2 * Copyright (c) 1999-2006 Robert N. M. Watson
5 * This software was developed by Robert Watson for the TrustedBSD Project.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * Developed by the TrustedBSD Project.
31 * ACL support routines specific to POSIX.1e access control lists. These are
32 * utility routines for code common across file systems implementing POSIX.1e
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/mount.h>
43 #include <sys/vnode.h>
44 #include <sys/errno.h>
49 * Implement a version of vaccess() that understands POSIX.1e ACL semantics;
50 * the access ACL has already been prepared for evaluation by the file system
51 * and is passed via 'uid', 'gid', and 'acl'. Return 0 on success, else an
55 vaccess_acl_posix1e(enum vtype type, uid_t file_uid, gid_t file_gid,
56 struct acl *acl, accmode_t accmode, struct ucred *cred, int *privused)
58 struct acl_entry *acl_other, *acl_mask;
59 accmode_t dac_granted;
60 accmode_t priv_granted;
61 accmode_t acl_mask_granted;
64 KASSERT((accmode & ~(VEXEC | VWRITE | VREAD | VADMIN | VAPPEND)) == 0,
65 ("invalid bit in accmode"));
68 * Look for a normal, non-privileged way to access the file/directory
69 * as requested. If it exists, go with that. Otherwise, attempt to
70 * use privileges granted via priv_granted. In some cases, which
71 * privileges to use may be ambiguous due to "best match", in which
72 * case fall back on first match for the time being.
78 * Determine privileges now, but don't apply until we've found a DAC
79 * entry that matches but has failed to allow access.
81 * XXXRW: Ideally, we'd determine the privileges required before
87 if ((accmode & VEXEC) && !priv_check_cred(cred,
89 priv_granted |= VEXEC;
91 if ((accmode & VEXEC) && !priv_check_cred(cred,
93 priv_granted |= VEXEC;
96 if ((accmode & VREAD) && !priv_check_cred(cred, PRIV_VFS_READ, 0))
97 priv_granted |= VREAD;
99 if (((accmode & VWRITE) || (accmode & VAPPEND)) &&
100 !priv_check_cred(cred, PRIV_VFS_WRITE, 0))
101 priv_granted |= (VWRITE | VAPPEND);
103 if ((accmode & VADMIN) && !priv_check_cred(cred, PRIV_VFS_ADMIN, 0))
104 priv_granted |= VADMIN;
107 * The owner matches if the effective uid associated with the
108 * credential matches that of the ACL_USER_OBJ entry. While we're
109 * doing the first scan, also cache the location of the ACL_MASK and
110 * ACL_OTHER entries, preventing some future iterations.
112 acl_mask = acl_other = NULL;
113 for (i = 0; i < acl->acl_cnt; i++) {
114 switch (acl->acl_entry[i].ae_tag) {
116 if (file_uid != cred->cr_uid)
119 dac_granted |= VADMIN;
120 if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
121 dac_granted |= VEXEC;
122 if (acl->acl_entry[i].ae_perm & ACL_READ)
123 dac_granted |= VREAD;
124 if (acl->acl_entry[i].ae_perm & ACL_WRITE)
125 dac_granted |= (VWRITE | VAPPEND);
126 if ((accmode & dac_granted) == accmode)
130 * XXXRW: Do privilege lookup here.
132 if ((accmode & (dac_granted | priv_granted)) ==
134 if (privused != NULL)
141 acl_mask = &acl->acl_entry[i];
145 acl_other = &acl->acl_entry[i];
154 * An ACL_OTHER entry should always exist in a valid access ACL. If
155 * it doesn't, then generate a serious failure. For now, this means
156 * a debugging message and EPERM, but in the future should probably
159 if (acl_other == NULL) {
161 * XXX This should never happen
163 printf("vaccess_acl_posix1e: ACL_OTHER missing\n");
168 * Checks against ACL_USER, ACL_GROUP_OBJ, and ACL_GROUP fields are
169 * masked by an ACL_MASK entry, if any. As such, first identify the
170 * ACL_MASK field, then iterate through identifying potential user
171 * matches, then group matches. If there is no ACL_MASK, assume that
172 * the mask allows all requests to succeed.
174 if (acl_mask != NULL) {
175 acl_mask_granted = 0;
176 if (acl_mask->ae_perm & ACL_EXECUTE)
177 acl_mask_granted |= VEXEC;
178 if (acl_mask->ae_perm & ACL_READ)
179 acl_mask_granted |= VREAD;
180 if (acl_mask->ae_perm & ACL_WRITE)
181 acl_mask_granted |= (VWRITE | VAPPEND);
183 acl_mask_granted = VEXEC | VREAD | VWRITE | VAPPEND;
186 * Check ACL_USER ACL entries. There will either be one or no
187 * matches; if there is one, we accept or rejected based on the
188 * match; otherwise, we continue on to groups.
