syzbot reported the following uninit-value access issue [1]:

netlink_to_full_skb() creates a new `skb` and puts the `skb->data`
passed as a 1st arg of netlink_to_full_skb() onto new `skb`. The data
size is specified as `len` and passed to skb_put_data(). This `len`
is based on `skb->end` that is not data offset but buffer offset. The
`skb->end` contains data and tailroom. Since the tailroom is not
initialized when the new `skb` created, KMSAN detects uninitialized
memory area when copying the data.

This patch resolved this issue by correct the len from `skb->end` to
`skb->len`, which is the actual data offset.

BUG: KMSAN: kernel-infoleak-after-free in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
BUG: KMSAN: kernel-infoleak-after-free in copy_to_user_iter lib/iov_iter.c:24 [inline]
BUG: KMSAN: kernel-infoleak-after-free in iterate_ubuf include/linux/iov_iter.h:29 [inline]
BUG: KMSAN: kernel-infoleak-after-free in iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
BUG: KMSAN: kernel-infoleak-after-free in iterate_and_advance include/linux/iov_iter.h:271 [inline]
BUG: KMSAN: kernel-infoleak-after-free in _copy_to_iter+0x364/0x2520 lib/iov_iter.c:186
 instrument_copy_to_user include/linux/instrumented.h:114 [inline]
 copy_to_user_iter lib/iov_iter.c:24 [inline]
 iterate_ubuf include/linux/iov_iter.h:29 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
 iterate_and_advance include/linux/iov_iter.h:271 [inline]
 _copy_to_iter+0x364/0x2520 lib/iov_iter.c:186
 copy_to_iter include/linux/uio.h:197 [inline]
 simple_copy_to_iter+0x68/0xa0 net/core/datagram.c:532
 __skb_datagram_iter+0x123/0xdc0 net/core/datagram.c:420
 skb_copy_datagram_iter+0x5c/0x200 net/core/datagram.c:546
 skb_copy_datagram_msg include/linux/skbuff.h:3960 [inline]
 packet_recvmsg+0xd9c/0x2000 net/packet/af_packet.c:3482
 sock_recvmsg_nosec net/socket.c:1044 [inline]
 sock_recvmsg net/socket.c:1066 [inline]
 sock_read_iter+0x467/0x580 net/socket.c:1136
 call_read_iter include/linux/fs.h:2014 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x8f6/0xe00 fs/read_write.c:470
 ksys_read+0x20f/0x4c0 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x93/0xd0 fs/read_write.c:621
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was stored to memory at:
 skb_put_data include/linux/skbuff.h:2622 [inline]
 netlink_to_full_skb net/netlink/af_netlink.c:181 [inline]
 __netlink_deliver_tap_skb net/netlink/af_netlink.c:298 [inline]
 __netlink_deliver_tap+0x5be/0xc90 net/netlink/af_netlink.c:325
 netlink_deliver_tap net/netlink/af_netlink.c:338 [inline]
 netlink_deliver_tap_kernel net/netlink/af_netlink.c:347 [inline]
 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
 netlink_unicast+0x10f1/0x1250 net/netlink/af_netlink.c:1368
 netlink_sendmsg+0x1238/0x13d0 net/netlink/af_netlink.c:1910
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmsg net/socket.c:2667 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at:
 free_pages_prepare mm/page_alloc.c:1087 [inline]
 free_unref_page_prepare+0xb0/0xa40 mm/page_alloc.c:2347
 free_unref_page_list+0xeb/0x1100 mm/page_alloc.c:2533
 release_pages+0x23d3/0x2410 mm/swap.c:1042
 free_pages_and_swap_cache+0xd9/0xf0 mm/swap_state.c:316
 tlb_batch_pages_flush mm/mmu_gather.c:98 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
 tlb_flush_mmu+0x6f5/0x980 mm/mmu_gather.c:300
 tlb_finish_mmu+0x101/0x260 mm/mmu_gather.c:392
 exit_mmap+0x49e/0xd30 mm/mmap.c:3321
 __mmput+0x13f/0x530 kernel/fork.c:1349
 mmput+0x8a/0xa0 kernel/fork.c:1371
 exit_mm+0x1b8/0x360 kernel/exit.c:567
 do_exit+0xd57/0x4080 kernel/exit.c:858
 do_group_exit+0x2fd/0x390 kernel/exit.c:1021
 __do_sys_exit_group kernel/exit.c:1032 [inline]
 __se_sys_exit_group kernel/exit.c:1030 [inline]
 __x64_sys_exit_group+0x3c/0x50 kernel/exit.c:1030
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Bytes 3852-3903 of 3904 are uninitialized
Memory access of size 3904 starts at ffff88812ea1e000
Data copied to user address 0000000020003280

