The code in l2tp_tunnel_register() is racy in several ways:
1. It modifies the tunnel socket _after_ publishing it.
2. It calls setup_udp_tunnel_sock() on an existing socket without
locking.
3. It changes sock lock class on fly, which triggers many syzbot
reports.
This patch amends all of them by moving socket initialization code
before publishing and under sock lock. As suggested by Jakub, the
l2tp lockdep class is not necessary as we can just switch to
bh_lock_sock_nested().
Fixes: 37159ef2c1 ("l2tp: fix a lockdep splat")
Fixes: 6b9f34239b ("l2tp: fix races in tunnel creation")
Reported-by: syzbot+52866e24647f9a23403f@syzkaller.appspotmail.com
Reported-by: syzbot+94cc2a66fc228b23f360@syzkaller.appspotmail.com
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Guillaume Nault <gnault@redhat.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Tom Parkin <tparkin@katalix.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp uses l2tp_tunnel_list to track all registered tunnels and
to allocate tunnel ID's. IDR can do the same job.
More importantly, with IDR we can hold the ID before a successful
registration so that we don't need to worry about late error
handling, it is not easy to rollback socket changes.
This is a preparation for the following fix.
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Guillaume Nault <gnault@redhat.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Tom Parkin <tparkin@katalix.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When holding a reader-writer spin lock we cannot sleep. Calling
setup_udp_tunnel_sock() with write lock held violates this rule, because we
end up calling percpu_down_read(), which might sleep, as syzbot reports
[1]:
__might_resched.cold+0x222/0x26b kernel/sched/core.c:9890
percpu_down_read include/linux/percpu-rwsem.h:49 [inline]
cpus_read_lock+0x1b/0x140 kernel/cpu.c:310
static_key_slow_inc+0x12/0x20 kernel/jump_label.c:158
udp_tunnel_encap_enable include/net/udp_tunnel.h:187 [inline]
setup_udp_tunnel_sock+0x43d/0x550 net/ipv4/udp_tunnel_core.c:81
l2tp_tunnel_register+0xc51/0x1210 net/l2tp/l2tp_core.c:1509
pppol2tp_connect+0xcdc/0x1a10 net/l2tp/l2tp_ppp.c:723
Trim the writer-side critical section for sk_callback_lock down to the
minimum, so that it covers only operations on sk_user_data.
Also, when grabbing the sk_callback_lock, we always need to disable BH, as
Eric points out. Failing to do so leads to deadlocks because we acquire
sk_callback_lock in softirq context, which can get stuck waiting on us if:
1) it runs on the same CPU, or
CPU0
----
lock(clock-AF_INET6);
<Interrupt>
lock(clock-AF_INET6);
2) lock ordering leads to priority inversion
CPU0 CPU1
---- ----
lock(clock-AF_INET6);
local_irq_disable();
lock(&tcp_hashinfo.bhash[i].lock);
lock(clock-AF_INET6);
<Interrupt>
lock(&tcp_hashinfo.bhash[i].lock);
... as syzbot reports [2,3]. Use the _bh variants for write_(un)lock.
[1] https://lore.kernel.org/netdev/0000000000004e78ec05eda79749@google.com/
[2] https://lore.kernel.org/netdev/000000000000e38b6605eda76f98@google.com/
[3] https://lore.kernel.org/netdev/000000000000dfa31e05eda76f75@google.com/
v2:
- Check and set sk_user_data while holding sk_callback_lock for both
L2TP encapsulation types (IP and UDP) (Tetsuo)
Cc: Tom Parkin <tparkin@katalix.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Fixes: b68777d54f ("l2tp: Serialize access to sk_user_data with sk_callback_lock")
Reported-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot+703d9e154b3b58277261@syzkaller.appspotmail.com
Reported-by: syzbot+50680ced9e98a61f7698@syzkaller.appspotmail.com
Reported-by: syzbot+de987172bb74a381879b@syzkaller.appspotmail.com
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
sk->sk_user_data has multiple users, which are not compatible with each
other. Writers must synchronize by grabbing the sk->sk_callback_lock.
l2tp currently fails to grab the lock when modifying the underlying tunnel
socket fields. Fix it by adding appropriate locking.
