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fs/cifs: make share unaccessible at root level mountable

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if, when mounting //HOST/share/sub/dir/foo we can query /sub/dir/foo but
not any of the path components above:

- store the /sub/dir/foo prefix in the cifs super_block info
- in the superblock, set root dentry to the subpath dentry (instead of
  the share root)
- set a flag in the superblock to remember it
- use prefixpath when building path from a dentry

fixes bso#8950

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>
This commit is contained in:
Aurelien Aptel 2016-05-25 19:59:09 +02:00 committed by Steve French
parent bd975d1eea
commit a6b5058faf
5 changed files with 104 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/cifs/cifs_fs_sb.h
View File

@ -46,6 +46,9 @@
#define CIFS_MOUNT_CIFS_BACKUPUID 0x200000 /* backup intent bit for a user */
#define CIFS_MOUNT_CIFS_BACKUPGID 0x400000 /* backup intent bit for a group */
#define CIFS_MOUNT_MAP_SFM_CHR 0x800000 /* SFM/MAC mapping for illegal chars */
#define CIFS_MOUNT_USE_PREFIX_PATH 0x1000000 /* make subpath with unaccessible
* root mountable
*/
struct cifs_sb_info {
struct rb_root tlink_tree;
@ -67,5 +70,6 @@ struct cifs_sb_info {
struct backing_dev_info bdi;
struct delayed_work prune_tlinks;
struct rcu_head rcu;
char *prepath;
};
#endif /* _CIFS_FS_SB_H */

14
fs/cifs/cifsfs.c
View File

@ -689,6 +689,14 @@ cifs_do_mount(struct file_system_type *fs_type,
goto out_cifs_sb;
}
if (volume_info->prepath) {
cifs_sb->prepath = kstrdup(volume_info->prepath, GFP_KERNEL);
if (cifs_sb->prepath == NULL) {
root = ERR_PTR(-ENOMEM);
goto out_cifs_sb;
}
}
cifs_setup_cifs_sb(volume_info, cifs_sb);
rc = cifs_mount(cifs_sb, volume_info);
@ -727,7 +735,11 @@ cifs_do_mount(struct file_system_type *fs_type,
sb->s_flags |= MS_ACTIVE;
}
root = cifs_get_root(volume_info, sb);
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH)
root = dget(sb->s_root);
else
root = cifs_get_root(volume_info, sb);
if (IS_ERR(root))
goto out_super;

49
fs/cifs/connect.c
View File

@ -3485,6 +3485,44 @@ cifs_get_volume_info(char *mount_data, const char *devname)
return volume_info;
}
static int
cifs_are_all_path_components_accessible(struct TCP_Server_Info *server,
unsigned int xid,
struct cifs_tcon *tcon,
struct cifs_sb_info *cifs_sb,
char *full_path)
{
int rc;
char *s;
char sep, tmp;
sep = CIFS_DIR_SEP(cifs_sb);
s = full_path;
rc = server->ops->is_path_accessible(xid, tcon, cifs_sb, "");
while (rc == 0) {
/* skip separators */
while (*s == sep)
s++;
if (!*s)
break;
/* next separator */
while (*s && *s != sep)
s++;
/*
* temporarily null-terminate the path at the end of
* the current component
*/
tmp = *s;
*s = 0;
rc = server->ops->is_path_accessible(xid, tcon, cifs_sb,
full_path);
*s = tmp;
}
return rc;
}
int
cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *volume_info)
{
@ -3622,6 +3660,16 @@ remote_path_check:
kfree(full_path);
goto mount_fail_check;
}
rc = cifs_are_all_path_components_accessible(server,
xid, tcon, cifs_sb,
full_path);
if (rc != 0) {
cifs_dbg(VFS, "cannot query dirs between root and final path, "
"enabling CIFS_MOUNT_USE_PREFIX_PATH\n");
cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
rc = 0;
}
kfree(full_path);
}
@ -3891,6 +3939,7 @@ cifs_umount(struct cifs_sb_info *cifs_sb)
bdi_destroy(&cifs_sb->bdi);
kfree(cifs_sb->mountdata);
kfree(cifs_sb->prepath);
call_rcu(&cifs_sb->rcu, delayed_free);
}

