summaryrefslogtreecommitdiff
path: root/fs/cifs/misc.c
diff options
context:
space:
mode:
authorPaulo Alcantara <pc@manguebit.com>2023-03-01 01:01:54 +0300
committerSteve French <stfrench@microsoft.com>2023-03-02 03:18:25 +0300
commitb9ee2e307c6b06384b6f9e393a9b8e048e8fc277 (patch)
tree56eddce76ca31f3fa8fb2fbe26a300e9bd80f38d /fs/cifs/misc.c
parent4c0421fa6df136ff869a078594b4b7b7637e566a (diff)
downloadlinux-b9ee2e307c6b06384b6f9e393a9b8e048e8fc277.tar.xz
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: c877ce47e137 ("cifs: reduce roundtrips on create/qinfo requests") CC: stable@vger.kernel.org # 6.2 Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs/misc.c')
-rw-r--r--fs/cifs/misc.c67
1 files changed, 67 insertions, 0 deletions
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 2905734eb289..0c6c1fc8dae9 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -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