1 /*- 2 * Copyright (c) 1999, 2000, 2001 Robert N. M. Watson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 /* 27 * Support functionality for the POSIX.1e ACL interface 28 * These calls are intended only to be called within the library. 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #include <sys/types.h> 35 #include "namespace.h" 36 #include <sys/acl.h> 37 #include "un-namespace.h" 38 #include <errno.h> 39 #include <grp.h> 40 #include <pwd.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 44 #include "acl_support.h" 45 46 #define ACL_STRING_PERM_WRITE 'w' 47 #define ACL_STRING_PERM_READ 'r' 48 #define ACL_STRING_PERM_EXEC 'x' 49 #define ACL_STRING_PERM_NONE '-' 50 51 /* 52 * _posix1e_acl_entry_compare -- compare two acl_entry structures to 53 * determine the order they should appear in. Used by _posix1e_acl_sort to 54 * sort ACL entries into the kernel-desired order -- i.e., the order useful 55 * for evaluation and O(n) validity checking. Beter to have an O(nlogn) sort 56 * in userland and an O(n) in kernel than to have both in kernel. 57 */ 58 typedef int (*compare)(const void *, const void *); 59 static int 60 _posix1e_acl_entry_compare(struct acl_entry *a, struct acl_entry *b) 61 { 62 /* 63 * First, sort between tags -- conveniently defined in the correct 64 * order for verification. 65 */ 66 if (a->ae_tag < b->ae_tag) 67 return (-1); 68 if (a->ae_tag > b->ae_tag) 69 return (1); 70 71 /* 72 * Next compare uids/gids on appropriate types. 73 */ 74 75 if (a->ae_tag == ACL_USER || a->ae_tag == ACL_GROUP) { 76 if (a->ae_id < b->ae_id) 77 return (-1); 78 if (a->ae_id > b->ae_id) 79 return (1); 80 81 /* shouldn't be equal, fall through to the invalid case */ 82 } 83 84 /* 85 * Don't know how to sort multiple entries of the rest--either it's 86 * a bad entry, or there shouldn't be more than one. Ignore and the 87 * validity checker can get it later. 88 */ 89 return (0); 90 } 91 92 /* 93 * _posix1e_acl_sort -- sort ACL entries in POSIX.1e-formatted ACLs 94 * Give the opportunity to fail, although we don't currently have a way 95 * to fail. 96 */ 97 int 98 _posix1e_acl_sort(acl_t acl) 99 { 100 struct acl *acl_int; 101 102 acl_int = &acl->ats_acl; 103 104 qsort(&acl_int->acl_entry[0], acl_int->acl_cnt, 105 sizeof(struct acl_entry), (compare) _posix1e_acl_entry_compare); 106 107 return (0); 108 } 109 110 /* 111 * acl_posix1e -- in what situations should we acl_sort before submission? 112 * We apply posix1e ACL semantics for any ACL of type ACL_TYPE_ACCESS or 113 * ACL_TYPE_DEFAULT 114 */ 115 int 116 _posix1e_acl(acl_t acl, acl_type_t type) 117 { 118 119 return ((type == ACL_TYPE_ACCESS) || (type == ACL_TYPE_DEFAULT)); 120 } 121 122 /* 123 * _posix1e_acl_check -- given an ACL, check its validity. This is mirrored 124 * from code in sys/kern/kern_acl.c, and if changes are made in one, they 125 * should be made in the other also. This copy of acl_check is made 126 * available * in userland for the benefit of processes wanting to check ACLs 127 * for validity before submitting them to the kernel, or for performing 128 * in userland file system checking. Needless to say, the kernel makes 129 * the real checks on calls to get/setacl. 130 * 131 * See the comments in kernel for explanation -- just briefly, it assumes 132 * an already sorted ACL, and checks based on that assumption. The 133 * POSIX.1e interface, acl_valid(), will perform the sort before calling 134 * this. Returns 0 on success, EINVAL on failure. 