From 36b701fae12ac763a568037e4e7c96b5727a8b3e Mon Sep 17 00:00:00 2001 From: Laura Garcia Liebana Date: Wed, 14 Sep 2016 15:00:02 +0200 Subject: [PATCH] netfilter: nf_tables: validate maximum value of u32 netlink attributes 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 4da449ae1df9 ("netfilter: nft_exthdr: Add size check on u8 nft_exthdr attributes"). Fixes: 96518518cc41 ("netfilter: add nftables") Suggested-by: Pablo Neira Ayuso Signed-off-by: Laura Garcia Liebana Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_tables.h | 1 + net/netfilter/nf_tables_api.c | 25 +++++++++++++++++++++++++ net/netfilter/nft_bitwise.c | 8 +++++++- net/netfilter/nft_byteorder.c | 15 +++++++++++++-- net/netfilter/nft_cmp.c | 3 +++ net/netfilter/nft_exthdr.c | 12 +++++++----- net/netfilter/nft_immediate.c | 4 ++++ 7 files changed, 60 insertions(+), 8 deletions(-) diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index a7a7ceb..5031e07 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -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); diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index bd9715e..b70d3ea 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -4410,6 +4410,31 @@ static int nf_tables_check_loops(const struct nft_ctx *ctx, } /** + * 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 * * @attr: netlink attribute diff --git a/net/netfilter/nft_bitwise.c b/net/netfilter/nft_bitwise.c index d71cc18..31c15ed 100644 --- a/net/netfilter/nft_bitwise.c +++ b/net/netfilter/nft_bitwise.c @@ -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) diff --git a/net/netfilter/nft_byteorder.c b/net/netfilter/nft_byteorder.c index b78c28b..ee63d98 100644 --- a/net/netfilter/nft_byteorder.c +++ b/net/netfilter/nft_byteorder.c @@ -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; diff --git a/net/netfilter/nft_cmp.c b/net/netfilter/nft_cmp.c index e25b35d..2e53739 100644 --- a/net/netfilter/nft_cmp.c +++ b/net/netfilter/nft_cmp.c @@ -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; diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c index 82c264e..a84cf3d 100644 --- a/net/netfilter/nft_exthdr.c +++ b/net/netfilter/nft_exthdr.c @@ -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; diff --git a/net/netfilter/nft_immediate.c b/net/netfilter/nft_immediate.c index db3b746..d17018f 100644 --- a/net/netfilter/nft_immediate.c +++ b/net/netfilter/nft_immediate.c @@ -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]); -- 2.7.4