6.12-stable review patch. If anyone has any objections, please let me know.
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From: Fernando Fernandez Mancera fmancera@suse.de
[ Upstream commit f359b809d54c6e3dd1d039b97e0b68390b0e53e4 ]
Referencing a synproxy stateful object from OUTPUT hook causes kernel crash due to infinite recursive calls:
BUG: TASK stack guard page was hit at 000000008bda5b8c (stack is 000000003ab1c4a5..00000000494d8b12) [...] Call Trace: __find_rr_leaf+0x99/0x230 fib6_table_lookup+0x13b/0x2d0 ip6_pol_route+0xa4/0x400 fib6_rule_lookup+0x156/0x240 ip6_route_output_flags+0xc6/0x150 __nf_ip6_route+0x23/0x50 synproxy_send_tcp_ipv6+0x106/0x200 synproxy_send_client_synack_ipv6+0x1aa/0x1f0 nft_synproxy_do_eval+0x263/0x310 nft_do_chain+0x5a8/0x5f0 [nf_tables nft_do_chain_inet+0x98/0x110 nf_hook_slow+0x43/0xc0 __ip6_local_out+0xf0/0x170 ip6_local_out+0x17/0x70 synproxy_send_tcp_ipv6+0x1a2/0x200 synproxy_send_client_synack_ipv6+0x1aa/0x1f0 [...]
Implement objref and objrefmap expression validate functions.
Currently, only NFT_OBJECT_SYNPROXY object type requires validation. This will also handle a jump to a chain using a synproxy object from the OUTPUT hook.
Now when trying to reference a synproxy object in the OUTPUT hook, nft will produce the following error:
synproxy_crash.nft: Error: Could not process rule: Operation not supported synproxy name mysynproxy ^^^^^^^^^^^^^^^^^^^^^^^^
Fixes: ee394f96ad75 ("netfilter: nft_synproxy: add synproxy stateful object support") Reported-by: Georg Pfuetzenreuter georg.pfuetzenreuter@suse.com Closes: https://bugzilla.suse.com/1250237 Signed-off-by: Fernando Fernandez Mancera fmancera@suse.de Reviewed-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/nft_objref.c | 39 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+)
diff --git a/net/netfilter/nft_objref.c b/net/netfilter/nft_objref.c index 8ee66a86c3bc7..1a62e384766a7 100644 --- a/net/netfilter/nft_objref.c +++ b/net/netfilter/nft_objref.c @@ -22,6 +22,35 @@ void nft_objref_eval(const struct nft_expr *expr, obj->ops->eval(obj, regs, pkt); }
+static int nft_objref_validate_obj_type(const struct nft_ctx *ctx, u32 type) +{ + unsigned int hooks; + + switch (type) { + case NFT_OBJECT_SYNPROXY: + if (ctx->family != NFPROTO_IPV4 && + ctx->family != NFPROTO_IPV6 && + ctx->family != NFPROTO_INET) + return -EOPNOTSUPP; + + hooks = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD); + + return nft_chain_validate_hooks(ctx->chain, hooks); + default: + break; + } + + return 0; +} + +static int nft_objref_validate(const struct nft_ctx *ctx, + const struct nft_expr *expr) +{ + struct nft_object *obj = nft_objref_priv(expr); + + return nft_objref_validate_obj_type(ctx, obj->ops->type->type); +} + static int nft_objref_init(const struct nft_ctx *ctx, const struct nft_expr *expr, const struct nlattr * const tb[]) @@ -93,6 +122,7 @@ static const struct nft_expr_ops nft_objref_ops = { .activate = nft_objref_activate, .deactivate = nft_objref_deactivate, .dump = nft_objref_dump, + .validate = nft_objref_validate, .reduce = NFT_REDUCE_READONLY, };
@@ -197,6 +227,14 @@ static void nft_objref_map_destroy(const struct nft_ctx *ctx, nf_tables_destroy_set(ctx, priv->set); }
+static int nft_objref_map_validate(const struct nft_ctx *ctx, + const struct nft_expr *expr) +{ + const struct nft_objref_map *priv = nft_expr_priv(expr); + + return nft_objref_validate_obj_type(ctx, priv->set->objtype); +} + static const struct nft_expr_ops nft_objref_map_ops = { .type = &nft_objref_type, .size = NFT_EXPR_SIZE(sizeof(struct nft_objref_map)), @@ -206,6 +244,7 @@ static const struct nft_expr_ops nft_objref_map_ops = { .deactivate = nft_objref_map_deactivate, .destroy = nft_objref_map_destroy, .dump = nft_objref_map_dump, + .validate = nft_objref_map_validate, .reduce = NFT_REDUCE_READONLY, };