l2tp: l2tp_debugfs: fix Clang -Wformat warnings

When building with Clang we encounter the following warnings:
| net/l2tp/l2tp_debugfs.c:187:40: error: format specifies type 'unsigned
| short' but th

l2tp: l2tp_debugfs: fix Clang -Wformat warnings

When building with Clang we encounter the following warnings:
| net/l2tp/l2tp_debugfs.c:187:40: error: format specifies type 'unsigned
| short' but the argument has type 'u32' (aka 'unsigned int')
| [-Werror,-Wformat] seq_printf(m, " nr %hu, ns %hu\n", session->nr,
| session->ns);
-
| net/l2tp/l2tp_debugfs.c:196:32: error: format specifies type 'unsigned
| short' but the argument has type 'int' [-Werror,-Wformat]
| session->l2specific_type, l2tp_get_l2specific_len(session));
-
| net/l2tp/l2tp_debugfs.c:219:6: error: format specifies type 'unsigned
| short' but the argument has type 'u32' (aka 'unsigned int')
| [-Werror,-Wformat] session->nr, session->ns,

Both session->nr and ->nc are of type `u32`. The currently used format
specifier is `%hu` which describes a `u16`. My proposed fix is to listen
to Clang and use the correct format specifier `%u`.

For the warning at line 196, l2tp_get_l2specific_len() returns an int
and should therefore be using the `%d` format specifier.

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Signed-off-by: Justin Stitt <justinstitt@google.com>
Acked-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: add netns refcount tracker to l2tp_dfs_seq_data

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/l2tp: convert tunnel rwlock_t to rcu

Previously commit e02d494d2c60 ("l2tp: Convert rwlock to RCU") converted
most, but not all, rwlock instances in the l2tp subsystem to RCU.

The remaining rwl

net/l2tp: convert tunnel rwlock_t to rcu

Previously commit e02d494d2c60 ("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>

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l2tp: remove tunnel and session debug flags field

The l2tp subsystem now uses standard kernel logging APIs for
informational and warning messages, and tracepoints for debug
information.

Now that th

l2tp: remove tunnel and session debug flags field

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>

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l2tp: WARN_ON rather than BUG_ON in l2tp_dfs_seq_start

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

l2tp: WARN_ON rather than BUG_ON in l2tp_dfs_seq_start

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>

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l2tp: check socket address type in l2tp_dfs_seq_tunnel_show

checkpatch warns about indentation and brace balancing around the
conditionally compiled code for AF_INET6 support in
l2tp_dfs_seq_tunnel_

l2tp: check socket address type in l2tp_dfs_seq_tunnel_show

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>

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l2tp: cleanup comparisons to NULL

checkpatch warns about comparisons to NULL, e.g.

CHECK: Comparison to NULL could be written "!rt"
#474: FILE: net/l2tp/l2tp_ip.c:474:
+

l2tp: cleanup comparisons to NULL

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>

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l2tp: prefer seq_puts for unformatted output

checkpatch warns about use of seq_printf where seq_puts would do.

Modify l2tp_debugfs accordingly.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Sign

l2tp: prefer seq_puts for unformatted output

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>

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l2tp: cleanup wonky alignment of line-broken function calls

Arguments should be aligned with the function call open parenthesis as
per checkpatch. Tweak some function calls which were not aligned
c

l2tp: cleanup wonky alignment of line-broken function calls

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>

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l2tp: cleanup comments

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

l2tp: cleanup comments

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>

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l2tp: cleanup whitespace use

Fix up various whitespace issues as reported by checkpatch.pl:

* remove spaces around operators where appropriate,
* add missing blank lines following declarations,

l2tp: cleanup whitespace use

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>

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l2tp: no need to check return value of debugfs_create functions

When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic sho

l2tp: no need to check return value of debugfs_create functions

When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.

