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authorSabrina Dubroca <sd@queasysnail.net>2018-02-26 16:13:43 +0100
committerDavid S. Miller <davem@davemloft.net>2018-02-27 11:13:36 -0500
commitc7272c2f1229125f74f22dcdd59de9bbd804f1c8 (patch)
tree4f70a439a495a90316a1ba294b9ddadcbf7cf292 /net
parentMerge branch 'for-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth (diff)
downloadlinux-dev-c7272c2f1229125f74f22dcdd59de9bbd804f1c8.tar.xz
linux-dev-c7272c2f1229125f74f22dcdd59de9bbd804f1c8.zip
net: ipv4: don't allow setting net.ipv4.route.min_pmtu below 68
According to RFC 1191 sections 3 and 4, ICMP frag-needed messages indicating an MTU below 68 should be rejected: A host MUST never reduce its estimate of the Path MTU below 68 octets. and (talking about ICMP frag-needed's Next-Hop MTU field): This field will never contain a value less than 68, since every router "must be able to forward a datagram of 68 octets without fragmentation". Furthermore, by letting net.ipv4.route.min_pmtu be set to negative values, we can end up with a very large PMTU when (-1) is cast into u32. Let's also make ip_rt_min_pmtu a u32, since it's only ever compared to unsigned ints. Reported-by: Jianlin Shi <jishi@redhat.com> Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> Reviewed-by: Stefano Brivio <sbrivio@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/route.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index a4f44d815a61..95484376ec9b 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -128,10 +128,13 @@ static int ip_rt_redirect_silence __read_mostly = ((HZ / 50) << (9 + 1));
static int ip_rt_error_cost __read_mostly = HZ;
static int ip_rt_error_burst __read_mostly = 5 * HZ;
static int ip_rt_mtu_expires __read_mostly = 10 * 60 * HZ;
-static int ip_rt_min_pmtu __read_mostly = 512 + 20 + 20;
+static u32 ip_rt_min_pmtu __read_mostly = 512 + 20 + 20;
static int ip_rt_min_advmss __read_mostly = 256;
static int ip_rt_gc_timeout __read_mostly = RT_GC_TIMEOUT;
+
+static int ip_min_valid_pmtu __read_mostly = IPV4_MIN_MTU;
+
/*
* Interface to generic destination cache.
*/
@@ -2933,7 +2936,8 @@ static struct ctl_table ipv4_route_table[] = {
.data = &ip_rt_min_pmtu,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &ip_min_valid_pmtu,
},
{
.procname = "min_adv_mss",