src/shared/acl-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2011,2013 Lennart Poettering
   4 ***/
   5
   6 #include <errno.h>
   7 #include <stdbool.h>
   8
   9 #include "acl-util.h"
  10 #include "alloc-util.h"
  11 #include "string-util.h"
  12 #include "strv.h"
  13 #include "user-util.h"
  14 #include "util.h"
  15
  16 int acl_find_uid(acl_t acl, uid_t uid, acl_entry_t *entry) {
  17         acl_entry_t i;
  18         int r;
  19
  20         assert(acl);
  21         assert(entry);
  22
  23         for (r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
  24              r > 0;
  25              r = acl_get_entry(acl, ACL_NEXT_ENTRY, &i)) {
  26
  27                 acl_tag_t tag;
  28                 uid_t *u;
  29                 bool b;
  30
  31                 if (acl_get_tag_type(i, &tag) < 0)
  32                         return -errno;
  33
  34                 if (tag != ACL_USER)
  35                         continue;
  36
  37                 u = acl_get_qualifier(i);
  38                 if (!u)
  39                         return -errno;
  40
  41                 b = *u == uid;
  42                 acl_free(u);
  43
  44                 if (b) {
  45                         *entry = i;
  46                         return 1;
  47                 }
  48         }
  49         if (r < 0)
  50                 return -errno;
  51
  52         return 0;
  53 }
  54
  55 int calc_acl_mask_if_needed(acl_t *acl_p) {
  56         acl_entry_t i;
  57         int r;
  58         bool need = false;
  59
  60         assert(acl_p);
  61
  62         for (r = acl_get_entry(*acl_p, ACL_FIRST_ENTRY, &i);
  63              r > 0;
  64              r = acl_get_entry(*acl_p, ACL_NEXT_ENTRY, &i)) {
  65                 acl_tag_t tag;
  66
  67                 if (acl_get_tag_type(i, &tag) < 0)
  68                         return -errno;
  69
  70                 if (tag == ACL_MASK)
  71                         return 0;
  72
  73                 if (IN_SET(tag, ACL_USER, ACL_GROUP))
  74                         need = true;
  75         }
  76         if (r < 0)
  77                 return -errno;
  78
  79         if (need && acl_calc_mask(acl_p) < 0)
  80                 return -errno;
  81
  82         return need;
  83 }
  84
  85 int add_base_acls_if_needed(acl_t *acl_p, const char *path) {
  86         acl_entry_t i;
  87         int r;
  88         bool have_user_obj = false, have_group_obj = false, have_other = false;
  89         struct stat st;
  90         _cleanup_(acl_freep) acl_t basic = NULL;
  91
  92         assert(acl_p);
  93
  94         for (r = acl_get_entry(*acl_p, ACL_FIRST_ENTRY, &i);
  95              r > 0;
  96              r = acl_get_entry(*acl_p, ACL_NEXT_ENTRY, &i)) {
  97                 acl_tag_t tag;
  98
  99                 if (acl_get_tag_type(i, &tag) < 0)
 100                         return -errno;
 101
 102                 if (tag == ACL_USER_OBJ)
 103                         have_user_obj = true;
 104                 else if (tag == ACL_GROUP_OBJ)
 105                         have_group_obj = true;
 106                 else if (tag == ACL_OTHER)
 107                         have_other = true;
 108                 if (have_user_obj && have_group_obj && have_other)
 109                         return 0;
 110         }
 111         if (r < 0)
 112                 return -errno;
 113
 114         r = stat(path, &st);
 115         if (r < 0)
 116                 return -errno;
 117
 118         basic = acl_from_mode(st.st_mode);
 119         if (!basic)
 120                 return -errno;
 121
 122         for (r = acl_get_entry(basic, ACL_FIRST_ENTRY, &i);
 123              r > 0;
 124              r = acl_get_entry(basic, ACL_NEXT_ENTRY, &i)) {
 125                 acl_tag_t tag;
 126                 acl_entry_t dst;
 127
 128                 if (acl_get_tag_type(i, &tag) < 0)
 129                         return -errno;
 130
 131                 if ((tag == ACL_USER_OBJ && have_user_obj) ||
 132                     (tag == ACL_GROUP_OBJ && have_group_obj) ||
 133                     (tag == ACL_OTHER && have_other))
 134                         continue;
 135
 136                 r = acl_create_entry(acl_p, &dst);
 137                 if (r < 0)
 138                         return -errno;
 139
 140                 r = acl_copy_entry(dst, i);
