linux/fs/9p/xattr.c
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   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
  25ssize_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 */
  70ssize_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 */
  96int 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
 103int 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
 135ssize_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
 140static 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
 149static 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
 159static 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
 165static 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
 172static 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
 179const 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};
 191