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 * Note that we truncate user and group names, rather than error out, as 246 * this is consistent with other tools manipulating user and group names. 247 * XXX NOT THREAD SAFE, RELIES ON GETPWUID, GETGRGID 248 * XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE 249 * MAY HAVE SIDE-EFFECTS 250 */ 251 int 252 _posix1e_acl_id_to_name(acl_tag_t tag, uid_t id, ssize_t buf_len, char *buf) 253 { 254 struct group *g; 255 struct passwd *p; 256 int i; 257 258 switch(tag) { 259 case ACL_USER: 260 p = getpwuid(id); 261 if (!p) 262 i = snprintf(buf, buf_len, "%d", id); 263 else 264 i = snprintf(buf, buf_len, "%s", p->pw_name); 265 266 if (i < 0) { 267 errno = ENOMEM; 268 return (-1); 269 } 270 return (0); 271 272 case ACL_GROUP: 273 g = getgrgid(id); 274 if (g == NULL) 275 i = snprintf(buf, buf_len, "%d", id); 276 else 277 i = snprintf(buf, buf_len, "%s", g->gr_name); 278 279 if (i < 0) { 280 errno = ENOMEM; 281 return (-1); 282 } 283 return (0); 284 285 default: 286 return (EINVAL); 287 } 288 } 289 290 /* 291 * Given a right-shifted permission (i.e., direct ACL_PERM_* mask), fill 292 * in a string describing the permissions. 293 */ 294 int 295 _posix1e_acl_perm_to_string(acl_perm_t perm, ssize_t buf_len, char *buf) 296 { 297 298 if (buf_len < _POSIX1E_ACL_STRING_PERM_MAXSIZE + 1) { 299 errno = ENOMEM; 300 return (-1); 301 } 302 303 if ((perm | ACL_PERM_BITS) != ACL_PERM_BITS) { 304 errno = EINVAL; 305 return (-1); 306 } 307 308 buf[3] = 0; /* null terminate */ 309 310 if (perm & ACL_READ) 311 buf[0] = ACL_STRING_PERM_READ; 312 else 313 buf[0] = ACL_STRING_PERM_NONE; 314 315 if (perm & ACL_WRITE) 316 buf[1] = ACL_STRING_PERM_WRITE; 317 else 318 buf[1] = ACL_STRING_PERM_NONE; 319 320 if (perm & ACL_EXECUTE) 321 buf[2] = ACL_STRING_PERM_EXEC; 322 else 323 buf[2] = ACL_STRING_PERM_NONE; 324 325 return (0); 326 } 327 328 /* 329 * given a string, return a permission describing it 330 */ 331 int 332 _posix1e_acl_string_to_perm(char *string, acl_perm_t *perm) 333 { 334 acl_perm_t myperm = ACL_PERM_NONE; 335 char *ch; 336 337 ch = string; 338 while (*ch) { 339 switch(*ch) { 340 case ACL_STRING_PERM_READ: 341 myperm |= ACL_READ; 342 break; 343 case ACL_STRING_PERM_WRITE: 344 myperm |= ACL_WRITE; 345 break; 346 case ACL_STRING_PERM_EXEC: 347 myperm |= ACL_EXECUTE; 348 break; 349 case ACL_STRING_PERM_NONE: 350 break; 351 default: 352 return (EINVAL); 353 } 354 ch++; 355 } 356 357 *perm = myperm; 358 return (0); 359 } 360 361 /* 362 * Add an ACL entry without doing much checking, et al 363 */ 364 int 365 _posix1e_acl_add_entry(acl_t acl, acl_tag_t tag, uid_t id, acl_perm_t perm) 366 { 367 struct acl *acl_int; 368 struct acl_entry *e; 369 370 acl_int = &acl->ats_acl; 371 372 if (acl_int->acl_cnt >= ACL_MAX_ENTRIES) { 373 errno = ENOMEM; 374 return (-1); 375 } 376 377 e = &(acl_int->acl_entry[acl_int->acl_cnt]); 378 e->ae_perm = perm; 379 e->ae_tag = tag; 380 e->ae_id = id; 381 acl_int->acl_cnt++; 382 383 return (0); 384 } 385