20
fs/cifs/dir.c
View File

@ -84,6 +84,7 @@ build_path_from_dentry(struct dentry *direntry)
struct dentry *temp;
int namelen;
int dfsplen;
int pplen = 0;
char *full_path;
char dirsep;
struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
@ -95,8 +96,12 @@ build_path_from_dentry(struct dentry *direntry)
dfsplen = strnlen(tcon->treeName, MAX_TREE_SIZE + 1);
else
dfsplen = 0;
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH)
pplen = cifs_sb->prepath ? strlen(cifs_sb->prepath) + 1 : 0;
cifs_bp_rename_retry:
namelen = dfsplen;
namelen = dfsplen + pplen;
seq = read_seqbegin(&rename_lock);
rcu_read_lock();
for (temp = direntry; !IS_ROOT(temp);) {
@ -137,7 +142,7 @@ cifs_bp_rename_retry:
}
}
rcu_read_unlock();
if (namelen != dfsplen || read_seqretry(&rename_lock, seq)) {
if (namelen != dfsplen + pplen || read_seqretry(&rename_lock, seq)) {
cifs_dbg(FYI, "did not end path lookup where expected. namelen=%ddfsplen=%d\n",
namelen, dfsplen);
/* presumably this is only possible if racing with a rename
@ -153,6 +158,17 @@ cifs_bp_rename_retry:
those safely to '/' if any are found in the middle of the prepath */
/* BB test paths to Windows with '/' in the midst of prepath */
if (pplen) {
int i;
cifs_dbg(FYI, "using cifs_sb prepath <%s>\n", cifs_sb->prepath);
memcpy(full_path+dfsplen+1, cifs_sb->prepath, pplen-1);
full_path[dfsplen] = '\\';
for (i = 0; i < pplen-1; i++)
if (full_path[dfsplen+1+i] == '/')
full_path[dfsplen+1+i] = CIFS_DIR_SEP(cifs_sb);
}
if (dfsplen) {
strncpy(full_path, tcon->treeName, dfsplen);
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {

22
fs/cifs/inode.c
View File

@ -1002,10 +1002,26 @@ struct inode *cifs_root_iget(struct super_block *sb)
struct inode *inode = NULL;
long rc;
struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
char *path = NULL;
int len;
if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH)
&& cifs_sb->prepath) {
len = strlen(cifs_sb->prepath);
path = kzalloc(len + 2 /* leading sep + null */, GFP_KERNEL);
if (path == NULL)
return ERR_PTR(-ENOMEM);
path[0] = '/';
memcpy(path+1, cifs_sb->prepath, len);
} else {
path = kstrdup("", GFP_KERNEL);
if (path == NULL)
return ERR_PTR(-ENOMEM);
}
xid = get_xid();
if (tcon->unix_ext) {
rc = cifs_get_inode_info_unix(&inode, "", sb, xid);
rc = cifs_get_inode_info_unix(&inode, path, sb, xid);
/* some servers mistakenly claim POSIX support */
if (rc != -EOPNOTSUPP)
goto iget_no_retry;
@ -1013,7 +1029,8 @@ struct inode *cifs_root_iget(struct super_block *sb)
tcon->unix_ext = false;
}
rc = cifs_get_inode_info(&inode, "", NULL, sb, xid, NULL);
convert_delimiter(path, CIFS_DIR_SEP(cifs_sb));
rc = cifs_get_inode_info(&inode, path, NULL, sb, xid, NULL);
iget_no_retry:
if (!inode) {
@ -1042,6 +1059,7 @@ iget_no_retry:
}
out:
kfree(path);
/* can not call macro free_xid here since in a void func
* TODO: This is no longer true
*/