linux.git/net/sctp, branch v5.12

net/sctp: fix race condition in sctp_destroy_sock

2021-04-13T21:59:46+00:00

If sctp_destroy_sock is called without sock_net(sk)->sctp.addr_wq_lock
held and sp->do_auto_asconf is true, then an element is removed
from the auto_asconf_splist without any proper locking.

This can happen in the following functions:
1. In sctp_accept, if sctp_sock_migrate fails.
2. In inet_create or inet6_create, if there is a bpf program
   attached to BPF_CGROUP_INET_SOCK_CREATE which denies
   creation of the sctp socket.

The bug is fixed by acquiring addr_wq_lock in sctp_destroy_sock
instead of sctp_close.

This addresses CVE-2021-23133.

Reported-by: Or Cohen 
Reviewed-by: Xin Long 
Fixes: 610236587600 ("bpf: Add new cgroup attach type to enable sock modifications")
Signed-off-by: Or Cohen 
Acked-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller

net-ipv6: bugfix - raw & sctp - switch to ipv6_can_nonlocal_bind()

2021-04-05T19:56:52+00:00

Found by virtue of ipv6 raw sockets not honouring the per-socket
IP{,V6}_FREEBIND setting.

Based on hits found via:
  git grep '[.]ip_nonlocal_bind'
We fix both raw ipv6 sockets to honour IP{,V6}_FREEBIND and IP{,V6}_TRANSPARENT,
and we fix sctp sockets to honour IP{,V6}_TRANSPARENT (they already honoured
FREEBIND), and not just the ipv6 'ip_nonlocal_bind' sysctl.

The helper is defined as:
  static inline bool ipv6_can_nonlocal_bind(struct net *net, struct inet_sock *inet) {
    return net->ipv6.sysctl.ip_nonlocal_bind || inet->freebind || inet->transparent;
  }
so this change only widens the accepted opt-outs and is thus a clean bugfix.

I'm not entirely sure what 'fixes' tag to add, since this is AFAICT an ancient bug,
but IMHO this should be applied to stable kernels as far back as possible.
As such I'm adding a 'fixes' tag with the commit that originally added the helper,
which happened in 4.19.  Backporting to older LTS kernels (at least 4.9 and 4.14)
would presumably require open-coding it or backporting the helper as well.

Other possibly relevant commits:
  v4.18-rc6-1502-g83ba4645152d net: add helpers checking if socket can be bound to nonlocal address
  v4.18-rc6-1431-gd0c1f01138c4 net/ipv6: allow any source address for sendmsg pktinfo with ip_nonlocal_bind
  v4.14-rc5-271-gb71d21c274ef sctp: full support for ipv6 ip_nonlocal_bind & IP_FREEBIND
  v4.7-rc7-1883-g9b9742022888 sctp: support ipv6 nonlocal bind
  v4.1-12247-g35a256fee52c ipv6: Nonlocal bind

Cc: Lorenzo Colitti 
Fixes: 83ba4645152d ("net: add helpers checking if socket can be bound to nonlocal address")
Signed-off-by: Maciej Żenczykowski 
Reviewed-By: Lorenzo Colitti 
Signed-off-by: David S. Miller

sctp: move sk_route_caps check and set into sctp_outq_flush_transports

2021-03-19T18:34:49+00:00

The sk's sk_route_caps is set in sctp_packet_config, and later it
only needs to change when traversing the transport_list in a loop,
as the dst might be changed in the tx path.

So move sk_route_caps check and set into sctp_outq_flush_transports
from sctp_packet_transmit. This also fixes a dst leak reported by
Chen Yi:

  https://bugzilla.kernel.org/show_bug.cgi?id=212227

As calling sk_setup_caps() in sctp_packet_transmit may also set the
sk_route_caps for the ctrl sock in a netns. When the netns is being
deleted, the ctrl sock's releasing is later than dst dev's deleting,
which will cause this dev's deleting to hang and dmesg error occurs:

  unregister_netdevice: waiting for xxx to become free. Usage count = 1

Reported-by: Chen Yi 
Fixes: bcd623d8e9fa ("sctp: call sk_setup_caps in sctp_packet_transmit instead")
Signed-off-by: Xin Long 
Signed-off-by: David S. Miller

net: sctp: trivial: fix typo in comment

2021-03-04T21:48:32+00:00

Fix typo of 'overflow' for comment in sctp_tsnmap_check().

