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sctp: fix ICMP processing if skb is non-linear

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[ Upstream commit 804ec7ebe8ea003999ca8d1bfc499edc6a9e07df ]

sometimes ICMP replies to INIT chunks are ignored by the client, even if
the encapsulated SCTP headers match an open socket. This happens when the
ICMP packet is carried by a paged skb: use skb_header_pointer() to read
packet contents beyond the SCTP header, so that chunk header and initiate
tag are validated correctly.

v2:
- don't use skb_header_pointer() to read the transport header, since
  icmp_socket_deliver() already puts these 8 bytes in the linear area.
- change commit message to make specific reference to INIT chunks.

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Davide Caratti 2017-05-25 19:14:56 +02:00 committed by Greg Kroah-Hartman
parent 4b81271ed1
commit 1de51502a0
1 changed files with 9 additions and 7 deletions
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16
net/sctp/input.c
View File

@ -473,15 +473,14 @@ struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
struct sctp_association **app,
struct sctp_transport **tpp)
{
struct sctp_init_chunk *chunkhdr, _chunkhdr;
union sctp_addr saddr;
union sctp_addr daddr;
struct sctp_af *af;
struct sock *sk = NULL;
struct sctp_association *asoc;
struct sctp_transport *transport = NULL;
struct sctp_init_chunk *chunkhdr;
__u32 vtag = ntohl(sctphdr->vtag);
int len = skb->len - ((void *)sctphdr - (void *)skb->data);
*app = NULL; *tpp = NULL;
@ -516,13 +515,16 @@ struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
* discard the packet.
*/
if (vtag == 0) {
chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
+ sizeof(__be32) ||
/* chunk header + first 4 octects of init header */
chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) +
sizeof(struct sctphdr),
sizeof(struct sctp_chunkhdr) +
sizeof(__be32), &_chunkhdr);
if (!chunkhdr ||
chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag)
goto out;
}
} else if (vtag != asoc->c.peer_vtag) {
goto out;
}