 141                 if (r < 0)
 142                         return -errno;
 143         }
 144         if (r < 0)
 145                 return -errno;
 146         return 0;
 147 }
 148
 149 int acl_search_groups(const char *path, char ***ret_groups) {
 150         _cleanup_strv_free_ char **g = NULL;
 151         _cleanup_(acl_freep) acl_t acl = NULL;
 152         bool ret = false;
 153         acl_entry_t entry;
 154         int r;
 155
 156         assert(path);
 157
 158         acl = acl_get_file(path, ACL_TYPE_DEFAULT);
 159         if (!acl)
 160                 return -errno;
 161
 162         r = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
 163         for (;;) {
 164                 _cleanup_(acl_free_gid_tpp) gid_t *gid = NULL;
 165                 acl_tag_t tag;
 166
 167                 if (r < 0)
 168                         return -errno;
 169                 if (r == 0)
 170                         break;
 171
 172                 if (acl_get_tag_type(entry, &tag) < 0)
 173                         return -errno;
 174
 175                 if (tag != ACL_GROUP)
 176                         goto next;
 177
 178                 gid = acl_get_qualifier(entry);
 179                 if (!gid)
 180                         return -errno;
 181
 182                 if (in_gid(*gid) > 0) {
 183                         if (!ret_groups)
 184                                 return true;
 185
 186                         ret = true;
 187                 }
 188
 189                 if (ret_groups) {
 190                         char *name;
 191
 192                         name = gid_to_name(*gid);
 193                         if (!name)
 194                                 return -ENOMEM;
 195
 196                         r = strv_consume(&g, name);
 197                         if (r < 0)
 198                                 return r;
 199                 }
 200
 201         next:
 202                 r = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
 203         }
 204
 205         if (ret_groups)
 206                 *ret_groups = TAKE_PTR(g);
 207
 208         return ret;
 209 }
 210
 211 int parse_acl(const char *text, acl_t *acl_access, acl_t *acl_default, bool want_mask) {
 212         _cleanup_free_ char **a = NULL, **d = NULL; /* strings are not freed */
 213         _cleanup_strv_free_ char **split;
 214         char **entry;
 215         int r = -EINVAL;
 216         _cleanup_(acl_freep) acl_t a_acl = NULL, d_acl = NULL;
 217
 218         split = strv_split(text, ",");
 219         if (!split)
 220                 return -ENOMEM;
 221
 222         STRV_FOREACH(entry, split) {
 223                 char *p;
 224
 225                 p = startswith(*entry, "default:");
 226                 if (!p)
 227                         p = startswith(*entry, "d:");
 228
 229                 if (p)
 230                         r = strv_push(&d, p);
 231                 else
 232                         r = strv_push(&a, *entry);
 233                 if (r < 0)
 234                         return r;
 235         }
 236
 237         if (!strv_isempty(a)) {
 238                 _cleanup_free_ char *join;
 239
 240                 join = strv_join(a, ",");
 241                 if (!join)
 242                         return -ENOMEM;
 243
 244                 a_acl = acl_from_text(join);
 245                 if (!a_acl)
 246                         return -errno;
 247
 248                 if (want_mask) {
 249                         r = calc_acl_mask_if_needed(&a_acl);
 250                         if (r < 0)
 251                                 return r;
 252                 }
 253         }
 254
 255         if (!strv_isempty(d)) {
 256                 _cleanup_free_ char *join;
 257
 258                 join = strv_join(d, ",");
 259                 if (!join)
 260                         return -ENOMEM;
 261
 262                 d_acl = acl_from_text(join);
 263                 if (!d_acl)
 264                         return -errno;
 265
 266                 if (want_mask) {
 267                         r = calc_acl_mask_if_needed(&d_acl);
 268                         if (r < 0)
 269                                 return r;
 270                 }
 271         }
 272
 273         *acl_access = TAKE_PTR(a_acl);
 274         *acl_default = TAKE_PTR(d_acl);
 275
 276         return 0;
