linux.git/net/packet/internal.h, branch v6.4 Linux kernel source tree net/packet: support mergeable feature of virtio 2023-04-21T11:01:58+00:00 Jianfeng Tan henry.tjf@antgroup.com 2023-04-19T07:24:16+00:00 dfc39d4026fb2432363c0f77543c4cf3adca4c7b Packet sockets, like tap, can be used as the backend for kernel vhost. In packet sockets, virtio net header size is currently hardcoded to be the size of struct virtio_net_hdr, which is 10 bytes; however, it is not always the case: some virtio features, such as mrg_rxbuf, need virtio net header to be 12-byte long. Mergeable buffers, as a virtio feature, is worthy of supporting: packets that are larger than one-mbuf size will be dropped in vhost worker's handle_rx if mrg_rxbuf feature is not used, but large packets cannot be avoided and increasing mbuf's size is not economical. With this virtio feature enabled by virtio-user, packet sockets with hardcoded 10-byte virtio net header will parse mac head incorrectly in packet_snd by taking the last two bytes of virtio net header as part of mac header. This incorrect mac header parsing will cause packet to be dropped due to invalid ether head checking in later under-layer device packet receiving. By adding extra field vnet_hdr_sz with utilizing holes in struct packet_sock to record currently used virtio net header size and supporting extra sockopt PACKET_VNET_HDR_SZ to set specified vnet_hdr_sz, packet sockets can know the exact length of virtio net header that virtio user gives. In packet_snd, tpacket_snd and packet_recvmsg, instead of using hardcoded virtio net header size, it can get the exact vnet_hdr_sz from corresponding packet_sock, and parse mac header correctly based on this information to avoid the packets being mistakenly dropped. Signed-off-by: Jianfeng Tan <henry.tjf@antgroup.com> Co-developed-by: Anqi Shen <amy.saq@antgroup.com> Signed-off-by: Anqi Shen <amy.saq@antgroup.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Packet sockets, like tap, can be used as the backend for kernel vhost.
In packet sockets, virtio net header size is currently hardcoded to be
the size of struct virtio_net_hdr, which is 10 bytes; however, it is not
always the case: some virtio features, such as mrg_rxbuf, need virtio
net header to be 12-byte long.

Mergeable buffers, as a virtio feature, is worthy of supporting: packets
that are larger than one-mbuf size will be dropped in vhost worker's
handle_rx if mrg_rxbuf feature is not used, but large packets
cannot be avoided and increasing mbuf's size is not economical.

With this virtio feature enabled by virtio-user, packet sockets with
hardcoded 10-byte virtio net header will parse mac head incorrectly in
packet_snd by taking the last two bytes of virtio net header as part of
mac header.
This incorrect mac header parsing will cause packet to be dropped due to
invalid ether head checking in later under-layer device packet receiving.

By adding extra field vnet_hdr_sz with utilizing holes in struct
packet_sock to record currently used virtio net header size and supporting
extra sockopt PACKET_VNET_HDR_SZ to set specified vnet_hdr_sz, packet
sockets can know the exact length of virtio net header that virtio user
gives.
In packet_snd, tpacket_snd and packet_recvmsg, instead of using
hardcoded virtio net header size, it can get the exact vnet_hdr_sz from
corresponding packet_sock, and parse mac header correctly based on this
information to avoid the packets being mistakenly dropped.

Signed-off-by: Jianfeng Tan <henry.tjf@antgroup.com>
Co-developed-by: Anqi Shen <amy.saq@antgroup.com>
Signed-off-by: Anqi Shen <amy.saq@antgroup.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet: remove po->xmit 2023-03-19T10:57:54+00:00 Eric Dumazet edumazet@google.com 2023-03-17T16:20:02+00:00 105a201ebf3312990b96c4fbaade22e31402f8cc Use PACKET_SOCK_QDISC_BYPASS atomic bit instead of a pointer. This removes one indirect call in fast path, and READ_ONCE()/WRITE_ONCE() annotations as well. Signed-off-by: Eric Dumazet <edumazet@google.com> Suggested-by: Willem de Bruijn <willemb@google.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Use PACKET_SOCK_QDISC_BYPASS atomic bit instead of a pointer.

