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netfilter: nf_tables: validate maximum value of u32 netlink attributes

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Fetch value and validate u32 netlink attribute. This validation is
usually required when the u32 netlink attributes are being stored in a
field whose size is smaller.

This patch revisits 4da449ae1d ("netfilter: nft_exthdr: Add size check
on u8 nft_exthdr attributes").

Fixes: 96518518cc ("netfilter: add nftables")
Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Laura Garcia Liebana 2016-09-14 15:00:02 +02:00 committed by Pablo Neira Ayuso
parent 2b03bf7324
commit 36b701fae1
7 changed files with 60 additions and 8 deletions
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1
include/net/netfilter/nf_tables.h
View File

@ -145,6 +145,7 @@ static inline enum nft_registers nft_type_to_reg(enum nft_data_types type)
return type == NFT_DATA_VERDICT ? NFT_REG_VERDICT : NFT_REG_1 * NFT_REG_SIZE / NFT_REG32_SIZE;
}
unsigned int nft_parse_u32_check(const struct nlattr *attr, int max, u32 *dest);
unsigned int nft_parse_register(const struct nlattr *attr);
int nft_dump_register(struct sk_buff *skb, unsigned int attr, unsigned int reg);

25
net/netfilter/nf_tables_api.c
View File

@ -4409,6 +4409,31 @@ static int nf_tables_check_loops(const struct nft_ctx *ctx,
return 0;
}
/**
* nft_parse_u32_check - fetch u32 attribute and check for maximum value
*
* @attr: netlink attribute to fetch value from
* @max: maximum value to be stored in dest
* @dest: pointer to the variable
*
* Parse, check and store a given u32 netlink attribute into variable.
* This function returns -ERANGE if the value goes over maximum value.
* Otherwise a 0 is returned and the attribute value is stored in the
* destination variable.
*/
unsigned int nft_parse_u32_check(const struct nlattr *attr, int max, u32 *dest)
{
int val;
val = ntohl(nla_get_be32(attr));
if (val > max)
return -ERANGE;
*dest = val;
return 0;
}
EXPORT_SYMBOL_GPL(nft_parse_u32_check);
/**
* nft_parse_register - parse a register value from a netlink attribute
*

8
net/netfilter/nft_bitwise.c
View File

@ -52,6 +52,7 @@ static int nft_bitwise_init(const struct nft_ctx *ctx,
{
struct nft_bitwise *priv = nft_expr_priv(expr);
struct nft_data_desc d1, d2;
u32 len;
int err;
if (tb[NFTA_BITWISE_SREG] == NULL ||
@ -61,7 +62,12 @@ static int nft_bitwise_init(const struct nft_ctx *ctx,
tb[NFTA_BITWISE_XOR] == NULL)
return -EINVAL;
priv->len = ntohl(nla_get_be32(tb[NFTA_BITWISE_LEN]));
err = nft_parse_u32_check(tb[NFTA_BITWISE_LEN], U8_MAX, &len);
if (err < 0)
return err;
priv->len = len;
priv->sreg = nft_parse_register(tb[NFTA_BITWISE_SREG]);
err = nft_validate_register_load(priv->sreg, priv->len);
if (err < 0)

15
net/netfilter/nft_byteorder.c
View File

@ -99,6 +99,7 @@ static int nft_byteorder_init(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
{
struct nft_byteorder *priv = nft_expr_priv(expr);
u32 size, len;
int err;
if (tb[NFTA_BYTEORDER_SREG] == NULL ||
@ -117,7 +118,12 @@ static int nft_byteorder_init(const struct nft_ctx *ctx,
return -EINVAL;
}
priv->size = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_SIZE]));
err = nft_parse_u32_check(tb[NFTA_BYTEORDER_SIZE], U8_MAX, &size);
if (err < 0)
return err;
priv->size = size;
switch (priv->size) {
case 2:
case 4:
@ -128,7 +134,12 @@ static int nft_byteorder_init(const struct nft_ctx *ctx,
}
priv->sreg = nft_parse_register(tb[NFTA_BYTEORDER_SREG]);
priv->len = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_LEN]));
err = nft_parse_u32_check(tb[NFTA_BYTEORDER_LEN], U8_MAX, &len);
if (err < 0)
return err;
priv->len = len;
err = nft_validate_register_load(priv->sreg, priv->len);
if (err < 0)
return err;

3
net/netfilter/nft_cmp.c
View File

@ -84,6 +84,9 @@ static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
if (err < 0)
return err;
if (desc.len > U8_MAX)
return -ERANGE;
priv->op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
priv->len = desc.len;
return 0;

12
net/netfilter/nft_exthdr.c
View File

@ -59,7 +59,7 @@ static int nft_exthdr_init(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
{
struct nft_exthdr *priv = nft_expr_priv(expr);
u32 offset, len;
u32 offset, len, err;
if (tb[NFTA_EXTHDR_DREG] == NULL ||
tb[NFTA_EXTHDR_TYPE] == NULL ||
@ -67,11 +67,13 @@ static int nft_exthdr_init(const struct nft_ctx *ctx,
tb[NFTA_EXTHDR_LEN] == NULL)
return -EINVAL;
offset = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OFFSET]));
len = ntohl(nla_get_be32(tb[NFTA_EXTHDR_LEN]));
err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
if (err < 0)
return err;
if (offset > U8_MAX || len > U8_MAX)
return -ERANGE;
err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
if (err < 0)
return err;
priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
priv->offset = offset;

4
net/netfilter/nft_immediate.c
View File

@ -53,6 +53,10 @@ static int nft_immediate_init(const struct nft_ctx *ctx,
tb[NFTA_IMMEDIATE_DATA]);
if (err < 0)
return err;
if (desc.len > U8_MAX)
return -ERANGE;
priv->dlen = desc.len;
priv->dreg = nft_parse_register(tb[NFTA_IMMEDIATE_DREG]);