netfilter: nf_tables: validate registers coming from userspace.

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>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d71a33a..1f5a0ee 100644 (file)
--- 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 nlattr *attr, int max, u32 *dest)
 }
 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 nlattr *attr, u8 *sreg, u32 len)
        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 struct nft_ctx *ctx,
        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;