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 <pablo@netfilter.org>
Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index a7a7ceb..5031e07 100644 (file)
--- 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 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -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
  *

diff --git a/net/netfilter/nft_bitwise.c b/net/netfilter/nft_bitwise.c
index d71cc18..31c15ed 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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]);