| Message ID | 20200804214409.105658-1-ssuryaextr@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | Pablo Neira |
| Headers | show |
| Series | [nf,v2] netfilter: nf_tables: nft_exthdr: the presence return value should be little-endian | expand |
On Tue, Aug 04, 2020 at 05:44:09PM -0400, Stephen Suryaputra wrote: > On big-endian machine, the returned register data when the exthdr is > present is not being compared correctly because little-endian is > assumed. The function nft_cmp_fast_mask(), called by nft_cmp_fast_eval() > and nft_cmp_fast_init(), calls cpu_to_le32(). Applied, thanks.
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c index 07782836fad6..3c48cdc8935d 100644 --- a/net/netfilter/nft_exthdr.c +++ b/net/netfilter/nft_exthdr.c @@ -44,7 +44,7 @@ static void nft_exthdr_ipv6_eval(const struct nft_expr *expr, err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL); if (priv->flags & NFT_EXTHDR_F_PRESENT) { - *dest = (err >= 0); + nft_reg_store8(dest, err >= 0); return; } else if (err < 0) { goto err; @@ -141,7 +141,7 @@ static void nft_exthdr_ipv4_eval(const struct nft_expr *expr, err = ipv4_find_option(nft_net(pkt), skb, &offset, priv->type); if (priv->flags & NFT_EXTHDR_F_PRESENT) { - *dest = (err >= 0); + nft_reg_store8(dest, err >= 0); return; } else if (err < 0) { goto err;
On big-endian machine, the returned register data when the exthdr is present is not being compared correctly because little-endian is assumed. The function nft_cmp_fast_mask(), called by nft_cmp_fast_eval() and nft_cmp_fast_init(), calls cpu_to_le32(). The following dump also shows that little endian is assumed: $ nft --debug=netlink add rule ip recordroute forward ip option rr exists counter ip [ exthdr load ipv4 1b @ 7 + 0 present => reg 1 ] [ cmp eq reg 1 0x01000000 ] [ counter pkts 0 bytes 0 ] Lastly, debug print in nft_cmp_fast_init() and nft_cmp_fast_eval() when RR option exists in the packet shows that the comparison fails because the assumption: nft_cmp_fast_init:189 priv->sreg=4 desc.len=8 mask=0xff000000 data.data[0]=0x10003e0 nft_cmp_fast_eval:57 regs->data[priv->sreg=4]=0x1 mask=0xff000000 priv->data=0x1000000 v2: use nft_reg_store8() instead (Florian Westphal). Also to avoid the warnings reported by kernel test robot. Fixes: dbb5281a1f84 ("netfilter: nf_tables: add support for matching IPv4 options") Fixes: c078ca3b0c5b ("netfilter: nft_exthdr: Add support for existence check") Signed-off-by: Stephen Suryaputra <ssuryaextr@gmail.com> --- net/netfilter/nft_exthdr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)