[PATCH 5.17 21/39] netfilter: nf_tables: validate registers coming from userspace.

Greg Kroah-Hartman
2022-03-25T15:34:36Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

commit 6e1acfa387b9ff82cfc7db8cc3b6959221a95851 upstream.

Bail out in case userspace uses unsupported registers.

Fixes: 49499c3e6e18 ("netfilter: nf_tables: switch registers to 32 bit addressing")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/netfilter/nf_tables_api.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)

--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9275,17 +9275,23 @@ int nft_parse_u32_check(const struct nla
}
EXPORT_SYMBOL_GPL(nft_parse_u32_check);

-static unsigned int nft_parse_register(const struct nlattr *attr)
+static unsigned int nft_parse_register(const struct nlattr *attr, u32 *preg)
{
unsigned int reg;

reg = ntohl(nla_get_be32(attr));
switch (reg) {
case NFT_REG_VERDICT...NFT_REG_4:
- return reg * NFT_REG_SIZE / NFT_REG32_SIZE;
+ *preg = reg * NFT_REG_SIZE / NFT_REG32_SIZE;
+ break;
+ case NFT_REG32_00...NFT_REG32_15:
+ *preg = reg + NFT_REG_SIZE / NFT_REG32_SIZE - NFT_REG32_00;
+ break;
default:
- return reg + NFT_REG_SIZE / NFT_REG32_SIZE - NFT_REG32_00;
+ return -ERANGE;
}
+
+ return 0;
}

/**
@@ -9327,7 +9333,10 @@ int nft_parse_register_load(const struct
u32 reg;
int err;

- reg = nft_parse_register(attr);
+ err = nft_parse_register(attr, &reg);
+ if (err < 0)
+ return err;
+
err = nft_validate_register_load(reg, len);
if (err < 0)
return err;
@@ -9382,7 +9391,10 @@ int nft_parse_register_store(const struc
int err;
u32 reg;

- reg = nft_parse_register(attr);
+ err = nft_parse_register(attr, &reg);
+ if (err < 0)
+ return err;
+
err = nft_validate_register_store(ctx, reg, data, type, len);
if (err < 0)
return err;