[ 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@vger.kernel.org Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-20478 Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com --- fs/ksmbd/mgmt/user_session.c | 68 ++++++++++++++++++++---------------- fs/ksmbd/mgmt/user_session.h | 1 + fs/ksmbd/smb2pdu.c | 1 + fs/ksmbd/smb2pdu.h | 2 ++ 4 files changed, 41 insertions(+), 31 deletions(-)
diff --git a/fs/ksmbd/mgmt/user_session.c b/fs/ksmbd/mgmt/user_session.c index 68d40025cfbf..3840de7773b9 100644 --- a/fs/ksmbd/mgmt/user_session.c +++ b/fs/ksmbd/mgmt/user_session.c @@ -165,70 +165,73 @@ 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) @@ -237,6 +240,8 @@ 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; @@ -315,6 +320,7 @@ 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 b6a9e7a6aae4..f99d475b28db 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 ef4550152721..2ebd252894de 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -1875,6 +1875,7 @@ 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) ssleep(5); diff --git a/fs/ksmbd/smb2pdu.h b/fs/ksmbd/smb2pdu.h index 9cde1f8e8428..a774889e0aa5 100644 --- a/fs/ksmbd/smb2pdu.h +++ b/fs/ksmbd/smb2pdu.h @@ -619,6 +619,8 @@ struct create_context { __u8 Buffer[0]; } __packed;
+#define SMB2_SESSION_TIMEOUT (10 * HZ) + struct create_durable_req_v2 { struct create_context ccontext; __u8 Name[8];