Also, there is no need to store the individual debugfs file name, just
remove the whole directory all at once, saving a local variable.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guillaume Nault <g.nault@alphalink.fr>
Cc: netdev@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of th

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 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 as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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l2tp: ignore L2TP_ATTR_MTU

This attribute's handling is broken. It can only be used when creating
Ethernet pseudo-wires, in which case its value can be used as the
initial MTU for the l2tpeth device

l2tp: ignore L2TP_ATTR_MTU

This attribute's handling is broken. It can only be used when creating
Ethernet pseudo-wires, in which case its value can be used as the
initial MTU for the l2tpeth device.
However, when handling update requests, L2TP_ATTR_MTU only modifies
session->mtu. This value is never propagated to the l2tpeth device.
Dump requests also return the value of session->mtu, which is not
synchronised anymore with the device MTU.

The same problem occurs if the device MTU is properly updated using the
generic IFLA_MTU attribute. In this case, session->mtu is not updated,
and L2TP_ATTR_MTU will report an invalid value again when dumping the
session.

It does not seem worthwhile to complexify l2tp_eth.c to synchronise
session->mtu with the device MTU. Even the ip-l2tp manpage advises to
use 'ip link' to initialise the MTU of l2tpeth devices (iproute2 does
not handle L2TP_ATTR_MTU at all anyway). So let's just ignore it
entirely.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: drop ->mru from struct l2tp_session

This field is not used.

Treat PPPIOC*MRU the same way as PPPIOC*FLAGS: "get" requests return 0,
while "set" requests vadidate the user supplied pointer but

l2tp: drop ->mru from struct l2tp_session

This field is not used.

Treat PPPIOC*MRU the same way as PPPIOC*FLAGS: "get" requests return 0,
while "set" requests vadidate the user supplied pointer but discard its
value.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: ignore L2TP_ATTR_DATA_SEQ netlink attribute

The value of this attribute is never used.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.ne

l2tp: ignore L2TP_ATTR_DATA_SEQ netlink attribute

The value of this attribute is never used.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: remove .show from struct l2tp_tunnel

This callback has never been implemented.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

l2tp: consistent reference counting in procfs and debufs

The 'pppol2tp' procfs and 'l2tp/tunnels' debugfs files handle reference
counting of sessions differently than for tunnels.

For consistency,

l2tp: consistent reference counting in procfs and debufs

The 'pppol2tp' procfs and 'l2tp/tunnels' debugfs files handle reference
counting of sessions differently than for tunnels.

For consistency, use the same mechanism for handling both sessions and
tunnels. That is, drop the reference on the previous session just
before looking up the next one (rather than in .show()). If necessary
(if dump stops before *_next_session() returns NULL), drop the last
reference in .stop().

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: fix {pppol2tp, l2tp_dfs}_seq_stop() in case of seq_file overflow

Commit 0e0c3fee3a59 ("l2tp: hold reference on tunnels printed in pppol2tp proc file")
assumed that if pppol2tp_seq_stop() was c

l2tp: fix {pppol2tp, l2tp_dfs}_seq_stop() in case of seq_file overflow

Commit 0e0c3fee3a59 ("l2tp: hold reference on tunnels printed in pppol2tp proc file")
assumed that if pppol2tp_seq_stop() was called with non-NULL private
data (the 'v' pointer), then pppol2tp_seq_start() would not be called
again. It turns out that this isn't guaranteed, and overflowing the
seq_file's buffer in pppol2tp_seq_show() is a way to get into this
situation.

Therefore, pppol2tp_seq_stop() needs to reset pd->tunnel, so that
pppol2tp_seq_start() won't drop a reference again if it gets called.
We also have to clear pd->session, because the rest of the code expects
a non-NULL tunnel when pd->session is set.

The l2tp_debugfs module has the same issue. Fix it in the same way.

Fixes: 0e0c3fee3a59 ("l2tp: hold reference on tunnels printed in pppol2tp proc file")
Fixes: f726214d9b23 ("l2tp: hold reference on tunnels printed in l2tp/tunnels debugfs file")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: hold reference on tunnels printed in l2tp/tunnels debugfs file

Use l2tp_tunnel_get_nth() instead of l2tp_tunnel_find_nth(), to be safe
against concurrent tunnel deletion.