We err on the side of safety and grab the sk_callback_lock also inside the
sk_destruct callback overridden by l2tp, even though there should be no
refs allowing access to the sock at the time when sk_destruct gets called.
v4:
- serialize write to sk_user_data in l2tp sk_destruct
v3:
- switch from sock lock to sk_callback_lock
- document write-protection for sk_user_data
v2:
- update Fixes to point to origin of the bug
- use real names in Reported/Tested-by tags
Cc: Tom Parkin <tparkin@katalix.com>
Fixes: 3557baabf2 ("[L2TP]: PPP over L2TP driver core")
Reported-by: Haowei Yan <g1042620637@gmail.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Previously commit e02d494d2c ("l2tp: Convert rwlock to RCU") converted
most, but not all, rwlock instances in the l2tp subsystem to RCU.
The remaining rwlock protects the per-tunnel hashlist of sessions which
is used for session lookups in the UDP-encap data path.
Convert the remaining rwlock to rcu to improve performance of UDP-encap
tunnels.
Note that the tunnel and session, which both live on RCU-protected
lists, use slightly different approaches to incrementing their refcounts
in the various getter functions.
The tunnel has to use refcount_inc_not_zero because the tunnel shutdown
process involves dropping the refcount to zero prior to synchronizing
RCU readers (via. kfree_rcu).
By contrast, the session shutdown removes the session from the list(s)
it is on, synchronizes with readers, and then decrements the session
refcount. Since the getter functions increment the session refcount
with the RCU read lock held we prevent getters seeing a zero session
refcount, and therefore don't need to use refcount_inc_not_zero.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The reference count leak issue may take place in an error handling
path. If both conditions of tunnel->version == L2TP_HDR_VER_3 and the
return value of l2tp_v3_ensure_opt_in_linear is nonzero, the function
would directly jump to label invalid, without decrementing the reference
count of the l2tp_session object session increased earlier by
l2tp_tunnel_get_session(). This may result in refcount leaks.
Fix this issue by decrease the reference count before jumping to the
label invalid.
Fixes: 4522a70db7 ("l2tp: fix reading optional fields of L2TPv3")
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_tunnel_register() registers a tunnel without fully
initializing its attribute. This can allow another kernel thread
running l2tp_xmit_core() to access the uninitialized data and
then cause a kernel NULL pointer dereference error, as shown below.
Thread 1 Thread 2
//l2tp_tunnel_register()
list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
//pppol2tp_connect()
tunnel = l2tp_tunnel_get(sock_net(sk), info.tunnel_id);
// Fetch the new tunnel
...
//l2tp_xmit_core()
struct sock *sk = tunnel->sock;
...
bh_lock_sock(sk);
//Null pointer error happens
tunnel->sock = sk;
Fix this bug by initializing tunnel->sock before adding the
tunnel into l2tp_tunnel_list.
Reviewed-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Sishuai Gong <sishuai@purdue.edu>
Reported-by: Sishuai Gong <sishuai@purdue.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
s/verifed/verified/
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 5ee759cda5 ("l2tp: use standard API for warning log messages")
changed a number of warnings about invalid packets in the receive path
so that they are always shown, instead of only when a special L2TP debug
flag is set. Even with rate limiting these warnings can easily cause
significant log spam - potentially triggered by a malicious party
sending invalid packets on purpose.
In addition these warnings were noticed by projects like Tunneldigger [1],
which uses L2TP for its data path, but implements its own control
protocol (which is sufficiently different from L2TP data packets that it
would always be passed up to userspace even with future extensions of
L2TP).
Some of the warnings were already redundant, as l2tp_stats has a counter
for these packets. This commit adds one additional counter for invalid
packets that are passed up to userspace. Packets with unknown session are
not counted as invalid, as there is nothing wrong with the format of
these packets.
With the additional counter, all of these messages are either redundant
or benign, so we reduce them to pr_debug_ratelimited().
[1] https://github.com/wlanslovenija/tunneldigger/issues/160
Fixes: 5ee759cda5 ("l2tp: use standard API for warning log messages")
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Historically L2TP core statistics count the L2TP header in the
per-session and per-tunnel byte counts tracked for transmission and
receipt.
Now that l2tp_xmit_skb updates tx stats, it is necessary for
l2tp_xmit_core to pass out the length of the transmitted packet so that
the statistics can be updated correctly.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_tunnel_closeall is called as a part of tunnel shutdown in order to
close all the sessions held by the tunnel. The code it uses to close a
session duplicates what l2tp_session_delete does.
