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From: Paulo Alcantara <pc@cjr.nz>
Date: Mon, 14 Jun 2021 12:58:20 -0300
Subject: [PATCH] cifs: fix check of dfs interlinks
Git-commit: 889c2a700799f3b6f82210925e1faf4a9b833c4a
References: bsc#1185902
Patch-mainline: v5.14-rc1

Interlink is a special type of DFS link that resolves to a different
DFS domain-based namespace.  To determine whether it is an interlink
or not, check if ReferralServers and StorageServers bits are set to 1
and 0 respectively in ReferralHeaderFlags, as specified in MS-DFSC
3.1.5.4.5 Determining Whether a Referral Response is an Interlink.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
 fs/cifs/dfs_cache.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -25,8 +25,7 @@
 #define CACHE_MAX_ENTRIES 64
 #define CACHE_MIN_TTL 120 /* 2 minutes */
 
-#define IS_INTERLINK_SET(v) ((v) & (DFSREF_REFERRAL_SERVER | \
-				    DFSREF_STORAGE_SERVER))
+#define IS_DFS_INTERLINK(v) (((v) & DFSREF_REFERRAL_SERVER) && !((v) & DFSREF_STORAGE_SERVER))
 
 struct cache_dfs_tgt {
 	char *name;
@@ -283,7 +282,7 @@ static int dfscache_proc_show(struct seq
 				   "cache entry: path=%s,type=%s,ttl=%d,etime=%ld,hdr_flags=0x%x,ref_flags=0x%x,interlink=%s,path_consumed=%d,expired=%s\n",
 				   ce->path, ce->srvtype == DFS_TYPE_ROOT ? "root" : "link",
 				   ce->ttl, ce->etime.tv_nsec, ce->ref_flags, ce->hdr_flags,
-				   IS_INTERLINK_SET(ce->hdr_flags) ? "yes" : "no",
+				   IS_DFS_INTERLINK(ce->hdr_flags) ? "yes" : "no",
 				   ce->path_consumed, cache_entry_expired(ce) ? "yes" : "no");
 
 			list_for_each_entry(t, &ce->tlist, list) {
@@ -352,7 +351,7 @@ static inline void dump_ce(const struct
 		 ce->srvtype == DFS_TYPE_ROOT ? "root" : "link", ce->ttl,
 		 ce->etime.tv_nsec,
 		 ce->hdr_flags, ce->ref_flags,
-		 IS_INTERLINK_SET(ce->hdr_flags) ? "yes" : "no",
+		 IS_DFS_INTERLINK(ce->hdr_flags) ? "yes" : "no",
 		 ce->path_consumed,
 		 cache_entry_expired(ce) ? "yes" : "no");
 	dump_tgts(ce);