 221                         q = read_line(policy, NAME_MAX, &buf);
 222                         if (q < 0)
 223                                 return log_error_errno(q, "Failed to read line from %s: %m", entry->d_name);
 224                         if (q == 0)
 225                                 break;
 226
 227                         if (!fputs(buf, dst)) {
 228                                 if (r == 0)
 229                                         r = -EINVAL;
 230                                 log_error_errno(errno, "Failed to write line to /sys/fs/smackfs/netlabel: %m");
 231                                 break;
 232                         }
 233                         q = fflush_and_check(dst);
 234                         if (q < 0) {
 235                                 if (r == 0)
 236                                         r = q;
 237                                 log_error_errno(q, "Failed to flush writes to /sys/fs/smackfs/netlabel: %m");
 238                                 break;
 239                         }
 240                 }
 241         }
 242
 243         return r;
 244 }
 245
 246 static int write_onlycap_list(void) {
 247         _cleanup_close_ int onlycap_fd = -1;
 248         _cleanup_free_ char *list = NULL;
 249         _cleanup_fclose_ FILE *f = NULL;
 250         size_t len = 0, allocated = 0;
 251         int r;
 252
 253         f = fopen("/etc/smack/onlycap", "re");
 254         if (!f) {
 255                 if (errno != ENOENT)
 256                         log_warning_errno(errno, "Failed to read '/etc/smack/onlycap': %m");
 257
 258                 return errno == ENOENT ? ENOENT : -errno;
 259         }
 260
 261         for (;;) {
 262                 _cleanup_free_ char *buf = NULL;
 263                 size_t l;
 264
 265                 r = read_line(f, LONG_LINE_MAX, &buf);
 266                 if (r < 0)
 267                         return log_error_errno(r, "Failed to read line from /etc/smack/onlycap: %m");
 268                 if (r == 0)
 269                         break;
 270
 271                 if (isempty(buf) || strchr(COMMENTS, *buf))
 272                         continue;
 273
 274                 l = strlen(buf);
 275                 if (!GREEDY_REALLOC(list, allocated, len + l + 1))
 276                         return log_oom();
 277
 278                 stpcpy(list + len, buf)[0] = ' ';
 279                 len += l + 1;
 280         }
 281
 282         if (len == 0)
 283                 return 0;
 284
 285         list[len - 1] = 0;
 286
 287         onlycap_fd = open("/sys/fs/smackfs/onlycap", O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 288         if (onlycap_fd < 0) {
 289                 if (errno != ENOENT)
 290                         log_warning_errno(errno, "Failed to open '/sys/fs/smackfs/onlycap': %m");
 291                 return -errno; /* negative error */
 292         }
 293
 294         r = write(onlycap_fd, list, len);
 295         if (r < 0)
 296                 return log_error_errno(errno, "Failed to write onlycap list(%s) to '/sys/fs/smackfs/onlycap': %m", list);
 297
 298         return 0;
 299 }
 300
 301 #endif
 302
 303 int mac_smack_setup(bool *loaded_policy) {
 304
 305 #if ENABLE_SMACK
 306
 307         int r;
 308
 309         assert(loaded_policy);
 310
 311         r = write_access2_rules("/etc/smack/accesses.d/");
 312         switch(r) {
 313         case -ENOENT:
 314                 log_debug("Smack is not enabled in the kernel.");
 315                 return 0;
 316         case ENOENT:
 317                 log_debug("Smack access rules directory '/etc/smack/accesses.d/' not found");
 318                 return 0;
 319         case 0:
 320                 log_info("Successfully loaded Smack policies.");
 321                 break;
 322         default:
 323                 log_warning_errno(r, "Failed to load Smack access rules, ignoring: %m");
 324                 return 0;
 325         }
 326
 327 #ifdef SMACK_RUN_LABEL
 328         r = write_string_file("/proc/self/attr/current", SMACK_RUN_LABEL, WRITE_STRING_FILE_DISABLE_BUFFER);
 329         if (r < 0)
 330                 log_warning_errno(r, "Failed to set SMACK label \"" SMACK_RUN_LABEL "\" on self: %m");
 331         r = write_string_file("/sys/fs/smackfs/ambient", SMACK_RUN_LABEL, WRITE_STRING_FILE_DISABLE_BUFFER);
 332         if (r < 0)
 333                 log_warning_errno(r, "Failed to set SMACK ambient label \"" SMACK_RUN_LABEL "\": %m");
 334         r = write_string_file("/sys/fs/smackfs/netlabel",
 335                               "0.0.0.0/0 " SMACK_RUN_LABEL, WRITE_STRING_FILE_DISABLE_BUFFER);
 336         if (r < 0)
 337                 log_warning_errno(r, "Failed to set SMACK netlabel rule \"0.0.0.0/0 " SMACK_RUN_LABEL "\": %m");
 338         r = write_string_file("/sys/fs/smackfs/netlabel", "127.0.0.1 -CIPSO", WRITE_STRING_FILE_DISABLE_BUFFER);
 339         if (r < 0)
 340                 log_warning_errno(r, "Failed to set SMACK netlabel rule \"127.0.0.1 -CIPSO\": %m");
 341 #endif
 342
 343         r = write_cipso2_rules("/etc/smack/cipso.d/");
 344         switch(r) {
 345         case -ENOENT:
 346                 log_debug("Smack/CIPSO is not enabled in the kernel.");
 347                 return 0;
 348         case ENOENT:
 349                 log_debug("Smack/CIPSO access rules directory '/etc/smack/cipso.d/' not found");
 350                 break;
 351         case 0:
 352                 log_info("Successfully loaded Smack/CIPSO policies.");
 353                 break;
 354         default:
 355                 log_warning_errno(r, "Failed to load Smack/CIPSO access rules, ignoring: %m");
 356                 break;
 357         }
 358
 359         r = write_netlabel_rules("/etc/smack/netlabel.d/");
 360         switch(r) {
 361         case -ENOENT:
 362                 log_debug("Smack/CIPSO is not enabled in the kernel.");
 363                 return 0;
 364         case ENOENT:
 365                 log_debug("Smack network host rules directory '/etc/smack/netlabel.d/' not found");
 366                 break;
 367         case 0:
 368                 log_info("Successfully loaded Smack network host rules.");
 369                 break;
 370         default:
 371                 log_warning_errno(r, "Failed to load Smack network host rules: %m, ignoring.");
 372                 break;
 373         }
 374
 375         r = write_onlycap_list();
 376         switch(r) {
 377         case -ENOENT:
 378                 log_debug("Smack is not enabled in the kernel.");
 379                 break;
 380         case ENOENT:
 381                 log_debug("Smack onlycap list file '/etc/smack/onlycap' not found");
 382                 break;
 383         case 0:
 384                 log_info("Successfully wrote Smack onlycap list.");
 385                 break;
 386         default:
 387                 log_emergency_errno(r, "Failed to write Smack onlycap list: %m");
 388                 return r;
 389         }
 390
 391         *loaded_policy = true;
 392
 393 #endif
 394
 395         return 0;
 396 }