Rather than duplicating the code, have l2tp_tunnel_closeall call
l2tp_session_delete instead.
This involves a very minor change to locking in l2tp_tunnel_closeall.
Previously, l2tp_tunnel_closeall checked the session "dead" flag while
holding tunnel->hlist_lock. This allowed for the code to step to the
next session in the list without releasing the lock if the current
session happened to be in the process of closing already.
By calling l2tp_session_delete instead, l2tp_tunnel_closeall must now
drop and regain the hlist lock for each session in the tunnel list.
Given that the likelihood of a session being in the process of closing
when the tunnel is closed, it seems worth this very minor potential
loss of efficiency to avoid duplication of the session delete code.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The l2tp tunnel and session structures contain a "magic feather" field
which was originally intended to help trace lifetime bugs in the code.
Since the introduction of the shared kernel refcount code in refcount.h,
and l2tp's porting to those APIs, we are covered by the refcount code's
checks and warnings. Duplicating those checks in the l2tp code isn't
useful.
However, magic feather checks are still useful to help to detect bugs
stemming from misuse/trampling of the sk_user_data pointer in struct
sock. The l2tp code makes extensive use of sk_user_data to stash
pointers to the tunnel and session structures, and if another subsystem
overwrites sk_user_data it's important to detect this.
As such, rework l2tp's magic feather checks to focus on validating the
tunnel and session data structures when they're extracted from
sk_user_data.
* Add a new accessor function l2tp_sk_to_tunnel which contains a magic
feather check, and is used by l2tp_core and l2tp_ip[6]
* Comment l2tp_udp_encap_recv which doesn't use this new accessor function
because of the specific nature of the codepath it is called in
* Drop l2tp_session_queue_purge's check on the session magic feather:
it is called from code which is walking the tunnel session list, and
hence doesn't need validation
* Drop l2tp_session_free's check on the tunnel magic feather: the
intention of this check is covered by refcount.h's reference count
sanity checking
* Add session magic validation in pppol2tp_ioctl. On failure return
-EBADF, which mirrors the approach in pppol2tp_[sg]etsockopt.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_xmit_skb has a number of failure paths which are not reflected in
the tunnel and session statistics because the stats are updated by
l2tp_xmit_core. Hence any errors occurring before l2tp_xmit_core is
called are missed from the statistics.
Refactor the transmit path slightly to capture all error paths.
l2tp_xmit_skb now leaves all the actual work of transmission to
l2tp_xmit_core, and updates the statistics based on l2tp_xmit_core's
return code.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The data_len argument passed to l2tp_xmit_core is no longer used, so
remove it.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All callers pass the session structure's hdr_len field as the header
length parameter to l2tp_xmit_skb.
Since we're passing a pointer to the session structure to l2tp_xmit_skb
anyway, there's not much point breaking the header length out as a
separate argument.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The l2tp subsystem now uses standard kernel logging APIs for
informational and warning messages, and tracepoints for debug
information.
Now that the tunnel and session debug flags are unused, remove the field
from the core structures.
Various system calls (in the case of l2tp_ppp) and netlink messages
handle the getting and setting of debug flags. To avoid userspace
breakage don't modify the API of these calls; simply ignore set
requests, and send dummy data for get requests.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add lifetime event tracing for tunnel and session instances, tracking
tunnel and session registration, deletion, and eventual freeing.
Port the data path sequence number debug logging to use trace points
rather than custom debug macros.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The l2tp subsystem doesn't currently make use of tracepoints.
As a starting point for adding tracepoints, add skeleton infrastructure
for defining tracepoints for the subsystem, and for having them build
appropriately whether compiled into the kernel or built as a module.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The l2tp_* log wrappers only emit messages of a given category if the
tunnel or session structure has the appropriate flag set in its debug
field. Flags default to being unset.
For warning messages, this doesn't make a lot of sense since an
administrator is likely to want to know about datapath warnings without
needing to tweak the debug flags setting for a given tunnel or session
instance.
Modify l2tp_warn callsites to use pr_warn_ratelimited instead for
unconditional output of warning messages.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_ppp in particular had a lot of log messages for tracing
[get|set]sockopt calls. These aren't especially useful, so remove
these messages.
