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>
In SCTP, selection of active (T.ACT) and retransmission (T.RET)
transports is being done whenever transport control operations
(UP, DOWN, PF, ...) are engaged through sctp_assoc_control_transport().
Commits 4c47af4d5e ("net: sctp: rework multihoming retransmission
path selection to rfc4960") and a7288c4dd5 ("net: sctp: improve
sctp_select_active_and_retran_path selection") have both improved
it towards a more fine-grained and optimal path selection.
Currently, the selection algorithm for T.ACT and T.RET is as follows:
1) Elect the two most recently used ACTIVE transports T1, T2 for
T.ACT, T.RET, where T.ACT<-T1 and T1 is most recently used
2) In case primary path T.PRI not in {T1, T2} but ACTIVE, set
T.ACT<-T.PRI and T.RET<-T1
3) If only T1 is ACTIVE from the set, set T.ACT<-T1 and T.RET<-T1
4) If none is ACTIVE, set T.ACT<-best(T.PRI, T.RET, T3) where
T3 is the most recently used (if avail) in PF, set T.RET<-T.PRI
Prior to above commits, 4) was simply a camp on T.ACT<-T.PRI and
T.RET<-T.PRI, ignoring possible paths in PF. Camping on T.PRI is
still slightly suboptimal as it can lead to the following scenario:
Setup:
<A> <B>
T1: p1p1 (10.0.10.10) <==> .'`) <==> p1p1 (10.0.10.12) <= T.PRI
T2: p1p2 (10.0.10.20) <==> (_ . ) <==> p1p2 (10.0.10.22)
net.sctp.rto_min = 1000
net.sctp.path_max_retrans = 2
net.sctp.pf_retrans = 0
net.sctp.hb_interval = 1000
T.PRI is permanently down, T2 is put briefly into PF state (e.g. due to
link flapping). Here, the first time transmission is sent over PF path
T2 as it's the only non-INACTIVE path, but the retransmitted data-chunks
are sent over the INACTIVE path T1 (T.PRI), which is not good.
After the patch, it's choosing better transports in both cases by
modifying step 4):
4) If none is ACTIVE, set T.ACT_new<-best(T.ACT_old, T3) where T3 is
the most recently used (if avail) in PF, set T.RET<-T.ACT_new
This will still select a best possible path in PF if available (which
can also include T.PRI/T.RET), and set both T.ACT/T.RET to it.
In case sctp_assoc_control_transport() *just* put T.ACT_old into INACTIVE
as it transitioned from ACTIVE->PF->INACTIVE and stays in INACTIVE just
for a very short while before going back ACTIVE, it will guarantee that
this path will be reselected for T.ACT/T.RET since T3 (PF) is not
available.
Previously, this was not possible, as we would only select between T.PRI
and T.RET, and a possible T3 would be NULL due to the fact that we have
just transitioned T3 in sctp_assoc_control_transport() from PF->INACTIVE
and would select a suboptimal path when T.PRI/T.RET have worse properties.
In the case that T.ACT_old permanently went to INACTIVE during this
transition and there's no PF path available, plus T.PRI and T.RET are
INACTIVE as well, we would now camp on T.ACT_old, but if everything is
being INACTIVE there's really not much we can do except hoping for a
successful HB to bring one of the transports back up again and, thus
cause a new selection through sctp_assoc_control_transport().
Now both tests work fine:
Case 1:
1. T1 S(ACTIVE) T.ACT
T2 S(ACTIVE) T.RET
2. T1 S(ACTIVE) T.ACT, T.RET
T2 S(PF)
3. T1 S(ACTIVE) T.ACT, T.RET
T2 S(INACTIVE)
5. T1 S(PF) T.ACT, T.RET
T2 S(INACTIVE)
[ 5.1 T1 S(INACTIVE) T.ACT, T.RET
T2 S(INACTIVE) ]
6. T1 S(ACTIVE) T.ACT, T.RET
T2 S(INACTIVE)
7. T1 S(ACTIVE) T.ACT
T2 S(ACTIVE) T.RET
Case 2:
1. T1 S(ACTIVE) T.ACT
T2 S(ACTIVE) T.RET
2. T1 S(PF)
T2 S(ACTIVE) T.ACT, T.RET
3. T1 S(INACTIVE)
T2 S(ACTIVE) T.ACT, T.RET
5. T1 S(INACTIVE)
T2 S(PF) T.ACT, T.RET
[ 5.1 T1 S(INACTIVE)
T2 S(INACTIVE) T.ACT, T.RET ]
6. T1 S(INACTIVE)
T2 S(ACTIVE) T.ACT, T.RET
7. T1 S(ACTIVE) T.ACT
T2 S(ACTIVE) T.RET
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When both transports are the same, we don't have to go down that
road only to realize that we will return the very same transport.
