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_da_format.h"
  14 #include "xfs_da_btree.h"
  15 #include "xfs_attr.h"
  16 #include "xfs_trace.h"
  17 #include "xfs_error.h"
  18 #include "xfs_acl.h"
  19 #include "xfs_trans.h"
  20 #include "xfs_xattr.h"
  21
  22 #include <linux/posix_acl_xattr.h>
  23
  24 /*
  25  * Locking scheme:
  26  *  - all ACL updates are protected by inode->i_mutex, which is taken before
  27  *    calling into this file.
  28  */
  29
  30 STATIC struct posix_acl *
  31 xfs_acl_from_disk(
  32         struct xfs_mount        *mp,
  33         const struct xfs_acl    *aclp,
  34         int                     len,
  35         int                     max_entries)
  36 {
  37         struct posix_acl_entry *acl_e;
  38         struct posix_acl *acl;
  39         const struct xfs_acl_entry *ace;
  40         unsigned int count, i;
  41
  42         if (len < sizeof(*aclp)) {
  43                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
  44                                 len);
  45                 return ERR_PTR(-EFSCORRUPTED);
  46         }
  47
  48         count = be32_to_cpu(aclp->acl_cnt);
  49         if (count > max_entries || XFS_ACL_SIZE(count) != len) {
  50                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
  51                                 len);
  52                 return ERR_PTR(-EFSCORRUPTED);
  53         }
  54
  55         acl = posix_acl_alloc(count, GFP_KERNEL);
  56         if (!acl)
  57                 return ERR_PTR(-ENOMEM);
  58
  59         for (i = 0; i < count; i++) {
  60                 acl_e = &acl->a_entries[i];
  61                 ace = &aclp->acl_entry[i];
  62
  63                 /*
  64                  * The tag is 32 bits on disk and 16 bits in core.
  65                  *
  66                  * Because every access to it goes through the core
  67                  * format first this is not a problem.
  68                  */
  69                 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
  70                 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
  71
  72                 switch (acl_e->e_tag) {
  73                 case ACL_USER:
  74                         acl_e->e_uid = make_kuid(&init_user_ns,
  75                                                  be32_to_cpu(ace->ae_id));
  76                         break;
  77                 case ACL_GROUP:
  78                         acl_e->e_gid = make_kgid(&init_user_ns,
  79                                                  be32_to_cpu(ace->ae_id));
  80                         break;
  81                 case ACL_USER_OBJ:
  82                 case ACL_GROUP_OBJ:
  83                 case ACL_MASK:
  84                 case ACL_OTHER:
  85                         break;
  86                 default:
  87                         goto fail;
  88                 }
  89         }
  90         return acl;
  91
  92 fail:
  93         posix_acl_release(acl);
  94         return ERR_PTR(-EINVAL);
  95 }
  96
  97 STATIC void
  98 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
  99 {
 100         const struct posix_acl_entry *acl_e;
 101         struct xfs_acl_entry *ace;
 102         int i;
 103
 104         aclp->acl_cnt = cpu_to_be32(acl->a_count);
 105         for (i = 0; i < acl->a_count; i++) {
 106                 ace = &aclp->acl_entry[i];
 107                 acl_e = &acl->a_entries[i];
 108
 109                 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
 110                 switch (acl_e->e_tag) {
 111                 case ACL_USER:
 112                         ace->ae_id = cpu_to_be32(
 113                                         from_kuid(&init_user_ns, acl_e->e_uid));
 114                         break;
 115                 case ACL_GROUP:
 116                         ace->ae_id = cpu_to_be32(
 117                                         from_kgid(&init_user_ns, acl_e->e_gid));
 118                         break;
 119                 default:
 120                         ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
 121                         break;
 122                 }
 123
 124                 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
 125         }
 126 }
 127
 128 struct posix_acl *
 129 xfs_get_acl(struct inode *inode, int type, bool rcu)
 130 {
 131         struct xfs_inode        *ip = XFS_I(inode);
 132         struct xfs_mount        *mp = ip->i_mount;
 133         struct posix_acl        *acl = NULL;
 134         struct xfs_da_args      args = {
 135                 .dp             = ip,
 136                 .attr_filter    = XFS_ATTR_ROOT,
 137                 .valuelen       = XFS_ACL_MAX_SIZE(mp),
 138         };
 139         int                     error;
 140
 141         if (rcu)
 142                 return ERR_PTR(-ECHILD);
 143
 144         trace_xfs_get_acl(ip);
 145
 146         switch (type) {
 147         case ACL_TYPE_ACCESS:
 148                 args.name = SGI_ACL_FILE;
 149                 break;
 150         case ACL_TYPE_DEFAULT:
 151                 args.name = SGI_ACL_DEFAULT;
 152                 break;
 153         default:
 154                 BUG();
 155         }
 156         args.namelen = strlen(args.name);
 157
 158         /*
 159          * If the attribute doesn't exist make sure we have a negative cache
 160          * entry, for any other error assume it is transient.
