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