We are guaranteed that curr is always non-NULL. Therefore, just
short-circuit this special case.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Conflicts:
drivers/net/Makefile
net/ipv6/sysctl_net_ipv6.c
Two ipv6_table_template[] additions overlap, so the index
of the ipv6_table[x] assignments needed to be adjusted.
In the drivers/net/Makefile case, we've gotten rid of the
garbage whereby we had to list every single USB networking
driver in the top-level Makefile, there is just one
"USB_NETWORKING" that guards everything.
Signed-off-by: David S. Miller <davem@davemloft.net>
When dealing with ICMPv[46] Error Message, function icmp_socket_deliver()
and icmpv6_notify() do some valid checks on packet's length, but then some
protocols check packet's length redaudantly. So remove those duplicated
statements, and increase counter ICMP_MIB_INERRORS/ICMP6_MIB_INERRORS in
function icmp_socket_deliver() and icmpv6_notify() respectively.
In addition, add missed counter in udp6/udplite6 when socket is NULL.
Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The SCTP socket extensions API document describes the v4mapping option as
follows:
8.1.15. Set/Clear IPv4 Mapped Addresses (SCTP_I_WANT_MAPPED_V4_ADDR)
This socket option is a Boolean flag which turns on or off the
mapping of IPv4 addresses. If this option is turned on, then IPv4
addresses will be mapped to V6 representation. If this option is
turned off, then no mapping will be done of V4 addresses and a user
will receive both PF_INET6 and PF_INET type addresses on the socket.
See [RFC3542] for more details on mapped V6 addresses.
This description isn't really in line with what the code does though.
Introduce addr_to_user (renamed addr_v4map), which should be called
before any sockaddr is passed back to user space. The new function
places the sockaddr into the correct format depending on the
SCTP_I_WANT_MAPPED_V4_ADDR option.
Audit all places that touched v4mapped and either sanely construct
a v4 or v6 address then call addr_to_user, or drop the
unnecessary v4mapped check entirely.
Audit all places that call addr_to_user and verify they are on a sycall
return path.
Add a custom getname that formats the address properly.
Several bugs are addressed:
- SCTP_I_WANT_MAPPED_V4_ADDR=0 often returned garbage for
addresses to user space
- The addr_len returned from recvmsg was not correct when
returning AF_INET on a v6 socket
- flowlabel and scope_id were not zerod when promoting
a v4 to v6
- Some syscalls like bind and connect behaved differently
depending on v4mapped
Tested bind, getpeername, getsockname, connect, and recvmsg for proper
behaviour in v4mapped = 1 and 0 cases.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Jason reported an oops caused by SCTP on his ARM machine with
SCTP authentication enabled:
Internal error: Oops: 17 [#1] ARM
CPU: 0 PID: 104 Comm: sctp-test Not tainted 3.13.0-68744-g3632f30c9b20-dirty #1
task: c6eefa40 ti: c6f52000 task.ti: c6f52000
PC is at sctp_auth_calculate_hmac+0xc4/0x10c
LR is at sg_init_table+0x20/0x38
pc : [<c024bb80>] lr : [<c00f32dc>] psr: 40000013
sp : c6f538e8 ip : 00000000 fp : c6f53924
r10: c6f50d80 r9 : 00000000 r8 : 00010000
r7 : 00000000 r6 : c7be4000 r5 : 00000000 r4 : c6f56254
r3 : c00c8170 r2 : 00000001 r1 : 00000008 r0 : c6f1e660
Flags: nZcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
Control: 0005397f Table: 06f28000 DAC: 00000015
Process sctp-test (pid: 104, stack limit = 0xc6f521c0)
Stack: (0xc6f538e8 to 0xc6f54000)
[...]
