fs/9p/xattr.c

   1 // SPDX-License-Identifier: LGPL-2.1
   2 /*
   3  * Copyright IBM Corporation, 2010
   4  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/fs.h>
   9 #include <linux/sched.h>
  10 #include <linux/uio.h>
  11 #include <linux/posix_acl_xattr.h>
  12 #include <net/9p/9p.h>
  13 #include <net/9p/client.h>
  14
  15 #include "fid.h"
  16 #include "xattr.h"
  17
  18 ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
  19                            void *buffer, size_t buffer_size)
  20 {
  21         ssize_t retval;
  22         u64 attr_size;
  23         struct p9_fid *attr_fid;
  24         struct kvec kvec = {.iov_base = buffer, .iov_len = buffer_size};
  25         struct iov_iter to;
  26         int err;
  27
  28         iov_iter_kvec(&to, ITER_DEST, &kvec, 1, buffer_size);
  29
  30         attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
  31         if (IS_ERR(attr_fid)) {
  32                 retval = PTR_ERR(attr_fid);
  33                 p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
  34                          retval);
  35                 return retval;
  36         }
  37         if (attr_size > buffer_size) {
  38                 if (buffer_size)
  39                         retval = -ERANGE;
  40                 else if (attr_size > SSIZE_MAX)
  41                         retval = -EOVERFLOW;
  42                 else /* request to get the attr_size */
  43                         retval = attr_size;
  44         } else {
  45                 iov_iter_truncate(&to, attr_size);
  46                 retval = p9_client_read(attr_fid, 0, &to, &err);
  47                 if (err)
  48                         retval = err;
  49         }
  50         p9_fid_put(attr_fid);
  51         return retval;
  52 }
  53
  54
  55 /*
  56  * v9fs_xattr_get()
  57  *
  58  * Copy an extended attribute into the buffer
  59  * provided, or compute the buffer size required.
  60  * Buffer is NULL to compute the size of the buffer required.
  61  *
  62  * Returns a negative error number on failure, or the number of bytes
  63  * used / required on success.
  64  */
  65 ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
  66                        void *buffer, size_t buffer_size)
  67 {
  68         struct p9_fid *fid;
  69         int ret;
  70
  71         p9_debug(P9_DEBUG_VFS, "name = '%s' value_len = %zu\n",
  72                  name, buffer_size);
  73         fid = v9fs_fid_lookup(dentry);
  74         if (IS_ERR(fid))
  75                 return PTR_ERR(fid);
  76         ret = v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
  77         p9_fid_put(fid);
  78
  79         return ret;
  80 }
  81
  82 /*
  83  * v9fs_xattr_set()
  84  *
  85  * Create, replace or remove an extended attribute for this inode. Buffer
  86  * is NULL to remove an existing extended attribute, and non-NULL to
  87  * either replace an existing extended attribute, or create a new extended
  88  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
  89  * specify that an extended attribute must exist and must not exist
  90  * previous to the call, respectively.
  91  *
  92  * Returns 0, or a negative error number on failure.
  93  */
  94 int v9fs_xattr_set(struct dentry *dentry, const char *name,
  95                    const void *value, size_t value_len, int flags)
  96 {
  97         int ret;
  98         struct p9_fid *fid;
  99
 100         fid  = v9fs_fid_lookup(dentry);
 101         if (IS_ERR(fid))
 102                 return PTR_ERR(fid);
 103         ret = v9fs_fid_xattr_set(fid, name, value, value_len, flags);
 104         p9_fid_put(fid);
 105         return ret;
 106 }
 107
 108 int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
 109                    const void *value, size_t value_len, int flags)
 110 {
 111         struct kvec kvec = {.iov_base = (void *)value, .iov_len = value_len};
 112         struct iov_iter from;
 113         int retval, err;
 114
 115         iov_iter_kvec(&from, ITER_SOURCE, &kvec, 1, value_len);
 116
 117         p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
 118                  name, value_len, flags);
 119
 120         /* Clone it */
 121         fid = clone_fid(fid);
 122         if (IS_ERR(fid))
 123                 return PTR_ERR(fid);
 124
 125         /*
 126          * On success fid points to xattr
 127          */
 128         retval = p9_client_xattrcreate(fid, name, value_len, flags);
 129         if (retval < 0)
 130                 p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
 131                          retval);
 132         else
 133                 p9_client_write(fid, 0, &from, &retval);
 134         err = p9_fid_put(fid);
 135         if (!retval && err)
 136                 retval = err;
 137         return retval;
 138 }
 139
 140 ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 141 {
 142         /* Txattrwalk with an empty string lists xattrs instead */
 143         return v9fs_xattr_get(dentry, "", buffer, buffer_size);
 144 }
 145
 146 static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
 147                                   struct dentry *dentry, struct inode *inode,
 148                                   const char *name, void *buffer, size_t size)
 149 {
 150         const char *full_name = xattr_full_name(handler, name);
 151
 152         return v9fs_xattr_get(dentry, full_name, buffer, size);
 153 }
 154
 155 static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
 156                                   struct mnt_idmap *idmap,
 157                                   struct dentry *dentry, struct inode *inode,
 158                                   const char *name, const void *value,
 159                                   size_t size, int flags)
 160 {
 161         const char *full_name = xattr_full_name(handler, name);
 162
 163         return v9fs_xattr_set(dentry, full_name, value, size, flags);
 164 }
 165
 166 static const struct xattr_handler v9fs_xattr_user_handler = {
 167         .prefix = XATTR_USER_PREFIX,
 168         .get    = v9fs_xattr_handler_get,
 169         .set    = v9fs_xattr_handler_set,
 170 };
 171
 172 static const struct xattr_handler v9fs_xattr_trusted_handler = {
 173         .prefix = XATTR_TRUSTED_PREFIX,
 174         .get    = v9fs_xattr_handler_get,
 175         .set    = v9fs_xattr_handler_set,
 176 };
 177
 178 #ifdef CONFIG_9P_FS_SECURITY
 179 static const struct xattr_handler v9fs_xattr_security_handler = {
 180         .prefix = XATTR_SECURITY_PREFIX,
 181         .get    = v9fs_xattr_handler_get,
 182         .set    = v9fs_xattr_handler_set,
 183 };
 184 #endif
 185
 186 const struct xattr_handler * const v9fs_xattr_handlers[] = {
 187         &v9fs_xattr_user_handler,
 188         &v9fs_xattr_trusted_handler,
 189 #ifdef CONFIG_9P_FS_SECURITY
 190         &v9fs_xattr_security_handler,
 191 #endif
 192         NULL
 193 };