fs/xfs/xfs_xattr.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2008 Christoph Hellwig.
   4  * Portions Copyright (C) 2000-2008 Silicon Graphics, Inc.
   5  */
   6
   7 #include "xfs.h"
   8 #include "xfs_shared.h"
   9 #include "xfs_format.h"
  10 #include "xfs_log_format.h"
  11 #include "xfs_da_format.h"
  12 #include "xfs_trans_resv.h"
  13 #include "xfs_mount.h"
  14 #include "xfs_inode.h"
  15 #include "xfs_da_btree.h"
  16 #include "xfs_attr.h"
  17 #include "xfs_acl.h"
  18 #include "xfs_log.h"
  19 #include "xfs_xattr.h"
  20
  21 #include <linux/posix_acl_xattr.h>
  22
  23 /*
  24  * Get permission to use log-assisted atomic exchange of file extents.
  25  *
  26  * Callers must not be running any transactions or hold any inode locks, and
  27  * they must release the permission by calling xlog_drop_incompat_feat
  28  * when they're done.
  29  */
  30 static inline int
  31 xfs_attr_grab_log_assist(
  32         struct xfs_mount        *mp)
  33 {
  34         int                     error = 0;
  35
  36         /*
  37          * Protect ourselves from an idle log clearing the logged xattrs log
  38          * incompat feature bit.
  39          */
  40         xlog_use_incompat_feat(mp->m_log);
  41
  42         /*
  43          * If log-assisted xattrs are already enabled, the caller can use the
  44          * log assisted swap functions with the log-incompat reference we got.
  45          */
  46         if (xfs_sb_version_haslogxattrs(&mp->m_sb))
  47                 return 0;
  48
  49         /* Enable log-assisted xattrs. */
  50         error = xfs_add_incompat_log_feature(mp,
  51                         XFS_SB_FEAT_INCOMPAT_LOG_XATTRS);
  52         if (error)
  53                 goto drop_incompat;
  54
  55         xfs_warn_mount(mp, XFS_OPSTATE_WARNED_LARP,
  56  "EXPERIMENTAL logged extended attributes feature in use. Use at your own risk!");
  57
  58         return 0;
  59 drop_incompat:
  60         xlog_drop_incompat_feat(mp->m_log);
  61         return error;
  62 }
  63
  64 static inline void
  65 xfs_attr_rele_log_assist(
  66         struct xfs_mount        *mp)
  67 {
  68         xlog_drop_incompat_feat(mp->m_log);
  69 }
  70
  71 static inline bool
  72 xfs_attr_want_log_assist(
  73         struct xfs_mount        *mp)
  74 {
  75 #ifdef DEBUG
  76         /* Logged xattrs require a V5 super for log_incompat */
  77         return xfs_has_crc(mp) && xfs_globals.larp;
  78 #else
  79         return false;
  80 #endif
  81 }
  82
  83 /*
  84  * Set or remove an xattr, having grabbed the appropriate logging resources
  85  * prior to calling libxfs.
  86  */
  87 int
  88 xfs_attr_change(
  89         struct xfs_da_args      *args)
  90 {
  91         struct xfs_mount        *mp = args->dp->i_mount;
  92         bool                    use_logging = false;
  93         int                     error;
  94
  95         ASSERT(!(args->op_flags & XFS_DA_OP_LOGGED));
  96
  97         if (xfs_attr_want_log_assist(mp)) {
  98                 error = xfs_attr_grab_log_assist(mp);
  99                 if (error)
 100                         return error;
 101
 102                 args->op_flags |= XFS_DA_OP_LOGGED;
 103                 use_logging = true;
 104         }
 105
 106         error = xfs_attr_set(args);
 107
 108         if (use_logging)
 109                 xfs_attr_rele_log_assist(mp);
 110         return error;
 111 }
 112
 113
 114 static int
 115 xfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused,
 116                 struct inode *inode, const char *name, void *value, size_t size)
 117 {
 118         struct xfs_da_args      args = {
 119                 .dp             = XFS_I(inode),
 120                 .attr_filter    = handler->flags,
 121                 .name           = name,
 122                 .namelen        = strlen(name),
 123                 .value          = value,
 124                 .valuelen       = size,
 125         };
 126         int                     error;
 127
 128         error = xfs_attr_get(&args);
 129         if (error)
 130                 return error;
 131         return args.valuelen;
 132 }
 133
 134 static int
 135 xfs_xattr_set(const struct xattr_handler *handler,
 136               struct mnt_idmap *idmap, struct dentry *unused,
 137               struct inode *inode, const char *name, const void *value,
 138               size_t size, int flags)
 139 {
 140         struct xfs_da_args      args = {
 141                 .dp             = XFS_I(inode),
 142                 .attr_filter    = handler->flags,
 143                 .attr_flags     = flags,
 144                 .name           = name,
 145                 .namelen        = strlen(name),
 146                 .value          = (void *)value,
 147                 .valuelen       = size,
 148         };
 149         int                     error;
 150
 151         error = xfs_attr_change(&args);
 152         if (!error && (handler->flags & XFS_ATTR_ROOT))
 153                 xfs_forget_acl(inode, name);
 154         return error;
 155 }
 156
 157 static const struct xattr_handler xfs_xattr_user_handler = {
 158         .prefix = XATTR_USER_PREFIX,
 159         .flags  = 0, /* no flags implies user namespace */
