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Jakub suggests:
> I have a different request :) Matt, once this ends up in net-next
> (end of this week) could you refactor it to use nlmsg_payload() ?
> It doesn't exist in net but this is exactly why it was added.
This refactors the additions to both mctp_dump_addrinfo(), and
mctp_rtm_getneigh() - two cases where we're calling nlh_data() on an
an incoming netlink message, without a prior nlmsg_parse().
For the neigh.c case, we cannot hit the failure where the nlh does not
contain a full ndmsg at present, as the core handler
(net/core/neighbour.c, neigh_get()) has already validated the size
through neigh_valid_req_get(), and would have failed the get operation
before the MCTP hander is called.
However, relying on that is a bit fragile, so apply the nlmsg_payload
refector here too.
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://patch.msgid.link/20250521-mctp-nlmsg-payload-v2-1-e85df160c405@codeconstruct.com.au
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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In mctp_dump_addrinfo, ifa_index can be used to filter interfaces, but
only when the struct ifaddrmsg is provided. Otherwise it will be
comparing to uninitialised memory - reproducible in the syzkaller case from
dhcpd, or busybox "ip addr show".
The kernel MCTP implementation has always filtered by ifa_index, so
existing userspace programs expecting to dump MCTP addresses must
already be passing a valid ifa_index value (either 0 or a real index).
BUG: KMSAN: uninit-value in mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
rtnl_dump_all+0x3ec/0x5b0 net/core/rtnetlink.c:4380
rtnl_dumpit+0xd5/0x2f0 net/core/rtnetlink.c:6824
netlink_dump+0x97b/0x1690 net/netlink/af_netlink.c:2309
Fixes: 583be982d934 ("mctp: Add device handling and netlink interface")
Reported-by: syzbot+e76d52dadc089b9d197f@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68135815.050a0220.3a872c.000e.GAE@google.com/
Reported-by: syzbot+1065a199625a388fce60@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/681357d6.050a0220.14dd7d.000d.GAE@google.com/
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://patch.msgid.link/20250508-mctp-addr-dump-v2-1-c8a53fd2dd66@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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mctp_dump_addrinfo() is one of the last users of
net->dev_index_head[] in the control path.
Switch to for_each_netdev_dump() for better scalability.
Use C99 for mctp_device_rtnl_msg_handlers[] to prepare
future RTNL removal from mctp_dump_addrinfo()
(mdev->addrs is not yet RCU protected)
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Matt Johnston <matt@codeconstruct.com.au>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://patch.msgid.link/20241206223811.1343076-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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MCTP control protocol implementations are transport binding dependent.
Endpoint discovery is mandatory based on transport binding.
Message timing requirements are specified in each respective transport
binding specification.
However, we currently have no means to get this information from MCTP
links.
Add a IFLA_MCTP_PHYS_BINDING netlink link attribute, which represents
the transport type using the DMTF DSP0239-defined type numbers, returned
as part of RTM_GETLINK data.
We get an IFLA_MCTP_PHYS_BINDING attribute for each MCTP link, for
example:
- 0x00 (unspec) for loopback interface;
- 0x01 (SMBus/I2C) for mctpi2c%d interfaces; and
- 0x05 (serial) for mctpserial%d interfaces.
Signed-off-by: Khang Nguyen <khangng@os.amperecomputing.com>
Reviewed-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://patch.msgid.link/20241105071915.821871-1-khangng@os.amperecomputing.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The next patch will add init_srcu_struct() in rtnl_af_register(),
then we need to handle its error.
Let's add the error handling in advance to make the following
patch cleaner.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Since introduced, mctp has been ignoring the returned value of
rtnl_register_module(), which could fail silently.
Handling the error allows users to view a module as an all-or-nothing
thing in terms of the rtnetlink functionality. This prevents syzkaller
from reporting spurious errors from its tests, where OOM often occurs
and module is automatically loaded.
Let's handle the errors by rtnl_register_many().