This removes one indirect call in fast path,
and READ_ONCE()/WRITE_ONCE() annotations as well.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Willem de Bruijn <willemb@google.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
af_packet: preserve const qualifier in pkt_sk() 2023-03-18T12:23:33+00:00 Eric Dumazet edumazet@google.com 2023-03-17T15:55:31+00:00 68ac9a8b6e65c7cbbe96541353dab1b3f8de2043 We can change pkt_sk() to propagate const qualifier of its argument, thanks to container_of_const() This should avoid some potential errors caused by accidental (const -> not_const) promotion. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Reviewed-by: Simon Horman <simon.horman@corigine.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
We can change pkt_sk() to propagate const qualifier of its argument,
thanks to container_of_const()

This should avoid some potential errors caused by accidental
(const -> not_const) promotion.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet: convert po->pressure to an atomic flag 2023-03-17T08:52:06+00:00 Eric Dumazet edumazet@google.com 2023-03-16T01:10:14+00:00 791a3e9f1a86fe8eb09173c9788493b8b5c957f4 Not only this removes some READ_ONCE()/WRITE_ONCE(), this also removes one integer. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Not only this removes some READ_ONCE()/WRITE_ONCE(),
this also removes one integer.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet: convert po->running to an atomic flag 2023-03-17T08:52:06+00:00 Eric Dumazet edumazet@google.com 2023-03-16T01:10:13+00:00 61edf479818e63978cabd243b82ca80f8948a313 Instead of consuming 32 bits for po->running, use one available bit in po->flags. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Instead of consuming 32 bits for po->running, use
one available bit in po->flags.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet: convert po->has_vnet_hdr to an atomic flag 2023-03-17T08:52:05+00:00 Eric Dumazet edumazet@google.com 2023-03-16T01:10:12+00:00 50d935eafee292fc432d5ac8c8715a6492961abc po->has_vnet_hdr can be read locklessly. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
po->has_vnet_hdr can be read locklessly.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet: convert po->tp_loss to an atomic flag 2023-03-17T08:52:05+00:00 Eric Dumazet edumazet@google.com 2023-03-16T01:10:11+00:00 164bddace2e03f6005e650cb88f101a66ebdc05a tp_loss can be read locklessly. Convert it to an atomic flag to avoid races. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
tp_loss can be read locklessly.

Convert it to an atomic flag to avoid races.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet: convert po->tp_tx_has_off to an atomic flag 2023-03-17T08:52:05+00:00 Eric Dumazet edumazet@google.com 2023-03-16T01:10:10+00:00 7438344660fa55b33b8234c1797c886eb73667a7 This is to use existing space in po->flags, and reclaim the storage used by the non atomic bit fields. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
This is to use existing space in po->flags, and reclaim
the storage used by the non atomic bit fields.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet: convert po->auxdata to an atomic flag 2023-03-17T08:52:05+00:00 Eric Dumazet edumazet@google.com 2023-03-16T01:10:08+00:00 fd53c297aa7b077ae98a3d3d2d3aa278a1686ba6 po->auxdata can be read while another thread is changing its value, potentially raising KCSAN splat. Convert it to PACKET_SOCK_AUXDATA flag. Fixes: 8dc419447415 ("[PACKET]: Add optional checksum computation for recvmsg") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
po->auxdata can be read while another thread
is changing its value, potentially raising KCSAN splat.

Convert it to PACKET_SOCK_AUXDATA flag.

Fixes: 8dc419447415 ("[PACKET]: Add optional checksum computation for recvmsg")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet: convert po->origdev to an atomic flag 2023-03-17T08:52:05+00:00 Eric Dumazet edumazet@google.com 2023-03-16T01:10:07+00:00 ee5675ecdf7a4e713ed21d98a70c2871d6ebed01 syzbot/KCAN reported that po->origdev can be read while another thread is changing its value. We can avoid this splat by converting this field to an actual bit. Following patches will convert remaining 1bit fields. Fixes: 80feaacb8a64 ("[AF_PACKET]: Add option to return orig_dev to userspace.") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
syzbot/KCAN reported that po->origdev can be read
while another thread is changing its value.

We can avoid this splat by converting this field
to an actual bit.

Following patches will convert remaining 1bit fields.

Fixes: 80feaacb8a64 ("[AF_PACKET]: Add option to return orig_dev to userspace.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>