diff options
| author | Davide Caratti <dcaratti@redhat.com> | 2020-10-15 18:39:27 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2020-10-15 11:45:19 -0700 |
| commit | 346e320cb2103edef709c4466a29140c4a8e527a (patch) | |
| tree | 405af21ad80b77a0bfda44fa68bbf92051c9c979 /net | |
| parent | 54086c5a7f159749bc521706bae329cbce3971e9 (diff) | |
netfilter: nftables: allow re-computing sctp CRC-32C in 'payload' statements
nftables payload statements are used to mangle SCTP headers, but they can
only replace the Internet Checksum. As a consequence, nftables rules that
mangle sport/dport/vtag in SCTP headers potentially generate packets that
are discarded by the receiver, unless the CRC-32C is "offloaded" (e.g the
rule mangles a skb having 'ip_summed' equal to 'CHECKSUM_PARTIAL'.
Fix this extending uAPI definitions and L4 checksum update function, in a
way that userspace programs (e.g. nft) can instruct the kernel to compute
CRC-32C in SCTP headers. Also ensure that LIBCRC32C is built if NF_TABLES
is 'y' or 'm' in the kernel build configuration.
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/Kconfig | 1 | ||||
| -rw-r--r-- | net/netfilter/nft_payload.c | 28 |
2 files changed, 29 insertions, 0 deletions
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 25313c29d799..52370211e46b 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -441,6 +441,7 @@ endif # NF_CONNTRACK config NF_TABLES select NETFILTER_NETLINK + select LIBCRC32C tristate "Netfilter nf_tables support" help nftables is the new packet classification framework that intends to diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c index 7a2e59638499..dcd3c7b8a367 100644 --- a/net/netfilter/nft_payload.c +++ b/net/netfilter/nft_payload.c @@ -22,6 +22,7 @@ #include <linux/icmpv6.h> #include <linux/ip.h> #include <linux/ipv6.h> +#include <net/sctp/checksum.h> static bool nft_payload_rebuild_vlan_hdr(const struct sk_buff *skb, int mac_off, struct vlan_ethhdr *veth) @@ -484,6 +485,19 @@ static int nft_payload_l4csum_offset(const struct nft_pktinfo *pkt, return 0; } +static int nft_payload_csum_sctp(struct sk_buff *skb, int offset) +{ + struct sctphdr *sh; + + if (skb_ensure_writable(skb, offset + sizeof(*sh))) + return -1; + + sh = (struct sctphdr *)(skb->data + offset); + sh->checksum = sctp_compute_cksum(skb, offset); + skb->ip_summed = CHECKSUM_UNNECESSARY; + return 0; +} + static int nft_payload_l4csum_update(const struct nft_pktinfo *pkt, struct sk_buff *skb, __wsum fsum, __wsum tsum) @@ -587,6 +601,13 @@ static void nft_payload_set_eval(const struct nft_expr *expr, skb_store_bits(skb, offset, src, priv->len) < 0) goto err; + if (priv->csum_type == NFT_PAYLOAD_CSUM_SCTP && + pkt->tprot == IPPROTO_SCTP && + skb->ip_summed != CHECKSUM_PARTIAL) { + if (nft_payload_csum_sctp(skb, pkt->xt.thoff)) + goto err; + } + return; err: regs->verdict.code = NFT_BREAK; @@ -623,6 +644,13 @@ static int nft_payload_set_init(const struct nft_ctx *ctx, case NFT_PAYLOAD_CSUM_NONE: case NFT_PAYLOAD_CSUM_INET: break; + case NFT_PAYLOAD_CSUM_SCTP: + if (priv->base != NFT_PAYLOAD_TRANSPORT_HEADER) + return -EINVAL; + + if (priv->csum_offset != offsetof(struct sctphdr, checksum)) + return -EINVAL; + break; default: return -EOPNOTSUPP; } |