1 /*- 2 * Copyright (c) 1999 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 * $FreeBSD$ 27 */ 28 /* 29 * Support functionality for the POSIX.1e ACL interface 30 * These calls are intended only to be called within the library. 31 */ 32 33 #include <sys/types.h> 34 #include <sys/acl.h> 35 #include <errno.h> 36 #include <grp.h> 37 #include <pwd.h> 38 #include <stdio.h> 39 #include <stdlib.h> 40 41 #include "acl_support.h" 42 43 #define ACL_STRING_PERM_WRITE 'w' 44 #define ACL_STRING_PERM_READ 'r' 45 #define ACL_STRING_PERM_EXEC 'x' 46 #define ACL_STRING_PERM_NONE '-' 47 48 /* 49 * acl_entry_compare -- compare two acl_entry structures to determine the 50 * order they should appear in. Used by acl_sort to sort ACL entries into 51 * the kernel-desired order -- i.e., the order useful for evaluation and 52 * O(n) validity checking. Beter to have an O(nlogn) sort in userland and 53 * an O(n) in kernel than to have both in kernel. 54 */ 55 typedef int (*compare)(const void *, const void *); 56 static int 57 acl_entry_compare(struct acl_entry *a, struct acl_entry *b) 58 { 59 /* 60 * First, sort between tags -- conveniently defined in the correct 61 * order for verification. 62 */ 63 if (a->ae_tag < b->ae_tag) 64 return (-1); 65 if (a->ae_tag > b->ae_tag) 66 return (1); 67 68 /* 69 * Next compare uids/gids on appropriate types. 70 */ 71 72 if (a->ae_tag == ACL_USER || a->ae_tag == ACL_GROUP) { 73 if (a->ae_id < b->ae_id) 74 return (-1); 75 if (a->ae_id > b->ae_id) 76 return (1); 77 78 /* shouldn't be equal, fall through to the invalid case */ 79 } 80 81 /* 82 * Don't know how to sort multiple entries of the rest--either it's 83 * a bad entry, or there shouldn't be more than one. Ignore and the 84 * validity checker can get it later. 85 */ 86 return (0); 87 } 88 89 /* 90 * acl_sort -- sort ACL entries. 91 * Give the opportunity to fail, althouh we don't currently have a way 92 * to fail. 93 */ 94 int 95 acl_sort(acl_t acl) 96 { 97 98 qsort(&acl->acl_entry[0], acl->acl_cnt, sizeof(struct acl_entry), 99 (compare) acl_entry_compare); 100 101 return (0); 102 } 103 104 /* 105 * acl_posix1e -- in what situations should we acl_sort before submission? 106 * We apply posix1e ACL semantics for any ACL of type ACL_TYPE_ACCESS or 107 * ACL_TYPE_DEFAULT 108 */ 109 int 110 acl_posix1e(acl_t acl, acl_type_t type) 111 { 112 113 return ((type == ACL_TYPE_ACCESS) || (type == ACL_TYPE_DEFAULT)); 114 } 115 116 /* 117 * acl_check -- given an ACL, check its validity. This is mirrored from 118 * code in sys/kern/kern_acl.c, and if changes are made in one, they should 119 * be made in the other also. This copy of acl_check is made available 120 * in userland for the benefit of processes wanting to check ACLs for 121 * validity before submitting them to the kernel, or for performing 122 * in userland file system checking. Needless to say, the kernel makes 123 * the real checks on calls to get/setacl. 124 * 125 * See the comments in kernel for explanation -- just briefly, it assumes 126 * an already sorted ACL, and checks based on that assumption. The 127 * POSIX.1e interface, acl_valid(), will perform the sort before calling 128 * this. Returns 0 on success, EINVAL on failure. 