Commit b9ee2e30 authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Steve French
Browse files

cifs: improve checking of DFS links over STATUS_OBJECT_NAME_INVALID 



Do not map STATUS_OBJECT_NAME_INVALID to -EREMOTE under non-DFS
shares, or 'nodfs' mounts or CONFIG_CIFS_DFS_UPCALL=n builds.
Otherwise, in the slow path, get a referral to figure out whether it
is an actual DFS link.

This could be simply reproduced under a non-DFS share by running the
following

  $ mount.cifs //srv/share /mnt -o ...
  $ cat /mnt/$(printf '\U110000')
  cat: '/mnt/'$'\364\220\200\200': Object is remote

Fixes: c877ce47 ("cifs: reduce roundtrips on create/qinfo requests")
CC: stable@vger.kernel.org # 6.2
Signed-off-by: default avatarPaulo Alcantara (SUSE) <pc@manguebit.com>
Reviewed-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 4c0421fa

fs/cifs/cifsproto.h

+15 −5
Original line number Diff line number Diff line
@@ -667,11 +667,21 @@ static inline int get_dfs_path(const unsigned int xid, struct cifs_ses *ses, 
int match_target_ip(struct TCP_Server_Info *server,

		    const char *share, size_t share_len,

		    bool *result);



int cifs_dfs_query_info_nonascii_quirk(const unsigned int xid,

int cifs_inval_name_dfs_link_error(const unsigned int xid,

				   struct cifs_tcon *tcon,

				   struct cifs_sb_info *cifs_sb,

				   const char *full_path,

				   bool *islink);

#else

static inline int cifs_inval_name_dfs_link_error(const unsigned int xid,

				   struct cifs_tcon *tcon,

				   struct cifs_sb_info *cifs_sb,

				       const char *dfs_link_path);

				   const char *full_path,

				   bool *islink)

{

	*islink = false;

	return 0;

}

#endif



static inline int cifs_create_options(struct cifs_sb_info *cifs_sb, int options)

fs/cifs/misc.c

+67 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include "cifsfs.h"

#ifdef CONFIG_CIFS_DFS_UPCALL

#include "dns_resolve.h"

#include "dfs_cache.h"

#endif

#include "fs_context.h"

#include "cached_dir.h"
@@ -1198,4 +1199,70 @@ int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix) 
	cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;

	return 0;

}



/*

 * Handle weird Windows SMB server behaviour. It responds with

 * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request for

 * "\<server>\<dfsname>\<linkpath>" DFS reference, where <dfsname> contains

 * non-ASCII unicode symbols.

 */

int cifs_inval_name_dfs_link_error(const unsigned int xid,

				   struct cifs_tcon *tcon,

				   struct cifs_sb_info *cifs_sb,

				   const char *full_path,

				   bool *islink)

{

	struct cifs_ses *ses = tcon->ses;

	size_t len;

	char *path;

	char *ref_path;



	*islink = false;



	/*

	 * Fast path - skip check when @full_path doesn't have a prefix path to

	 * look up or tcon is not DFS.

	 */

	if (strlen(full_path) < 2 || !cifs_sb ||

	    (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) ||

	    !is_tcon_dfs(tcon) || !ses->server->origin_fullpath)

		return 0;



	/*

	 * Slow path - tcon is DFS and @full_path has prefix path, so attempt

	 * to get a referral to figure out whether it is an DFS link.

	 */

	len = strnlen(tcon->tree_name, MAX_TREE_SIZE + 1) + strlen(full_path) + 1;

	path = kmalloc(len, GFP_KERNEL);

	if (!path)

		return -ENOMEM;



	scnprintf(path, len, "%s%s", tcon->tree_name, full_path);

	ref_path = dfs_cache_canonical_path(path + 1, cifs_sb->local_nls,

					    cifs_remap(cifs_sb));

	kfree(path);



	if (IS_ERR(ref_path)) {

		if (PTR_ERR(ref_path) != -EINVAL)

			return PTR_ERR(ref_path);

	} else {

		struct dfs_info3_param *refs = NULL;

		int num_refs = 0;



		/*

		 * XXX: we are not using dfs_cache_find() here because we might

		 * end filling all the DFS cache and thus potentially

		 * removing cached DFS targets that the client would eventually

		 * need during failover.