CPU: 1 PID: 5043 Comm: syz-executor297 Not tainted 6.7.0-rc5-syzkaller-00047-g5bd7ef53ffe5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023

Fixes: 1853c9496460 ("netlink, mmap: transform mmap skb into full skb on taps")
Reported-and-tested-by: syzbot+34ad5fab48f7bf510349@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=34ad5fab48f7bf510349 [1]
Signed-off-by: Ryosuke Yasuoka <ryasuoka@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240221074053.1794118-1-ryasuoka@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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>

As explained in commit e03781879a0d ("drop_monitor: Require
'CAP_SYS_ADMIN' when joining "events" group"), the "flags" field in the
multicast group structure reuses uAPI flags despite the field not being
exposed to user space. This makes it impossible to extend its use
without adding new uAPI flags, which is inappropriate for internal
kernel checks.

Solve this by adding internal flags (i.e., "GENL_MCAST_*") and convert
the existing users to use them instead of the uAPI flags.

Tested using the reproducers in commit 44ec98ea5ea9 ("psample: Require
'CAP_NET_ADMIN' when joining "packets" group") and commit e03781879a0d
("drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group").

No functional changes intended.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Make the code using filter function a bit nicer by consolidating the
filter function arguments using typedef.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Introduce an xarray for Generic netlink family to store per-socket
private. Initialize this xarray only if family uses per-socket privs.

Introduce genl_sk_priv_get() to get the socket priv pointer for a family
and initialize it in case it does not exist.
Introduce __genl_sk_priv_get() to obtain socket priv pointer for a
family under RCU read lock.

Allow family to specify the priv size, init() and destroy() callbacks.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Cross-merge networking fixes after downstream PR.

Conflicts:

drivers/net/ethernet/stmicro/stmmac/dwmac5.c
drivers/net/ethernet/stmicro/stmmac/dwmac5.h
drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
drivers/net/ethernet/stmicro/stmmac/hwif.h
  37e4b8df27bc ("net: stmmac: fix FPE events losing")
  c3f3b97238f6 ("net: stmmac: Refactor EST implementation")
https://lore.kernel.org/all/20231206110306.01e91114@canb.auug.org.au/

Adjacent changes:

net/ipv4/tcp_ao.c
  9396c4ee93f9 ("net/tcp: Don't store TCP-AO maclen on reqsk")
  7b0f570f879a ("tcp: Move TCP-AO bits from cookie_v[46]_check() to tcp_ao_syncookie().")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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>

if a PF has 256 or more VFs, ip link command will allocate an order 3
memory or more, and maybe trigger OOM due to memory fragment,
the VFs needed memory size is computed in rtnl_vfinfo_size.

so introduce nlmsg_new_large which calls netlink_alloc_large_skb in
which vmalloc is used for large memory, to avoid the failure of
allocating memory

    ip invoked oom-killer: gfp_mask=0xc2cc0(GFP_KERNEL|__GFP_NOWARN|\
	__GFP_COMP|__GFP_NOMEMALLOC), order=3, oom_score_adj=0
    CPU: 74 PID: 204414 Comm: ip Kdump: loaded Tainted: P           OE
    Call Trace:
    dump_stack+0x57/0x6a
    dump_header+0x4a/0x210
    oom_kill_process+0xe4/0x140
    out_of_memory+0x3e8/0x790
    __alloc_pages_slowpath.constprop.116+0x953/0xc50
    __alloc_pages_nodemask+0x2af/0x310
    kmalloc_large_node+0x38/0xf0
    __kmalloc_node_track_caller+0x417/0x4d0
    __kmalloc_reserve.isra.61+0x2e/0x80
    __alloc_skb+0x82/0x1c0
    rtnl_getlink+0x24f/0x370
    rtnetlink_rcv_msg+0x12c/0x350
    netlink_rcv_skb+0x50/0x100
    netlink_unicast+0x1b2/0x280
    netlink_sendmsg+0x355/0x4a0
    sock_sendmsg+0x5b/0x60
    ____sys_sendmsg+0x1ea/0x250
    ___sys_sendmsg+0x88/0xd0
    __sys_sendmsg+0x5e/0xa0
    do_syscall_64+0x33/0x40
    entry_SYSCALL_64_after_hwframe+0x44/0xa9
    RIP: 0033:0x7f95a65a5b70

Cc: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Link: https://lore.kernel.org/r/20231115120108.3711-1-lirongqing@baidu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

W=1 builds now warn if a module is built without
a MODULE_DESCRIPTION(). Fill it in for sock_diag.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently, split ops of doit and dumpit are merged into a single iter
item when they are subsequent. However, there is no guarantee that the
dumpit op is for the same cmd as doit op.

Fix this by checking if cmd is the same for both.
This problem does not occur in existing families.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20231021112711.660606-2-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>