129 */ 130 int 131 acl_check(struct acl *acl) 132 { 133 struct acl_entry *entry; /* current entry */ 134 uid_t obj_uid=-1, obj_gid=-1, highest_uid=0, highest_gid=0; 135 int stage = ACL_USER_OBJ; 136 int i = 0; 137 int count_user_obj=0, count_user=0, count_group_obj=0, 138 count_group=0, count_mask=0, count_other=0; 139 140 /* printf("acl_check: checking acl with %d entries\n", acl->acl_cnt); */ 141 while (i < acl->acl_cnt) { 142 143 entry = &acl->acl_entry[i]; 144 145 if ((entry->ae_perm | ACL_PERM_BITS) != ACL_PERM_BITS) 146 return (EINVAL); 147 148 switch(entry->ae_tag) { 149 case ACL_USER_OBJ: 150 /* printf("acl_check: %d: ACL_USER_OBJ\n", i); */ 151 if (stage > ACL_USER_OBJ) 152 return (EINVAL); 153 stage = ACL_USER; 154 count_user_obj++; 155 obj_uid = entry->ae_id; 156 break; 157 158 case ACL_USER: 159 /* printf("acl_check: %d: ACL_USER\n", i); */ 160 if (stage > ACL_USER) 161 return (EINVAL); 162 stage = ACL_USER; 163 if (entry->ae_id == obj_uid) 164 return (EINVAL); 165 if (count_user && (entry->ae_id <= highest_uid)) 166 return (EINVAL); 167 highest_uid = entry->ae_id; 168 count_user++; 169 break; 170 171 case ACL_GROUP_OBJ: 172 /* printf("acl_check: %d: ACL_GROUP_OBJ\n", i); */ 173 if (stage > ACL_GROUP_OBJ) 174 return (EINVAL); 175 stage = ACL_GROUP; 176 count_group_obj++; 177 obj_gid = entry->ae_id; 178 break; 179 180 case ACL_GROUP: 181 /* printf("acl_check: %d: ACL_GROUP\n", i); */ 182 if (stage > ACL_GROUP) 183 return (EINVAL); 184 stage = ACL_GROUP; 185 if (entry->ae_id == obj_gid) 186 return (EINVAL); 187 if (count_group && (entry->ae_id <= highest_gid)) 188 return (EINVAL); 189 highest_gid = entry->ae_id; 190 count_group++; 191 break; 192 193 case ACL_MASK: 194 /* printf("acl_check: %d: ACL_MASK\n", i); */ 195 if (stage > ACL_MASK) 196 return (EINVAL); 197 stage = ACL_MASK; 198 count_mask++; 199 break; 200 201 case ACL_OTHER: 202 /* printf("acl_check: %d: ACL_OTHER\n", i); */ 203 if (stage > ACL_OTHER) 204 return (EINVAL); 205 stage = ACL_OTHER; 206 count_other++; 207 break; 208 209 default: 210 /* printf("acl_check: %d: INVALID\n", i); */ 211 return (EINVAL); 212 } 213 i++; 214 } 215 216 if (count_user_obj != 1) 217 return (EINVAL); 218 219 if (count_group_obj != 1) 220 return (EINVAL); 221 222 if (count_mask != 0 && count_mask != 1) 223 return (EINVAL); 224 225 if (count_other != 1) 226 return (EINVAL); 227 228 return (0); 229 } 230 231 232 /* 233 * Given a uid/gid, return a username/groupname for the text form of an ACL 234 * XXX NOT THREAD SAFE, RELIES ON GETPWUID, GETGRGID 235 * XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE 236 * MAY HAVE SIDE-EFFECTS 237 */ 238 int 239 acl_id_to_name(acl_tag_t tag, uid_t id, ssize_t buf_len, char *buf) 240 { 241 struct group *g; 242 struct passwd *p; 243 int i; 244 245 switch(tag) { 246 case ACL_USER: 247 p = getpwuid(id); 248 if (!p) 249 i = snprintf(buf, buf_len, "%d", id); 250 else 251 i = snprintf(buf, buf_len, "%s", p->pw_name); 252 253 if (i >= buf_len) { 