fs/9p/xattr.c

   1 /*
   2  * Copyright IBM Corporation, 2010
   3  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of version 2.1 of the GNU Lesser General Public License
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  12  *
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/fs.h>
  17 #include <linux/sched.h>
  18 #include <linux/uio.h>
  19 #include <net/9p/9p.h>
  20 #include <net/9p/client.h>
  21
  22 #include "fid.h"
  23 #include "xattr.h"
  24
  25 ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
  26                            void *buffer, size_t buffer_size)
  27 {
  28         ssize_t retval;
  29         u64 attr_size;
  30         struct p9_fid *attr_fid;
  31         struct kvec kvec = {.iov_base = buffer, .iov_len = buffer_size};
  32         struct iov_iter to;
  33         int err;
  34
  35         iov_iter_kvec(&to, READ, &kvec, 1, buffer_size);
  36
  37         attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
  38         if (IS_ERR(attr_fid)) {
  39                 retval = PTR_ERR(attr_fid);
  40                 p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
  41                          retval);
  42                 return retval;
  43         }
  44         if (attr_size > buffer_size) {
  45                 if (!buffer_size) /* request to get the attr_size */
  46                         retval = attr_size;
  47                 else
  48                         retval = -ERANGE;
  49         } else {
  50                 iov_iter_truncate(&to, attr_size);
  51                 retval = p9_client_read(attr_fid, 0, &to, &err);
  52                 if (err)
  53                         retval = err;
  54         }
  55         p9_client_clunk(attr_fid);
  56         return retval;
  57 }
  58
  59
  60 /*
  61  * v9fs_xattr_get()
  62  *
  63  * Copy an extended attribute into the buffer
  64  * provided, or compute the buffer size required.
  65  * Buffer is NULL to compute the size of the buffer required.
  66  *
  67  * Returns a negative error number on failure, or the number of bytes
  68  * used / required on success.
  69  */
  70 ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
  71                        void *buffer, size_t buffer_size)
  72 {
  73         struct p9_fid *fid;
  74
  75         p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
  76                  name, buffer_size);
  77         fid = v9fs_fid_lookup(dentry);
  78         if (IS_ERR(fid))
  79                 return PTR_ERR(fid);
  80
  81         return v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
  82 }
  83
  84 /*
  85  * v9fs_xattr_set()
  86  *
  87  * Create, replace or remove an extended attribute for this inode. Buffer
  88  * is NULL to remove an existing extended attribute, and non-NULL to
  89  * either replace an existing extended attribute, or create a new extended
  90  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
  91  * specify that an extended attribute must exist and must not exist
  92  * previous to the call, respectively.
  93  *
  94  * Returns 0, or a negative error number on failure.
  95  */
  96 int v9fs_xattr_set(struct dentry *dentry, const char *name,
  97                    const void *value, size_t value_len, int flags)
  98 {
  99         struct p9_fid *fid = v9fs_fid_lookup(dentry);
 100         return v9fs_fid_xattr_set(fid, name, value, value_len, flags);
 101 }
 102
 103 int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
 104                    const void *value, size_t value_len, int flags)
 105 {
 106         struct kvec kvec = {.iov_base = (void *)value, .iov_len = value_len};
 107         struct iov_iter from;
 108         int retval, err;
 109
 110         iov_iter_kvec(&from, WRITE, &kvec, 1, value_len);
 111
 112         p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
 113                  name, value_len, flags);
 114
 115         /* Clone it */
 116         fid = clone_fid(fid);
 117         if (IS_ERR(fid))
 118                 return PTR_ERR(fid);
 119
 120         /*
 121          * On success fid points to xattr
 122          */
 123         retval = p9_client_xattrcreate(fid, name, value_len, flags);
 124         if (retval < 0)
 125                 p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
 126                          retval);
 127         else
 128                 p9_client_write(fid, 0, &from, &retval);
 129         err = p9_client_clunk(fid);
 130         if (!retval && err)
 131                 retval = err;
 132         return retval;
 133 }
 134
 135 ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 136 {
 137         return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
 138 }
 139
 140 static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
 141                                   struct dentry *dentry, struct inode *inode,
 142                                   const char *name, void *buffer, size_t size)
 143 {
 144         const char *full_name = xattr_full_name(handler, name);
 145
 146         return v9fs_xattr_get(dentry, full_name, buffer, size);
 147 }
 148
 149 static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
 150                                   struct dentry *dentry, struct inode *inode,
 151                                   const char *name, const void *value,
 152                                   size_t size, int flags)
 153 {
 154         const char *full_name = xattr_full_name(handler, name);
 155
 156         return v9fs_xattr_set(dentry, full_name, value, size, flags);
 157 }
 158
 159 static struct xattr_handler v9fs_xattr_user_handler = {
 160         .prefix = XATTR_USER_PREFIX,
 161         .get    = v9fs_xattr_handler_get,
 162         .set    = v9fs_xattr_handler_set,
 163 };
 164
 165 static struct xattr_handler v9fs_xattr_trusted_handler = {
 166         .prefix = XATTR_TRUSTED_PREFIX,
 167         .get    = v9fs_xattr_handler_get,
 168         .set    = v9fs_xattr_handler_set,
 169 };
 170
 171 #ifdef CONFIG_9P_FS_SECURITY
 172 static struct xattr_handler v9fs_xattr_security_handler = {
 173         .prefix = XATTR_SECURITY_PREFIX,
 174         .get    = v9fs_xattr_handler_get,
 175         .set    = v9fs_xattr_handler_set,
 176 };
 177 #endif
 178
 179 const struct xattr_handler *v9fs_xattr_handlers[] = {
 180         &v9fs_xattr_user_handler,
 181         &v9fs_xattr_trusted_handler,
 182 #ifdef CONFIG_9P_FS_POSIX_ACL
 183         &v9fs_xattr_acl_access_handler,
 184         &v9fs_xattr_acl_default_handler,
 185 #endif
 186 #ifdef CONFIG_9P_FS_SECURITY
 187         &v9fs_xattr_security_handler,
 188 #endif
 189         NULL
 190 };