Fixes: 583be982d934 ("mctp: Add device handling and netlink interface")
Fixes: 831119f88781 ("mctp: Add neighbour netlink interface")
Fixes: 06d2f4c583a7 ("mctp: Add netlink route management")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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The unregister check could be incorrectly triggered if a netdev
changes its type after register. That is possible for a tun device
using TUNSETLINK ioctl, resulting in mctp unregister failing
and the netdev unregister waiting forever.
This was encountered by https://github.com/openthread/openthread/issues/8523
Neither check at register or unregister is required. They were added in
an attempt to track down mctp_ptr being set unexpectedly, which should
not happen in normal operation.
Fixes: 7b1871af75f3 ("mctp: Warn if pointer is set for a wrong dev type")
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20221215054933.2403401-1-matt@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The function mctp_unregister() reclaims the device's relevant resource
when a netcard detaches. However, a running routine may be unaware of
this and cause the use-after-free of the mdev->addrs object.
The race condition can be demonstrated below
cleanup thread another thread
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unregister_netdev() | mctp_sendmsg()
... | ...
mctp_unregister() | rt = mctp_route_lookup()
... | mctl_local_output()
kfree(mdev->addrs) | ...
| saddr = rt->dev->addrs[0];
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An attacker can adopt the (recent provided) mtcpserial driver with pty
to fake the device detaching and use the userfaultfd to increase the
race success chance (in mctp_sendmsg). The KASan report for such a POC
is shown below:
[ 86.051955] ==================================================================
[ 86.051955] BUG: KASAN: use-after-free in mctp_local_output+0x4e9/0xb7d
[ 86.051955] Read of size 1 at addr ffff888005f298c0 by task poc/295
[ 86.051955]
[ 86.051955] Call Trace:
[ 86.051955] <TASK>
[ 86.051955] dump_stack_lvl+0x33/0x42
[ 86.051955] print_report.cold.13+0xb2/0x6b3
[ 86.051955] ? preempt_schedule_irq+0x57/0x80
[ 86.051955] ? mctp_local_output+0x4e9/0xb7d
[ 86.051955] kasan_report+0xa5/0x120
[ 86.051955] ? mctp_local_output+0x4e9/0xb7d
[ 86.051955] mctp_local_output+0x4e9/0xb7d
[ 86.051955] ? mctp_dev_set_key+0x79/0x79
[ 86.051955] ? copyin+0x38/0x50
[ 86.051955] ? _copy_from_iter+0x1b6/0xf20
[ 86.051955] ? sysvec_apic_timer_interrupt+0x97/0xb0
[ 86.051955] ? asm_sysvec_apic_timer_interrupt+0x12/0x20
[ 86.051955] ? mctp_local_output+0x1/0xb7d
[ 86.051955] mctp_sendmsg+0x64d/0xdb0
[ 86.051955] ? mctp_sk_close+0x20/0x20
[ 86.051955] ? __fget_light+0x2fd/0x4f0
[ 86.051955] ? mctp_sk_close+0x20/0x20
[ 86.051955] sock_sendmsg+0xdd/0x110
[ 86.051955] __sys_sendto+0x1cc/0x2a0
[ 86.051955] ? __ia32_sys_getpeername+0xa0/0xa0
[ 86.051955] ? new_sync_write+0x335/0x550
[ 86.051955] ? alloc_file+0x22f/0x500
[ 86.051955] ? __ip_do_redirect+0x820/0x1820
[ 86.051955] ? vfs_write+0x44d/0x7b0
[ 86.051955] ? vfs_write+0x44d/0x7b0
[ 86.051955] ? fput_many+0x15/0x120
[ 86.051955] ? ksys_write+0x155/0x1b0
[ 86.051955] ? __ia32_sys_read+0xa0/0xa0
[ 86.051955] __x64_sys_sendto+0xd8/0x1b0
[ 86.051955] ? exit_to_user_mode_prepare+0x2f/0x120
[ 86.051955] ? syscall_exit_to_user_mode+0x12/0x20
[ 86.051955] do_syscall_64+0x3a/0x80
[ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 86.051955] RIP: 0033:0x7f82118a56b3
