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Commit a6b5058f authored by Aurelien Aptel's avatar Aurelien Aptel Committed by Steve French
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fs/cifs: make share unaccessible at root level mountable 



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: default avatarAurelien Aptel <aaptel@suse.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: default avatarPavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: default avatarSteve French <smfrench@gmail.com>
parent bd975d1e

fs/cifs/cifs_fs_sb.h

+4 −0
Original line number Diff line number Diff line
@@ -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 */

fs/cifs/cifsfs.c

+13 −1
Original line number Diff line number Diff line
@@ -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;

	}



	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;

fs/cifs/connect.c

+49 −0
Original line number Diff line number Diff line
@@ -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 @@ cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *volume_info) 
			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);

}

fs/cifs/dir.c

+18 −2
Original line number Diff line number Diff line
@@ -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 @@ build_path_from_dentry(struct dentry *direntry) 
		}

	}

	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 @@ build_path_from_dentry(struct dentry *direntry) 
	   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) {

fs/cifs/inode.c

+20 −2
Original line number Diff line number Diff line
@@ -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 @@ struct inode *cifs_root_iget(struct super_block *sb) 
	}



out:

	kfree(path);

	/* can not call macro free_xid here since in a void func

	 * TODO: This is no longer true

	 */