Backtrace:
[<c024babc>] (sctp_auth_calculate_hmac+0x0/0x10c) from [<c0249af8>] (sctp_packet_transmit+0x33c/0x5c8)
[<c02497bc>] (sctp_packet_transmit+0x0/0x5c8) from [<c023e96c>] (sctp_outq_flush+0x7fc/0x844)
[<c023e170>] (sctp_outq_flush+0x0/0x844) from [<c023ef78>] (sctp_outq_uncork+0x24/0x28)
[<c023ef54>] (sctp_outq_uncork+0x0/0x28) from [<c0234364>] (sctp_side_effects+0x1134/0x1220)
[<c0233230>] (sctp_side_effects+0x0/0x1220) from [<c02330b0>] (sctp_do_sm+0xac/0xd4)
[<c0233004>] (sctp_do_sm+0x0/0xd4) from [<c023675c>] (sctp_assoc_bh_rcv+0x118/0x160)
[<c0236644>] (sctp_assoc_bh_rcv+0x0/0x160) from [<c023d5bc>] (sctp_inq_push+0x6c/0x74)
[<c023d550>] (sctp_inq_push+0x0/0x74) from [<c024a6b0>] (sctp_rcv+0x7d8/0x888)
While we already had various kind of bugs in that area
ec0223ec48 ("net: sctp: fix sctp_sf_do_5_1D_ce to verify if
we/peer is AUTH capable") and b14878ccb7 ("net: sctp: cache
auth_enable per endpoint"), this one is a bit of a different
kind.
Giving a bit more background on why SCTP authentication is
needed can be found in RFC4895:
SCTP uses 32-bit verification tags to protect itself against
blind attackers. These values are not changed during the
lifetime of an SCTP association.
Looking at new SCTP extensions, there is the need to have a
method of proving that an SCTP chunk(s) was really sent by
the original peer that started the association and not by a
malicious attacker.
To cause this bug, we're triggering an INIT collision between
peers; normal SCTP handshake where both sides intent to
authenticate packets contains RANDOM; CHUNKS; HMAC-ALGO
parameters that are being negotiated among peers:
---------- INIT[RANDOM; CHUNKS; HMAC-ALGO] ---------->
<------- INIT-ACK[RANDOM; CHUNKS; HMAC-ALGO] ---------
-------------------- COOKIE-ECHO -------------------->
<-------------------- COOKIE-ACK ---------------------
RFC4895 says that each endpoint therefore knows its own random
number and the peer's random number *after* the association
has been established. The local and peer's random number along
with the shared key are then part of the secret used for
calculating the HMAC in the AUTH chunk.
Now, in our scenario, we have 2 threads with 1 non-blocking
SEQ_PACKET socket each, setting up common shared SCTP_AUTH_KEY
and SCTP_AUTH_ACTIVE_KEY properly, and each of them calling
sctp_bindx(3), listen(2) and connect(2) against each other,
thus the handshake looks similar to this, e.g.:
---------- INIT[RANDOM; CHUNKS; HMAC-ALGO] ---------->
<------- INIT-ACK[RANDOM; CHUNKS; HMAC-ALGO] ---------
<--------- INIT[RANDOM; CHUNKS; HMAC-ALGO] -----------
-------- INIT-ACK[RANDOM; CHUNKS; HMAC-ALGO] -------->
...
Since such collisions can also happen with verification tags,
the RFC4895 for AUTH rather vaguely says under section 6.1:
In case of INIT collision, the rules governing the handling
of this Random Number follow the same pattern as those for
the Verification Tag, as explained in Section 5.2.4 of
RFC 2960 [5]. Therefore, each endpoint knows its own Random
Number and the peer's Random Number after the association
has been established.
In RFC2960, section 5.2.4, we're eventually hitting Action B:
B) In this case, both sides may be attempting to start an
association at about the same time but the peer endpoint
started its INIT after responding to the local endpoint's
INIT. Thus it may have picked a new Verification Tag not
being aware of the previous Tag it had sent this endpoint.
The endpoint should stay in or enter the ESTABLISHED
state but it MUST update its peer's Verification Tag from
the State Cookie, stop any init or cookie timers that may
running and send a COOKIE ACK.
In other words, the handling of the Random parameter is the
same as behavior for the Verification Tag as described in
Action B of section 5.2.4.
