/*- * Copyright (c) 1999 Robert N. M. Watson * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * *$FreeBSD: src/lib/libposix1e/acl_support.c,v 1.3 2000/01/26 04:19:37 rwatson Exp $ *$DragonFly: src/lib/libposix1e/acl_support.c,v 1.3 2005/08/04 17:27:09 drhodus Exp $ */ /* * Support functionality for the POSIX.1e ACL interface * These calls are intended only to be called within the library. */ #include <sys/types.h> #include <sys/acl.h> #include <errno.h> #include <grp.h> #include <pwd.h> #include <stdio.h> #include <stdlib.h> #include "acl_support.h" #define ACL_STRING_PERM_WRITE 'w' #define ACL_STRING_PERM_READ 'r' #define ACL_STRING_PERM_EXEC 'x' #define ACL_STRING_PERM_NONE '-' /* * acl_entry_compare -- compare two acl_entry structures to determine the * order they should appear in. Used by acl_sort to sort ACL entries into * the kernel-desired order -- i.e., the order useful for evaluation and * O(n) validity checking. Beter to have an O(nlogn) sort in userland and * an O(n) in kernel than to have both in kernel. */ typedef int (*compare)(const void *, const void *); static int acl_entry_compare(struct acl_entry *a, struct acl_entry *b) { /* * First, sort between tags -- conveniently defined in the correct * order for verification. */ if (a->ae_tag < b->ae_tag) return (-1); if (a->ae_tag > b->ae_tag) return (1); /* * Next compare uids/gids on appropriate types. */ if (a->ae_tag == ACL_USER || a->ae_tag == ACL_GROUP) { if (a->ae_id < b->ae_id) return (-1); if (a->ae_id > b->ae_id) return (1); /* shouldn't be equal, fall through to the invalid case */ } /* * Don't know how to sort multiple entries of the rest--either it's * a bad entry, or there shouldn't be more than one. Ignore and the * validity checker can get it later. */ return (0); } /* * acl_sort -- sort ACL entries. * Give the opportunity to fail, althouh we don't currently have a way * to fail. */ int acl_sort(acl_t acl) { qsort(&acl->acl_entry[0], acl->acl_cnt, sizeof(struct acl_entry), (compare) acl_entry_compare); return (0); } /* * acl_posix1e -- in what situations should we acl_sort before submission? * We apply posix1e ACL semantics for any ACL of type ACL_TYPE_ACCESS or * ACL_TYPE_DEFAULT */ int acl_posix1e(acl_t acl, acl_type_t type) { return ((type == ACL_TYPE_ACCESS) || (type == ACL_TYPE_DEFAULT)); } /* * acl_check -- given an ACL, check its validity. This is mirrored from * code in sys/kern/kern_acl.c, and if changes are made in one, they should * be made in the other also. This copy of acl_check is made available * in userland for the benefit of processes wanting to check ACLs for * validity before submitting them to the kernel, or for performing * in userland file system checking. Needless to say, the kernel makes * the real checks on calls to get/setacl. * * See the comments in kernel for explanation -- just briefly, it assumes * an already sorted ACL, and checks based on that assumption. The * POSIX.1e interface, acl_valid(), will perform the sort before calling * this. Returns 0 on success, EINVAL on failure. */ int acl_check(struct acl *acl) { struct acl_entry *entry; /* current entry */ uid_t obj_uid=-1, obj_gid=-1, highest_uid=0, highest_gid=0; int stage = ACL_USER_OBJ; int i = 0; int count_user_obj=0, count_user=0, count_group_obj=0, count_group=0, count_mask=0, count_other=0; /* printf("acl_check: checking acl with %d entries\n", acl->acl_cnt); */ while (i < acl->acl_cnt) { entry = &acl->acl_entry[i]; if ((entry->ae_perm | ACL_PERM_BITS) != ACL_PERM_BITS) return (EINVAL); switch(entry->ae_tag) { case ACL_USER_OBJ: /* printf("acl_check: %d: ACL_USER_OBJ\n", i); */ if (stage > ACL_USER_OBJ) return (EINVAL); stage = ACL_USER; count_user_obj++; obj_uid = entry->ae_id; break; case ACL_USER: /* printf("acl_check: %d: ACL_USER\n", i); */ if (stage > ACL_USER) return (EINVAL); stage = ACL_USER; if (entry->ae_id == obj_uid) return (EINVAL); if (count_user && (entry->ae_id <= highest_uid)) return (EINVAL); highest_uid = entry->ae_id; count_user++; break; case