diff options
| author | Pablo Neira Ayuso <pablo@netfilter.org> | 2021-07-27 17:23:30 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2021-07-27 17:34:35 +0200 |
| commit | 93c824172a975ed03c66649c3513f446a9ff07b2 (patch) | |
| tree | e1810ddeff1dafa277cfe9d7a623e6890ef2a3a2 /src | |
| parent | be9bd9cc7288477e54bef0225321ffa72b409116 (diff) | |
netlink_linearize: incorrect netlink bytecode with binary operation and flags
nft generates incorrect bytecode when combining flag datatype and binary
operations:
# nft --debug=netlink add rule meh tcp_flags 'tcp flags & (fin | syn | rst | ack) syn'
ip
[ meta load l4proto => reg 1 ]
[ cmp eq reg 1 0x00000006 ]
[ payload load 1b @ transport header + 13 => reg 1 ]
[ bitwise reg 1 = ( reg 1 & 0x00000017 ) ^ 0x00000000 ]
[ bitwise reg 1 = ( reg 1 & 0x00000002 ) ^ 0x00000000 ]
[ cmp neq reg 1 0x00000000 ]
Note the double bitwise expression. The last two expressions are not
correct either since it should match on the syn flag, ie. 0x2.
After this patch, netlink bytecode generation looks correct:
# nft --debug=netlink add rule meh tcp_flags 'tcp flags & (fin | syn | rst | ack) syn'
ip
[ meta load l4proto => reg 1 ]
[ cmp eq reg 1 0x00000006 ]
[ payload load 1b @ transport header + 13 => reg 1 ]
[ bitwise reg 1 = ( reg 1 & 0x00000017 ) ^ 0x00000000 ]
[ cmp eq reg 1 0x00000002 ]
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/netlink_linearize.c | 38 |
1 files changed, 23 insertions, 15 deletions
diff --git a/src/netlink_linearize.c b/src/netlink_linearize.c index 9ab3ec3e..eb53ccec 100644 --- a/src/netlink_linearize.c +++ b/src/netlink_linearize.c @@ -481,23 +481,31 @@ static void netlink_gen_flagcmp(struct netlink_linearize_ctx *ctx, netlink_gen_raw_data(zero, expr->right->byteorder, len, &nld); netlink_gen_data(expr->right, &nld2); - nle = alloc_nft_expr("bitwise"); - netlink_put_register(nle, NFTNL_EXPR_BITWISE_SREG, sreg); - netlink_put_register(nle, NFTNL_EXPR_BITWISE_DREG, sreg); - nftnl_expr_set_u32(nle, NFTNL_EXPR_BITWISE_LEN, len); - nftnl_expr_set(nle, NFTNL_EXPR_BITWISE_MASK, &nld2.value, nld2.len); - nftnl_expr_set(nle, NFTNL_EXPR_BITWISE_XOR, &nld.value, nld.len); - nft_rule_add_expr(ctx, nle, &expr->location); - - nle = alloc_nft_expr("cmp"); - netlink_put_register(nle, NFTNL_EXPR_CMP_SREG, sreg); - if (expr->op == OP_NEG) + if (expr->left->etype == EXPR_BINOP) { + nle = alloc_nft_expr("cmp"); + netlink_put_register(nle, NFTNL_EXPR_CMP_SREG, sreg); nftnl_expr_set_u32(nle, NFTNL_EXPR_CMP_OP, NFT_CMP_EQ); - else - nftnl_expr_set_u32(nle, NFTNL_EXPR_CMP_OP, NFT_CMP_NEQ); + nftnl_expr_set(nle, NFTNL_EXPR_CMP_DATA, nld2.value, nld2.len); + nft_rule_add_expr(ctx, nle, &expr->location); + } else { + nle = alloc_nft_expr("bitwise"); + netlink_put_register(nle, NFTNL_EXPR_BITWISE_SREG, sreg); + netlink_put_register(nle, NFTNL_EXPR_BITWISE_DREG, sreg); + nftnl_expr_set_u32(nle, NFTNL_EXPR_BITWISE_LEN, len); + nftnl_expr_set(nle, NFTNL_EXPR_BITWISE_MASK, &nld2.value, nld2.len); + nftnl_expr_set(nle, NFTNL_EXPR_BITWISE_XOR, &nld.value, nld.len); + nft_rule_add_expr(ctx, nle, &expr->location); - nftnl_expr_set(nle, NFTNL_EXPR_CMP_DATA, nld.value, nld.len); - nft_rule_add_expr(ctx, nle, &expr->location); + nle = alloc_nft_expr("cmp"); + netlink_put_register(nle, NFTNL_EXPR_CMP_SREG, sreg); + if (expr->op == OP_NEG) + nftnl_expr_set_u32(nle, NFTNL_EXPR_CMP_OP, NFT_CMP_EQ); + else + nftnl_expr_set_u32(nle, NFTNL_EXPR_CMP_OP, NFT_CMP_NEQ); + + nftnl_expr_set(nle, NFTNL_EXPR_CMP_DATA, nld.value, nld.len); + nft_rule_add_expr(ctx, nle, &expr->location); + } mpz_clear(zero); release_register(ctx, expr->left); |