Several log messages flagging error conditions were logged using
l2tp_info: they're better off as l2tp_warn.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp had logging to trace data frame receipt and transmission, including
code to dump packet contents. This was originally intended to aid
debugging of core l2tp packet handling, but is of limited use now that
code is stable.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All of the l2tp subsystem's exported symbols are exported using
EXPORT_SYMBOL_GPL, except for l2tp_recv_common and l2tp_ioctl.
These functions alone are not useful without the rest of the l2tp
infrastructure, so there's no practical benefit to these symbols using a
different export policy.
Change these exports to use EXPORT_SYMBOL_GPL for consistency with the
rest of l2tp.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The structure of an L2TP data packet header varies depending on the
version of the L2TP protocol being used.
struct l2tp_session used to have a build_header callback to abstract
this difference away. It's clearer to simply choose the correct
function to use when building the data packet (and we save on the
function pointer in the session structure).
This approach does mean dereferencing the parent tunnel structure in
order to determine the tunnel version, but we're doing that in the
transmit path in any case.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_session_delete is used to schedule a session instance for deletion.
The function itself always returns zero, and none of its direct callers
check its return value, so have the function return void.
This change de-facto changes the l2tp netlink session_delete callback
prototype since all pseudowires currently use l2tp_session_delete for
their implementation of that operation.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Tunnel and session instances are reference counted, and shouldn't be
directly freed by pseudowire code.
Rather than exporting l2tp_tunnel_free and l2tp_session_free, make them
private to l2tp_core.c, and export the refcount functions instead.
In order to do this, the refcount functions cannot be declared as
inline. Since the codepaths which take and drop tunnel and session
references are not directly in the datapath this shouldn't cause
performance issues.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When __l2tp_session_unhash was first added it was used outside of
l2tp_core.c, but that's no longer the case.
As such, there's no longer a need to export the function. Make it
private inside l2tp_core.c, and relocate it to avoid having to declare
the function prototype in l2tp_core.h.
Since the function is no longer used outside l2tp_core.c, remove the
"__" prefix since we don't need to indicate anything special about its
expected use to callers.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_session_free called BUG_ON if the tunnel magic feather value wasn't
correct. The intent of this was to catch lifetime bugs; for example
early tunnel free due to incorrect use of reference counts.
Since the tunnel magic feather being wrong indicates either early free
or structure corruption, we can avoid doing more damage by simply
leaving the tunnel structure alone. If the tunnel refcount isn't
dropped when it should be, the tunnel instance will remain in the
kernel, resulting in the tunnel structure and socket leaking.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_session_free is only called by l2tp_session_dec_refcount when the
reference count reaches zero, so it's of limited value to validate the
reference count value in l2tp_session_free itself.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_session_queue_purge is used during session shutdown to drop any
skbs queued for reordering purposes according to L2TP dataplane rules.
The BUG_ON in this function checks the session magic feather in an
attempt to catch lifetime bugs.
Rather than crashing the kernel with a BUG_ON, we can simply WARN_ON and
refuse to do anything more -- in the worst case this could result in a
leak. However this is highly unlikely given that the session purge only
occurs from codepaths which have obtained the session by means of a lookup
via. the parent tunnel and which check the session "dead" flag to
protect against shutdown races.
While we're here, have l2tp_session_queue_purge return void rather than
an integer, since neither of the callsites checked the return value.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_tunnel_closeall is only called from l2tp_core.c, and it's easy
to statically analyse the code path calling it to validate that it
should never be passed a NULL tunnel pointer.
Having a BUG_ON checking the tunnel pointer triggers a checkpatch
warning. Since the BUG_ON is of no value, remove it to avoid the
warning.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_session_queue_purge is only called from l2tp_core.c, and it's easy
to statically analyse the code paths calling it to validate that it
should never be passed a NULL session pointer.
Having a BUG_ON checking the session pointer triggers a checkpatch
warning. Since the BUG_ON is of no value, remove it to avoid the
warning.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
checkpatch warns about multiple assignments.
Update l2tp accordingly.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Passing "sizeof(struct blah)" in kzalloc calls is less readable,
potentially prone to future bugs if the type of the pointer is changed,
and triggers checkpatch warnings.
Tweak the kzalloc calls in l2tp which use this form to avoid the
warning.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
These checks are all simple and don't benefit from extra braces to
clarify intent. Remove them for easier-reading code.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
checkpatch warns about comparisons to NULL, e.g.
