6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Paulo Alcantara pc@manguebit.com
[ Upstream commit 343d7fe6df9e247671440a932b6a73af4fa86d95 ]
Customers have reported use-after-free in @ses->auth_key.response with SMB2.1 + sign mounts which occurs due to following race:
task A task B cifs_mount() dfs_mount_share() get_session() cifs_mount_get_session() cifs_send_recv() cifs_get_smb_ses() compound_send_recv() cifs_setup_session() smb2_setup_request() kfree_sensitive() smb2_calc_signature() crypto_shash_setkey() *UAF*
Fix this by ensuring that we have a valid @ses->auth_key.response by checking whether @ses->ses_status is SES_GOOD or SES_EXITING with @ses->ses_lock held. After commit 24a9799aa8ef ("smb: client: fix UAF in smb2_reconnect_server()"), we made sure to call ->logoff() only when @ses was known to be good (e.g. valid ->auth_key.response), so it's safe to access signing key when @ses->ses_status == SES_EXITING.
Cc: stable@vger.kernel.org Reported-by: Jay Shin jaeshin@redhat.com Signed-off-by: Paulo Alcantara (Red Hat) pc@manguebit.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/client/smb2proto.h | 2 -- fs/smb/client/smb2transport.c | 56 +++++++++++++++++++++++++---------- 2 files changed, 40 insertions(+), 18 deletions(-)
diff --git a/fs/smb/client/smb2proto.h b/fs/smb/client/smb2proto.h index fd90d8e5a1d1..750e4e397b13 100644 --- a/fs/smb/client/smb2proto.h +++ b/fs/smb/client/smb2proto.h @@ -37,8 +37,6 @@ extern struct mid_q_entry *smb2_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst); extern struct mid_q_entry *smb2_setup_async_request( struct TCP_Server_Info *server, struct smb_rqst *rqst); -extern struct cifs_ses *smb2_find_smb_ses(struct TCP_Server_Info *server, - __u64 ses_id); extern struct cifs_tcon *smb2_find_smb_tcon(struct TCP_Server_Info *server, __u64 ses_id, __u32 tid); extern int smb2_calc_signature(struct smb_rqst *rqst, diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c index 73eae1b16034..4a43802375b3 100644 --- a/fs/smb/client/smb2transport.c +++ b/fs/smb/client/smb2transport.c @@ -74,7 +74,7 @@ smb311_crypto_shash_allocate(struct TCP_Server_Info *server)
static -int smb2_get_sign_key(__u64 ses_id, struct TCP_Server_Info *server, u8 *key) +int smb3_get_sign_key(__u64 ses_id, struct TCP_Server_Info *server, u8 *key) { struct cifs_chan *chan; struct TCP_Server_Info *pserver; @@ -168,16 +168,41 @@ smb2_find_smb_ses_unlocked(struct TCP_Server_Info *server, __u64 ses_id) return NULL; }
-struct cifs_ses * -smb2_find_smb_ses(struct TCP_Server_Info *server, __u64 ses_id) +static int smb2_get_sign_key(struct TCP_Server_Info *server, + __u64 ses_id, u8 *key) { struct cifs_ses *ses; + int rc = -ENOENT; + + if (SERVER_IS_CHAN(server)) + server = server->primary_server;
spin_lock(&cifs_tcp_ses_lock); - ses = smb2_find_smb_ses_unlocked(server, ses_id); - spin_unlock(&cifs_tcp_ses_lock); + list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) { + if (ses->Suid != ses_id) + continue;
- return ses; + rc = 0; + spin_lock(&ses->ses_lock); + switch (ses->ses_status) { + case SES_EXITING: /* SMB2_LOGOFF */ + case SES_GOOD: + if (likely(ses->auth_key.response)) { + memcpy(key, ses->auth_key.response, + SMB2_NTLMV2_SESSKEY_SIZE); + } else { + rc = -EIO; + } + break; + default: + rc = -EAGAIN; + break; + } + spin_unlock(&ses->ses_lock); + break; + } + spin_unlock(&cifs_tcp_ses_lock); + return rc; }
static struct cifs_tcon * @@ -236,14 +261,16 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server, unsigned char *sigptr = smb2_signature; struct kvec *iov = rqst->rq_iov; struct smb2_hdr *shdr = (struct smb2_hdr *)iov[0].iov_base; - struct cifs_ses *ses; struct shash_desc *shash = NULL; struct smb_rqst drqst; + __u64 sid = le64_to_cpu(shdr->SessionId); + u8 key[SMB2_NTLMV2_SESSKEY_SIZE];
- ses = smb2_find_smb_ses(server, le64_to_cpu(shdr->SessionId)); - if (unlikely(!ses)) { - cifs_server_dbg(FYI, "%s: Could not find session\n", __func__); - return -ENOENT; + rc = smb2_get_sign_key(server, sid, key); + if (unlikely(rc)) { + cifs_server_dbg(FYI, "%s: [sesid=0x%llx] couldn't find signing key: %d\n", + __func__, sid, rc); + return rc; }
memset(smb2_signature, 0x0, SMB2_HMACSHA256_SIZE); @@ -260,8 +287,7 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server, shash = server->secmech.hmacsha256; }
- rc = crypto_shash_setkey(shash->tfm, ses->auth_key.response, - SMB2_NTLMV2_SESSKEY_SIZE); + rc = crypto_shash_setkey(shash->tfm, key, sizeof(key)); if (rc) { cifs_server_dbg(VFS, "%s: Could not update with response\n", @@ -303,8 +329,6 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server, out: if (allocate_crypto) cifs_free_hash(&shash); - if (ses) - cifs_put_smb_ses(ses); return rc; }
@@ -570,7 +594,7 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server, struct smb_rqst drqst; u8 key[SMB3_SIGN_KEY_SIZE];
- rc = smb2_get_sign_key(le64_to_cpu(shdr->SessionId), server, key); + rc = smb3_get_sign_key(le64_to_cpu(shdr->SessionId), server, key); if (unlikely(rc)) { cifs_server_dbg(FYI, "%s: Could not get signing key\n", __func__); return rc;