From: Theodor Arsenij Larionov-Trichkine A fib expression in a netdev egress base chain dereferences nft_in(pkt), NULL on the transmit path, causing a NULL pointer dereference at eval. nft_fib_validate() masks the hook with NF_INET_* values, but netdev hook numbers are a separate enum that aliases them (NF_NETDEV_EGRESS == NF_INET_LOCAL_IN), so an egress chain passes validation and then faults. Add nft_fib_netdev_validate() that limits each result/flag to the netdev hook where the device it reads exists: the input-device cases (OIF, OIFNAME, ADDRTYPE with F_IIF) to ingress, the output-device case (ADDRTYPE with F_OIF) to egress, ADDRTYPE with no device flag to both. Also restrict nft_fib_validate() to NFPROTO_IPV4/IPV6/INET so its NF_INET_* masks are not applied to another family's hooks. Fixes: 42df6e1d221d ("netfilter: Introduce egress hook") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/netfilter-devel/ajxsjcDOnwllMfoR@strlen.de/ Signed-off-by: Theodor Arsenij Larionov-Trichkine Signed-off-by: Florian Westphal --- net/netfilter/nft_fib.c | 9 +++++++++ net/netfilter/nft_fib_netdev.c | 29 ++++++++++++++++++++++++++++- 2 files changed, 37 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nft_fib.c b/net/netfilter/nft_fib.c index e048f05694cd..89555380f1c5 100644 --- a/net/netfilter/nft_fib.c +++ b/net/netfilter/nft_fib.c @@ -31,6 +31,15 @@ int nft_fib_validate(const struct nft_ctx *ctx, const struct nft_expr *expr) const struct nft_fib *priv = nft_expr_priv(expr); unsigned int hooks; + switch (ctx->family) { + case NFPROTO_IPV4: + case NFPROTO_IPV6: + case NFPROTO_INET: + break; + default: + return -EOPNOTSUPP; + } + switch (priv->result) { case NFT_FIB_RESULT_OIF: case NFT_FIB_RESULT_OIFNAME: diff --git a/net/netfilter/nft_fib_netdev.c b/net/netfilter/nft_fib_netdev.c index 3f3478abd845..5774a7544027 100644 --- a/net/netfilter/nft_fib_netdev.c +++ b/net/netfilter/nft_fib_netdev.c @@ -50,6 +50,33 @@ static void nft_fib_netdev_eval(const struct nft_expr *expr, regs->verdict.code = NFT_BREAK; } +static int nft_fib_netdev_validate(const struct nft_ctx *ctx, + const struct nft_expr *expr) +{ + const struct nft_fib *priv = nft_expr_priv(expr); + unsigned int hooks; + + switch (priv->result) { + case NFT_FIB_RESULT_OIF: + case NFT_FIB_RESULT_OIFNAME: + hooks = (1 << NF_NETDEV_INGRESS); + break; + case NFT_FIB_RESULT_ADDRTYPE: + if (priv->flags & NFTA_FIB_F_IIF) + hooks = (1 << NF_NETDEV_INGRESS); + else if (priv->flags & NFTA_FIB_F_OIF) + hooks = (1 << NF_NETDEV_EGRESS); + else + hooks = (1 << NF_NETDEV_INGRESS) | + (1 << NF_NETDEV_EGRESS); + break; + default: + return -EINVAL; + } + + return nft_chain_validate_hooks(ctx->chain, hooks); +} + static struct nft_expr_type nft_fib_netdev_type; static const struct nft_expr_ops nft_fib_netdev_ops = { .type = &nft_fib_netdev_type, @@ -57,7 +84,7 @@ static const struct nft_expr_ops nft_fib_netdev_ops = { .eval = nft_fib_netdev_eval, .init = nft_fib_init, .dump = nft_fib_dump, - .validate = nft_fib_validate, + .validate = nft_fib_netdev_validate, }; static struct nft_expr_type nft_fib_netdev_type __read_mostly = { -- 2.53.0