Author: kp
Date: Sat Apr 18 07:50:30 2020
New Revision: 360068
URL: https://svnweb.freebsd.org/changeset/base/360068
Log:
ethersubr: Make the mac address generation more robust
If we create two (vnet) jails and create a bridge interface in each
we end up
with the same mac address on both bridge interfaces.
These very often conflicts, resulting in same mac address in both
jails.
Mitigate this problem by including the jail name in the mac address.
Reviewed by: kevans, melifaro
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D24383
Modified:
head/sys/kern/kern_jail.c
head/sys/net/if_ethersubr.c
head/sys/sys/jail.h
Modified: head/sys/kern/kern_jail.c
==============================================================================
--- head/sys/kern/kern_jail.c Sat Apr 18 03:14:16 2020 (r360067)
+++ head/sys/kern/kern_jail.c Sat Apr 18 07:50:30 2020 (r360068)
@@ -2920,6 +2920,15 @@ getcredhostid(struct ucred *cred, unsigned
long *hosti
mtx_unlock(&cred->cr_prison->pr_mtx);
}
+void
+getjailname(struct ucred *cred, char *name, size_t len)
+{
+
+ mtx_lock(&cred->cr_prison->pr_mtx);
+ strlcpy(name, cred->cr_prison->pr_name, len);
+ mtx_unlock(&cred->cr_prison->pr_mtx);
+}
+
#ifdef VIMAGE
/*
* Determine whether the prison represented by cred owns
Modified: head/sys/net/if_ethersubr.c
==============================================================================
--- head/sys/net/if_ethersubr.c Sat Apr 18 03:14:16 2020 (r360067)
+++ head/sys/net/if_ethersubr.c Sat Apr 18 07:50:30 2020 (r360068)
@@ -1419,27 +1419,39 @@ ether_8021q_frame(struct mbuf **mp, struct
ifnet *ife,
/*
* Allocate an address from the FreeBSD Foundation OUI. This uses a
- * cryptographic hash function on the containing jail's UUID and the
interface
- * name to attempt to provide a unique but stable address.
Pseudo-interfaces
- * which require a MAC address should use this function to allocate
- * non-locally-administered addresses.
+ * cryptographic hash function on the containing jail's name, UUID
and the
+ * interface name to attempt to provide a unique but stable address.
+ * Pseudo-interfaces which require a MAC address should use this
function to
+ * allocate non-locally-administered addresses.
*/
void
ether_gen_addr(struct ifnet *ifp, struct ether_addr *hwaddr)
{
-#define ETHER_GEN_ADDR_BUFSIZ HOSTUUIDLEN + IFNAMSIZ + 2
SHA1_CTX ctx;
- char buf[ETHER_GEN_ADDR_BUFSIZ];
+ char *buf;
char uuid[HOSTUUIDLEN + 1];
uint64_t addr;
int i, sz;
char digest[SHA1_RESULTLEN];
+ char jailname[MAXHOSTNAMELEN];
getcredhostuuid(curthread->td_ucred, uuid, sizeof(uuid));
- sz = snprintf(buf, ETHER_GEN_ADDR_BUFSIZ, "%s-%s", uuid,
ifp->if_xname);
+ /* If each (vnet) jail would also have a unique hostuuid this would
not
+ * be necessary. */
+ getjailname(curthread->td_ucred, jailname, sizeof(jailname));
+ sz = asprintf(&buf, M_TEMP, "%s-%s-%s", uuid, if_name(ifp),
+ jailname);
+ if (sz < 0) {
+ /* Fall back to a random mac address. */