190 for (i = 0; i < acl->acl_cnt; i++) {
191 switch (acl->acl_entry[i].ae_tag) {
193 if (acl->acl_entry[i].ae_id != cred->cr_uid)
196 if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
197 dac_granted |= VEXEC;
198 if (acl->acl_entry[i].ae_perm & ACL_READ)
199 dac_granted |= VREAD;
200 if (acl->acl_entry[i].ae_perm & ACL_WRITE)
201 dac_granted |= (VWRITE | VAPPEND);
202 dac_granted &= acl_mask_granted;
203 if ((accmode & dac_granted) == accmode)
206 * XXXRW: Do privilege lookup here.
208 if ((accmode & (dac_granted | priv_granted)) !=
212 if (privused != NULL)
219 * Group match is best-match, not first-match, so find a "best"
220 * match. Iterate across, testing each potential group match. Make
221 * sure we keep track of whether we found a match or not, so that we
222 * know if we should try again with any available privilege, or if we
223 * should move on to ACL_OTHER.
226 for (i = 0; i < acl->acl_cnt; i++) {
227 switch (acl->acl_entry[i].ae_tag) {
229 if (!groupmember(file_gid, cred))
232 if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
233 dac_granted |= VEXEC;
234 if (acl->acl_entry[i].ae_perm & ACL_READ)
235 dac_granted |= VREAD;
236 if (acl->acl_entry[i].ae_perm & ACL_WRITE)
237 dac_granted |= (VWRITE | VAPPEND);
238 dac_granted &= acl_mask_granted;
240 if ((accmode & dac_granted) == accmode)
247 if (!groupmember(acl->acl_entry[i].ae_id, cred))
250 if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
251 dac_granted |= VEXEC;
252 if (acl->acl_entry[i].ae_perm & ACL_READ)
253 dac_granted |= VREAD;
254 if (acl->acl_entry[i].ae_perm & ACL_WRITE)
255 dac_granted |= (VWRITE | VAPPEND);
256 dac_granted &= acl_mask_granted;
258 if ((accmode & dac_granted) == accmode)
269 if (group_matched == 1) {
271 * There was a match, but it did not grant rights via pure
272 * DAC. Try again, this time with privilege.
274 for (i = 0; i < acl->acl_cnt; i++) {
275 switch (acl->acl_entry[i].ae_tag) {
277 if (!groupmember(file_gid, cred))
280 if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
281 dac_granted |= VEXEC;
282 if (acl->acl_entry[i].ae_perm & ACL_READ)
283 dac_granted |= VREAD;
284 if (acl->acl_entry[i].ae_perm & ACL_WRITE)
285 dac_granted |= (VWRITE | VAPPEND);
286 dac_granted &= acl_mask_granted;
289 * XXXRW: Do privilege lookup here.
291 if ((accmode & (dac_granted | priv_granted))
295 if (privused != NULL)
300 if (!groupmember(acl->acl_entry[i].ae_id,
304 if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
305 dac_granted |= VEXEC;
306 if (acl->acl_entry[i].ae_perm & ACL_READ)
307 dac_granted |= VREAD;
308 if (acl->acl_entry[i].ae_perm & ACL_WRITE)
309 dac_granted |= (VWRITE | VAPPEND);
310 dac_granted &= acl_mask_granted;
313 * XXXRW: Do privilege lookup here.
315 if ((accmode & (dac_granted | priv_granted))
319 if (privused != NULL)
328 * Even with privilege, group membership was not sufficient.
335 * Fall back on ACL_OTHER. ACL_MASK is not applied to ACL_OTHER.
338 if (acl_other->ae_perm & ACL_EXECUTE)
339 dac_granted |= VEXEC;
340 if (acl_other->ae_perm & ACL_READ)
341 dac_granted |= VREAD;
342 if (acl_other->ae_perm & ACL_WRITE)
343 dac_granted |= (VWRITE | VAPPEND);
345 if ((accmode & dac_granted) == accmode)
348 * XXXRW: Do privilege lookup here.
350 if ((accmode & (dac_granted | priv_granted)) == accmode) {
351 if (privused != NULL)
357 return ((accmode & VADMIN) ? EPERM : EACCES);
361 * For the purposes of filesystems maintaining the _OBJ entries in an inode
362 * with a mode_t field, this routine converts a mode_t entry to an
366 acl_posix1e_mode_to_perm(acl_tag_t tag, mode_t mode)
399 printf("acl_posix1e_mode_to_perm: invalid tag (%d)\n", tag);
405 * Given inode information (uid, gid, mode), return an acl entry of the
409 acl_posix1e_mode_to_entry(acl_tag_t tag, uid_t uid, gid_t gid, mode_t mode)
411 struct acl_entry acl_entry;
413 acl_entry.ae_tag = tag;
414 acl_entry.ae_perm = acl_posix1e_mode_to_perm(tag, mode);
415 acl_entry.ae_entry_type = 0;
416 acl_entry.ae_flags = 0;
419 acl_entry.ae_id = uid;
423 acl_entry.ae_id = gid;
427 acl_entry.ae_id = ACL_UNDEFINED_ID;
431 acl_entry.ae_id = ACL_UNDEFINED_ID;
432 printf("acl_posix1e_mode_to_entry: invalid tag (%d)\n", tag);
439 * Utility function to generate a file mode given appropriate ACL entries.
