linux/net/sctp
Daniel Borkmann 38ab1fa981 net: sctp: fix ABI mismatch through sctp_assoc_to_state helper
Since SCTP day 1, that is, 19b55a2af145 ("Initial commit") from lksctp
tree, the official <netinet/sctp.h> header carries a copy of enum
sctp_sstat_state that looks like (compared to the current in-kernel
enumeration):

  User definition:                     Kernel definition:

  enum sctp_sstat_state {              typedef enum {
    SCTP_EMPTY             = 0,          <removed>
    SCTP_CLOSED            = 1,          SCTP_STATE_CLOSED            = 0,
    SCTP_COOKIE_WAIT       = 2,          SCTP_STATE_COOKIE_WAIT       = 1,
    SCTP_COOKIE_ECHOED     = 3,          SCTP_STATE_COOKIE_ECHOED     = 2,
    SCTP_ESTABLISHED       = 4,          SCTP_STATE_ESTABLISHED       = 3,
    SCTP_SHUTDOWN_PENDING  = 5,          SCTP_STATE_SHUTDOWN_PENDING  = 4,
    SCTP_SHUTDOWN_SENT     = 6,          SCTP_STATE_SHUTDOWN_SENT     = 5,
    SCTP_SHUTDOWN_RECEIVED = 7,          SCTP_STATE_SHUTDOWN_RECEIVED = 6,
    SCTP_SHUTDOWN_ACK_SENT = 8,          SCTP_STATE_SHUTDOWN_ACK_SENT = 7,
  };                                   } sctp_state_t;

This header was later on also placed into the uapi, so that user space
programs can compile without having <netinet/sctp.h>, but the shipped
with <linux/sctp.h> instead.

While RFC6458 under 8.2.1.Association Status (SCTP_STATUS) says that
sstat_state can range from SCTP_CLOSED to SCTP_SHUTDOWN_ACK_SENT, we
nevertheless have a what it appears to be dummy SCTP_EMPTY state from
the very early days.

While it seems to do just nothing, commit 0b8f9e25b0 ("sctp: remove
completely unsed EMPTY state") did the right thing and removed this dead
code. That however, causes an off-by-one when the user asks the SCTP
stack via SCTP_STATUS API and checks for the current socket state thus
yielding possibly undefined behaviour in applications as they expect
the kernel to tell the right thing.

The enumeration had to be changed however as based on the current socket
state, we access a function pointer lookup-table through this. Therefore,
I think the best way to deal with this is just to add a helper function
sctp_assoc_to_state() to encapsulate the off-by-one quirk.

Reported-by: Tristan Su <sooqing@gmail.com>
Fixes: 0b8f9e25b0 ("sctp: remove completely unsed EMPTY state")
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-29 20:31:08 -07:00
..
Kconfig
Makefile net: sctp: Inline the functions from command.c 2014-07-08 14:38:48 -07:00
associola.c net: sctp: fix suboptimal edge-case on non-active active/retrans path selection 2014-08-22 11:31:30 -07:00
auth.c net: sctp: cache auth_enable per endpoint 2014-04-18 18:32:00 -04:00
bind_addr.c
chunk.c
debug.c
endpointola.c net: sctp: migrate most recently used transport to ktime 2014-06-11 12:23:17 -07:00
input.c net: fix the counter ICMP_MIB_INERRORS/ICMP6_MIB_INERRORS 2014-07-31 22:04:18 -07:00
inqueue.c
ipv6.c sctp: Fixup v4mapped behaviour to comply with Sock API 2014-07-31 21:49:06 -07:00
objcnt.c
output.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-08-05 18:46:26 -07:00
outqueue.c net: sctp: Rename SCTP_XMIT_NAGLE_DELAY to SCTP_XMIT_DELAY 2014-07-22 13:32:11 -07:00
primitive.c
probe.c
proc.c snmp: fix some left over of snmp stats 2014-05-14 15:33:47 -04:00
protocol.c sctp: Fixup v4mapped behaviour to comply with Sock API 2014-07-31 21:49:06 -07:00
sm_make_chunk.c ktime: add ktime_after and ktime_before helper 2014-06-11 12:23:17 -07:00
sm_sideeffect.c net: sctp: Don't transition to PF state when transport has exhausted 'Path.Max.Retrans'. 2014-04-27 23:41:14 -04:00
sm_statefuns.c net: sctp: remove unnecessary break after return/goto 2014-07-15 16:27:01 -07:00
sm_statetable.c
socket.c net: sctp: fix ABI mismatch through sctp_assoc_to_state helper 2014-08-29 20:31:08 -07:00
ssnmap.c
sysctl.c net: sctp: only warn in proc_sctp_do_alpha_beta if write 2014-07-02 18:44:07 -07:00
transport.c sctp: Fixup v4mapped behaviour to comply with Sock API 2014-07-31 21:49:06 -07:00
tsnmap.c
ulpevent.c sctp: Fixup v4mapped behaviour to comply with Sock API 2014-07-31 21:49:06 -07:00
ulpqueue.c sctp: add support for busy polling to sctp protocol 2014-04-20 18:18:55 -04:00