path: root/net/packet
diff options
authorWillem de Bruijn <willemb@google.com>2018-11-20 13:00:18 -0500
committerDavid S. Miller <davem@davemloft.net>2018-11-23 11:08:03 -0800
commit5cd8d46ea1562be80063f53c7c6a5f40224de623 (patch)
tree53ce4843c87bbbeed12992b26dc4e15cf8470eaf /net/packet
parentMerge branch 'ibmvnic-Fix-queue-and-buffer-accounting-errors' (diff)
packet: copy user buffers before orphan or clone
tpacket_snd sends packets with user pages linked into skb frags. It notifies that pages can be reused when the skb is released by setting skb->destructor to tpacket_destruct_skb. This can cause data corruption if the skb is orphaned (e.g., on transmit through veth) or cloned (e.g., on mirror to another psock). Create a kernel-private copy of data in these cases, same as tun/tap zerocopy transmission. Reuse that infrastructure: mark the skb as SKBTX_ZEROCOPY_FRAG, which will trigger copy in skb_orphan_frags(_rx). Unlike other zerocopy packets, do not set shinfo destructor_arg to struct ubuf_info. tpacket_destruct_skb already uses that ptr to notify when the original skb is released and a timestamp is recorded. Do not change this timestamp behavior. The ubuf_info->callback is not needed anyway, as no zerocopy notification is expected. Mark destructor_arg as not-a-uarg by setting the lower bit to 1. The resulting value is not a valid ubuf_info pointer, nor a valid tpacket_snd frame address. Add skb_zcopy_.._nouarg helpers for this. The fix relies on features introduced in commit 52267790ef52 ("sock: add MSG_ZEROCOPY"), so can be backported as is only to 4.14. Tested with from `./in_netns.sh ./txring_overwrite` from http://github.com/wdebruij/kerneltools/tests Fixes: 69e3c75f4d54 ("net: TX_RING and packet mmap") Reported-by: Anand H. Krishnan <anandhkrishnan@gmail.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
1 files changed, 2 insertions, 2 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index ec3095f13aae..a74650e98f42 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2394,7 +2394,7 @@ static void tpacket_destruct_skb(struct sk_buff *skb)
void *ph;
__u32 ts;
- ph = skb_shinfo(skb)->destructor_arg;
+ ph = skb_zcopy_get_nouarg(skb);
ts = __packet_set_timestamp(po, ph, skb);
@@ -2461,7 +2461,7 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
skb->mark = po->sk.sk_mark;
skb->tstamp = sockc->transmit_time;
sock_tx_timestamp(&po->sk, sockc->tsflags, &skb_shinfo(skb)->tx_flags);
- skb_shinfo(skb)->destructor_arg = ph.raw;
+ skb_zcopy_set_nouarg(skb, ph.raw);
skb_reserve(skb, hlen);