Looking at the code, we exactly hit the sctp_sf_do_dupcook_b()
case which triggers an SCTP_CMD_UPDATE_ASSOC command to the
side effect interpreter, and in fact it properly copies over
peer_{random, hmacs, chunks} parameters from the newly created
association to update the existing one.
Also, the old asoc_shared_key is being released and based on
the new params, sctp_auth_asoc_init_active_key() updated.
However, the issue observed in this case is that the previous
asoc->peer.auth_capable was 0, and has *not* been updated, so
that instead of creating a new secret, we're doing an early
return from the function sctp_auth_asoc_init_active_key()
leaving asoc->asoc_shared_key as NULL. However, we now have to
authenticate chunks from the updated chunk list (e.g. COOKIE-ACK).
That in fact causes the server side when responding with ...
<------------------ AUTH; COOKIE-ACK -----------------
... to trigger a NULL pointer dereference, since in
sctp_packet_transmit(), it discovers that an AUTH chunk is
being queued for xmit, and thus it calls sctp_auth_calculate_hmac().
Since the asoc->active_key_id is still inherited from the
endpoint, and the same as encoded into the chunk, it uses
asoc->asoc_shared_key, which is still NULL, as an asoc_key
and dereferences it in ...
crypto_hash_setkey(desc.tfm, &asoc_key->data[0], asoc_key->len)
... causing an oops. All this happens because sctp_make_cookie_ack()
called with the *new* association has the peer.auth_capable=1
and therefore marks the chunk with auth=1 after checking
sctp_auth_send_cid(), but it is *actually* sent later on over
the then *updated* association's transport that didn't initialize
its shared key due to peer.auth_capable=0. Since control chunks
in that case are not sent by the temporary association which
are scheduled for deletion, they are issued for xmit via
SCTP_CMD_REPLY in the interpreter with the context of the
*updated* association. peer.auth_capable was 0 in the updated
association (which went from COOKIE_WAIT into ESTABLISHED state),
since all previous processing that performed sctp_process_init()
was being done on temporary associations, that we eventually
throw away each time.
The correct fix is to update to the new peer.auth_capable
value as well in the collision case via sctp_assoc_update(),
so that in case the collision migrated from 0 -> 1,
sctp_auth_asoc_init_active_key() can properly recalculate
the secret. This therefore fixes the observed server panic.
Fixes: 730fc3d05c ("[SCTP]: Implete SCTP-AUTH parameter processing")
Reported-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
MSG_MORE and 'corking' a socket would require that the transmit of
a data chunk be delayed.
Rename the return value to be less specific.
Signed-off-by: David Laight <david.laight@aculab.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The check for Nagle contains 6 separate checks all of which must be true
before a data packet is delayed.
Separate out each into its own 'if (test) return SCTP_XMIT_OK' so that
the reasons can be individually described.
Also return directly with SCTP_XMIT_RWND_FULL.
Delete the now-unused 'retval' variable and 'finish' label from
sctp_packet_can_append_data().
Signed-off-by: David Laight <david.laight@aculab.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
With support of SCTP_SNDINFO/SCTP_RCVINFO as described in RFC6458,
5.3.4/5.3.5, we can now deprecate SCTP_SNDRCV. The RFC already
declares it as deprecated:
This structure mixes the send and receive path. SCTP_SNDINFO
(described in Section 5.3.4) and SCTP_RCVINFO (described in
Section 5.3.5) split this information. These structures should
be used, when possible, since SCTP_SNDRCV is deprecated.
So whenever a user tries to subscribe to sctp_data_io_event via
setsockopt(2) which triggers inclusion of SCTP_SNDRCV cmsg_type,
issue a warning in the log.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch implements section 8.1.31. of RFC6458, which adds support
for setting/retrieving SCTP_DEFAULT_SNDINFO:
Applications that wish to use the sendto() system call may wish
to specify a default set of parameters that would normally be
supplied through the inclusion of ancillary data. This socket
option allows such an application to set the default sctp_sndinfo
structure. The application that wishes to use this socket option
simply passes the sctp_sndinfo structure (defined in Section 5.3.4)
to this call. The input parameters accepted by this call include
snd_sid, snd_flags, snd_ppid, and snd_context. The snd_flags
parameter is composed of a bitwise OR of SCTP_UNORDERED, SCTP_EOF,
and SCTP_SENDALL. The snd_assoc_id field specifies the association
to which to apply the parameters. For a one-to-many style socket,
any of the predefined constants are also allowed in this field.