ACL_GROUP_OBJ: /* printf("acl_check: %d: ACL_GROUP_OBJ\n", i); */ if (stage > ACL_GROUP_OBJ) return (EINVAL); stage = ACL_GROUP; count_group_obj++; obj_gid = entry->ae_id; break; case ACL_GROUP: /* printf("acl_check: %d: ACL_GROUP\n", i); */ if (stage > ACL_GROUP) return (EINVAL); stage = ACL_GROUP; if (entry->ae_id == obj_gid) return (EINVAL); if (count_group && (entry->ae_id <= highest_gid)) return (EINVAL); highest_gid = entry->ae_id; count_group++; break; case ACL_MASK: /* printf("acl_check: %d: ACL_MASK\n", i); */ if (stage > ACL_MASK) return (EINVAL); stage = ACL_MASK; count_mask++; break; case ACL_OTHER: /* printf("acl_check: %d: ACL_OTHER\n", i); */ if (stage > ACL_OTHER) return (EINVAL); stage = ACL_OTHER; count_other++; break; default: /* printf("acl_check: %d: INVALID\n", i); */ return (EINVAL); } i++; } if (count_user_obj != 1) return (EINVAL); if (count_group_obj != 1) return (EINVAL); if (count_mask != 0 && count_mask != 1) return (EINVAL); if (count_other != 1) return (EINVAL); return (0); } /* * Given a uid/gid, return a username/groupname for the text form of an ACL * XXX NOT THREAD SAFE, RELIES ON GETPWUID, GETGRGID * XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE * MAY HAVE SIDE-EFFECTS */ int acl_id_to_name(acl_tag_t tag, uid_t id, ssize_t buf_len, char *buf) { struct group *g; struct passwd *p; int i; switch(tag) { case ACL_USER: p = getpwuid(id); if (!p) i = snprintf(buf, buf_len, "%d", id); else i = snprintf(buf, buf_len, "%s", p->pw_name); if (i >= buf_len) { errno = ENOMEM; return (-1); } return (0); case ACL_GROUP: g = getgrgid(id); if (!g) i = snprintf(buf, buf_len, "%d", id); else i = snprintf(buf, buf_len, "%s", g->gr_name); if (i >= buf_len) { errno = ENOMEM; return (-1); } return (0); default: return (EINVAL); } } /* * Given a username/groupname from a text form of an ACL, return the uid/gid * XXX NOT THREAD SAFE, RELIES ON GETPWNAM, GETGRNAM * XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE * MAY HAVE SIDE-EFFECTS * * XXX currently doesn't deal correctly with a numeric uid being passed * instead of a username. What is correct behavior here? Check chown. */ int acl_name_to_id(acl_tag_t tag, char *name, uid_t *id) { struct group *g; struct passwd *p; switch(tag) { case ACL_USER: p = getpwnam(name); if (!p) { errno = EINVAL; return (-1); } *id = p->pw_uid; return (0); case ACL_GROUP: g = getgrnam(name); if (g) { errno = EINVAL; return (-1); } *id = g->gr_gid; return (0); default: return (EINVAL); } } /* * Given a right-shifted permission (i.e., direct ACL_PERM_* mask), fill * in a string describing the permissions. */ int acl_perm_to_string(acl_perm_t perm, ssize_t buf_len, char *buf) { if (buf_len < ACL_STRING_PERM_MAXSIZE + 1) { errno = ENOMEM; return (-1); } if ((perm | ACL_PERM_BITS) != ACL_PERM_BITS) { errno = EINVAL; return (-1); } buf[3] = 0; /* null terminate */ if (perm & ACL_PERM_READ) buf[0] = ACL_STRING_PERM_READ; else buf[0] = ACL_STRING_PERM_NONE; if (perm & ACL_PERM_WRITE) buf[1] = ACL_STRING_PERM_WRITE; else buf[1] = ACL_STRING_PERM_NONE; if (perm & ACL_PERM_EXEC) buf[2] = ACL_STRING_PERM_EXEC; else buf[2] = ACL_STRING_PERM_NONE; return (0); } /* * given a string, return a permission describing it */ int acl_string_to_perm(char *string, acl_perm_t *perm) { acl_perm_t myperm = ACL_PERM_NONE; char *ch; ch = string; while (*ch) { switch(*ch) { case ACL_STRING_PERM_READ: myperm |= ACL_PERM_READ; break; case ACL_STRING_PERM_WRITE: myperm |= ACL_PERM_WRITE; break; case ACL_STRING_PERM_EXEC: myperm |= ACL_PERM_EXEC; break; case ACL_STRING_PERM_NONE: break; default: return (EINVAL); } ch++; } *perm = myperm; return (0); } /* * Add an ACL entry without doing much checking, et al */ int acl_add_entry(acl_t acl, acl_tag_t tag, uid_t id, acl_perm_t perm) { struct acl_entry *e; if (acl->acl_cnt >= ACL_MAX_ENTRIES) { errno = ENOMEM; return (-1); } e = &(acl->acl_entry[acl->acl_cnt]); e->ae_perm = perm; e->ae_tag = tag; e->ae_id = id; acl->acl_cnt++; return (0); }
