fs/xfs/xfs_acl.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2008, Christoph Hellwig
   4  * All Rights Reserved.
   5  */
   6 #include "xfs.h"
   7 #include "xfs_shared.h"
   8 #include "xfs_format.h"
   9 #include "xfs_log_format.h"
  10 #include "xfs_trans_resv.h"
  11 #include "xfs_mount.h"
  12 #include "xfs_inode.h"
  13 #include "xfs_attr.h"
  14 #include "xfs_trace.h"
  15 #include "xfs_error.h"
  16 #include "xfs_acl.h"
  17 #include "xfs_da_format.h"
  18 #include "xfs_da_btree.h"
  19
  20 #include <linux/posix_acl_xattr.h>
  21
  22 /*
  23  * Locking scheme:
  24  *  - all ACL updates are protected by inode->i_mutex, which is taken before
  25  *    calling into this file.
  26  */
  27
  28 STATIC struct posix_acl *
  29 xfs_acl_from_disk(
  30         struct xfs_mount        *mp,
  31         const struct xfs_acl    *aclp,
  32         int                     len,
  33         int                     max_entries)
  34 {
  35         struct posix_acl_entry *acl_e;
  36         struct posix_acl *acl;
  37         const struct xfs_acl_entry *ace;
  38         unsigned int count, i;
  39
  40         if (len < sizeof(*aclp)) {
  41                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
  42                                 len);
  43                 return ERR_PTR(-EFSCORRUPTED);
  44         }
  45
  46         count = be32_to_cpu(aclp->acl_cnt);
  47         if (count > max_entries || XFS_ACL_SIZE(count) != len) {
  48                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
  49                                 len);
  50                 return ERR_PTR(-EFSCORRUPTED);
  51         }
  52
  53         acl = posix_acl_alloc(count, GFP_KERNEL);
  54         if (!acl)
  55                 return ERR_PTR(-ENOMEM);
  56
  57         for (i = 0; i < count; i++) {
  58                 acl_e = &acl->a_entries[i];
  59                 ace = &aclp->acl_entry[i];
  60
  61                 /*
  62                  * The tag is 32 bits on disk and 16 bits in core.
  63                  *
  64                  * Because every access to it goes through the core
  65                  * format first this is not a problem.
  66                  */
  67                 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
  68                 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
  69
  70                 switch (acl_e->e_tag) {
  71                 case ACL_USER:
  72                         acl_e->e_uid = make_kuid(&init_user_ns,
  73                                                  be32_to_cpu(ace->ae_id));
  74                         break;
  75                 case ACL_GROUP:
  76                         acl_e->e_gid = make_kgid(&init_user_ns,
  77                                                  be32_to_cpu(ace->ae_id));
  78                         break;
  79                 case ACL_USER_OBJ:
  80                 case ACL_GROUP_OBJ:
  81                 case ACL_MASK:
  82                 case ACL_OTHER:
  83                         break;
  84                 default:
  85                         goto fail;
  86                 }
  87         }
  88         return acl;
  89
  90 fail:
  91         posix_acl_release(acl);
  92         return ERR_PTR(-EINVAL);
  93 }
  94
  95 STATIC void
  96 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
  97 {
  98         const struct posix_acl_entry *acl_e;
  99         struct xfs_acl_entry *ace;
 100         int i;
 101
 102         aclp->acl_cnt = cpu_to_be32(acl->a_count);
 103         for (i = 0; i < acl->a_count; i++) {
 104                 ace = &aclp->acl_entry[i];
 105                 acl_e = &acl->a_entries[i];
 106
 107                 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
 108                 switch (acl_e->e_tag) {
 109                 case ACL_USER:
 110                         ace->ae_id = cpu_to_be32(
 111                                         from_kuid(&init_user_ns, acl_e->e_uid));
 112                         break;
 113                 case ACL_GROUP:
 114                         ace->ae_id = cpu_to_be32(
 115                                         from_kgid(&init_user_ns, acl_e->e_gid));
 116                         break;
 117                 default:
 118                         ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
 119                         break;
 120                 }
 121
 122                 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
 123         }
 124 }
 125
 126 struct posix_acl *
 127 xfs_get_acl(struct inode *inode, int type)
 128 {
 129         struct xfs_inode        *ip = XFS_I(inode);
 130         struct xfs_mount        *mp = ip->i_mount;
 131         struct posix_acl        *acl = NULL;
 132         struct xfs_da_args      args = {
 133                 .dp             = ip,
 134                 .attr_filter    = XFS_ATTR_ROOT,
 135                 .valuelen       = XFS_ACL_MAX_SIZE(mp),
 136         };
 137         int                     error;
 138
 139         trace_xfs_get_acl(ip);
 140
 141         switch (type) {
 142         case ACL_TYPE_ACCESS:
 143                 args.name = SGI_ACL_FILE;
 144                 break;
 145         case ACL_TYPE_DEFAULT:
 146                 args.name = SGI_ACL_DEFAULT;
 147                 break;
 148         default:
 149                 BUG();
 150         }
 151         args.namelen = strlen(args.name);
 152
 153         /*
 154          * If the attribute doesn't exist make sure we have a negative cache
 155          * entry, for any other error assume it is transient.