CHECK: Comparison to NULL could be written "!rt"
#474: FILE: net/l2tp/l2tp_ip.c:474:
+ if (rt == NULL) {
These sort of comparisons are generally clearer and more readable
the way checkpatch suggests, so update l2tp accordingly.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
checkpatch warned about the L2TP_SKB_CB macro's use of its argument: add
braces to avoid the problem.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In l2tp_core.c both l2tp_tunnel_create and l2tp_session_create take
quite a number of arguments and have a correspondingly long prototype.
This is both quite difficult to scan visually, and triggers checkpatch
warnings.
Add a line break to make these function prototypes more readable.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_core has conditionally compiled code in l2tp_xmit_skb for IPv6
support. The structure of this code triggered a checkpatch warning
due to incorrect indentation.
Fix up the indentation to address the checkpatch warning.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Arguments should be aligned with the function call open parenthesis as
per checkpatch. Tweak some function calls which were not aligned
correctly.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Modify some l2tp comments to better adhere to kernel coding style, as
reported by checkpatch.pl.
Add descriptive comments for the l2tp per-net spinlocks to document
their use.
Fix an incorrect comment in l2tp_recv_common:
RFC2661 section 5.4 states that:
"The LNS controls enabling and disabling of sequence numbers by sending a
data message with or without sequence numbers present at any time during
the life of a session."
l2tp handles this correctly in l2tp_recv_common, but the comment around
the code was incorrect and confusing. Fix up the comment accordingly.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix up various whitespace issues as reported by checkpatch.pl:
* remove spaces around operators where appropriate,
* add missing blank lines following declarations,
* remove multiple blank lines, or trailing blank lines at the end of
functions.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the tx path of l2tp, l2tp_xmit_skb() calls skb_dst_set() to set
skb's dst. However, it will eventually call inet6_csk_xmit() or
ip_queue_xmit() where skb's dst will be overwritten by:
skb_dst_set_noref(skb, dst);
without releasing the old dst in skb. Then it causes dst/dev refcnt leak:
unregister_netdevice: waiting for eth0 to become free. Usage count = 1
This can be reproduced by simply running:
# modprobe l2tp_eth && modprobe l2tp_ip
# sh ./tools/testing/selftests/net/l2tp.sh
So before going to inet6_csk_xmit() or ip_queue_xmit(), skb's dst
should be dropped. This patch is to fix it by removing skb_dst_set()
from l2tp_xmit_skb() and moving skb_dst_drop() into l2tp_xmit_core().
Fixes: 3557baabf2 ("[L2TP]: PPP over L2TP driver core")
Reported-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: James Chapman <jchapman@katalix.com>
Tested-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
syzbot was able to trigger a crash after using an ISDN socket
and fool l2tp.
Fix this by making sure the UDP socket is of the proper family.
BUG: KASAN: slab-out-of-bounds in setup_udp_tunnel_sock+0x465/0x540 net/ipv4/udp_tunnel.c:78
Write of size 1 at addr ffff88808ed0c590 by task syz-executor.5/3018
CPU: 0 PID: 3018 Comm: syz-executor.5 Not tainted 5.7.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x188/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:382
__kasan_report.cold+0x20/0x38 mm/kasan/report.c:511
kasan_report+0x33/0x50 mm/kasan/common.c:625
setup_udp_tunnel_sock+0x465/0x540 net/ipv4/udp_tunnel.c:78
l2tp_tunnel_register+0xb15/0xdd0 net/l2tp/l2tp_core.c:1523
l2tp_nl_cmd_tunnel_create+0x4b2/0xa60 net/l2tp/l2tp_netlink.c:249
genl_family_rcv_msg_doit net/netlink/genetlink.c:673 [inline]
genl_family_rcv_msg net/netlink/genetlink.c:718 [inline]
genl_rcv_msg+0x627/0xdf0 net/netlink/genetlink.c:735
netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2469
genl_rcv+0x24/0x40 net/netlink/genetlink.c:746
netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:672
____sys_sendmsg+0x6e6/0x810 net/socket.c:2352
___sys_sendmsg+0x100/0x170 net/socket.c:2406
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45ca29
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007effe76edc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004fe1c0 RCX: 000000000045ca29
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000005
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000094e R14: 00000000004d5d00 R15: 00007effe76ee6d4
Allocated by task 3018:
save_stack+0x1b/0x40 mm/kasan/common.c:49
set_track mm/kasan/common.c:57 [inline]
__kasan_kmalloc mm/kasan/common.c:495 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
__do_kmalloc mm/slab.c:3656 [inline]
__kmalloc+0x161/0x7a0 mm/slab.c:3665
kmalloc include/linux/slab.h:560 [inline]
sk_prot_alloc+0x223/0x2f0 net/core/sock.c:1612
sk_alloc+0x36/0x1100 net/core/sock.c:1666
data_sock_create drivers/isdn/mISDN/socket.c:600 [inline]
mISDN_sock_create+0x272/0x400 drivers/isdn/mISDN/socket.c:796
__sock_create+0x3cb/0x730 net/socket.c:1428
sock_create net/socket.c:1479 [inline]
__sys_socket+0xef/0x200 net/socket.c:1521
__do_sys_socket net/socket.c:1530 [inline]
__se_sys_socket net/socket.c:1528 [inline]
__x64_sys_socket+0x6f/0xb0 net/socket.c:1528
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
Freed by task 2484:
save_stack+0x1b/0x40 mm/kasan/common.c:49
set_track mm/kasan/common.c:57 [inline]
kasan_set_free_info mm/kasan/common.c:317 [inline]
__kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
__cache_free mm/slab.c:3426 [inline]
kfree+0x109/0x2b0 mm/slab.c:3757
kvfree+0x42/0x50 mm/util.c:603
__free_fdtable+0x2d/0x70 fs/file.c:31
put_files_struct fs/file.c:420 [inline]
put_files_struct+0x248/0x2e0 fs/file.c:413
exit_files+0x7e/0xa0 fs/file.c:445
do_exit+0xb04/0x2dd0 kernel/exit.c:791
do_group_exit+0x125/0x340 kernel/exit.c:894
get_signal+0x47b/0x24e0 kernel/signal.c:2739
do_signal+0x81/0x2240 arch/x86/kernel/signal.c:784
exit_to_usermode_loop+0x26c/0x360 arch/x86/entry/common.c:161
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
entry_SYSCALL_64_after_hwframe+0x49/0xb3
The buggy address belongs to the object at ffff88808ed0c000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1424 bytes inside of
2048-byte region [ffff88808ed0c000, ffff88808ed0c800)
The buggy address belongs to the page:
page:ffffea00023b4300 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002838208 ffffea00015ba288 ffff8880aa000e00
raw: 0000000000000000 ffff88808ed0c000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff88808ed0c480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88808ed0c500: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88808ed0c580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88808ed0c600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88808ed0c680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
Fixes: 6b9f34239b ("l2tp: fix races in tunnel creation")
Fixes: fd558d186d ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: James Chapman <jchapman@katalix.com>
Cc: Guillaume Nault <gnault@redhat.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the past it was possible to create multiple L2TPv3 sessions with the
same session id as long as the sessions belonged to different tunnels.
The resulting sessions had issues when used with IP encapsulated tunnels,
but worked fine with UDP encapsulated ones. Some applications began to
rely on this behaviour to avoid having to negotiate unique session ids.
Some time ago a change was made to require session ids to be unique across
all tunnels, breaking the applications making use of this "feature".
This change relaxes the duplicate session id check to allow duplicates
if both of the colliding sessions belong to UDP encapsulated tunnels.
Fixes: dbdbc73b44 ("l2tp: fix duplicate session creation")
Signed-off-by: Ridge Kennedy <ridge.kennedy@alliedtelesis.co.nz>
Acked-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Passing NULL to l2tp_pernet causes a crash via BUG_ON.
Dereferencing net in net_generic() also has the same effect.
This patch removes the redundant BUG_ON check on the same parameter.
Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
commit 174e23810c
("sk_buff: drop all skb extensions on free and skb scrubbing") made napi
recycle always drop skb extensions. The additional skb_ext_del() that is
performed via nf_reset on napi skb recycle is not needed anymore.
Most nf_reset() calls in the stack are there so queued skb won't block
'rmmod nf_conntrack' indefinitely.
This removes the skb_ext_del from nf_reset, and renames it to a more
fitting nf_reset_ct().
In a few selected places, add a call to skb_ext_reset to make sure that
no active extensions remain.
I am submitting this for "net", because we're still early in the release
cycle. The patch applies to net-next too, but I think the rename causes
needless divergence between those trees.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Eric Dumazet