442 acl_posix1e_perms_to_mode(struct acl_entry *acl_user_obj_entry,
443 struct acl_entry *acl_group_obj_entry, struct acl_entry *acl_other_entry)
448 if (acl_user_obj_entry->ae_perm & ACL_EXECUTE)
450 if (acl_user_obj_entry->ae_perm & ACL_READ)
452 if (acl_user_obj_entry->ae_perm & ACL_WRITE)
454 if (acl_group_obj_entry->ae_perm & ACL_EXECUTE)
456 if (acl_group_obj_entry->ae_perm & ACL_READ)
458 if (acl_group_obj_entry->ae_perm & ACL_WRITE)
460 if (acl_other_entry->ae_perm & ACL_EXECUTE)
462 if (acl_other_entry->ae_perm & ACL_READ)
464 if (acl_other_entry->ae_perm & ACL_WRITE)
471 * Utility function to generate a file mode given a complete POSIX.1e access
472 * ACL. Note that if the ACL is improperly formed, this may result in a
476 acl_posix1e_acl_to_mode(struct acl *acl)
478 struct acl_entry *acl_mask, *acl_user_obj, *acl_group_obj, *acl_other;
482 * Find the ACL entries relevant to a POSIX permission mode.
484 acl_user_obj = acl_group_obj = acl_other = acl_mask = NULL;
485 for (i = 0; i < acl->acl_cnt; i++) {
486 switch (acl->acl_entry[i].ae_tag) {
488 acl_user_obj = &acl->acl_entry[i];
492 acl_group_obj = &acl->acl_entry[i];
496 acl_other = &acl->acl_entry[i];
500 acl_mask = &acl->acl_entry[i];
508 panic("acl_posix1e_acl_to_mode: bad ae_tag");
512 if (acl_user_obj == NULL || acl_group_obj == NULL || acl_other == NULL)
513 panic("acl_posix1e_acl_to_mode: missing base ae_tags");
516 * POSIX.1e specifies that if there is an ACL_MASK entry, we replace
517 * the mode "group" bits with its permissions. If there isn't, we
518 * use the ACL_GROUP_OBJ permissions.
520 if (acl_mask != NULL)
521 return (acl_posix1e_perms_to_mode(acl_user_obj, acl_mask,
524 return (acl_posix1e_perms_to_mode(acl_user_obj, acl_group_obj,
529 * Perform a syntactic check of the ACL, sufficient to allow an implementing
530 * filesystem to determine if it should accept this and rely on the POSIX.1e
534 acl_posix1e_check(struct acl *acl)
536 int num_acl_user_obj, num_acl_user, num_acl_group_obj, num_acl_group;
537 int num_acl_mask, num_acl_other, i;
540 * Verify that the number of entries does not exceed the maximum
543 * Verify that the correct number of various sorts of ae_tags are
545 * Exactly one ACL_USER_OBJ
546 * Exactly one ACL_GROUP_OBJ
547 * Exactly one ACL_OTHER
548 * If any ACL_USER or ACL_GROUP entries appear, then exactly one
549 * ACL_MASK entry must also appear.
551 * Verify that all ae_perm entries are in ACL_PERM_BITS.
553 * Verify all ae_tag entries are understood by this implementation.
555 * Note: Does not check for uniqueness of qualifier (ae_id) field.
557 num_acl_user_obj = num_acl_user = num_acl_group_obj = num_acl_group =
558 num_acl_mask = num_acl_other = 0;
559 if (acl->acl_cnt > ACL_MAX_ENTRIES || acl->acl_cnt < 0)
561 for (i = 0; i < acl->acl_cnt; i++) {
563 * Check for a valid tag.
565 switch(acl->acl_entry[i].ae_tag) {
567 acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
568 if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
573 acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
574 if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
579 if (acl->acl_entry[i].ae_id == ACL_UNDEFINED_ID)
584 if (acl->acl_entry[i].ae_id == ACL_UNDEFINED_ID)
589 acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
590 if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
595 acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
596 if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
604 * Check for valid perm entries.
606 if ((acl->acl_entry[i].ae_perm | ACL_PERM_BITS) !=
610 if ((num_acl_user_obj != 1) || (num_acl_group_obj != 1) ||
611 (num_acl_other != 1) || (num_acl_mask != 0 && num_acl_mask != 1))
613 if (((num_acl_group != 0) || (num_acl_user != 0)) &&
620 * Given a requested mode for a new object, and a default ACL, combine the
621 * two to produce a new mode. Be careful not to clear any bits that aren't
622 * intended to be affected by the POSIX.1e ACL. Eventually, this might also
623 * take the cmask as an argument, if we push that down into
624 * per-filesystem-code.
627 acl_posix1e_newfilemode(mode_t cmode, struct acl *dacl)
633 * The current composition policy is that a permission bit must be
634 * set in *both* the ACL and the requested creation mode for it to
635 * appear in the resulting mode/ACL. First clear any possibly
636 * effected bits, then reconstruct.
638 mode &= ACL_PRESERVE_MASK;
639 mode |= (ACL_OVERRIDE_MASK & cmode & acl_posix1e_acl_to_mode(dacl));