The field is ignored for one-to-one style sockets.
Joint work with Daniel Borkmann.
Signed-off-by: Geir Ola Vaagland <geirola@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch implements section 5.3.6. of RFC6458, that is, support
for 'SCTP Next Receive Information Structure' (SCTP_NXTINFO) which
is placed into ancillary data cmsghdr structure for each recvmsg()
call, if this information is already available when delivering the
current message.
This option can be enabled/disabled via setsockopt(2) on SOL_SCTP
level by setting an int value with 1/0 for SCTP_RECVNXTINFO in
user space applications as per RFC6458, section 8.1.30.
The sctp_nxtinfo structure is defined as per RFC as below ...
struct sctp_nxtinfo {
uint16_t nxt_sid;
uint16_t nxt_flags;
uint32_t nxt_ppid;
uint32_t nxt_length;
sctp_assoc_t nxt_assoc_id;
};
... and provided under cmsg_level IPPROTO_SCTP, cmsg_type
SCTP_NXTINFO, while cmsg_data[] contains struct sctp_nxtinfo.
Joint work with Daniel Borkmann.
Signed-off-by: Geir Ola Vaagland <geirola@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch implements section 5.3.5. of RFC6458, that is, support
for 'SCTP Receive Information Structure' (SCTP_RCVINFO) which is
placed into ancillary data cmsghdr structure for each recvmsg()
call.
This option can be enabled/disabled via setsockopt(2) on SOL_SCTP
level by setting an int value with 1/0 for SCTP_RECVRCVINFO in user
space applications as per RFC6458, section 8.1.29.
The sctp_rcvinfo structure is defined as per RFC as below ...
struct sctp_rcvinfo {
uint16_t rcv_sid;
uint16_t rcv_ssn;
uint16_t rcv_flags;
<-- 2 bytes hole -->
uint32_t rcv_ppid;
uint32_t rcv_tsn;
uint32_t rcv_cumtsn;
uint32_t rcv_context;
sctp_assoc_t rcv_assoc_id;
};
... and provided under cmsg_level IPPROTO_SCTP, cmsg_type
SCTP_RCVINFO, while cmsg_data[] contains struct sctp_rcvinfo.
An sctp_rcvinfo item always corresponds to the data in msg_iov.
Joint work with Daniel Borkmann.
Signed-off-by: Geir Ola Vaagland <geirola@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch implements section 5.3.4. of RFC6458, that is, support
for 'SCTP Send Information Structure' (SCTP_SNDINFO) which can be
placed into ancillary data cmsghdr structure for sendmsg() calls.
The sctp_sndinfo structure is defined as per RFC as below ...
struct sctp_sndinfo {
uint16_t snd_sid;
uint16_t snd_flags;
uint32_t snd_ppid;
uint32_t snd_context;
sctp_assoc_t snd_assoc_id;
};
... and supplied under cmsg_level IPPROTO_SCTP, cmsg_type
SCTP_SNDINFO, while cmsg_data[] contains struct sctp_sndinfo.
An sctp_sndinfo item always corresponds to the data in msg_iov.
Joint work with Daniel Borkmann.
Signed-off-by: Geir Ola Vaagland <geirola@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
While working on some other SCTP code, I noticed that some
structures shared with user space are leaking uninitialized
stack or heap buffer. In particular, struct sctp_sndrcvinfo
has a 2 bytes hole between .sinfo_flags and .sinfo_ppid that
remains unfilled by us in sctp_ulpevent_read_sndrcvinfo() when
putting this into cmsg. But also struct sctp_remote_error
contains a 2 bytes hole that we don't fill but place into a skb
through skb_copy_expand() via sctp_ulpevent_make_remote_error().
Both structures are defined by the IETF in RFC6458:
* Section 5.3.2. SCTP Header Information Structure:
The sctp_sndrcvinfo structure is defined below:
struct sctp_sndrcvinfo {
uint16_t sinfo_stream;
uint16_t sinfo_ssn;
uint16_t sinfo_flags;
<-- 2 bytes hole -->
uint32_t sinfo_ppid;
uint32_t sinfo_context;
uint32_t sinfo_timetolive;
uint32_t sinfo_tsn;
uint32_t sinfo_cumtsn;
sctp_assoc_t sinfo_assoc_id;
};
* 6.1.3. SCTP_REMOTE_ERROR:
A remote peer may send an Operation Error message to its peer.