Use the same mechani

l2tp: hold reference on tunnels printed in l2tp/tunnels debugfs file

Use l2tp_tunnel_get_nth() instead of l2tp_tunnel_find_nth(), to be safe
against concurrent tunnel deletion.

Use the same mechanism as in l2tp_ppp.c for dropping the reference
taken by l2tp_tunnel_get_nth(). That is, drop the reference just
before looking up the next tunnel. In case of error, drop the last
accessed tunnel in l2tp_dfs_seq_stop().

That was the last use of l2tp_tunnel_find_nth().

Fixes: 0ad6614048cf ("l2tp: Add debugfs files for dumping l2tp debug info")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: remove l2specific_len configurable parameter

Remove l2specific_len configuration parameter since now L2-Specific
Sublayer length is computed according to l2specific_type provided by
userspace.

l2tp: remove l2specific_len configurable parameter

Remove l2specific_len configuration parameter since now L2-Specific
Sublayer length is computed according to l2specific_type provided by
userspace.

Reviewed-by: Guillaume Nault <g.nault@alphalink.fr>
Tested-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: remove configurable payload offset

If L2TP_ATTR_OFFSET is set to a non-zero value in L2TPv3 tunnels, it
results in L2TPv3 packets being transmitted which might not be
compliant with the L2TPv3

l2tp: remove configurable payload offset

If L2TP_ATTR_OFFSET is set to a non-zero value in L2TPv3 tunnels, it
results in L2TPv3 packets being transmitted which might not be
compliant with the L2TPv3 RFC. This patch has l2tp ignore the offset
setting and send all packets with no offset.

In more detail:

L2TPv2 supports a variable offset from the L2TPv2 header to the
payload. The offset value is indicated by an optional field in the
L2TP header. Our L2TP implementation already detects the presence of
the optional offset and skips that many bytes when handling data
received packets. All transmitted packets are always transmitted with
no offset.

L2TPv3 has no optional offset field in the L2TPv3 packet
header. Instead, L2TPv3 defines optional fields in a "Layer-2 Specific
Sublayer". At the time when the original L2TP code was written, there
was talk at IETF of offset being implemented in a new Layer-2 Specific
Sublayer. A L2TP_ATTR_OFFSET netlink attribute was added so that this
offset could be configured and the intention was to allow it to be
also used to set the tx offset for L2TPv2. However, no L2TPv3 offset
was ever specified and the L2TP_ATTR_OFFSET parameter was forgotten
about.

Setting L2TP_ATTR_OFFSET results in L2TPv3 packets being transmitted
with the specified number of bytes padding between L2TPv3 header and
payload. This is not compliant with L2TPv3 RFC3931. This change
removes the configurable offset altogether while retaining
L2TP_ATTR_OFFSET for backwards compatibility. Any L2TP_ATTR_OFFSET
value is ignored.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: revert "l2tp: add peer_offset parameter"

Revert commit f15bc54eeecd ("l2tp: add peer_offset parameter"). This
is removed because it is adding another configurable offset and
configurable offse

l2tp: revert "l2tp: add peer_offset parameter"

Revert commit f15bc54eeecd ("l2tp: add peer_offset parameter"). This
is removed because it is adding another configurable offset and
configurable offsets are being removed.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: add peer_offset parameter

Introduce peer_offset parameter in order to add the capability
to specify two different values for payload offset on tx/rx side.
If just offset is provided by userspa

l2tp: add peer_offset parameter

Introduce peer_offset parameter in order to add the capability
to specify two different values for payload offset on tx/rx side.
If just offset is provided by userspace use it for rx side as well
in order to maintain compatibility with older l2tp versions

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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l2tp: remove ->ref() and ->deref()

The ->ref() and ->deref() callbacks are unused since PPP stopped using
them in ee40fb2e1eb5 ("l2tp: protect sock pointer of struct pppol2tp_session with RCU").

We

l2tp: remove ->ref() and ->deref()

The ->ref() and ->deref() callbacks are unused since PPP stopped using
them in ee40fb2e1eb5 ("l2tp: protect sock pointer of struct pppol2tp_session with RCU").

We can thus remove them from struct l2tp_session and drop the do_ref
parameter of l2tp_session_get*().

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

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