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FAILED: patch "[PATCH] ksmbd: validate owner of durable handle on reconnect" failed to apply to 6.1-stable tree

PATCH [email protected] 1 participant 1 message Apr 20

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Stable branch Kernel SMB3 server (ksmbd)
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The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 49110a8ce654bbe56bef7c5e44cce31f4b102b8a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026042045-mulled-diligent-a888@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 49110a8ce654bbe56bef7c5e44cce31f4b102b8a Mon Sep 17 00:00:00 2001
From: Namjae Jeon <[email protected]>
Date: Sun, 12 Apr 2026 22:16:16 +0900
Subject: [PATCH] ksmbd: validate owner of durable handle on reconnect

Currently, ksmbd does not verify if the user attempting to reconnect to a durable handle is the same user who originally opened the file. This allows any authenticated user to hijack an orphaned durable handle by predicting or brute-forcing the persistent ID.

According to MS-SMB2, the server MUST verify that the SecurityContext of the reconnect request matches the SecurityContext associated with the existing open.
Add a durable_owner structure to ksmbd_file to store the original opener's UID, GID, and account name. and catpure the owner information when a file handle becomes orphaned. and implementing ksmbd_vfs_compare_durable_owner() to validate the identity of the requester during SMB2_CREATE (DHnC).

Fixes c8efcc786146 ("ksmbd: add support for durable handles v1/v2")
Reported-by Davide Ornaghi <[email protected]>
Reported-by Navaneeth K <[email protected]>
Signed-off-by Namjae Jeon <[email protected]>
Signed-off-by Steve French <[email protected]>
fs/smb/server/mgmt/user_session.c +3 -5
index 39be2d2be86c..a86589408835 100644
@@ -382,12 +382,10 @@ void ksmbd_session_destroy(struct ksmbd_session *sess)
 		return;
 
 	delete_proc_session(sess);
-
+	ksmbd_tree_conn_session_logoff(sess);
+	ksmbd_destroy_file_table(sess);
 	if (sess->user)
 		ksmbd_free_user(sess->user);
-
-	ksmbd_tree_conn_session_logoff(sess);
-	ksmbd_destroy_file_table(&sess->file_table);
 	ksmbd_launch_ksmbd_durable_scavenger();
 	ksmbd_session_rpc_clear_list(sess);
 	free_channel_list(sess);

@@ -618,7 +616,7 @@ void destroy_previous_session(struct ksmbd_conn *conn,
 		goto out;
 	}
 
-	ksmbd_destroy_file_table(&prev_sess->file_table);
+	ksmbd_destroy_file_table(prev_sess);
 	prev_sess->state = SMB2_SESSION_EXPIRED;
 	ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_SETUP);
 	ksmbd_launch_ksmbd_durable_scavenger();
fs/smb/server/oplock.c +7 -0
index 9b2bb8764a80..cd3f28b0e7cb 100644
@@ -1841,6 +1841,7 @@ int smb2_check_durable_oplock(struct ksmbd_conn *conn,
 			      struct ksmbd_share_config *share,
 			      struct ksmbd_file *fp,
 			      struct lease_ctx_info *lctx,
+			      struct ksmbd_user *user,
 			      char *name)
 {
 	struct oplock_info *opinfo = opinfo_get(fp);

@@ -1849,6 +1850,12 @@ int smb2_check_durable_oplock(struct ksmbd_conn *conn,
 	if (!opinfo)
 		return 0;
 
+	if (ksmbd_vfs_compare_durable_owner(fp, user) == false) {
+		ksmbd_debug(SMB, "Durable handle reconnect failed: owner mismatch\n");
+		ret = -EBADF;
+		goto out;
+	}
+
 	if (opinfo->is_lease == false) {
 		if (lctx) {
 			pr_err("create context include lease\n");
fs/smb/server/oplock.h +1 -0
index 921e3199e4df..d91a8266e065 100644
@@ -126,5 +126,6 @@ int smb2_check_durable_oplock(struct ksmbd_conn *conn,
 			      struct ksmbd_share_config *share,
 			      struct ksmbd_file *fp,
 			      struct lease_ctx_info *lctx,
+			      struct ksmbd_user *user,
 			      char *name);
 #endif /* __KSMBD_OPLOCK_H */
fs/smb/server/smb2pdu.c +2 -1
index 764a78dec46a..d0b05878757e 100644
@@ -3013,7 +3013,8 @@ int smb2_open(struct ksmbd_work *work)
 		}
 
 		if (dh_info.reconnected == true) {
-			rc = smb2_check_durable_oplock(conn, share, dh_info.fp, lc, name);
+			rc = smb2_check_durable_oplock(conn, share, dh_info.fp,
+					lc, sess->user, name);
 			if (rc) {
 				ksmbd_put_durable_fd(dh_info.fp);
 				goto err_out2;
fs/smb/server/vfs_cache.c +78 -9

161 lines not on this page · raw message

fs/smb/server/vfs_cache.h +11 -1
index 78b506c5ef03..866f32c10d4d 100644
@@ -68,6 +68,13 @@ enum {
 	FP_CLOSED
 };
 
+/* Owner information for durable handle reconnect */
+struct durable_owner {
+	unsigned int uid;
+	unsigned int gid;
+	char *name;
+};
+
 struct ksmbd_file {
 	struct file			*filp;
 	u64				persistent_id;

@@ -114,6 +121,7 @@ struct ksmbd_file {
 	bool				is_resilient;
 
 	bool                            is_posix_ctxt;
+	struct durable_owner		owner;
 };
 
 static inline void set_ctx_actor(struct dir_context *ctx,

@@ -140,7 +148,7 @@ static inline bool ksmbd_stream_fd(struct ksmbd_file *fp)
 }
 
 int ksmbd_init_file_table(struct ksmbd_file_table *ft);
-void ksmbd_destroy_file_table(struct ksmbd_file_table *ft);
+void ksmbd_destroy_file_table(struct ksmbd_session *sess);
 int ksmbd_close_fd(struct ksmbd_work *work, u64 id);
 struct ksmbd_file *ksmbd_lookup_fd_fast(struct ksmbd_work *work, u64 id);
 struct ksmbd_file *ksmbd_lookup_foreign_fd(struct ksmbd_work *work, u64 id);

@@ -166,6 +174,8 @@ void ksmbd_free_global_file_table(void);
 void ksmbd_set_fd_limit(unsigned long limit);
 void ksmbd_update_fstate(struct ksmbd_file_table *ft, struct ksmbd_file *fp,
 			 unsigned int state);
+bool ksmbd_vfs_compare_durable_owner(struct ksmbd_file *fp,
+		struct ksmbd_user *user);
 
 /*
  * INODE hash