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| author | Theodor Arsenij Larionov-Trichkine <theodorlarionov@gmail.com> | 2026-06-29 12:53:11 +0200 |
|---|---|---|
| committer | Florian Westphal <fw@strlen.de> | 2026-06-30 06:37:12 +0200 |
| commit | d07955dd34ecae17d35d8c7d0a273a3fba653a8c (patch) | |
| tree | 68fd828631652f8e206adb5b9c8df7feb338765e /net | |
| parent | bf5355cfdede3e30b30e63a5a74f6bdaafb26082 (diff) | |
| download | linux-2.6-d07955dd34ecae17d35d8c7d0a273a3fba653a8c.tar.gz linux-2.6-d07955dd34ecae17d35d8c7d0a273a3fba653a8c.zip | |
netfilter: nft_fib: reject fib expression on the netdev egress hook
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 <theodorlarionov@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/nft_fib.c | 9 | ||||
| -rw-r--r-- | net/netfilter/nft_fib_netdev.c | 29 |
2 files changed, 37 insertions, 1 deletions
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 = { |