mpls_getroute() builds the RTM_NEWROUTE reply to an RTM_GETROUTE
request by filling a struct rtmsg allocated from an skb whose data
area is not zeroed (alloc_skb(NLMSG_GOODSIZE, ...)). It sets every
field of the header except rtm_tos:
r = nlmsg_data(nlh);
r->rtm_family = AF_MPLS;
r->rtm_dst_len = 20;
r->rtm_src_len = 0;
r->rtm_table = RT_TABLE_MAIN;
r->rtm_type = RTN_UNICAST;
r->rtm_scope = RT_SCOPE_UNIVERSE;
r->rtm_protocol = rt->rt_protocol;
r->rtm_flags = 0;
struct rtmsg has no padding, so the one uninitialised byte rtm_tos
(offset 3) is copied straight to user space on recvmsg(), leaking a
byte of uninitialised heap memory. This is in contrast to
mpls_dump_route(), which fills the very same header and does set
rtm_tos = 0.
Initialize rtm_tos to 0, matching mpls_dump_route().
Reproduced with KMSAN by adding an MPLS route and issuing a
non-RTM_F_FIB_MATCH RTM_GETROUTE for its label:
BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x36c/0x33f0
_copy_to_iter+0x36c/0x33f0
__skb_datagram_iter+0x196/0x12c0
skb_copy_datagram_iter+0x5b/0x210
netlink_recvmsg+0x37b/0xef0
...
Uninit was created at:
__alloc_skb+0x8ca/0x10e0
mpls_getroute+0x1280/0x3a40
rtnetlink_rcv_msg+0x1138/0x15a0
...
Byte 19 of 64 is uninitialized
(byte 19 = nlmsghdr(16) + rtmsg offset 3 = rtm_tos)
Fixes: 397fc9e5ce ("mpls: route get support")
Signed-off-by: Yehyeong Lee <yhlee@isslab.korea.ac.kr>
Link: https://patch.msgid.link/20260723010830.289917-1-yhlee@isslab.korea.ac.kr
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
On CONFIG_INET=n builds, mpls_valid_fib_dump_req() walks the parsed
attribute table itself instead of calling ip_valid_fib_dump_req(). The
RTA_OIF arm passes tb[RTA_OIF] to nla_get_u32() without checking it is
present, so an RTM_GETROUTE dump for AF_MPLS with strict checking and no
RTA_OIF hits a NULL dereference.
RTM_GETROUTE is RTNL_KIND_GET, which rtnetlink_rcv_msg() permits without
CAP_NET_ADMIN, so an unprivileged user can trigger it.
Oops: general protection fault, probably for non-canonical address
0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:mpls_valid_fib_dump_req (net/mpls/af_mpls.c:2189)
Call Trace:
mpls_dump_routes (net/mpls/af_mpls.c:2236)
netlink_dump (net/netlink/af_netlink.c:2331)
__netlink_dump_start (net/netlink/af_netlink.c:2446)
rtnetlink_rcv_msg (net/core/rtnetlink.c:7033)
netlink_rcv_skb (net/netlink/af_netlink.c:2556)
netlink_unicast (net/netlink/af_netlink.c:1345)
netlink_sendmsg (net/netlink/af_netlink.c:1900)
__sock_sendmsg (net/socket.c:790)
____sys_sendmsg (net/socket.c:2684)
___sys_sendmsg (net/socket.c:2738)
__sys_sendmsg (net/socket.c:2770)
do_syscall_64 (arch/x86/entry/syscall_64.c:94)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
Skip unset attributes, as ip_valid_fib_dump_req() does.
Fixes: 196cfebf89 ("net/mpls: Handle kernel side filtering of route dumps")
Assisted-by: Claude:claude-opus-4-8
Reported-by: Xiang Mei <xmei5@asu.edu>
Signed-off-by: Weiming Shi <bestswngs@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20260711114958.1009619-3-bestswngs@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Commit 22e36ea9f5 ("inet: allow ip_valid_fib_dump_req() to
be called with RTNL or RCU") introduced the rtnl_held field in
struct fib_dump_filter to switch __dev_get_by_index() and
dev_get_by_index_rcu() depending on the caller's context.
This field served as an interim measure while we were incrementally
converting all callers of ip_valid_fib_dump_req() to RCU.
Now that all users (IPv4, IPv6, ipmr, ip6mr, and MPLS) have
been converted to RCU, the field is no longer necessary.
Let's remove it.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260604224712.3209821-8-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
As IPv6 is built-in only, the ipv6_stub infrastructure is no longer
necessary.