135 */ 136 int 137 _posix1e_acl_check(acl_t acl) 138 { 139 struct acl *acl_int; 140 struct acl_entry *entry; /* current entry */ 141 uid_t obj_uid=-1, obj_gid=-1, highest_uid=0, highest_gid=0; 142 int stage = ACL_USER_OBJ; 143 int i = 0; 144 int count_user_obj=0, count_user=0, count_group_obj=0, 145 count_group=0, count_mask=0, count_other=0; 146 147 acl_int = &acl->ats_acl; 148 149 /* printf("_posix1e_acl_check: checking acl with %d entries\n", 150 acl->acl_cnt); */ 151 while (i < acl_int->acl_cnt) { 152 entry = &acl_int->acl_entry[i]; 153 154 if ((entry->ae_perm | ACL_PERM_BITS) != ACL_PERM_BITS) 155 return (EINVAL); 156 157 switch(entry->ae_tag) { 158 case ACL_USER_OBJ: 159 /* printf("_posix1e_acl_check: %d: ACL_USER_OBJ\n", 160 i); */ 161 if (stage > ACL_USER_OBJ) 162 return (EINVAL); 163 stage = ACL_USER; 164 count_user_obj++; 165 obj_uid = entry->ae_id; 166 break; 167 168 case ACL_USER: 169 /* printf("_posix1e_acl_check: %d: ACL_USER\n", i); */ 170 if (stage > ACL_USER) 171 return (EINVAL); 172 stage = ACL_USER; 173 if (entry->ae_id == obj_uid) 174 return (EINVAL); 175 if (count_user && (entry->ae_id <= highest_uid)) 176 return (EINVAL); 177 highest_uid = entry->ae_id; 178 count_user++; 179 break; 180 181 case ACL_GROUP_OBJ: 182 /* printf("_posix1e_acl_check: %d: ACL_GROUP_OBJ\n", 183 i); */ 184 if (stage > ACL_GROUP_OBJ) 185 return (EINVAL); 186 stage = ACL_GROUP; 187 count_group_obj++; 188 obj_gid = entry->ae_id; 189 break; 190 191 case ACL_GROUP: 192 /* printf("_posix1e_acl_check: %d: ACL_GROUP\n", i); */ 193 if (stage > ACL_GROUP) 194 return (EINVAL); 195 stage = ACL_GROUP; 196 if (entry->ae_id == obj_gid) 197 return (EINVAL); 198 if (count_group && (entry->ae_id <= highest_gid)) 199 return (EINVAL); 200 highest_gid = entry->ae_id; 201 count_group++; 202 break; 203 204 case ACL_MASK: 205 /* printf("_posix1e_acl_check: %d: ACL_MASK\n", i); */ 206 if (stage > ACL_MASK) 207 return (EINVAL); 208 stage = ACL_MASK; 209 count_mask++; 210 break; 211 212 case ACL_OTHER: 213 /* printf("_posix1e_acl_check: %d: ACL_OTHER\n", i); */ 214 if (stage > ACL_OTHER) 215 return (EINVAL); 216 stage = ACL_OTHER; 217 count_other++; 218 break; 219 220 default: 221 /* printf("_posix1e_acl_check: %d: INVALID\n", i); */ 222 return (EINVAL); 223 } 224 i++; 225 } 226 227 if (count_user_obj != 1) 228 return (EINVAL); 229 230 if (count_group_obj != 1) 231 return (EINVAL); 232 233 if (count_mask != 0 && count_mask != 1) 234 return (EINVAL); 235 236 if (count_other != 1) 237 return (EINVAL); 238 239 return (0); 240 } 241 242 243 /* 244 * Given a uid/gid, return a username/groupname for the text form of an ACL 245 * XXX NOT THREAD SAFE, RELIES ON GETPWUID, GETGRGID 246 * XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE 247 * MAY HAVE SIDE-EFFECTS 248 */ 249 int 250 _posix1e_acl_id_to_name(acl_tag_t tag, uid_t id, ssize_t buf_len, char *buf) 251 { 252 struct group *g; 253 struct passwd *p; 254 int i; 255 256 switch(tag) { 257 case ACL_USER: 258 p = getpwuid(id); 259 if (!p) 260 i = snprintf(buf, buf_len, "%d", id); 261 else 262 i = snprintf(buf, buf_len, "%s", p->pw_name); 263 264 if (i < 0 || i >= buf_len) { 265 errno = ENOMEM; 266 return (-1); 267 } 268 return (0); 269 270 case ACL_GROUP: 271 g = getgrgid(id); 272 if (g == NULL) 273 i = snprintf(buf, buf_len, "%d", id); 274 else 275 i = snprintf(buf, buf_len, "%s", g->gr_name); 276 277 if (i < 0 || i >= buf_len) { 278 errno = ENOMEM; 279 return (-1); 280 } 281 return (0); 282 283 default: 284 return (EINVAL); 285 } 286 } 287 288 289 /* 290 * Given a username/groupname from a text form of an ACL, return the uid/gid 291 * XXX NOT THREAD SAFE, RELIES ON GETPWNAM, GETGRNAM 292 * XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE 293 * MAY HAVE SIDE-EFFECTS 294 * 295 * XXX currently doesn't deal correctly with a numeric uid being passed 296 * instead of a username. What is correct behavior here? Check chown. 297 */ 298 int 299 _posix1e_acl_name_to_id(acl_tag_t tag, char *name, uid_t *id) 300 { 301 struct group *g; 302 struct passwd *p; 303 unsigned long l; 304 char *endp; 305 306 switch(tag) { 307 case ACL_USER: 308 p = getpwnam(name); 309 if (p == NULL) { 310 l = strtoul(name, &endp, 0); 311 if (*endp != '\0' || l != (unsigned long)(uid_t)l) { 312 errno = EINVAL; 313 return (-1); 314 } 315 *id = (uid_t)l; 316 return (0); 317 } 318 *id = p->pw_uid; 319 return (0); 320 321 case ACL_GROUP: 322 g = getgrnam(name); 323 if (g == NULL) { 324 l = strtoul(name, &endp, 0); 325 if (*endp != '\0' || l != (unsigned long)(gid_t)l) { 326 errno = EINVAL; 327 return (-1); 328 } 329 *id = (gid_t)l; 330 return (0); 331 } 332 *id = g->gr_gid; 333 return (0); 334 335 default: 336 return (EINVAL); 337 } 338 } 339 340 341 /* 342 * Given a right-shifted permission (i.e., direct ACL_PERM_* mask), fill 343 * in a string describing the permissions. 344 */ 345 int 346 _posix1e_acl_perm_to_string(acl_perm_t perm, ssize_t buf_len, char *buf) 347 { 348 349 if (buf_len < _POSIX1E_ACL_STRING_PERM_MAXSIZE + 1) { 350 errno = ENOMEM; 351 return (-1); 352 } 353 354 if ((perm | ACL_PERM_BITS) != ACL_PERM_BITS) { 355 errno = EINVAL; 356 return (-1); 357 } 358 359 buf[3] = 0; /* null terminate */ 360 361 if (perm & ACL_READ) 362 buf[0] = ACL_STRING_PERM_READ; 363 else 364 buf[0] = ACL_STRING_PERM_NONE; 365 366 if (perm & ACL_WRITE) 367 buf[1] = ACL_STRING_PERM_WRITE; 368 else 369 buf[1] = ACL_STRING_PERM_NONE; 370 371 if (perm & ACL_EXECUTE) 372 buf[2] = ACL_STRING_PERM_EXEC; 373 else 374 buf[2] = ACL_STRING_PERM_NONE; 375 376 return (0); 377 } 378 379 /* 380 * given a string, return a permission describing it 381 */ 382 int 383 _posix1e_acl_string_to_perm(char *string, acl_perm_t *perm) 384 { 385 acl_perm_t myperm = ACL_PERM_NONE; 386 char *ch; 387 388 ch = string; 389 while (*ch) { 390 switch(*ch) { 391 case ACL_STRING_PERM_READ: 392 myperm |= ACL_READ; 393 break; 394 case ACL_STRING_PERM_WRITE: 395 myperm |= ACL_WRITE; 396 break; 397 case ACL_STRING_PERM_EXEC: 398 myperm |= ACL_EXECUTE; 399 break; 400 case ACL_STRING_PERM_NONE: 401 break; 402 default: 403 return (EINVAL); 404 } 405 ch++; 406 } 407 408 *perm = myperm; 409 return (0); 410 } 411 412 /* 413 * Add an ACL entry without doing much checking, et al 414 */ 415 int 416 _posix1e_acl_add_entry(acl_t acl, acl_tag_t tag, uid_t id, acl_perm_t perm) 417 { 418 struct acl *acl_int; 419 struct acl_entry *e; 420 421 acl_int = &acl->ats_acl; 422 423 if (acl_int->acl_cnt >= ACL_MAX_ENTRIES) { 424 errno = ENOMEM; 425 return (-1); 426 } 427 428 e = &(acl_int->acl_entry[acl_int->acl_cnt]); 429 e->ae_perm = perm; 430 e->ae_tag = tag; 431 e->ae_id = id; 432 acl_int->acl_cnt++; 433 434 return (0); 435 } 436