		 */

		if (ses->server->ops->get_dfs_refer &&

		    !ses->server->ops->get_dfs_refer(xid, ses, ref_path, &refs,

						     &num_refs, cifs_sb->local_nls,

						     cifs_remap(cifs_sb)))

			*islink = refs[0].server_type == DFS_TYPE_LINK;

		free_dfs_info_array(refs, num_refs);

		kfree(ref_path);

	}

	return 0;

}

#endif

fs/cifs/smb2inode.c

+11 −10
Original line number Diff line number Diff line
@@ -527,12 +527,13 @@ int smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon, 
			 struct cifs_sb_info *cifs_sb, const char *full_path,

			 struct cifs_open_info_data *data, bool *adjust_tz, bool *reparse)

{

	int rc;

	__u32 create_options = 0;

	struct cifsFileInfo *cfile;

	struct cached_fid *cfid = NULL;

	struct kvec err_iov[3] = {};

	int err_buftype[3] = {};

	bool islink;

	int rc, rc2;



	*adjust_tz = false;

	*reparse = false;
@@ -580,14 +581,14 @@ int smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon, 
					      SMB2_OP_QUERY_INFO, cfile, NULL, NULL,

					      NULL, NULL);

			goto out;

		} else if (rc != -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) &&

			   hdr->Status == STATUS_OBJECT_NAME_INVALID) {

			/*

			 * Handle weird Windows SMB server behaviour. It responds with

			 * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request

			 * for "\<server>\<dfsname>\<linkpath>" DFS reference,

			 * where <dfsname> contains non-ASCII unicode symbols.

			 */

		} else if (rc != -EREMOTE && hdr->Status == STATUS_OBJECT_NAME_INVALID) {

			rc2 = cifs_inval_name_dfs_link_error(xid, tcon, cifs_sb,

							     full_path, &islink);

			if (rc2) {

				rc = rc2;

				goto out;

			}

			if (islink)

				rc = -EREMOTE;

		}

		if (rc == -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) && cifs_sb &&

fs/cifs/smb2ops.c

+13 −10
Original line number Diff line number Diff line
@@ -796,7 +796,6 @@ static int 
smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,

			struct cifs_sb_info *cifs_sb, const char *full_path)

{

	int rc;

	__le16 *utf16_path;

	__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;

	int err_buftype = CIFS_NO_BUFFER;
@@ -804,6 +803,8 @@ smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon, 
	struct kvec err_iov = {};

	struct cifs_fid fid;

	struct cached_fid *cfid;

	bool islink;

	int rc, rc2;



	rc = open_cached_dir(xid, tcon, full_path, cifs_sb, true, &cfid);

	if (!rc) {
@@ -833,15 +834,17 @@ smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon, 


		if (unlikely(!hdr || err_buftype == CIFS_NO_BUFFER))

			goto out;

		/*

		 * Handle weird Windows SMB server behaviour. It responds with

		 * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request

		 * for "\<server>\<dfsname>\<linkpath>" DFS reference,

		 * where <dfsname> contains non-ASCII unicode symbols.

		 */

		if (rc != -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) &&

		    hdr->Status == STATUS_OBJECT_NAME_INVALID)



		if (rc != -EREMOTE && hdr->Status == STATUS_OBJECT_NAME_INVALID) {

			rc2 = cifs_inval_name_dfs_link_error(xid, tcon, cifs_sb,

							     full_path, &islink);

			if (rc2) {

				rc = rc2;

				goto out;

			}

			if (islink)

				rc = -EREMOTE;

		}

		if (rc == -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) && cifs_sb &&

		    (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS))

			rc = -EOPNOTSUPP;