[ 86.051955] RSP: 002b:00007ffdb154b110 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
[ 86.051955] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f82118a56b3
[ 86.051955] RDX: 0000000000000010 RSI: 00007f8211cd4000 RDI: 0000000000000007
[ 86.051955] RBP: 00007ffdb154c1d0 R08: 00007ffdb154b164 R09: 000000000000000c
[ 86.051955] R10: 0000000000000000 R11: 0000000000000293 R12: 000055d779800db0
[ 86.051955] R13: 00007ffdb154c2b0 R14: 0000000000000000 R15: 0000000000000000
[ 86.051955] </TASK>
[ 86.051955]
[ 86.051955] Allocated by task 295:
[ 86.051955] kasan_save_stack+0x1c/0x40
[ 86.051955] __kasan_kmalloc+0x84/0xa0
[ 86.051955] mctp_rtm_newaddr+0x242/0x610
[ 86.051955] rtnetlink_rcv_msg+0x2fd/0x8b0
[ 86.051955] netlink_rcv_skb+0x11c/0x340
[ 86.051955] netlink_unicast+0x439/0x630
[ 86.051955] netlink_sendmsg+0x752/0xc00
[ 86.051955] sock_sendmsg+0xdd/0x110
[ 86.051955] __sys_sendto+0x1cc/0x2a0
[ 86.051955] __x64_sys_sendto+0xd8/0x1b0
[ 86.051955] do_syscall_64+0x3a/0x80
[ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 86.051955]
[ 86.051955] Freed by task 301:
[ 86.051955] kasan_save_stack+0x1c/0x40
[ 86.051955] kasan_set_track+0x21/0x30
[ 86.051955] kasan_set_free_info+0x20/0x30
[ 86.051955] __kasan_slab_free+0x104/0x170
[ 86.051955] kfree+0x8c/0x290
[ 86.051955] mctp_dev_notify+0x161/0x2c0
[ 86.051955] raw_notifier_call_chain+0x8b/0xc0
[ 86.051955] unregister_netdevice_many+0x299/0x1180
[ 86.051955] unregister_netdevice_queue+0x210/0x2f0
[ 86.051955] unregister_netdev+0x13/0x20
[ 86.051955] mctp_serial_close+0x6d/0xa0
[ 86.051955] tty_ldisc_kill+0x31/0xa0
[ 86.051955] tty_ldisc_hangup+0x24f/0x560
[ 86.051955] __tty_hangup.part.28+0x2ce/0x6b0
[ 86.051955] tty_release+0x327/0xc70
[ 86.051955] __fput+0x1df/0x8b0
[ 86.051955] task_work_run+0xca/0x150
[ 86.051955] exit_to_user_mode_prepare+0x114/0x120
[ 86.051955] syscall_exit_to_user_mode+0x12/0x20
[ 86.051955] do_syscall_64+0x46/0x80
[ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 86.051955]
[ 86.051955] The buggy address belongs to the object at ffff888005f298c0
[ 86.051955] which belongs to the cache kmalloc-8 of size 8
[ 86.051955] The buggy address is located 0 bytes inside of
[ 86.051955] 8-byte region [ffff888005f298c0, ffff888005f298c8)
[ 86.051955]
[ 86.051955] The buggy address belongs to the physical page:
[ 86.051955] flags: 0x100000000000200(slab|node=0|zone=1)
[ 86.051955] raw: 0100000000000200 dead000000000100 dead000000000122 ffff888005c42280
[ 86.051955] raw: 0000000000000000 0000000080660066 00000001ffffffff 0000000000000000
[ 86.051955] page dumped because: kasan: bad access detected
[ 86.051955]
[ 86.051955] Memory state around the buggy address:
[ 86.051955] ffff888005f29780: 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00
[ 86.051955] ffff888005f29800: fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc
[ 86.051955] >ffff888005f29880: fc fc fc fb fc fc fc fc fa fc fc fc fc fa fc fc
[ 86.051955] ^
[ 86.051955] ffff888005f29900: fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc
[ 86.051955] ffff888005f29980: fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc
[ 86.051955] ==================================================================
To this end, just like the commit e04480920d1e ("Bluetooth: defer
cleanup of resources in hci_unregister_dev()") this patch defers the
destructive kfree(mdev->addrs) in mctp_unregister to the mctp_dev_put,
where the refcount of mdev is zero and the entire device is reclaimed.
