From: Namjae Jeon linkinjeon@kernel.org
commit ea174a91893956450510945a0c5d1a10b5323656 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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(-)
--- a/fs/ksmbd/mgmt/user_session.c +++ b/fs/ksmbd/mgmt/user_session.c @@ -165,70 +165,73 @@ static struct ksmbd_session *__session_l 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; - } - } - 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; + 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); } } - - 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_look
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_c 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); --- 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) --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -1873,6 +1873,7 @@ out_err: 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); --- 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];