With this patch the internal use of the skb_trimmed is reduced to the ICMPv6/IGMP checksum verification. And for the length checks the newly introduced helper functions are used instead of calculating and checking with skb->len directly.
These changes should hopefully make it easier to verify that length checks are performed properly.
Signed-off-by: Linus Lüssing linus.luessing@c0d3.blue --- net/ipv4/igmp.c | 51 ++++++++++++++++++----------------------- net/ipv6/mcast_snoop.c | 62 ++++++++++++++++++++++++-------------------------- 2 files changed, 52 insertions(+), 61 deletions(-)
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index b1f6d93282d7..a40e48ded10d 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -1493,22 +1493,22 @@ static int ip_mc_check_igmp_reportv3(struct sk_buff *skb)
len += sizeof(struct igmpv3_report);
- return pskb_may_pull(skb, len) ? 0 : -EINVAL; + return ip_mc_may_pull(skb, len) ? 0 : -EINVAL; }
static int ip_mc_check_igmp_query(struct sk_buff *skb) { - unsigned int len = skb_transport_offset(skb); - - len += sizeof(struct igmphdr); - if (skb->len < len) - return -EINVAL; + unsigned int transport_len = ip_transport_len(skb); + unsigned int len;
/* IGMPv{1,2}? */ - if (skb->len != len) { + if (transport_len != sizeof(struct igmphdr)) { /* or IGMPv3? */ - len += sizeof(struct igmpv3_query) - sizeof(struct igmphdr); - if (skb->len < len || !pskb_may_pull(skb, len)) + if (transport_len < sizeof(struct igmpv3_query)) + return -EINVAL; + + len = skb_transport_offset(skb) + sizeof(struct igmpv3_query); + if (!ip_mc_may_pull(skb, len)) return -EINVAL; }
@@ -1544,35 +1544,24 @@ static inline __sum16 ip_mc_validate_checksum(struct sk_buff *skb) return skb_checksum_simple_validate(skb); }
-static int __ip_mc_check_igmp(struct sk_buff *skb) - +static int ip_mc_check_igmp_csum(struct sk_buff *skb) { - struct sk_buff *skb_chk; - unsigned int transport_len; unsigned int len = skb_transport_offset(skb) + sizeof(struct igmphdr); - int ret = -EINVAL; + unsigned int transport_len = ip_transport_len(skb); + struct sk_buff *skb_chk;
- transport_len = ntohs(ip_hdr(skb)->tot_len) - ip_hdrlen(skb); + if (!ip_mc_may_pull(skb, len)) + return -EINVAL;
skb_chk = skb_checksum_trimmed(skb, transport_len, ip_mc_validate_checksum); if (!skb_chk) - goto err; + return -EINVAL;
- if (!pskb_may_pull(skb_chk, len)) - goto err; - - ret = ip_mc_check_igmp_msg(skb_chk); - if (ret) - goto err; - - ret = 0; - -err: - if (skb_chk && skb_chk != skb) + if (skb_chk != skb) kfree_skb(skb_chk);
- return ret; + return 0; }
/** @@ -1600,7 +1589,11 @@ int ip_mc_check_igmp(struct sk_buff *skb) if (ip_hdr(skb)->protocol != IPPROTO_IGMP) return -ENOMSG;
- return __ip_mc_check_igmp(skb); + ret = ip_mc_check_igmp_csum(skb); + if (ret < 0) + return ret; + + return ip_mc_check_igmp_msg(skb); } EXPORT_SYMBOL(ip_mc_check_igmp);
diff --git a/net/ipv6/mcast_snoop.c b/net/ipv6/mcast_snoop.c index 1a917dc80d5e..a72ddfc40eb3 100644 --- a/net/ipv6/mcast_snoop.c +++ b/net/ipv6/mcast_snoop.c @@ -77,27 +77,27 @@ static int ipv6_mc_check_mld_reportv2(struct sk_buff *skb)
len += sizeof(struct mld2_report);
- return pskb_may_pull(skb, len) ? 0 : -EINVAL; + return ipv6_mc_may_pull(skb, len) ? 0 : -EINVAL; }
static int ipv6_mc_check_mld_query(struct sk_buff *skb) { + unsigned int transport_len = ipv6_transport_len(skb); struct mld_msg *mld; - unsigned int len = skb_transport_offset(skb); + unsigned int len;
/* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */ if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) return -EINVAL;
- len += sizeof(struct mld_msg); - if (skb->len < len) - return -EINVAL; - /* MLDv1? */ - if (skb->len != len) { + if (transport_len != sizeof(struct mld_msg)) { /* or MLDv2? */ - len += sizeof(struct mld2_query) - sizeof(struct mld_msg); - if (skb->len < len || !pskb_may_pull(skb, len)) + if (transport_len < sizeof(struct mld2_query)) + return -EINVAL; + + len = skb_transport_offset(skb) + sizeof(struct mld2_query); + if (!ipv6_mc_may_pull(skb, len)) return -EINVAL; }
@@ -115,7 +115,13 @@ static int ipv6_mc_check_mld_query(struct sk_buff *skb)
static int ipv6_mc_check_mld_msg(struct sk_buff *skb) { - struct mld_msg *mld = (struct mld_msg *)skb_transport_header(skb); + unsigned int len = skb_transport_offset(skb) + sizeof(struct mld_msg); + struct mld_msg *mld; + + if (!ipv6_mc_may_pull(skb, len)) + return -EINVAL; + + mld = (struct mld_msg *)skb_transport_header(skb);
switch (mld->mld_type) { case ICMPV6_MGM_REDUCTION: @@ -136,36 +142,24 @@ static inline __sum16 ipv6_mc_validate_checksum(struct sk_buff *skb) return skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo); }
-static int __ipv6_mc_check_mld(struct sk_buff *skb) - +static int ipv6_mc_check_icmpv6(struct sk_buff *skb) { - struct sk_buff *skb_chk = NULL; - unsigned int transport_len; - unsigned int len = skb_transport_offset(skb) + sizeof(struct mld_msg); - int ret = -EINVAL; + unsigned int len = skb_transport_offset(skb) + sizeof(struct icmp6hdr); + unsigned int transport_len = ipv6_transport_len(skb); + struct sk_buff *skb_chk;
- transport_len = ntohs(ipv6_hdr(skb)->payload_len); - transport_len -= skb_transport_offset(skb) - sizeof(struct ipv6hdr); + if (!ipv6_mc_may_pull(skb, len)) + return -EINVAL;
skb_chk = skb_checksum_trimmed(skb, transport_len, ipv6_mc_validate_checksum); if (!skb_chk) - goto err; + return -EINVAL;
- if (!pskb_may_pull(skb_chk, len)) - goto err; - - ret = ipv6_mc_check_mld_msg(skb_chk); - if (ret) - goto err; - - ret = 0; - -err: - if (skb_chk && skb_chk != skb) + if (skb_chk != skb) kfree_skb(skb_chk);
- return ret; + return 0; }
/** @@ -195,6 +189,10 @@ int ipv6_mc_check_mld(struct sk_buff *skb) if (ret < 0) return ret;
- return __ipv6_mc_check_mld(skb); + ret = ipv6_mc_check_icmpv6(skb); + if (ret < 0) + return ret; + + return ipv6_mc_check_mld_msg(skb); } EXPORT_SYMBOL(ipv6_mc_check_mld);