This message indicates a variety of error conditions on an
association. The entire ERROR chunk as it appears on the wire
is included in an SCTP_REMOTE_ERROR event. Please refer to the
SCTP specification [RFC4960] and any extensions for a list of
possible error formats. An SCTP error notification has the
following format:
struct sctp_remote_error {
uint16_t sre_type;
uint16_t sre_flags;
uint32_t sre_length;
uint16_t sre_error;
<-- 2 bytes hole -->
sctp_assoc_t sre_assoc_id;
uint8_t sre_data[];
};
Fix this by setting both to 0 before filling them out. We also
have other structures shared between user and kernel space in
SCTP that contains holes (e.g. struct sctp_paddrthlds), but we
copy that buffer over from user space first and thus don't need
to care about it in that cases.
While at it, we can also remove lengthy comments copied from
the draft, instead, we update the comment with the correct RFC
number where one can look it up.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
sctp_init_cmd_seq() and sctp_next_cmd() are only called from one place.
The call sequence for sctp_add_cmd_sf() is likely to be longer than
the inlined code.
With sctp_add_cmd_sf() inlined the compiler can optimise repeated calls.
Signed-off-by: David Laight <david.laight@aculab.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Only warn if the value is written to alpha or beta. We don't care
emitting a one-time warning when only reading it.
Reported-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
RFC4960, section 8.3 says:
On an idle destination address that is allowed to heartbeat,
it is recommended that a HEARTBEAT chunk is sent once per RTO
of that destination address plus the protocol parameter
'HB.interval', with jittering of +/- 50% of the RTO value,
and exponential backoff of the RTO if the previous HEARTBEAT
is unanswered.
Currently, we calculate jitter via sctp_jitter() function first,
and then add its result to the current RTO for the new timeout:
TMO = RTO + (RAND() % RTO) - (RTO / 2)
`------------------------^-=> sctp_jitter()
Instead, we can just simplify all this by directly calculating:
TMO = (RTO / 2) + (RAND() % RTO)
With the help of prandom_u32_max(), we don't need to open code
our own global PRNG, but can instead just make use of the per
CPU implementation of prandom with better quality numbers. Also,
we can now spare us the conditional for divide by zero check
since no div or mod operation needs to be used. Note that
prandom_u32_max() won't emit the same result as a mod operation,
but we really don't care here as we only want to have a random
number scaled into RTO interval.
Note, exponential RTO backoff is handeled elsewhere, namely in
sctp_do_8_2_transport_strike().
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When writing to the sysctl field net.sctp.auth_enable, it can well
be that the user buffer we handed over to proc_dointvec() via
proc_sctp_do_auth() handler contains something other than integers.
In that case, we would set an uninitialized 4-byte value from the
stack to net->sctp.auth_enable that can be leaked back when reading
the sysctl variable, and it can unintentionally turn auth_enable
on/off based on the stack content since auth_enable is interpreted
as a boolean.
Fix it up by making sure proc_dointvec() returned sucessfully.
Fixes: b14878ccb7 ("net: sctp: cache auth_enable per endpoint")
Reported-by: Florian Westphal <fwestpha@redhat.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
sysctl handler proc_sctp_do_hmac_alg(), proc_sctp_do_rto_min() and
proc_sctp_do_rto_max() do not properly reflect some error cases
when writing values via sysctl from internal proc functions such
as proc_dointvec() and proc_dostring().
In all these cases we pass the test for write != 0 and partially
do additional work just to notice that additional sanity checks
fail and we return with hard-coded -EINVAL while proc_do*
functions might also return different errors. So fix this up by
simply testing a successful return of proc_do* right after
calling it.
This also allows to propagate its return value onwards to the user.
While touching this, also fix up some minor style issues.
Fixes: 4f3fdf3bc5 ("sctp: add check rto_min and rto_max in sysctl")
Fixes: 3c68198e75 ("sctp: Make hmac algorithm selection for cookie generation dynamic")
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Daniel Borkmann
zhuyj
David S. Miller
Eric Dumazet
Duan Jiong
Jason Gunthorpe
David Laight
Geir Ola Vaagland
Fabian Frederick