 161          */
 162         error = xfs_attr_get(&args);
 163         if (!error) {
 164                 acl = xfs_acl_from_disk(mp, args.value, args.valuelen,
 165                                         XFS_ACL_MAX_ENTRIES(mp));
 166         } else if (error != -ENOATTR) {
 167                 acl = ERR_PTR(error);
 168         }
 169
 170         kvfree(args.value);
 171         return acl;
 172 }
 173
 174 int
 175 __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 176 {
 177         struct xfs_inode        *ip = XFS_I(inode);
 178         struct xfs_da_args      args = {
 179                 .dp             = ip,
 180                 .attr_filter    = XFS_ATTR_ROOT,
 181         };
 182         int                     error;
 183
 184         switch (type) {
 185         case ACL_TYPE_ACCESS:
 186                 args.name = SGI_ACL_FILE;
 187                 break;
 188         case ACL_TYPE_DEFAULT:
 189                 if (!S_ISDIR(inode->i_mode))
 190                         return acl ? -EACCES : 0;
 191                 args.name = SGI_ACL_DEFAULT;
 192                 break;
 193         default:
 194                 return -EINVAL;
 195         }
 196         args.namelen = strlen(args.name);
 197
 198         if (acl) {
 199                 args.valuelen = XFS_ACL_SIZE(acl->a_count);
 200                 args.value = kvzalloc(args.valuelen, GFP_KERNEL);
 201                 if (!args.value)
 202                         return -ENOMEM;
 203                 xfs_acl_to_disk(args.value, acl);
 204                 error = xfs_attr_change(&args, XFS_ATTRUPDATE_UPSERT);
 205                 kvfree(args.value);
 206         } else {
 207                 error = xfs_attr_change(&args, XFS_ATTRUPDATE_REMOVE);
 208                 /*
 209                  * If the attribute didn't exist to start with that's fine.
 210                  */
 211                 if (error == -ENOATTR)
 212                         error = 0;
 213         }
 214
 215         if (!error)
 216                 set_cached_acl(inode, type, acl);
 217         return error;
 218 }
 219
 220 static int
 221 xfs_acl_set_mode(
 222         struct inode            *inode,
 223         umode_t                 mode)
 224 {
 225         struct xfs_inode        *ip = XFS_I(inode);
 226         struct xfs_mount        *mp = ip->i_mount;
 227         struct xfs_trans        *tp;
 228         int                     error;
 229
 230         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
 231         if (error)
 232                 return error;
 233
 234         xfs_ilock(ip, XFS_ILOCK_EXCL);
 235         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 236         inode->i_mode = mode;
 237         inode_set_ctime_current(inode);
 238         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 239
 240         if (xfs_has_wsync(mp))
 241                 xfs_trans_set_sync(tp);
 242         return xfs_trans_commit(tp);
 243 }
 244
 245 int
 246 xfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 247             struct posix_acl *acl, int type)
 248 {
 249         umode_t mode;
 250         bool set_mode = false;
 251         int error = 0;
 252         struct inode *inode = d_inode(dentry);
 253
 254         if (!acl)
 255                 goto set_acl;
 256
 257         error = -E2BIG;
 258         if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
 259                 return error;
 260
 261         if (type == ACL_TYPE_ACCESS) {
 262                 error = posix_acl_update_mode(idmap, inode, &mode, &acl);
 263                 if (error)
 264                         return error;
 265                 set_mode = true;
 266         }
 267
 268  set_acl:
 269         /*
 270          * We set the mode after successfully updating the ACL xattr because the
 271          * xattr update can fail at ENOSPC and we don't want to change the mode
 272          * if the ACL update hasn't been applied.
 273          */
 274         error =  __xfs_set_acl(inode, acl, type);
 275         if (!error && set_mode && mode != inode->i_mode)
 276                 error = xfs_acl_set_mode(inode, mode);
 277         return error;
 278 }
 279
 280 /*
 281  * Invalidate any cached ACLs if the user has bypassed the ACL interface.
 282  * We don't validate the content whatsoever so it is caller responsibility to
 283  * provide data in valid format and ensure i_mode is consistent.
 284  */
 285 void
 286 xfs_forget_acl(
 287         struct inode            *inode,
 288         const char              *name)
 289 {
 290         if (!strcmp(name, SGI_ACL_FILE))
 291                 forget_cached_acl(inode, ACL_TYPE_ACCESS);
 292         else if (!strcmp(name, SGI_ACL_DEFAULT))
 293                 forget_cached_acl(inode, ACL_TYPE_DEFAULT);
 294 }