[ Upstream commit b5590270068c4324dac4a2b5a4a156e02e21339f ]
__netlink_dump_start() releases nlk->cb_mutex right before
calling netlink_dump() which grabs it again.
This seems dangerous, even if KASAN did not bother yet.
Add a @lock_taken parameter to netlink_dump() to let it
grab the mutex if called from netlink_recvmsg() only.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 234ec0b6034b16869d45128b8cd2dc6ffe596f04 ]
I analyze the potential sleeping issue of the following processes:
Thread A Thread B
... netlink_create //ref = 1
do_mq_notify ...
sock = netlink_getsockbyfilp ... //ref = 2
info->notify_sock = sock; ...
... netlink_sendmsg
... skb = netlink_alloc_large_skb //skb->head is vmalloced
... netlink_unicast
... sk = netlink_getsockbyportid //ref = 3
... netlink_sendskb
... __netlink_sendskb
... skb_queue_tail //put skb to sk_receive_queue
... sock_put //ref = 2
... ...
... netlink_release
... deferred_put_nlk_sk //ref = 1
mqueue_flush_file
spin_lock
remove_notification
netlink_sendskb
sock_put //ref = 0
sk_free
...
__sk_destruct
netlink_sock_destruct
skb_queue_purge //get skb from sk_receive_queue
...
__skb_queue_purge_reason
kfree_skb_reason
__kfree_skb
...
skb_release_all
skb_release_head_state
netlink_skb_destructor
vfree(skb->head) //sleeping while holding spinlock
In netlink_sendmsg, if the memory pointed to by skb->head is allocated by
vmalloc, and is put to sk_receive_queue queue, also the skb is not freed.
When the mqueue executes flush, the sleeping bug will occur. Use
vfree_atomic instead of vfree in netlink_skb_destructor to solve the issue.
Fixes: c05cdb1b864f ("netlink: allow large data transfers from user-space")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Link: https://lore.kernel.org/r/20240122011807.2110357-1-shaozhengchao@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit e03781879a0d524ce3126678d50a80484a513c4b upstream.
The "NET_DM" generic netlink family notifies drop locations over the
"events" multicast group. This is problematic since by default generic
netlink allows non-root users to listen to these notifications.
Fix by adding a new field to the generic netlink multicast group
structure that when set prevents non-root users or root without the
'CAP_SYS_ADMIN' capability (in the user namespace owning the network
namespace) from joining the group. Set this field for the "events"
group. Use 'CAP_SYS_ADMIN' rather than 'CAP_NET_ADMIN' because of the
nature of the information that is shared over this group.
Note that the capability check in this case will always be performed
against the initial user namespace since the family is not netns aware
and only operates in the initial network namespace.
A new field is added to the structure rather than using the "flags"
field because the existing field uses uAPI flags and it is inappropriate
to add a new uAPI flag for an internal kernel check. In net-next we can
rework the "flags" field to use internal flags and fold the new field
into it. But for now, in order to reduce the amount of changes, add a
new field.
Since the information can only be consumed by root, mark the control
plane operations that start and stop the tracing as root-only using the
'GENL_ADMIN_PERM' flag.
Tested using [1].
Before:
# capsh -- -c ./dm_repo
# capsh --drop=cap_sys_admin -- -c ./dm_repo
After:
# capsh -- -c ./dm_repo
# capsh --drop=cap_sys_admin -- -c ./dm_repo
Failed to join "events" multicast group
[1]
$ cat dm.c
#include <stdio.h>
#include <netlink/genl/ctrl.h>
#include <netlink/genl/genl.h>
#include <netlink/socket.h>
int main(int argc, char **argv)
{
struct nl_sock *sk;
int grp, err;
sk = nl_socket_alloc();
if (!sk) {
fprintf(stderr, "Failed to allocate socket\n");
return -1;
}
err = genl_connect(sk);
if (err) {
fprintf(stderr, "Failed to connect socket\n");
return err;
}
grp = genl_ctrl_resolve_grp(sk, "NET_DM", "events");
if (grp < 0) {
fprintf(stderr,
"Failed to resolve \"events\" multicast group\n");
return grp;
}
err = nl_socket_add_memberships(sk, grp, NFNLGRP_NONE);
if (err) {
fprintf(stderr, "Failed to join \"events\" multicast group\n");
return err;
}
return 0;
}
$ gcc -I/usr/include/libnl3 -lnl-3 -lnl-genl-3 -o dm_repo dm.c
Fixes: 9a8afc8d3962 ("Network Drop Monitor: Adding drop monitor implementation & Netlink protocol")
Reported-by: "The UK's National Cyber Security Centre (NCSC)" <security@ncsc.gov.uk>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231206213102.1824398-3-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is a partial backport of upstream commit 4d54cc32112d ("mptcp:
avoid lock_fast usage in accept path"). It is only a partial backport
because the patch in the link below was erroneously squash-merged into
upstream commit 4d54cc32112d ("mptcp: avoid lock_fast usage in accept
path"). Below is the original patch description from Florian Westphal:
"
genetlink sets NL_CFG_F_NONROOT_RECV for its netlink socket so anyone can
subscribe to multicast messages.
rtnetlink doesn't allow this unconditionally, rtnetlink_bind() restricts
bind requests to CAP_NET_ADMIN for a few groups.
This allows to set GENL_UNS_ADMIN_PERM flag on genl mcast groups to
mandate CAP_NET_ADMIN.
This will be used by the upcoming mptcp netlink event facility which
exposes the token (mptcp connection identifier) to userspace.
"
Link: https://lore.kernel.org/mptcp/20210213000001.379332-8-mathew.j.martineau@linux.intel.com/
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
From: Florian Westphal <fw@strlen.de>
commit f2764bd4f6a8dffaec3e220728385d9756b3c2cb upstream.
When I added support to allow generic netlink multicast groups to be
restricted to subscribers with CAP_NET_ADMIN I was unaware that a
genl_bind implementation already existed in the past.
It was reverted due to ABBA deadlock:
1. ->netlink_bind gets called with the table lock held.
2. genetlink bind callback is invoked, it grabs the genl lock.
But when a new genl subsystem is (un)registered, these two locks are
taken in reverse order.
One solution would be to revert again and add a comment in genl
referring 1e82a62fec613, "genetlink: remove genl_bind").
This would need a second change in mptcp to not expose the raw token
value anymore, e.g. by hashing the token with a secret key so userspace
can still associate subflow events with the correct mptcp connection.
However, Paolo Abeni reminded me to double-check why the netlink table is
locked in the first place.
I can't find one. netlink_bind() is already called without this lock
when userspace joins a group via NETLINK_ADD_MEMBERSHIP setsockopt.
Same holds for the netlink_unbind operation.
Digging through the history, commit f773608026ee1
("netlink: access nlk groups safely in netlink bind and getname")
expanded the lock scope.
commit 3a20773beeeeade ("net: netlink: cap max groups which will be considered in netlink_bind()")
... removed the nlk->ngroups access that the lock scope
extension was all about.
Reduce the lock scope again and always call ->netlink_bind without
the table lock.
The Fixes tag should be vs. the patch mentioned in the link below,
but that one got squash-merged into the patch that came earlier in the
series.
Fixes: 4d54cc32112d8d ("mptcp: avoid lock_fast usage in accept path")
Link: https://lore.kernel.org/mptcp/20210213000001.379332-8-mathew.j.martineau@linux.intel.com/T/#u
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Xin Long <lucien.xin@gmail.com>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Sean Tranchetti <stranche@codeaurora.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Eric Dumazet