 160         .get    = xfs_xattr_get,
 161         .set    = xfs_xattr_set,
 162 };
 163
 164 static const struct xattr_handler xfs_xattr_trusted_handler = {
 165         .prefix = XATTR_TRUSTED_PREFIX,
 166         .flags  = XFS_ATTR_ROOT,
 167         .get    = xfs_xattr_get,
 168         .set    = xfs_xattr_set,
 169 };
 170
 171 static const struct xattr_handler xfs_xattr_security_handler = {
 172         .prefix = XATTR_SECURITY_PREFIX,
 173         .flags  = XFS_ATTR_SECURE,
 174         .get    = xfs_xattr_get,
 175         .set    = xfs_xattr_set,
 176 };
 177
 178 const struct xattr_handler *xfs_xattr_handlers[] = {
 179         &xfs_xattr_user_handler,
 180         &xfs_xattr_trusted_handler,
 181         &xfs_xattr_security_handler,
 182         NULL
 183 };
 184
 185 static void
 186 __xfs_xattr_put_listent(
 187         struct xfs_attr_list_context *context,
 188         char *prefix,
 189         int prefix_len,
 190         unsigned char *name,
 191         int namelen)
 192 {
 193         char *offset;
 194         int arraytop;
 195
 196         if (context->count < 0 || context->seen_enough)
 197                 return;
 198
 199         if (!context->buffer)
 200                 goto compute_size;
 201
 202         arraytop = context->count + prefix_len + namelen + 1;
 203         if (arraytop > context->firstu) {
 204                 context->count = -1;    /* insufficient space */
 205                 context->seen_enough = 1;
 206                 return;
 207         }
 208         offset = context->buffer + context->count;
 209         memcpy(offset, prefix, prefix_len);
 210         offset += prefix_len;
 211         strncpy(offset, (char *)name, namelen);                 /* real name */
 212         offset += namelen;
 213         *offset = '\0';
 214
 215 compute_size:
 216         context->count += prefix_len + namelen + 1;
 217         return;
 218 }
 219
 220 static void
 221 xfs_xattr_put_listent(
 222         struct xfs_attr_list_context *context,
 223         int             flags,
 224         unsigned char   *name,
 225         int             namelen,
 226         int             valuelen)
 227 {
 228         char *prefix;
 229         int prefix_len;
 230
 231         ASSERT(context->count >= 0);
 232
 233         if (flags & XFS_ATTR_ROOT) {
 234 #ifdef CONFIG_XFS_POSIX_ACL
 235                 if (namelen == SGI_ACL_FILE_SIZE &&
 236                     strncmp(name, SGI_ACL_FILE,
 237                             SGI_ACL_FILE_SIZE) == 0) {
 238                         __xfs_xattr_put_listent(
 239                                         context, XATTR_SYSTEM_PREFIX,
 240                                         XATTR_SYSTEM_PREFIX_LEN,
 241                                         XATTR_POSIX_ACL_ACCESS,
 242                                         strlen(XATTR_POSIX_ACL_ACCESS));
 243                 } else if (namelen == SGI_ACL_DEFAULT_SIZE &&
 244                          strncmp(name, SGI_ACL_DEFAULT,
 245                                  SGI_ACL_DEFAULT_SIZE) == 0) {
 246                         __xfs_xattr_put_listent(
 247                                         context, XATTR_SYSTEM_PREFIX,
 248                                         XATTR_SYSTEM_PREFIX_LEN,
 249                                         XATTR_POSIX_ACL_DEFAULT,
 250                                         strlen(XATTR_POSIX_ACL_DEFAULT));
 251                 }
 252 #endif
 253
 254                 /*
 255                  * Only show root namespace entries if we are actually allowed to
 256                  * see them.
 257                  */
 258                 if (!capable(CAP_SYS_ADMIN))
 259                         return;
 260
 261                 prefix = XATTR_TRUSTED_PREFIX;
 262                 prefix_len = XATTR_TRUSTED_PREFIX_LEN;
 263         } else if (flags & XFS_ATTR_SECURE) {
 264                 prefix = XATTR_SECURITY_PREFIX;
 265                 prefix_len = XATTR_SECURITY_PREFIX_LEN;
 266         } else {
 267                 prefix = XATTR_USER_PREFIX;
 268                 prefix_len = XATTR_USER_PREFIX_LEN;
 269         }
 270
 271         __xfs_xattr_put_listent(context, prefix, prefix_len, name,
 272                                 namelen);
 273         return;
 274 }
 275
 276 ssize_t
 277 xfs_vn_listxattr(
 278         struct dentry   *dentry,
 279         char            *data,
 280         size_t          size)
 281 {
 282         struct xfs_attr_list_context context;
 283         struct inode    *inode = d_inode(dentry);
 284         int             error;
 285
 286         /*
 287          * First read the regular on-disk attributes.
 288          */
 289         memset(&context, 0, sizeof(context));
 290         context.dp = XFS_I(inode);
 291         context.resynch = 1;
 292         context.buffer = size ? data : NULL;
 293         context.bufsize = size;
 294         context.firstu = context.bufsize;
 295         context.put_listent = xfs_xattr_put_listent;
 296
 297         error = xfs_attr_list(&context);
 298         if (error)
 299                 return error;
 300         if (context.count < 0)
 301                 return -ERANGE;
 302
 303         return context.count;
 304 }