kernel/linux.git/include/net/inet_hashtables.h, branch v4.19.265

secure_seq: use the 64 bits of the siphash for port offset calculation

2022-06-06T06:24:20+00:00

commit b2d057560b8107c633b39aabe517ff9d93f285e3 upstream. SipHash replaced MD5 in secure_ipv{4,6}_port_ephemeral() via commit 7cd23e5300c1 ("secure_seq: use SipHash in place of MD5"), but the output remained truncated to 32-bit only. In order to exploit more bits from the hash, let's make the functions return the full 64-bit of siphash_3u32(). We also make sure the port offset calculation in __inet_hash_connect() remains done on 32-bit to avoid the need for div_u64_rem() and an extra cost on 32-bit systems. Cc: Jason A. Donenfeld Cc: Moshe Kol Cc: Yossi Gilad Cc: Amit Klein Reviewed-by: Eric Dumazet Signed-off-by: Willy Tarreau Signed-off-by: Jakub Kicinski [SG: Adjusted context] Signed-off-by: Stefan Ghinea Signed-off-by: Greg Kroah-Hartman

tcp: fix race condition when creating child sockets from syncookies

2022-04-27T11:39:42+00:00

[ Upstream commit 01770a166165738a6e05c3d911fb4609cc4eb416 ] When the TCP stack is in SYN flood mode, the server child socket is created from the SYN cookie received in a TCP packet with the ACK flag set. The child socket is created when the server receives the first TCP packet with a valid SYN cookie from the client. Usually, this packet corresponds to the final step of the TCP 3-way handshake, the ACK packet. But is also possible to receive a valid SYN cookie from the first TCP data packet sent by the client, and thus create a child socket from that SYN cookie. Since a client socket is ready to send data as soon as it receives the SYN+ACK packet from the server, the client can send the ACK packet (sent by the TCP stack code), and the first data packet (sent by the userspace program) almost at the same time, and thus the server will equally receive the two TCP packets with valid SYN cookies almost at the same instant. When such event happens, the TCP stack code has a race condition that occurs between the momement a lookup is done to the established connections hashtable to check for the existence of a connection for the same client, and the moment that the child socket is added to the established connections hashtable. As a consequence, this race condition can lead to a situation where we add two child sockets to the established connections hashtable and deliver two sockets to the userspace program to the same client. This patch fixes the race condition by checking if an existing child socket exists for the same client when we are adding the second child socket to the established connections socket. If an existing child socket exists, we drop the packet and discard the second child socket to the same client. Signed-off-by: Ricardo Dias Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20201120111133.GA67501@rdias-suse-pc.lan Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

tcp/dccp: fix possible race __inet_lookup_established()

2020-01-04T18:13:41+00:00

commit 8dbd76e79a16b45b2ccb01d2f2e08dbf64e71e40 upstream. Michal Kubecek and Firo Yang did a very nice analysis of crashes happening in __inet_lookup_established(). Since a TCP socket can go from TCP_ESTABLISH to TCP_LISTEN (via a close()/socket()/listen() cycle) without a RCU grace period, I should not have changed listeners linkage in their hash table. They must use the nulls protocol (Documentation/RCU/rculist_nulls.txt), so that a lookup can detect a socket in a hash list was moved in another one. Since we added code in commit d296ba60d8e2 ("soreuseport: Resolve merge conflict for v4/v6 ordering fix"), we have to add hlist_nulls_add_tail_rcu() helper. Fixes: 3b24d854cb35 ("tcp/dccp: do not touch listener sk_refcnt under synflood") Signed-off-by: Eric Dumazet Reported-by: Michal Kubecek Reported-by: Firo Yang Reviewed-by: Michal Kubecek Link: https://lore.kernel.org/netdev/20191120083919.GH27852@unicorn.suse.cz/ Signed-off-by: Jakub Kicinski [stable-4.19: we also need to update code in __inet_lookup_listener() and inet6_lookup_listener() which has been removed in 5.0-rc1.] Signed-off-by: Michal Kubecek Signed-off-by: Greg Kroah-Hartman

inet: Add a 2nd listener hashtable (port+addr)

