Merge tag '6.4-rc-smb3-client-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6

Pull cifs fixes from Steve French:
 "smb3 client fixes, mostly DFS or reconnect related:

   - Two DFS connection sharing fixes

   - DFS refresh fix

   - Reconnect fix

   - Two potential use after free fixes

   - Also print prefix patch in mount debug msg

   - Two small cleanup fixes"

* tag '6.4-rc-smb3-client-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: Remove unneeded semicolon
  cifs: fix sharing of DFS connections
  cifs: avoid potential races when handling multiple dfs tcons
  cifs: protect access of TCP_Server_Info::{origin,leaf}_fullpath
  cifs: fix potential race when tree connecting ipc
  cifs: fix potential use-after-free bugs in TCP_Server_Info::hostname
  cifs: print smb3_fs_context::source when mounting
  cifs: protect session status check in smb2_reconnect()
  SMB3.1.1: correct definition for app_instance_id create contexts

Author: torvalds

fs/cifs/cifs_debug.c

@@ -280,8 +280,10 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 		seq_printf(m, "\n%d) ConnectionId: 0x%llx ",
 			c, server->conn_id);
 
+		spin_lock(&server->srv_lock);
 		if (server->hostname)
 			seq_printf(m, "Hostname: %s ", server->hostname);
+		spin_unlock(&server->srv_lock);
 #ifdef CONFIG_CIFS_SMB_DIRECT
 		if (!server->rdma)
 			goto skip_rdma;
@@ -623,10 +625,13 @@ static int cifs_stats_proc_show(struct seq_file *m, void *v)
 				server->fastest_cmd[j],
 				server->slowest_cmd[j]);
 		for (j = 0; j < NUMBER_OF_SMB2_COMMANDS; j++)
-			if (atomic_read(&server->smb2slowcmd[j]))
+			if (atomic_read(&server->smb2slowcmd[j])) {
+				spin_lock(&server->srv_lock);
 				seq_printf(m, "  %d slow responses from %s for command %d\n",
 					atomic_read(&server->smb2slowcmd[j]),
 					server->hostname, j);
+				spin_unlock(&server->srv_lock);
+			}
 #endif /* STATS2 */
 		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
 			list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {

fs/cifs/cifs_debug.h

@@ -81,19 +81,19 @@ do {									\
 
 #define cifs_server_dbg_func(ratefunc, type, fmt, ...)			\
 do {									\
-	const char *sn = "";						\
-	if (server && server->hostname)					\
-		sn = server->hostname;					\
+	spin_lock(&server->srv_lock);					\
 	if ((type) & FYI && cifsFYI & CIFS_INFO) {			\
 		pr_debug_ ## ratefunc("%s: \\\\%s " fmt,		\
-				      __FILE__, sn, ##__VA_ARGS__);	\
+				      __FILE__, server->hostname,	\
+				      ##__VA_ARGS__);			\
 	} else if ((type) & VFS) {					\
 		pr_err_ ## ratefunc("VFS: \\\\%s " fmt,			\
-				    sn, ##__VA_ARGS__);			\
+				    server->hostname, ##__VA_ARGS__);	\
 	} else if ((type) & NOISY && (NOISY != 0)) {			\
 		pr_debug_ ## ratefunc("\\\\%s " fmt,			\
-				      sn, ##__VA_ARGS__);		\
+				      server->hostname, ##__VA_ARGS__);	\
 	}								\
+	spin_unlock(&server->srv_lock);					\
 } while (0)
 
 #define cifs_server_dbg(type, fmt, ...)					\

fs/cifs/cifsfs.c

@@ -874,14 +874,12 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
 	struct cifs_mnt_data mnt_data;
 	struct dentry *root;
 
-	/*
-	 * Prints in Kernel / CIFS log the attempted mount operation
-	 *	If CIFS_DEBUG && cifs_FYI
-	 */
-	if (cifsFYI)
-		cifs_dbg(FYI, "Devname: %s flags: %d\n", old_ctx->UNC, flags);
-	else
-		cifs_info("Attempting to mount %s\n", old_ctx->UNC);
+	if (cifsFYI) {
+		cifs_dbg(FYI, "%s: devname=%s flags=0x%x\n", __func__,
+			 old_ctx->source, flags);
+	} else {
+		cifs_info("Attempting to mount %s\n", old_ctx->source);
+	}
 
 	cifs_sb = kzalloc(sizeof(struct cifs_sb_info), GFP_KERNEL);
 	if (cifs_sb == NULL) {

