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While with legacy iptables one had to independently manage IPv4 and IPv6 tables, with nftables it is possible to have dual-stack tables sharing the rules. Moreover, it was possible to use rules based on legacy iptables match/target modules in dual-stack nftables. Consider the following program: ``` /* #define TBL_FAMILY NFPROTO_IPV4 */ /* * creates something like below * table inet testfw { * chain input { * type filter hook prerouting priority filter; policy accept; * bytecode counter packets 0 bytes 0 accept * } * } * * compile: * cc -o nftbpf nftbpf.c -lnftnl -lmnl */ int main(void) { uint8_t buf[MNL_SOCKET_BUFFER_SIZE]; uint32_t seq, rule_seq, portid; struct mnl_nlmsg_batch *batch; struct nlmsghdr *nlh; struct mnl_socket *nl; int ret; struct xt_bpf_info_v1 *xt_bpf_info = malloc(sizeof(*xt_bpf_info)); struct nftnl_expr *m, *cnt, *im; struct nftnl_rule *r; struct nftnl_chain *c; struct nftnl_table *t = nftnl_table_alloc(); if (t == NULL) { perror("TABLE OOM"); exit(EXIT_FAILURE); } nftnl_table_set_u32(t, NFTNL_TABLE_FAMILY, TBL_FAMILY); nftnl_table_set_str(t, NFTNL_TABLE_NAME, TBL_NAME); c = nftnl_chain_alloc(); if (c == NULL) { perror("CHAIN OOM"); exit(EXIT_FAILURE); } nftnl_chain_set_str(c, NFTNL_CHAIN_TABLE, TBL_NAME); nftnl_chain_set_str(c, NFTNL_CHAIN_NAME, CHAIN_NAME); nftnl_chain_set_u32(c, NFTNL_CHAIN_HOOKNUM, NF_INET_PRE_ROUTING); nftnl_chain_set_u32(c, NFTNL_CHAIN_PRIO, 0); r = nftnl_rule_alloc(); if (r == NULL) { perror("RULE OOM"); exit(EXIT_FAILURE); } nftnl_rule_set_str(r, NFTNL_RULE_TABLE, TBL_NAME); nftnl_rule_set_str(r, NFTNL_RULE_CHAIN, CHAIN_NAME); nftnl_rule_set_u32(r, NFTNL_RULE_FAMILY, TBL_FAMILY); m = nftnl_expr_alloc("match"); if (m == NULL) { perror("MATCH OOM"); exit(EXIT_FAILURE); } nftnl_expr_set_str(m, NFTNL_EXPR_MT_NAME, "bpf"); nftnl_expr_set_u32(m, NFTNL_EXPR_MT_REV, 1); if (xt_bpf_info == NULL) { perror("XT_BPF OOM"); exit(EXIT_FAILURE); } /* * example from https://ipset.netfilter.org/iptables-extensions.man.html * should match TCP packets */ xt_bpf_info->mode = XT_BPF_MODE_BYTECODE; xt_bpf_info->bpf_program_num_elem = 4; xt_bpf_info->bpf_program[0].code = 48; xt_bpf_info->bpf_program[0].jt = 0; xt_bpf_info->bpf_program[0].jf = 0; xt_bpf_info->bpf_program[0].k = 9; xt_bpf_info->bpf_program[1].code = 21; xt_bpf_info->bpf_program[1].jt = 0; xt_bpf_info->bpf_program[1].jf = 1; xt_bpf_info->bpf_program[1].k = 6; xt_bpf_info->bpf_program[2].code = 6; xt_bpf_info->bpf_program[2].jt = 0; xt_bpf_info->bpf_program[2].jf = 0; xt_bpf_info->bpf_program[2].k = 1; xt_bpf_info->bpf_program[3].code = 6; xt_bpf_info->bpf_program[3].jt = 0; xt_bpf_info->bpf_program[3].jf = 0; xt_bpf_info->bpf_program[3].k = 0; nftnl_expr_set(m, NFTNL_EXPR_MT_INFO, xt_bpf_info, sizeof(*xt_bpf_info)); nftnl_rule_add_expr(r, m); cnt = nftnl_expr_alloc("counter"); if (cnt == NULL) { perror("COUNTER OOM"); exit(EXIT_FAILURE); } nftnl_expr_set_u64(cnt, NFTNL_EXPR_CTR_PACKETS, 0); nftnl_expr_set_u64(cnt, NFTNL_EXPR_CTR_BYTES, 0); nftnl_rule_add_expr(r, cnt); im = nftnl_expr_alloc("immediate"); if (im == NULL) { perror("IMMEDIATE OOM"); exit(EXIT_FAILURE); } nftnl_expr_set_u32(im, NFTNL_EXPR_IMM_DREG, 0); nftnl_expr_set_u32(im, NFTNL_EXPR_IMM_VERDICT, 1); nftnl_rule_add_expr(r, im); seq = time(NULL); batch = mnl_nlmsg_batch_start(buf, sizeof(buf)); nftnl_batch_begin(mnl_nlmsg_batch_current(batch), seq++); mnl_nlmsg_batch_next(batch); nlh = nftnl_nlmsg_build_hdr(mnl_nlmsg_batch_current(batch), NFT_MSG_NEWTABLE, TBL_FAMILY, NLM_F_CREATE, seq++); nftnl_table_nlmsg_build_payload(nlh, t); nftnl_table_free(t); mnl_nlmsg_batch_next(batch); nlh = nftnl_nlmsg_build_hdr(mnl_nlmsg_batch_current(batch), NFT_MSG_NEWCHAIN, TBL_FAMILY, NLM_F_CREATE, seq++); nftnl_chain_nlmsg_build_payload(nlh, c); nftnl_chain_free(c); mnl_nlmsg_batch_next(batch); rule_seq = seq; nlh = nftnl_nlmsg_build_hdr(mnl_nlmsg_batch_current(batch), NFT_MSG_NEWRULE, TBL_FAMILY, NLM_F_APPEND | NLM_F_CREATE | NLM_F_ACK, seq++); nftnl_rule_nlmsg_build_payload(nlh, r); nftnl_rule_free(r); mnl_nlmsg_batch_next(batch); nftnl_batch_end(mnl_nlmsg_batch_current(batch), seq++); mnl_nlmsg_batch_next(batch); nftnl_batch_end(mnl_nlmsg_batch_current(batch), seq++); mnl_nlmsg_batch_next(batch); nl = mnl_socket_open(NETLINK_NETFILTER); if (nl == NULL) { perror("mnl_socket_open"); exit(EXIT_FAILURE); } if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) { perror("mnl_socket_bind"); exit(EXIT_FAILURE); } portid = mnl_socket_get_portid(nl); if (mnl_socket_sendto(nl, mnl_nlmsg_batch_head(batch), mnl_nlmsg_batch_size(batch)) < 0) { perror("mnl_socket_send"); exit(EXIT_FAILURE); } mnl_nlmsg_batch_stop(batch); ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); while (ret > 0) { ret = mnl_cb_run(buf, ret, rule_seq, portid, NULL, NULL); if (ret <= 0) break; ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); } if (ret == -1) { perror("error"); exit(EXIT_FAILURE); } mnl_socket_close(nl); return EXIT_SUCCESS; } ``` Above creates an INET dual-stack family table using xt_bpf based rule. After d0009effa886 ("netfilter: nf_tables: validate NFPROTO_* family") we get EOPNOTSUPP for the above configuration. Fix this by allowing NFPROTO_INET for nft_(match/target)_validate(), but also restrict the functions to classic iptables hooks. Changes in v2: * restrict nft_(match/target)_validate() to classic iptables hooks * rewrite example program to use unmodified libnftnl Fixes: d0009effa886 ("netfilter: nf_tables: validate NFPROTO_* family") Link: https://lore.kernel.org/all/Zc1PfoWN38UuFJRI@calendula/T/#mc947262582c90fec044c7a3398cc92fac7afea72 Reported-by: Jordan Griege Signed-off-by: Ignat Korchagin --- net/netfilter/nft_compat.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c index 1f9474fefe84..d3d11dede545 100644 --- a/net/netfilter/nft_compat.c +++ b/net/netfilter/nft_compat.c @@ -359,10 +359,20 @@ static int nft_target_validate(const struct nft_ctx *ctx, if (ctx->family != NFPROTO_IPV4 && ctx->family != NFPROTO_IPV6 && + ctx->family != NFPROTO_INET && ctx->family != NFPROTO_BRIDGE && ctx->family != NFPROTO_ARP) return -EOPNOTSUPP; + ret = nft_chain_validate_hooks(ctx->chain, + (1 << NF_INET_PRE_ROUTING) | + (1 << NF_INET_LOCAL_IN) | + (1 << NF_INET_FORWARD) | + (1 << NF_INET_LOCAL_OUT) | + (1 << NF_INET_POST_ROUTING)); + if (ret) + return ret; + if (nft_is_base_chain(ctx->chain)) { const struct nft_base_chain *basechain = nft_base_chain(ctx->chain); @@ -610,10 +620,20 @@ static int nft_match_validate(const struct nft_ctx *ctx, if (ctx->family != NFPROTO_IPV4 && ctx->family != NFPROTO_IPV6 && + ctx->family != NFPROTO_INET && ctx->family != NFPROTO_BRIDGE && ctx->family != NFPROTO_ARP) return -EOPNOTSUPP; + ret = nft_chain_validate_hooks(ctx->chain, + (1 << NF_INET_PRE_ROUTING) | + (1 << NF_INET_LOCAL_IN) | + (1 << NF_INET_FORWARD) | + (1 << NF_INET_LOCAL_OUT) | + (1 << NF_INET_POST_ROUTING)); + if (ret) + return ret; + if (nft_is_base_chain(ctx->chain)) { const struct nft_base_chain *basechain = nft_base_chain(ctx->chain); -- 2.39.2