2017-12-03T15:18:28+00:00

The current listener hashtable is hashed by port only. When a process is listening at many IP addresses with the same port (e.g. [IP1]:443, [IP2]:443... [IPN]:443), the inet[6]_lookup_listener() performance is degraded to a link list. It is prone to syn attack. UDP had a similar issue and a second hashtable was added to resolve it. This patch adds a second hashtable for the listener's sockets. The second hashtable is hashed by port and address. It cannot reuse the existing skc_portaddr_node which is shared with skc_bind_node. TCP listener needs to use skc_bind_node. Instead, this patch adds a hlist_node 'icsk_listen_portaddr_node' to the inet_connection_sock which the listener (like TCP) also belongs to. The new portaddr hashtable may need two lookup (First by IP:PORT. Second by INADDR_ANY:PORT if the IP:PORT is a not found). Hence, it implements a similar cut off as UDP such that it will only consult the new portaddr hashtable if the current port-only hashtable has >10 sk in the link-list. lhash2 and lhash2_mask are added to 'struct inet_hashinfo'. I take this chance to plug a 4 bytes hole. It is done by first moving the existing bind_bucket_cachep up and then add the new (int lhash2_mask, *lhash2) after the existing bhash_size. Signed-off-by: Martin KaFai Lau Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

inet: Add a count to struct inet_listen_hashbucket

2017-12-03T15:18:27+00:00

This patch adds a count to the 'struct inet_listen_hashbucket'. It counts how many sk is hashed to a bucket. It will be used to decide if the (to-be-added) portaddr listener's hashtable should be used during inet[6]_lookup_listener(). Signed-off-by: Martin KaFai Lau Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

net: ipv4: add second dif to inet socket lookups

2017-08-07T18:39:21+00:00

Add a second device index, sdif, to inet socket lookups. sdif is the index for ingress devices enslaved to an l3mdev. It allows the lookups to consider the enslaved device as well as the L3 domain when searching for a socket. TCP moves the data in the cb. Prior to tcp_v4_rcv (e.g., early demux) the ingress index is obtained from IPCB using inet_sdif and after the cb move in tcp_v4_rcv the tcp_v4_sdif helper is used. Signed-off-by: David Ahern Signed-off-by: David S. Miller

net: make sk_ehashfn() static

2017-07-03T10:29:14+00:00

sk_ehashfn() is only used from a single file. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: convert sock.sk_refcnt from atomic_t to refcount_t

2017-07-01T14:39:08+00:00

refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. This patch uses refcount_inc_not_zero() instead of atomic_inc_not_zero_hint() due to absense of a _hint() version of refcount API. If the hint() version must be used, we might need to revisit API. Signed-off-by: Elena Reshetova Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor Signed-off-by: David S. Miller

inet: reset tb->fastreuseport when adding a reuseport sk

2017-01-18T18:04:29+00:00

If we have non reuseport sockets on a tb we will set tb->fastreuseport to 0 and never set it again. Which means that in the future if we end up adding a bunch of reuseport sk's to that tb we'll have to do the expensive scan every time. Instead add the ipv4/ipv6 saddr fields to the bind bucket, as well as the family so we know what comparison to make, and the ipv6 only setting so we can make sure to compare with new sockets appropriately. Once one sk has made it onto the list we know that there are no potential bind conflicts on the owners list that match that sk's rcv_addr. So copy the sk's information into our bind bucket and set tb->fastruseport to FASTREUSESOCK_STRICT so we know we have to do an extra check for subsequent reuseport sockets and skip the expensive bind conflict check. Signed-off-by: Josef Bacik Signed-off-by: David S. Miller

inet: kill smallest_size and smallest_port

2017-01-18T18:04:29+00:00

In inet_csk_get_port we seem to be using smallest_port to figure out where the best place to look for a SO_REUSEPORT sk that matches with an existing set of SO_REUSEPORT's. However if we get to the logic if (smallest_size != -1) { port = smallest_port; goto have_port; } we will do a useless search, because we would have already done the inet_csk_bind_conflict for that port and it would have returned 1, otherwise we would have gone to found_tb and succeeded. Since this logic makes us do yet another trip through inet_csk_bind_conflict for a port we know won't work just delete this code and save us the time. Signed-off-by: Josef Bacik Signed-off-by: David S. Miller