sys/statx_np.c

   1 /*
   2  * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 #include <sys/types.h>
  24 #include <sys/acl.h>
  25 #include <sys/stat.h>
  26 #include <errno.h>
  27 #include <stdlib.h>
  28 #include <sys/syscall.h>
  29 #include <unistd.h>
  30 #include <fcntl.h>
  31
  32 #include <string.h>
  33 #include <stdio.h>
  34
  35 #define ACL_MIN_SIZE_HEURISTIC (sizeof(struct kauth_filesec) + 16 * sizeof(struct kauth_ace))
  36
  37 static int      statx_syscall(void *obj, struct stat *sb, void *fsacl, size_t *fsacl_size);
  38 static int      fstatx_syscall(void *obj, struct stat *sb, void *fsacl, size_t *fsacl_size);
  39 static int      lstatx_syscall(void *obj, struct stat *sb, void *fsacl, size_t *fsacl_size);
  40
  41 static int      statx1(void *obj,
  42                        int (* stat_syscall)(void *obj, struct stat *sb, void *fsacl, size_t *fsacl_size),
  43                        struct stat *sb, filesec_t fsec);
  44
  45 /*
  46  * Stat interfaces.
  47  */
  48 int
  49 statx_np(const char *path, struct stat *sb, filesec_t fsec)
  50 {
  51         if (fsec == NULL)
  52                 return(stat(path, sb));
  53         return(statx1((void *)&path, statx_syscall, sb, fsec));
  54 }
  55
  56 int
  57 fstatx_np(int fd, struct stat *sb, filesec_t fsec)
  58 {
  59         if (fsec == NULL)
  60                 return(fstat(fd, sb));
  61         return(statx1((void *)&fd, fstatx_syscall, sb, fsec));
  62 }
  63
  64 int
  65 lstatx_np(const char *path, struct stat *sb, filesec_t fsec)
  66 {
  67         if (fsec == NULL)
  68                 return(lstat(path, sb));
  69         return(statx1((void *)&path, lstatx_syscall, sb, fsec));
  70 }
  71
  72 /*
  73  * Stat syscalls
  74  */
  75 static int
  76 statx_syscall(void *obj, struct stat *sb, void *fsacl, size_t *fsacl_size)
  77 {
  78         const char *path = *(const char **)obj;
  79
  80         return(syscall(SYS_stat_extended, path, sb, fsacl, fsacl_size));
  81 }
  82
  83 static int
  84 fstatx_syscall(void *obj, struct stat *sb, void *fsacl, size_t *fsacl_size)
  85 {
  86         int fd = *(int *)obj;
  87         return(syscall(SYS_fstat_extended, fd, sb, fsacl, fsacl_size));
  88 }
  89
  90 static int
  91 lstatx_syscall(void *obj, struct stat *sb, void *fsacl, size_t *fsacl_size)
  92 {
  93         const char *path = *(const char **)obj;
  94         return(syscall(SYS_lstat_extended, path, sb, fsacl, fsacl_size));
  95 }
  96
  97 /*
  98  * Stat internals
  99  */
 100 static int
 101 statx1(void *obj,
 102     int (* stat_syscall)(void *obj, struct stat *sb, void *fsacl, size_t *fsacl_size),
 103     struct stat *sb, filesec_t fsec)
 104 {
 105         struct kauth_filesec *fsacl, *ofsacl;
 106         size_t fsacl_size, buffer_size;
 107         int error;
 108
 109         fsacl = NULL;
 110         error = 0;
 111
 112         /*
 113          * Allocate an initial buffer.
 114          */
 115         if ((fsacl = malloc(ACL_MIN_SIZE_HEURISTIC)) == NULL) {
 116                 error = ENOMEM;
 117                 goto out;
 118         }
 119         buffer_size = ACL_MIN_SIZE_HEURISTIC;
 120
 121         /*
 122          * Loop until we have the ACL.
 123          */
 124         for (;;) {
 125                 fsacl_size = buffer_size;
 126                 if ((error = stat_syscall(obj, sb, fsacl, &fsacl_size)) != 0)
 127                         goto out;
 128
 129                 /*
 130                  * No error, did we get the ACL?
 131                  */
 132                 if (fsacl_size <= buffer_size)
 133                         break;
 134
 135                 /* no, use supplied buffer size plus some padding */
 136                 ofsacl = fsacl;
 137                 fsacl = realloc(fsacl, fsacl_size + sizeof(struct kauth_ace) * 2);
 138                 if (fsacl == NULL) {
 139                         fsacl = ofsacl;
 140                         errno = ENOMEM;
 141                         goto out;
 142                 }
 143                 buffer_size = fsacl_size;
 144         }
 145
 146         /* populate filesec with values from stat */
 147         filesec_set_property(fsec, FILESEC_OWNER, &(sb->st_uid));
 148         filesec_set_property(fsec, FILESEC_GROUP, &(sb->st_gid));
 149         filesec_set_property(fsec, FILESEC_MODE, &(sb->st_mode));
 150
 151         /* if we got a kauth_filesec, take values from there too */
 152         if (fsacl_size >= sizeof(struct kauth_filesec)) {
 153                 filesec_set_property(fsec, FILESEC_UUID, &fsacl->fsec_owner);
 154                 filesec_set_property(fsec, FILESEC_GRPUUID, &fsacl->fsec_group);
 155
 156                 /* check to see whether there's actually an ACL here */
 157                 if (fsacl->fsec_acl.acl_entrycount != KAUTH_FILESEC_NOACL) {
 158                     filesec_set_property(fsec, FILESEC_ACL_ALLOCSIZE, &fsacl_size);
 159                     filesec_set_property(fsec, FILESEC_ACL_RAW, &fsacl);
 160                     fsacl = NULL;       /* avoid freeing it below */
 161                 } else {
 162                     filesec_set_property(fsec, FILESEC_ACL_ALLOCSIZE, NULL);
 163                     filesec_set_property(fsec, FILESEC_ACL_RAW, NULL);
 164                 }
 165         } else {
 166                 filesec_set_property(fsec, FILESEC_UUID, NULL);
 167                 filesec_set_property(fsec, FILESEC_GRPUUID, NULL);
 168                 filesec_set_property(fsec, FILESEC_ACL_ALLOCSIZE, NULL);
 169                 filesec_set_property(fsec, FILESEC_ACL_RAW, NULL);
 170         }
 171 out:
 172         if (fsacl != NULL)
 173                 free(fsacl);
 174         return(error);
 175 }