 156          */
 157         error = xfs_attr_get(&args);
 158         if (!error) {
 159                 acl = xfs_acl_from_disk(mp, args.value, args.valuelen,
 160                                         XFS_ACL_MAX_ENTRIES(mp));
 161         } else if (error != -ENOATTR) {
 162                 acl = ERR_PTR(error);
 163         }
 164
 165         kmem_free(args.value);
 166         return acl;
 167 }
 168
 169 int
 170 __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 171 {
 172         struct xfs_inode        *ip = XFS_I(inode);
 173         struct xfs_da_args      args = {
 174                 .dp             = ip,
 175                 .attr_filter    = XFS_ATTR_ROOT,
 176         };
 177         int                     error;
 178
 179         switch (type) {
 180         case ACL_TYPE_ACCESS:
 181                 args.name = SGI_ACL_FILE;
 182                 break;
 183         case ACL_TYPE_DEFAULT:
 184                 if (!S_ISDIR(inode->i_mode))
 185                         return acl ? -EACCES : 0;
 186                 args.name = SGI_ACL_DEFAULT;
 187                 break;
 188         default:
 189                 return -EINVAL;
 190         }
 191         args.namelen = strlen(args.name);
 192
 193         if (acl) {
 194                 args.valuelen = XFS_ACL_SIZE(acl->a_count);
 195                 args.value = kmem_zalloc_large(args.valuelen, 0);
 196                 if (!args.value)
 197                         return -ENOMEM;
 198                 xfs_acl_to_disk(args.value, acl);
 199         }
 200
 201         error = xfs_attr_set(&args);
 202         kmem_free(args.value);
 203
 204         /*
 205          * If the attribute didn't exist to start with that's fine.
 206          */
 207         if (!acl && error == -ENOATTR)
 208                 error = 0;
 209         if (!error)
 210                 set_cached_acl(inode, type, acl);
 211         return error;
 212 }
 213
 214 static int
 215 xfs_set_mode(struct inode *inode, umode_t mode)
 216 {
 217         int error = 0;
 218
 219         if (mode != inode->i_mode) {
 220                 struct iattr iattr;
 221
 222                 iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
 223                 iattr.ia_mode = mode;
 224                 iattr.ia_ctime = current_time(inode);
 225
 226                 error = xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
 227         }
 228
 229         return error;
 230 }
 231
 232 int
 233 xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 234 {
 235         umode_t mode;
 236         bool set_mode = false;
 237         int error = 0;
 238
 239         if (!acl)
 240                 goto set_acl;
 241
 242         error = -E2BIG;
 243         if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
 244                 return error;
 245
 246         if (type == ACL_TYPE_ACCESS) {
 247                 error = posix_acl_update_mode(inode, &mode, &acl);
 248                 if (error)
 249                         return error;
 250                 set_mode = true;
 251         }
 252
 253  set_acl:
 254         error =  __xfs_set_acl(inode, acl, type);
 255         if (error)
 256                 return error;
 257
 258         /*
 259          * We set the mode after successfully updating the ACL xattr because the
 260          * xattr update can fail at ENOSPC and we don't want to change the mode
 261          * if the ACL update hasn't been applied.
 262          */
 263         if (set_mode)
 264                 error = xfs_set_mode(inode, mode);
 265
 266         return error;
 267 }
 268
 269 /*
 270  * Invalidate any cached ACLs if the user has bypassed the ACL interface.
 271  * We don't validate the content whatsoever so it is caller responsibility to
 272  * provide data in valid format and ensure i_mode is consistent.
 273  */
 274 void
 275 xfs_forget_acl(
 276         struct inode            *inode,
 277         const char              *name)
 278 {
 279         if (!strcmp(name, SGI_ACL_FILE))
 280                 forget_cached_acl(inode, ACL_TYPE_ACCESS);
 281         else if (!strcmp(name, SGI_ACL_DEFAULT))
 282                 forget_cached_acl(inode, ACL_TYPE_DEFAULT);
 283 }