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| author | Zhenlei Huang <zlei@FreeBSD.org> | 2024-05-20 12:14:07 +0000 |
|---|---|---|
| committer | Zhenlei Huang <zlei@FreeBSD.org> | 2024-05-22 23:00:03 +0000 |
| commit | 34db75d21876ae406ff57fdc594f151fc4214109 (patch) | |
| tree | e8793353a240071a162de2b46a3d71fc93029d62 | |
| parent | b0a1a3138a37b7849d1fb735e6b5c2cd392a2e8b (diff) | |
| download | src-34db75d21876ae406ff57fdc594f151fc4214109.tar.gz src-34db75d21876ae406ff57fdc594f151fc4214109.zip | |
if_vxlan(4): Add checking for loops and nesting of tunnels
User misconfiguration, either tunnel loops, or a large number of
different nested tunnels, can overflow the kernel stack. Prevent that
by using if_tunnel_check_nesting().
PR: 278394
Diagnosed by: markj
Reviewed by: kp
Approved by: re (cperciva)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D45197
(cherry picked from commit 93fbfef0b50354b7a1620822454ef29cd415cb2d)
(cherry picked from commit 3ebd2b1c730834123a53b3eddcf9029fcf414782)
| -rw-r--r-- | sys/net/if_vxlan.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/sys/net/if_vxlan.c b/sys/net/if_vxlan.c index e6949bb5dc9a..87648abd116b 100644 --- a/sys/net/if_vxlan.c +++ b/sys/net/if_vxlan.c @@ -433,6 +433,21 @@ TUNABLE_INT("net.link.vxlan.legacy_port", &vxlan_legacy_port); static int vxlan_reuse_port = 0; TUNABLE_INT("net.link.vxlan.reuse_port", &vxlan_reuse_port); +/* + * This macro controls the default upper limitation on nesting of vxlan + * tunnels. By default it is 3, as the overhead of IPv6 vxlan tunnel is 70 + * bytes, this will create at most 210 bytes overhead and the most inner + * tunnel's MTU will be 1290 which will meet IPv6 minimum MTU size 1280. + * Be careful to configure the tunnels when raising the limit. A large + * number of nested tunnels can introduce system crash. + */ +#ifndef MAX_VXLAN_NEST +#define MAX_VXLAN_NEST 3 +#endif +static int max_vxlan_nesting = MAX_VXLAN_NEST; +SYSCTL_INT(_net_link_vxlan, OID_AUTO, max_nesting, CTLFLAG_RW, + &max_vxlan_nesting, 0, "Max nested tunnels"); + /* Default maximum number of addresses in the forwarding table. */ #ifndef VXLAN_FTABLE_MAX #define VXLAN_FTABLE_MAX 2000 @@ -2722,6 +2737,7 @@ vxlan_encap6(struct vxlan_softc *sc, const union vxlan_sockaddr *fvxlsa, #endif } +#define MTAG_VXLAN_LOOP 0x7876706c /* vxlp */ static int vxlan_transmit(struct ifnet *ifp, struct mbuf *m) { @@ -2747,6 +2763,13 @@ vxlan_transmit(struct ifnet *ifp, struct mbuf *m) m_freem(m); return (ENETDOWN); } + if (__predict_false(if_tunnel_check_nesting(ifp, m, MTAG_VXLAN_LOOP, + max_vxlan_nesting) != 0)) { + VXLAN_RUNLOCK(sc, &tracker); + m_freem(m); + if_inc_counter(ifp, IFCOUNTER_OERRORS, 1); + return (ELOOP); + } if ((m->m_flags & (M_BCAST | M_MCAST)) == 0) fe = vxlan_ftable_entry_lookup(sc, eh->ether_dhost); |