 277 }
 278
 279 static int acl_entry_equal(acl_entry_t a, acl_entry_t b) {
 280         acl_tag_t tag_a, tag_b;
 281
 282         if (acl_get_tag_type(a, &tag_a) < 0)
 283                 return -errno;
 284
 285         if (acl_get_tag_type(b, &tag_b) < 0)
 286                 return -errno;
 287
 288         if (tag_a != tag_b)
 289                 return false;
 290
 291         switch (tag_a) {
 292         case ACL_USER_OBJ:
 293         case ACL_GROUP_OBJ:
 294         case ACL_MASK:
 295         case ACL_OTHER:
 296                 /* can have only one of those */
 297                 return true;
 298         case ACL_USER: {
 299                 _cleanup_(acl_free_uid_tpp) uid_t *uid_a = NULL, *uid_b = NULL;
 300
 301                 uid_a = acl_get_qualifier(a);
 302                 if (!uid_a)
 303                         return -errno;
 304
 305                 uid_b = acl_get_qualifier(b);
 306                 if (!uid_b)
 307                         return -errno;
 308
 309                 return *uid_a == *uid_b;
 310         }
 311         case ACL_GROUP: {
 312                 _cleanup_(acl_free_gid_tpp) gid_t *gid_a = NULL, *gid_b = NULL;
 313
 314                 gid_a = acl_get_qualifier(a);
 315                 if (!gid_a)
 316                         return -errno;
 317
 318                 gid_b = acl_get_qualifier(b);
 319                 if (!gid_b)
 320                         return -errno;
 321
 322                 return *gid_a == *gid_b;
 323         }
 324         default:
 325                 assert_not_reached("Unknown acl tag type");
 326         }
 327 }
 328
 329 static int find_acl_entry(acl_t acl, acl_entry_t entry, acl_entry_t *out) {
 330         acl_entry_t i;
 331         int r;
 332
 333         for (r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
 334              r > 0;
 335              r = acl_get_entry(acl, ACL_NEXT_ENTRY, &i)) {
 336
 337                 r = acl_entry_equal(i, entry);
 338                 if (r < 0)
 339                         return r;
 340                 if (r > 0) {
 341                         *out = i;
 342                         return 1;
 343                 }
 344         }
 345         if (r < 0)
 346                 return -errno;
 347         return 0;
 348 }
 349
 350 int acls_for_file(const char *path, acl_type_t type, acl_t new, acl_t *acl) {
 351         _cleanup_(acl_freep) acl_t old;
 352         acl_entry_t i;
 353         int r;
 354
 355         old = acl_get_file(path, type);
 356         if (!old)
 357                 return -errno;
 358
 359         for (r = acl_get_entry(new, ACL_FIRST_ENTRY, &i);
 360              r > 0;
 361              r = acl_get_entry(new, ACL_NEXT_ENTRY, &i)) {
 362
 363                 acl_entry_t j;
 364
 365                 r = find_acl_entry(old, i, &j);
 366                 if (r < 0)
 367                         return r;
 368                 if (r == 0)
 369                         if (acl_create_entry(&old, &j) < 0)
 370                                 return -errno;
 371
 372                 if (acl_copy_entry(j, i) < 0)
 373                         return -errno;
 374         }
 375         if (r < 0)
 376                 return -errno;
 377
 378         *acl = TAKE_PTR(old);
 379
 380         return 0;
 381 }
 382
 383 int add_acls_for_user(int fd, uid_t uid) {
 384         _cleanup_(acl_freep) acl_t acl = NULL;
 385         acl_entry_t entry;
 386         acl_permset_t permset;
 387         int r;
 388
 389         acl = acl_get_fd(fd);
 390         if (!acl)
 391                 return -errno;
 392
 393         r = acl_find_uid(acl, uid, &entry);
 394         if (r <= 0) {
 395                 if (acl_create_entry(&acl, &entry) < 0 ||
 396                     acl_set_tag_type(entry, ACL_USER) < 0 ||
 397                     acl_set_qualifier(entry, &uid) < 0)
 398                         return -errno;
 399         }
 400
 401         /* We do not recalculate the mask unconditionally here,
 402          * so that the fchmod() mask above stays intact. */
 403         if (acl_get_permset(entry, &permset) < 0 ||
 404             acl_add_perm(permset, ACL_READ) < 0)
 405                 return -errno;
 406
 407         r = calc_acl_mask_if_needed(&acl);
 408         if (r < 0)
 409                 return r;
 410
 411         return acl_set_fd(fd, acl);
 412 }