This prevents the use-after-free because the sendmsg thread holds the
reference of mdev in the mctp_route object.
Fixes: 583be982d934 (mctp: Add device handling and netlink interface)
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20220422114340.32346-1-linma@zju.edu.cn
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Previously if an unregister notify handler ran twice (waiting for
netdev to be released) it would print a warning in mctp_unregister()
every subsequent time the unregister notify occured.
Instead we only need to worry about the case where a mctp_ptr is
set on an unknown device type.
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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net/mctp/device.c:140:11: warning: Assigned value is garbage or undefined
[clang-analyzer-core.uninitialized.Assign]
mcb->idx = idx;
- Not a real problem due to how the callback runs, fix the warning.
net/mctp/route.c:458:4: warning: Value stored to 'msk' is never read
[clang-analyzer-deadcode.DeadStores]
msk = container_of(key->sk, struct mctp_sock, sk);
- 'msk' dead assignment can be removed here.
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Previously there was a race that could allow the mctp_dev refcount
to hit zero:
rcu_read_lock();
mdev = __mctp_dev_get(dev);
// mctp_unregister() happens here, mdev->refs hits zero
mctp_dev_hold(dev);
rcu_read_unlock();
Now we make __mctp_dev_get() take the hold itself. It is safe to test
against the zero refcount because __mctp_dev_get() is called holding
rcu_read_lock and mctp_dev uses kfree_rcu().
Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Currently, we have mctp_address_ok(), which checks if an EID is in the
"valid" range of 8-254 inclusive. However, 0 and 255 may also be valid
addresses, depending on context. 0 is the NULL EID, which may be set
when physical addressing is used. 255 is valid as a destination address
for broadcasts.
This change renames mctp_address_ok to mctp_address_unicast, and adds
similar helpers for broadcast and null EIDs, which will be used in an
upcoming commit.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Nothing in ipv6.h needs ndisc.h, drop it.
Link: https://lore.kernel.org/r/20220203043457.2222388-1-kuba@kernel.org
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org>
Link: https://lore.kernel.org/r/20220203231240.2297588-1-kuba@kernel.org
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Userspace can receive notification of MCTP address changes via
RTNLGRP_MCTP_IFADDR rtnetlink multicast group.
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20211220023104.1965509-1-matt@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Now that we have an extension for MCTP data in skbs, populate the flow
when a key has been created for the packet, and add a device driver
operation to inform of flow destruction.
Includes a fix for a warning with test builds:
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Should not occur but is a sanity check.
May help tracking down Trinity reported issue
https://lore.kernel.org/lkml/20210913030701.GA5926@xsang-OptiPlex-9020/
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Currently, we tie the struct mctp_dev lifetime to the underlying struct
net_device, and hold/put that device as a proxy for a separate mctp_dev
refcount. This works because we're not holding any references to the
mctp_dev that are different from the netdev lifetime.
In a future change we'll break that assumption though, as we'll need to
hold mctp_dev references in a workqueue, which might live past the
netdev unregister notification.
In order to support that, this change introduces a refcount on the
mctp_dev, currently taken by the net_device->mctp_ptr reference, and
released on netdev unregister events. We can then use this for future
references that might outlast the net device.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Allowing TUN is useful for testing, to route packets to userspace or to
tunnel between machines.
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Currently we have a compile-time default network
(MCTP_INITIAL_DEFAULT_NET). This change introduces a default_net field
on the net namespace, allowing future configuration for new interfaces.
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add an initial neighbour table implementation, to be used in the route
output path.
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add a simple routing table, and a couple of route output handlers, and
the mctp packet_type & handler.
Includes changes from Matt Johnston <matt@codeconstruct.com.au>.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This change adds the infrastructure for managing MCTP netdevices; we add
a pointer to the AF_MCTP-specific data to struct netdevice, and hook up
the rtnetlink operations for adding and removing addresses.
Includes changes from Matt Johnston <matt@codeconstruct.com.au>.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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