This is a note to let you know that I've just added the patch titled
ksmbd: destroy expired sessions
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ksmbd-destroy-expired-sessions.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 12322e55bae970d02088aa34b13eb284b530c8bc
Author: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Date: Wed May 3 08:42:21 2023 +0900
ksmbd: destroy expired sessions
[ Upstream commit ea174a91893956450510945a0c5d1a10b5323656 ]
client can indefinitely send smb2 session setup requests with
the SessionId set to 0, thus indefinitely spawning new sessions,
and causing indefinite memory usage. This patch limit to the number
of sessions using expired timeout and session state.
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: zdi-disclosures@xxxxxxxxxxxxxx # ZDI-CAN-20478
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/ksmbd/mgmt/user_session.c b/fs/ksmbd/mgmt/user_session.c
index 69b85a98e2c35..b809f7987b9f4 100644
--- a/fs/ksmbd/mgmt/user_session.c
+++ b/fs/ksmbd/mgmt/user_session.c
@@ -174,70 +174,73 @@ static struct ksmbd_session *__session_lookup(unsigned long long id)
struct ksmbd_session *sess;
hash_for_each_possible(sessions_table, sess, hlist, id) {
- if (id == sess->id)
+ if (id == sess->id) {
+ sess->last_active = jiffies;
return sess;
+ }
}
return NULL;
}
+static void ksmbd_expire_session(struct ksmbd_conn *conn)
+{
+ unsigned long id;
+ struct ksmbd_session *sess;
+
+ xa_for_each(&conn->sessions, id, sess) {
+ if (sess->state != SMB2_SESSION_VALID ||
+ time_after(jiffies,
+ sess->last_active + SMB2_SESSION_TIMEOUT)) {
+ xa_erase(&conn->sessions, sess->id);
+ ksmbd_session_destroy(sess);
+ continue;
+ }
+ }
+}
+
int ksmbd_session_register(struct ksmbd_conn *conn,
struct ksmbd_session *sess)
{
sess->dialect = conn->dialect;
memcpy(sess->ClientGUID, conn->ClientGUID, SMB2_CLIENT_GUID_SIZE);
+ ksmbd_expire_session(conn);
return xa_err(xa_store(&conn->sessions, sess->id, sess, GFP_KERNEL));
}
-static int ksmbd_chann_del(struct ksmbd_conn *conn, struct ksmbd_session *sess)
+static void ksmbd_chann_del(struct ksmbd_conn *conn, struct ksmbd_session *sess)
{
struct channel *chann;
chann = xa_erase(&sess->ksmbd_chann_list, (long)conn);
if (!chann)
- return -ENOENT;
+ return;
kfree(chann);
-
- return 0;
}
void ksmbd_sessions_deregister(struct ksmbd_conn *conn)
{
struct ksmbd_session *sess;
+ unsigned long id;
- if (conn->binding) {
- int bkt;
-
- down_write(&sessions_table_lock);
- hash_for_each(sessions_table, bkt, sess, hlist) {
- if (!ksmbd_chann_del(conn, sess)) {
- up_write(&sessions_table_lock);
- goto sess_destroy;
- }
+ xa_for_each(&conn->sessions, id, sess) {
+ ksmbd_chann_del(conn, sess);
+ if (xa_empty(&sess->ksmbd_chann_list)) {
+ xa_erase(&conn->sessions, sess->id);
+ ksmbd_session_destroy(sess);
}
- up_write(&sessions_table_lock);
- } else {
- unsigned long id;
-
- xa_for_each(&conn->sessions, id, sess) {
- if (!ksmbd_chann_del(conn, sess))
- goto sess_destroy;
- }
- }
-
- return;
-
-sess_destroy:
- if (xa_empty(&sess->ksmbd_chann_list)) {
- xa_erase(&conn->sessions, sess->id);
- ksmbd_session_destroy(sess);
}
}
struct ksmbd_session *ksmbd_session_lookup(struct ksmbd_conn *conn,
unsigned long long id)
{
- return xa_load(&conn->sessions, id);
+ struct ksmbd_session *sess;
+
+ sess = xa_load(&conn->sessions, id);
+ if (sess)
+ sess->last_active = jiffies;
+ return sess;
}
struct ksmbd_session *ksmbd_session_lookup_slowpath(unsigned long long id)
@@ -246,6 +249,8 @@ struct ksmbd_session *ksmbd_session_lookup_slowpath(unsigned long long id)
down_read(&sessions_table_lock);
sess = __session_lookup(id);
+ if (sess)
+ sess->last_active = jiffies;
up_read(&sessions_table_lock);
return sess;
@@ -324,6 +329,7 @@ static struct ksmbd_session *__session_create(int protocol)
if (ksmbd_init_file_table(&sess->file_table))
goto error;
+ sess->last_active = jiffies;
sess->state = SMB2_SESSION_IN_PROGRESS;
set_session_flag(sess, protocol);
xa_init(&sess->tree_conns);
diff --git a/fs/ksmbd/mgmt/user_session.h b/fs/ksmbd/mgmt/user_session.h
index 44a3c67b2bd92..51f38e5b61abb 100644
--- a/fs/ksmbd/mgmt/user_session.h
+++ b/fs/ksmbd/mgmt/user_session.h
@@ -59,6 +59,7 @@ struct ksmbd_session {
__u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];
struct ksmbd_file_table file_table;
+ unsigned long last_active;
};
static inline int test_session_flag(struct ksmbd_session *sess, int bit)
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 51e95ea37195b..d6423f2fae6d9 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -1862,6 +1862,7 @@ int smb2_sess_setup(struct ksmbd_work *work)
if (sess->user && sess->user->flags & KSMBD_USER_FLAG_DELAY_SESSION)
try_delay = true;
+ sess->last_active = jiffies;
sess->state = SMB2_SESSION_EXPIRED;
if (try_delay) {
ksmbd_conn_set_need_reconnect(conn);
diff --git a/fs/ksmbd/smb2pdu.h b/fs/ksmbd/smb2pdu.h
index 0c8a770fe3189..df05c9b2504d4 100644
--- a/fs/ksmbd/smb2pdu.h
+++ b/fs/ksmbd/smb2pdu.h
@@ -61,6 +61,8 @@ struct preauth_integrity_info {
#define SMB2_SESSION_IN_PROGRESS BIT(0)
#define SMB2_SESSION_VALID BIT(1)
+#define SMB2_SESSION_TIMEOUT (10 * HZ)
+
struct create_durable_req_v2 {
struct create_context ccontext;
__u8 Name[8];
