smb: client: fix dir separator in SMB1 UNIX mounts

When calling cifs_mount_get_tcon() with SMB1 UNIX mounts,
@cifs_sb->mnt_cifs_flags needs to be read or updated only after
calling reset_cifs_unix_caps(), otherwise it might end up with missing
CIFS_MOUNT_POSIXACL and CIFS_MOUNT_POSIX_PATHS bits.

This fixes the wrong dir separator used in paths caused by the missing
CIFS_MOUNT_POSIX_PATHS bit in cifs_sb_info::mnt_cifs_flags.

Reported-by: "Kris Karas (Bug Reporting)" <bugs-a21@moonlit-rail.com>
Closes: https://lore.kernel.org/r/f758f4ff-4d54-4244-931d-38f469c3ff14@moonlit-rail.com
Fixes: 4fc3a43 ("smb: client: use atomic_t for mnt_cifs_flags")
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Cc: David Howells <dhowells@redhat.com>
Cc: linux-cifs@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: pcacjr

fs/smb/client/connect.c

@@ -3609,7 +3609,6 @@ int cifs_mount_get_tcon(struct cifs_mount_ctx *mnt_ctx)
 	server = mnt_ctx->server;
 	ctx = mnt_ctx->fs_ctx;
 	cifs_sb = mnt_ctx->cifs_sb;
-	sbflags = cifs_sb_flags(cifs_sb);
 
 	/* search for existing tcon to this server share */
 	tcon = cifs_get_tcon(mnt_ctx->ses, ctx);
@@ -3624,9 +3623,10 @@ int cifs_mount_get_tcon(struct cifs_mount_ctx *mnt_ctx)
 	 * path (i.e., do not remap / and \ and do not map any special characters)
 	 */
 	if (tcon->posix_extensions) {
-		sbflags |= CIFS_MOUNT_POSIX_PATHS;
-		sbflags &= ~(CIFS_MOUNT_MAP_SFM_CHR |
-			     CIFS_MOUNT_MAP_SPECIAL_CHR);
+		atomic_or(CIFS_MOUNT_POSIX_PATHS, &cifs_sb->mnt_cifs_flags);
+		atomic_andnot(CIFS_MOUNT_MAP_SFM_CHR |
+			      CIFS_MOUNT_MAP_SPECIAL_CHR,
+			      &cifs_sb->mnt_cifs_flags);
 	}
 
 #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
@@ -3650,6 +3650,7 @@ int cifs_mount_get_tcon(struct cifs_mount_ctx *mnt_ctx)
 #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 		tcon->unix_ext = 0; /* server does not support them */
 
+	sbflags = cifs_sb_flags(cifs_sb);
 	/* do not care if a following call succeed - informational */
 	if (!tcon->pipe && server->ops->qfs_tcon) {
 		server->ops->qfs_tcon(mnt_ctx->xid, tcon, cifs_sb);
@@ -3674,7 +3675,6 @@ int cifs_mount_get_tcon(struct cifs_mount_ctx *mnt_ctx)
 
 out:
 	mnt_ctx->tcon = tcon;
-	atomic_set(&cifs_sb->mnt_cifs_flags, sbflags);
 	return rc;
 }
 

fs/smb/client/smb1ops.c

@@ -49,7 +49,6 @@ void reset_cifs_unix_caps(unsigned int xid, struct cifs_tcon *tcon,
 
 	if (!CIFSSMBQFSUnixInfo(xid, tcon)) {
 		__u64 cap = le64_to_cpu(tcon->fsUnixInfo.Capability);
-		unsigned int sbflags;
 
 		cifs_dbg(FYI, "unix caps which server supports %lld\n", cap);
 		/*
@@ -76,29 +75,27 @@ void reset_cifs_unix_caps(unsigned int xid, struct cifs_tcon *tcon,
 		if (cap & CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)
 			cifs_dbg(VFS, "per-share encryption not supported yet\n");
 
-		if (cifs_sb)
-			sbflags = cifs_sb_flags(cifs_sb);
-
 		cap &= CIFS_UNIX_CAP_MASK;
 		if (ctx && ctx->no_psx_acl)
 			cap &= ~CIFS_UNIX_POSIX_ACL_CAP;
 		else if (CIFS_UNIX_POSIX_ACL_CAP & cap) {
 			cifs_dbg(FYI, "negotiated posix acl support\n");
-			if (cifs_sb)
-				sbflags |= CIFS_MOUNT_POSIXACL;
+			if (cifs_sb) {
+				atomic_or(CIFS_MOUNT_POSIXACL,
+					  &cifs_sb->mnt_cifs_flags);
+			}
 		}
 
 		if (ctx && ctx->posix_paths == 0)
 			cap &= ~CIFS_UNIX_POSIX_PATHNAMES_CAP;
 		else if (cap & CIFS_UNIX_POSIX_PATHNAMES_CAP) {
 			cifs_dbg(FYI, "negotiate posix pathnames\n");
-			if (cifs_sb)
-				sbflags |= CIFS_MOUNT_POSIX_PATHS;
+			if (cifs_sb) {
+				atomic_or(CIFS_MOUNT_POSIX_PATHS,
+					  &cifs_sb->mnt_cifs_flags);
+			}
 		}
 
-		if (cifs_sb)
-			atomic_set(&cifs_sb->mnt_cifs_flags, sbflags);
-
 		cifs_dbg(FYI, "Negotiate caps 0x%x\n", (int)cap);
 #ifdef CONFIG_CIFS_DEBUG2
 		if (cap & CIFS_UNIX_FCNTL_CAP)