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Diffstat (limited to 'net/ipv6/exthdrs.c')
-rw-r--r--net/ipv6/exthdrs.c73
1 files changed, 57 insertions, 16 deletions
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 95516138e861..83bd75713535 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -74,8 +74,20 @@ struct tlvtype_proc {
/* An unknown option is detected, decide what to do */
-static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff)
+static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff,
+ bool disallow_unknowns)
{
+ if (disallow_unknowns) {
+ /* If unknown TLVs are disallowed by configuration
+ * then always silently drop packet. Note this also
+ * means no ICMP parameter problem is sent which
+ * could be a good property to mitigate a reflection DOS
+ * attack.
+ */
+
+ goto drop;
+ }
+
switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
case 0: /* ignore */
return true;
@@ -89,25 +101,36 @@ static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff)
*/
if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
break;
+ /* fall through */
case 2: /* send ICMP PARM PROB regardless and drop packet */
icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
return false;
}
+drop:
kfree_skb(skb);
return false;
}
/* Parse tlv encoded option header (hop-by-hop or destination) */
-static bool ip6_parse_tlv(const struct tlvtype_proc *procs, struct sk_buff *skb)
+static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
+ struct sk_buff *skb,
+ int max_count)
{
- const struct tlvtype_proc *curr;
+ int len = (skb_transport_header(skb)[1] + 1) << 3;
const unsigned char *nh = skb_network_header(skb);
int off = skb_network_header_len(skb);
- int len = (skb_transport_header(skb)[1] + 1) << 3;
+ const struct tlvtype_proc *curr;
+ bool disallow_unknowns = false;
+ int tlv_count = 0;
int padlen = 0;
+ if (unlikely(max_count < 0)) {
+ disallow_unknowns = true;
+ max_count = -max_count;
+ }
+
if (skb_transport_offset(skb) + len > skb_headlen(skb))
goto bad;
@@ -148,6 +171,11 @@ static bool ip6_parse_tlv(const struct tlvtype_proc *procs, struct sk_buff *skb)
default: /* Other TLV code so scan list */
if (optlen > len)
goto bad;
+
+ tlv_count++;
+ if (tlv_count > max_count)
+ goto bad;
+
for (curr = procs; curr->type >= 0; curr++) {
if (curr->type == nh[off]) {
/* type specific length/alignment
@@ -158,10 +186,10 @@ static bool ip6_parse_tlv(const struct tlvtype_proc *procs, struct sk_buff *skb)
break;
}
}
- if (curr->type < 0) {
- if (ip6_tlvopt_unknown(skb, off) == 0)
- return false;
- }
+ if (curr->type < 0 &&
+ !ip6_tlvopt_unknown(skb, off, disallow_unknowns))
+ return false;
+
padlen = 0;
break;
}
@@ -186,7 +214,6 @@ static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
struct ipv6_destopt_hao *hao;
struct inet6_skb_parm *opt = IP6CB(skb);
struct ipv6hdr *ipv6h = ipv6_hdr(skb);
- struct in6_addr tmp_addr;
int ret;
if (opt->dsthao) {
@@ -228,9 +255,7 @@ static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
- tmp_addr = ipv6h->saddr;
- ipv6h->saddr = hao->addr;
- hao->addr = tmp_addr;
+ swap(ipv6h->saddr, hao->addr);
if (skb->tstamp == 0)
__net_timestamp(skb);
@@ -260,23 +285,31 @@ static int ipv6_destopt_rcv(struct sk_buff *skb)
__u16 dstbuf;
#endif
struct dst_entry *dst = skb_dst(skb);
+ struct net *net = dev_net(skb->dev);
+ int extlen;
if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
!pskb_may_pull(skb, (skb_transport_offset(skb) +
((skb_transport_header(skb)[1] + 1) << 3)))) {
__IP6_INC_STATS(dev_net(dst->dev), ip6_dst_idev(dst),
IPSTATS_MIB_INHDRERRORS);
+fail_and_free:
kfree_skb(skb);
return -1;
}
+ extlen = (skb_transport_header(skb)[1] + 1) << 3;
+ if (extlen > net->ipv6.sysctl.max_dst_opts_len)
+ goto fail_and_free;
+
opt->lastopt = opt->dst1 = skb_network_header_len(skb);
#if IS_ENABLED(CONFIG_IPV6_MIP6)
dstbuf = opt->dst1;
#endif
- if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
- skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
+ if (ip6_parse_tlv(tlvprocdestopt_lst, skb,
+ init_net.ipv6.sysctl.max_dst_opts_cnt)) {
+ skb->transport_header += extlen;
opt = IP6CB(skb);
#if IS_ENABLED(CONFIG_IPV6_MIP6)
opt->nhoff = dstbuf;
@@ -805,6 +838,8 @@ static const struct tlvtype_proc tlvprochopopt_lst[] = {
int ipv6_parse_hopopts(struct sk_buff *skb)
{
struct inet6_skb_parm *opt = IP6CB(skb);
+ struct net *net = dev_net(skb->dev);
+ int extlen;
/*
* skb_network_header(skb) is equal to skb->data, and
@@ -815,13 +850,19 @@ int ipv6_parse_hopopts(struct sk_buff *skb)
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
!pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
((skb_transport_header(skb)[1] + 1) << 3)))) {
+fail_and_free:
kfree_skb(skb);
return -1;
}
+ extlen = (skb_transport_header(skb)[1] + 1) << 3;
+ if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
+ goto fail_and_free;
+
opt->flags |= IP6SKB_HOPBYHOP;
- if (ip6_parse_tlv(tlvprochopopt_lst, skb)) {
- skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
+ if (ip6_parse_tlv(tlvprochopopt_lst, skb,
+ init_net.ipv6.sysctl.max_hbh_opts_cnt)) {
+ skb->transport_header += extlen;
opt = IP6CB(skb);
opt->nhoff = sizeof(struct ipv6hdr);
return 1;