Reported-by: Gustavo A. R. Silva 
Signed-off-by: Drew Fustini 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2021-02-10T21:30:12+00:00

net: fix iteration for sctp transport seq_files

2021-02-08T18:15:49+00:00

The sctp transport seq_file iterators take a reference to the transport
in the ->start and ->next functions and releases the reference in the
->show function.  The preferred handling for such resources is to
release them in the subsequent ->next or ->stop function call.

Since Commit 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration
code and interface") there is no guarantee that ->show will be called
after ->next, so this function can now leak references.

So move the sctp_transport_put() call to ->next and ->stop.

Fixes: 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code and interface")
Reported-by: Xin Long 
Signed-off-by: NeilBrown 
Acked-by: Marcelo Ricardo Leitner 
Signed-off-by: Jakub Kicinski

sctp: remove the NETIF_F_SG flag before calling skb_segment

2021-01-17T03:05:59+00:00

It makes more sense to clear NETIF_F_SG instead of set it when
calling skb_segment() in sctp_gso_segment(), since SCTP GSO is
using head_skb's fraglist, of which all frags are linear skbs.

This will make SCTP GSO code more understandable.

Suggested-by: Alexander Duyck 
Signed-off-by: Xin Long 
Signed-off-by: Jakub Kicinski

sctp: Fix some typo

2020-11-24T01:44:11+00:00

s/tranport/transport/

Signed-off-by: Christophe JAILLET 
Link: https://lore.kernel.org/r/20201122180704.1366636-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Jakub Kicinski

Merge https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-11-20T03:08:46+00:00

Signed-off-by: Jakub Kicinski

sctp: change to hold/put transport for proto_unreach_timer

2020-11-14T19:57:12+00:00

A call trace was found in Hangbin's Codenomicon testing with debug kernel:

  [ 2615.981988] ODEBUG: free active (active state 0) object type: timer_list hint: sctp_generate_proto_unreach_event+0x0/0x3a0 [sctp]
  [ 2615.995050] WARNING: CPU: 17 PID: 0 at lib/debugobjects.c:328 debug_print_object+0x199/0x2b0
  [ 2616.095934] RIP: 0010:debug_print_object+0x199/0x2b0
  [ 2616.191533] Call Trace:
  [ 2616.194265]  
  [ 2616.202068]  debug_check_no_obj_freed+0x25e/0x3f0
  [ 2616.207336]  slab_free_freelist_hook+0xeb/0x140
  [ 2616.220971]  kfree+0xd6/0x2c0
  [ 2616.224293]  rcu_do_batch+0x3bd/0xc70
  [ 2616.243096]  rcu_core+0x8b9/0xd00
  [ 2616.256065]  __do_softirq+0x23d/0xacd
  [ 2616.260166]  irq_exit+0x236/0x2a0
  [ 2616.263879]  smp_apic_timer_interrupt+0x18d/0x620
  [ 2616.269138]  apic_timer_interrupt+0xf/0x20
  [ 2616.273711]  

This is because it holds asoc when transport->proto_unreach_timer starts
and puts asoc when the timer stops, and without holding transport the
transport could be freed when the timer is still running.

So fix it by holding/putting transport instead for proto_unreach_timer
in transport, just like other timers in transport.

v1->v2:
  - Also use sctp_transport_put() for the "out_unlock:" path in
    sctp_generate_proto_unreach_event(), as Marcelo noticed.

Fixes: 50b5d6ad6382 ("sctp: Fix a race between ICMP protocol unreachable and connect()")
Reported-by: Hangbin Liu 
Signed-off-by: Xin Long 
Acked-by: Marcelo Ricardo Leitner 
Link: https://lore.kernel.org/r/102788809b554958b13b95d33440f5448113b8d6.1605331373.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski