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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>
As pointed out by Herbert in a recent related patch, the LSM hooks do
not have the necessary address family information to use the flowi
struct safely. As none of the LSMs currently use any of the protocol
specific flowi information, replace the flowi pointers with pointers
to the address family independent flowi_common struct.
Reported-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Bulk of the genetlink users can use smaller ops, move them.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
When an L2TPv3 session receives a data frame with an incorrect cookie
l2tp_core logs a warning message and bumps a stats counter to reflect
the fact that the packet has been dropped.
However, the stats counter in question is missing from the l2tp_netlink
get message for tunnel and session instances.
Include the statistic in the netlink get response.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
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>
All l2tp's informational and warning logging is now carried out using
standard kernel APIs.
Debugging information is now handled using tracepoints.
Now that no code is using the custom logging macros, remove them from
l2tp_core.h.
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>
l2tp can provide a better debug experience using tracepoints rather than
printk-style logging.
Add tracepoint definitions in trace.h for use in the l2tp subsystem
code.
Add preprocessor definitions for the length of session and tunnel names
in l2tp_core.h so we can reuse these in trace.h.
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>
* Improve the description of the key l2tp subsystem data structures.
* Add high-level description of the main APIs for interacting with l2tp
core.
* Add documentation for the l2tp netlink session command callbacks.
* Document the session pseudowire callbacks.
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>
checkpatch advises that WARN_ON and recovery code are preferred over
BUG_ON which crashes the kernel.
l2tp_ppp has a BUG_ON check of struct seq_file's private pointer in
pppol2tp_seq_start prior to accessing data through that pointer.
Rather than crashing, we can simply bail out early and return NULL in
order to terminate the seq file processing in much the same way as we do
when reaching the end of tunnel/session instances to render.
Retain a WARN_ON to help trace possible bugs in this area.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
checkpatch advises that WARN_ON and recovery code are preferred over
BUG_ON which crashes the kernel.
l2tp_ppp.c's BUG_ON checks of the l2tp session structure's "magic" field
occur in code paths where it's reasonably easy to recover:
* In the case of pppol2tp_sock_to_session, we can return NULL and the
caller will bail out appropriately. There is no change required to
any of the callsites of this function since they already handle
pppol2tp_sock_to_session returning NULL.
* In the case of pppol2tp_session_destruct we can just avoid
decrementing the reference count on the suspect session structure.
In the worst case scenario this results in a memory leak, which is
preferable to a crash.
Convert these uses of BUG_ON to WARN_ON accordingly.
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>
l2tp_dfs_seq_start had a BUG_ON to catch a possible programming error in
l2tp_dfs_seq_open.
Since we can easily bail out of l2tp_dfs_seq_start, prefer to do that
and flag the error with a WARN_ON rather than crashing the kernel.
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>
Rework the remaining setsockopt code to pass a sockptr_t instead of a
plain user pointer. This removes the last remaining set_fs(KERNEL_DS)
outside of architecture specific code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org> [ieee802154]
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
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>
When creating an L2TP tunnel using the netlink API, userspace must
either pass a socket FD for the tunnel to use (for managed tunnels),
or specify the tunnel source/destination address (for unmanaged
tunnels).
Since source/destination addresses may be AF_INET or AF_INET6, the l2tp
netlink code has conditionally compiled blocks to support IPv6.
Rather than embedding these directly into l2tp_nl_cmd_tunnel_create
(where it makes the code difficult to read and confuses checkpatch to
boot) split the handling of address-related attributes into a separate
function.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
l2tp_nl_tunnel_send has conditionally compiled code to support AF_INET6,
which makes the code difficult to follow and triggers checkpatch
warnings.
Split the code out into functions to handle the AF_INET v.s. AF_INET6
cases, which both improves readability and resolves the checkpatch
warnings.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
checkpatch warns about indentation and brace balancing around the
conditionally compiled code for AF_INET6 support in
l2tp_dfs_seq_tunnel_show.
By adding another check on the socket address type we can make the code
more readable while removing the checkpatch 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>
checkpatch warns about use of seq_printf where seq_puts would do.
Modify l2tp_debugfs accordingly.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use BIT(x) rather than (1<<x), reported by checkpatch.pl.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reported by checkpatch:
"WARNING: function definition argument 'struct sock *'
should also have an identifier name"
Add an identifier name to help document the prototype.
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>
Some l2tp code had line breaks which made the code more difficult to
read. These were originally motivated by the 80-character line width
coding guidelines, but were actually a negative from the perspective of
trying to follow the code.
Remove these linebreaks for clearer code, even if we do exceed 80
characters in width in some places.
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>