fs/cifs/cifsglob.h

@@ -736,17 +736,23 @@ struct TCP_Server_Info {
 #endif
 	struct mutex refpath_lock; /* protects leaf_fullpath */
 	/*
-	 * Canonical DFS full paths that were used to chase referrals in mount and reconnect.
+	 * origin_fullpath: Canonical copy of smb3_fs_context::source.
+	 *                  It is used for matching existing DFS tcons.
 	 *
-	 * origin_fullpath: first or original referral path
-	 * leaf_fullpath: last referral path (might be changed due to nested links in reconnect)
+	 * leaf_fullpath: Canonical DFS referral path related to this
+	 *                connection.
+	 *                It is used in DFS cache refresher, reconnect and may
+	 *                change due to nested DFS links.
 	 *
-	 * current_fullpath: pointer to either origin_fullpath or leaf_fullpath
-	 * NOTE: cannot be accessed outside cifs_reconnect() and smb2_reconnect()
+	 * Both protected by @refpath_lock and @srv_lock.  The @refpath_lock is
+	 * mosly used for not requiring a copy of @leaf_fullpath when getting
+	 * cached or new DFS referrals (which might also sleep during I/O).
+	 * While @srv_lock is held for making string and NULL comparions against
+	 * both fields as in mount(2) and cache refresh.
 	 *
-	 * format: \\HOST\SHARE\[OPTIONAL PATH]
+	 * format: \\HOST\SHARE[\OPTIONAL PATH]
 	 */
-	char *origin_fullpath, *leaf_fullpath, *current_fullpath;
+	char *origin_fullpath, *leaf_fullpath;
 };
 
 static inline bool is_smb1(struct TCP_Server_Info *server)
@@ -1232,8 +1238,8 @@ struct cifs_tcon {
 	struct cached_fids *cfids;
 	/* BB add field for back pointer to sb struct(s)? */
 #ifdef CONFIG_CIFS_DFS_UPCALL
-	struct list_head ulist; /* cache update list */
 	struct list_head dfs_ses_list;
+	struct delayed_work dfs_cache_work;
 #endif
 	struct delayed_work	query_interfaces; /* query interfaces workqueue job */
 };
@@ -1750,7 +1756,6 @@ struct cifs_mount_ctx {
 	struct TCP_Server_Info *server;
 	struct cifs_ses *ses;
 	struct cifs_tcon *tcon;
-	char *origin_fullpath, *leaf_fullpath;
 	struct list_head dfs_ses_list;
 };
 

fs/cifs/cifsproto.h

@@ -8,6 +8,7 @@
 #ifndef _CIFSPROTO_H
 #define _CIFSPROTO_H
 #include <linux/nls.h>
+#include <linux/ctype.h>
 #include "trace.h"
 #ifdef CONFIG_CIFS_DFS_UPCALL
 #include "dfs_cache.h"
@@ -572,7 +573,7 @@ extern int E_md4hash(const unsigned char *passwd, unsigned char *p16,
 extern struct TCP_Server_Info *
 cifs_find_tcp_session(struct smb3_fs_context *ctx);
 
-extern void cifs_put_smb_ses(struct cifs_ses *ses);
+void __cifs_put_smb_ses(struct cifs_ses *ses);
 
 extern struct cifs_ses *
 cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx);
@@ -696,4 +697,45 @@ struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon);
 void cifs_put_tcon_super(struct super_block *sb);
 int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry);
 
+/* Put references of @ses and @ses->dfs_root_ses */
+static inline void cifs_put_smb_ses(struct cifs_ses *ses)
+{
+	struct cifs_ses *rses = ses->dfs_root_ses;
+
+	__cifs_put_smb_ses(ses);
+	if (rses)
+		__cifs_put_smb_ses(rses);
+}
+
+/* Get an active reference of @ses and @ses->dfs_root_ses.
+ *
+ * NOTE: make sure to call this function when incrementing reference count of
+ * @ses to ensure that any DFS root session attached to it (@ses->dfs_root_ses)
+ * will also get its reference count incremented.
+ *
+ * cifs_put_smb_ses() will put both references, so call it when you're done.
+ */
+static inline void cifs_smb_ses_inc_refcount(struct cifs_ses *ses)
+{
+	lockdep_assert_held(&cifs_tcp_ses_lock);
+
+	ses->ses_count++;
+	if (ses->dfs_root_ses)
+		ses->dfs_root_ses->ses_count++;
+}
+
+static inline bool dfs_src_pathname_equal(const char *s1, const char *s2)
+{
+	if (strlen(s1) != strlen(s2))
+		return false;
+	for (; *s1; s1++, s2++) {
+		if (*s1 == '/' || *s1 == '\\') {
+			if (*s2 != '/' && *s2 != '\\')
+				return false;
+		} else if (tolower(*s1) != tolower(*s2))
+			return false;
+	}
+	return true;
+}
+
 #endif			/* _CIFSPROTO_H */