Convert remaining ipv6_stub users to make direct function calls. The
fallback functions introduced previously will prevent linkage errors
when CONFIG_IPV6 is disabled.
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Tested-by: Ricardo B. Marlière <rbm@suse.com>
Link: https://patch.msgid.link/20260325120928.15848-9-fmancera@suse.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The RCU-protected codepaths (mpls_forward, mpls_dump_routes) can have
an inconsistent view of platform_labels vs platform_label in case of a
concurrent resize (resize_platform_label_table, under
platform_mutex). This can lead to OOB accesses.
This patch adds a seqcount, so that we get a consistent snapshot.
Note that mpls_label_ok is also susceptible to this, so the check
against RTA_DST in rtm_to_route_config, done outside platform_mutex,
is not sufficient. This value gets passed to mpls_label_ok once more
in both mpls_route_add and mpls_route_del, so there is no issue, but
that additional check must not be removed.
Reported-by: Yuan Tan <tanyuan98@outlook.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Fixes: 7720c01f3f ("mpls: Add a sysctl to control the size of the mpls label table")
Fixes: dde1b38e87 ("mpls: Convert mpls_dump_routes() to RCU.")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://patch.msgid.link/cd8fca15e3eb7e212b094064cd83652e20fd9d31.1774284088.git.sd@queasysnail.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
RTM_NEWROUTE looks up dev under RCU (ip_route_output(),
ipv6_stub->ipv6_dst_lookup_flow(), netdev_get_by_index()),
and each neighbour holds the refcnt of its dev.
Also, net->mpls.platform_label is protected by a dedicated
per-netns mutex.
Now, no MPLS code depends on RTNL.
Let's drop RTNL for RTM_NEWROUTE, RTM_DELROUTE, and RTM_GETROUTE.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/20251029173344.2934622-14-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
mpls_dump_routes() sets fib_dump_filter.rtnl_held to true and
calls __dev_get_by_index() in mpls_valid_fib_dump_req().
This is the only RTNL dependant in mpls_dump_routes().
Also, synchronize_rcu() in resize_platform_label_table()
guarantees that net->mpls.platform_label is alive under RCU.
Let's convert mpls_dump_routes() to RCU and use dev_get_by_index_rcu().
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/20251029173344.2934622-11-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In many places, we uses rtnl_dereference() twice for
net->mpls.platform_label and net->mpls.platform_label[index].
Let's replace the code with mpls_route_input().
We do not use mpls_route_input() in mpls_dump_routes() since
we will rely on RCU there.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/20251029173344.2934622-10-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
mpls_route_input_rcu() is called from mpls_forward() and
mpls_getroute().
The former is under RCU, and the latter is under RTNL, so
mpls_route_input_rcu() uses rcu_dereference_rtnl().
Let's use rcu_dereference() in mpls_route_input_rcu() and
add an RTNL variant for mpls_getroute().
Later, we will remove rtnl_dereference() there.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/20251029173344.2934622-9-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We will replace RTNL with a per-netns mutex to protect dev->mpls_ptr.
Then, we will use rcu_dereference_protected() with the lockdep_is_held()
annotation, which requires net to access the per-netns mutex.
However, dev_net(dev) is not safe without RTNL.
Let's pass net to mpls_dev_get().
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/20251029173344.2934622-8-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
MPLS uses RTNL
1) to guarantee the lifetime of struct mpls_nh.nh_dev
2) to protect net->mpls.platform_label
, but neither actually requires RTNL.
If we do not call dev_put() in find_outdev() and call it
just before freeing struct mpls_route, we can drop RTNL for 1).
Let's hold the refcnt of mpls_nh.nh_dev and track it with
netdevice_tracker.
Two notable changes:
If mpls_nh_build_multi() fails to set up a neighbour, we need
to call netdev_put() for successfully created neighbours in
mpls_rt_free_rcu(), so the number of neighbours (rt->rt_nhn)
is now updated in each iteration.
When a dev is unregistered, mpls_ifdown() clones mpls_route
and replaces it with the clone, so the clone requires extra
netdev_hold().
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/20251029173344.2934622-3-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit cc34acd577 ("docs: net: document new locking reality")
introduced netif_ vs dev_ function semantics: the former expects locked
netdev, the latter takes care of the locking. We don't strictly
follow this semantics on either side, but there are more dev_xxx handlers
now that don't fit. Rename them to netif_xxx where appropriate.
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250717172333.1288349-6-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Yehyeong Lee
Kuniyuki Iwashima
Weiming Shi
Jakub Kicinski
Fernando Fernandez Mancera
Sabrina Dubroca
Eric Dumazet
Linus Torvalds
Kees Cook
Stanislav Fomichev