254 errno = ENOMEM; 255 return (-1); 256 } 257 return (0); 258 259 case ACL_GROUP: 260 g = getgrgid(id); 261 if (!g) 262 i = snprintf(buf, buf_len, "%d", id); 263 else 264 i = snprintf(buf, buf_len, "%s", g->gr_name); 265 266 if (i >= buf_len) { 267 errno = ENOMEM; 268 return (-1); 269 } 270 return (0); 271 272 default: 273 return (EINVAL); 274 } 275 } 276 277 278 /* 279 * Given a username/groupname from a text form of an ACL, return the uid/gid 280 * XXX NOT THREAD SAFE, RELIES ON GETPWNAM, GETGRNAM 281 * XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE 282 * MAY HAVE SIDE-EFFECTS 283 * 284 * XXX currently doesn't deal correctly with a numeric uid being passed 285 * instead of a username. What is correct behavior here? Check chown. 286 */ 287 int 288 acl_name_to_id(acl_tag_t tag, char *name, uid_t *id) 289 { 290 struct group *g; 291 struct passwd *p; 292 293 switch(tag) { 294 case ACL_USER: 295 p = getpwnam(name); 296 if (!p) { 297 errno = EINVAL; 298 return (-1); 299 } 300 *id = p->pw_uid; 301 return (0); 302 303 case ACL_GROUP: 304 g = getgrnam(name); 305 if (g) { 306 errno = EINVAL; 307 return (-1); 308 } 309 *id = g->gr_gid; 310 return (0); 311 312 default: 313 return (EINVAL); 314 } 315 } 316 317 318 /* 319 * Given a right-shifted permission (i.e., direct ACL_PERM_* mask), fill 320 * in a string describing the permissions. 321 */ 322 int 323 acl_perm_to_string(acl_perm_t perm, ssize_t buf_len, char *buf) 324 { 325 326 if (buf_len < ACL_STRING_PERM_MAXSIZE + 1) { 327 errno = ENOMEM; 328 return (-1); 329 } 330 331 if ((perm | ACL_PERM_BITS) != ACL_PERM_BITS) { 332 errno = EINVAL; 333 return (-1); 334 } 335 336 buf[3] = 0; /* null terminate */ 337 338 if (perm & ACL_PERM_READ) 339 buf[0] = ACL_STRING_PERM_READ; 340 else 341 buf[0] = ACL_STRING_PERM_NONE; 342 343 if (perm & ACL_PERM_WRITE) 344 buf[1] = ACL_STRING_PERM_WRITE; 345 else 346 buf[1] = ACL_STRING_PERM_NONE; 347 348 if (perm & ACL_PERM_EXEC) 349 buf[2] = ACL_STRING_PERM_EXEC; 350 else 351 buf[2] = ACL_STRING_PERM_NONE; 352 353 return (0); 354 } 355 356 /* 357 * given a string, return a permission describing it 358 */ 359 int 360 acl_string_to_perm(char *string, acl_perm_t *perm) 361 { 362 acl_perm_t myperm = ACL_PERM_NONE; 363 char *ch; 364 365 ch = string; 366 while (*ch) { 367 switch(*ch) { 368 case ACL_STRING_PERM_READ: 369 myperm |= ACL_PERM_READ; 370 break; 371 case ACL_STRING_PERM_WRITE: 372 myperm |= ACL_PERM_WRITE; 373 break; 374 case ACL_STRING_PERM_EXEC: 375 myperm |= ACL_PERM_EXEC; 376 break; 377 case ACL_STRING_PERM_NONE: 378 break; 379 default: 380 return (EINVAL); 381 } 382 ch++; 383 } 384 385 *perm = myperm; 386 return (0); 387 } 388 389 /* 390 * Add an ACL entry without doing much checking, et al 391 */ 392 int 393 acl_add_entry(acl_t acl, acl_tag_t tag, uid_t id, acl_perm_t perm) 394 { 395 struct acl_entry *e; 396 397 if (acl->acl_cnt >= ACL_MAX_ENTRIES) { 398 errno = ENOMEM; 399 return (-1); 400 } 401 402 e = &(acl->acl_entry[acl->acl_cnt]); 403 e->ae_perm = perm; 404 e->ae_tag = tag; 405 e->ae_id = id; 406 acl->acl_cnt++; 407 408 return (0); 409 } 410