fs/9p/xattr.c

0001 // SPDX-License-Identifier: LGPL-2.1
0002 /*
0003  * Copyright IBM Corporation, 2010
0004  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
0005  */
0006
0007 #include <linux/module.h>
0008 #include <linux/fs.h>
0009 #include <linux/sched.h>
0010 #include <linux/uio.h>
0011 #include <net/9p/9p.h>
0012 #include <net/9p/client.h>
0013
0014 #include "fid.h"
0015 #include "xattr.h"
0016
0017 ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
0018                void *buffer, size_t buffer_size)
0019 {
0020     ssize_t retval;
0021     u64 attr_size;
0022     struct p9_fid *attr_fid;
0023     struct kvec kvec = {.iov_base = buffer, .iov_len = buffer_size};
0024     struct iov_iter to;
0025     int err;
0026
0027     iov_iter_kvec(&to, READ, &kvec, 1, buffer_size);
0028
0029     attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
0030     if (IS_ERR(attr_fid)) {
0031         retval = PTR_ERR(attr_fid);
0032         p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
0033              retval);
0034         return retval;
0035     }
0036     if (attr_size > buffer_size) {
0037         if (!buffer_size) /* request to get the attr_size */
0038             retval = attr_size;
0039         else
0040             retval = -ERANGE;
0041     } else {
0042         iov_iter_truncate(&to, attr_size);
0043         retval = p9_client_read(attr_fid, 0, &to, &err);
0044         if (err)
0045             retval = err;
0046     }
0047     p9_fid_put(attr_fid);
0048     return retval;
0049 }
0050
0051
0052 /*
0053  * v9fs_xattr_get()
0054  *
0055  * Copy an extended attribute into the buffer
0056  * provided, or compute the buffer size required.
0057  * Buffer is NULL to compute the size of the buffer required.
0058  *
0059  * Returns a negative error number on failure, or the number of bytes
0060  * used / required on success.
0061  */
0062 ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
0063                void *buffer, size_t buffer_size)
0064 {
0065     struct p9_fid *fid;
0066     int ret;
0067
0068     p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
0069          name, buffer_size);
0070     fid = v9fs_fid_lookup(dentry);
0071     if (IS_ERR(fid))
0072         return PTR_ERR(fid);
0073     ret = v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
0074     p9_fid_put(fid);
0075
0076     return ret;
0077 }
0078
0079 /*
0080  * v9fs_xattr_set()
0081  *
0082  * Create, replace or remove an extended attribute for this inode. Buffer
0083  * is NULL to remove an existing extended attribute, and non-NULL to
0084  * either replace an existing extended attribute, or create a new extended
0085  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
0086  * specify that an extended attribute must exist and must not exist
0087  * previous to the call, respectively.
0088  *
0089  * Returns 0, or a negative error number on failure.
0090  */
0091 int v9fs_xattr_set(struct dentry *dentry, const char *name,
0092            const void *value, size_t value_len, int flags)
0093 {
0094     int ret;
0095     struct p9_fid *fid;
0096
0097     fid  = v9fs_fid_lookup(dentry);
0098     if (IS_ERR(fid))
0099         return PTR_ERR(fid);
0100     ret = v9fs_fid_xattr_set(fid, name, value, value_len, flags);
0101     p9_fid_put(fid);
0102     return ret;
0103 }
0104
0105 int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
0106            const void *value, size_t value_len, int flags)
0107 {
0108     struct kvec kvec = {.iov_base = (void *)value, .iov_len = value_len};
0109     struct iov_iter from;
0110     int retval, err;
0111
0112     iov_iter_kvec(&from, WRITE, &kvec, 1, value_len);
0113
0114     p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
0115          name, value_len, flags);
0116
0117     /* Clone it */
0118     fid = clone_fid(fid);
0119     if (IS_ERR(fid))
0120         return PTR_ERR(fid);
0121
0122     /*
0123      * On success fid points to xattr
0124      */
0125     retval = p9_client_xattrcreate(fid, name, value_len, flags);
0126     if (retval < 0)
0127         p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
0128              retval);
0129     else
0130         p9_client_write(fid, 0, &from, &retval);
0131     err = p9_fid_put(fid);
0132     if (!retval && err)
0133         retval = err;
0134     return retval;
0135 }
0136
0137 ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
0138 {
0139     return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
0140 }
0141
0142 static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
0143                   struct dentry *dentry, struct inode *inode,
0144                   const char *name, void *buffer, size_t size)
0145 {
0146     const char *full_name = xattr_full_name(handler, name);
0147
0148     return v9fs_xattr_get(dentry, full_name, buffer, size);
0149 }
0150
0151 static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
0152                   struct user_namespace *mnt_userns,
0153                   struct dentry *dentry, struct inode *inode,
0154                   const char *name, const void *value,
0155                   size_t size, int flags)
0156 {
0157     const char *full_name = xattr_full_name(handler, name);
0158
0159     return v9fs_xattr_set(dentry, full_name, value, size, flags);
0160 }
0161
0162 static struct xattr_handler v9fs_xattr_user_handler = {
0163     .prefix = XATTR_USER_PREFIX,
0164     .get    = v9fs_xattr_handler_get,
0165     .set    = v9fs_xattr_handler_set,
0166 };
0167
0168 static struct xattr_handler v9fs_xattr_trusted_handler = {
0169     .prefix = XATTR_TRUSTED_PREFIX,
0170     .get    = v9fs_xattr_handler_get,
0171     .set    = v9fs_xattr_handler_set,
0172 };
0173
0174 #ifdef CONFIG_9P_FS_SECURITY
0175 static struct xattr_handler v9fs_xattr_security_handler = {
0176     .prefix = XATTR_SECURITY_PREFIX,
0177     .get    = v9fs_xattr_handler_get,
0178     .set    = v9fs_xattr_handler_set,
0179 };
0180 #endif
0181
0182 const struct xattr_handler *v9fs_xattr_handlers[] = {
0183     &v9fs_xattr_user_handler,
0184     &v9fs_xattr_trusted_handler,
0185 #ifdef CONFIG_9P_FS_POSIX_ACL
0186     &v9fs_xattr_acl_access_handler,
0187     &v9fs_xattr_acl_default_handler,
0188 #endif
0189 #ifdef CONFIG_9P_FS_SECURITY
0190     &v9fs_xattr_security_handler,
0191 #endif
0192     NULL
0193 };