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