The branch main has been updated by kevans: URL: https://cgit.FreeBSD.org/src/commit/?id=2d741f33bd07bf94a59635db3c7b9e070a8a6e55
commit 2d741f33bd07bf94a59635db3c7b9e070a8a6e55 Author: Kyle Evans <[email protected]> AuthorDate: 2021-04-16 01:11:35 +0000 Commit: Kyle Evans <[email protected]> CommitDate: 2021-06-02 03:59:21 +0000 kern: ether_gen_addr: randomize on default hostuuid, too Currently, this will still hash the default (all zero) hostuuid and potentially arrive at a MAC address that has a high chance of collision if another interface of the same name appears in the same broadcast domain on another host without a hostuuid, e.g., some virtual machine setups. Instead of using the default hostuuid, just treat it as a failure and generate a random LA unicast MAC address. Reviewed by: bz, gbe, imp, kbowling, kp MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D29788 --- share/man/man9/ether_gen_addr.9 | 5 +++-- sys/kern/kern_jail.c | 1 - sys/net/if_ethersubr.c | 17 ++++++++++++++--- sys/sys/jail.h | 1 + 4 files changed, 18 insertions(+), 6 deletions(-) diff --git a/share/man/man9/ether_gen_addr.9 b/share/man/man9/ether_gen_addr.9 index 1b98a841736d..f69cb199e2c3 100644 --- a/share/man/man9/ether_gen_addr.9 +++ b/share/man/man9/ether_gen_addr.9 @@ -61,8 +61,9 @@ or on machines that do not use .Xr loader 8 . .Pp .Nm -can fail to derive a MAC address due to memory allocation failure. -In this case, a locally-administered unicast MAC address will be randomly +can fail to derive a MAC address due to memory allocation failure, or because +the hostid has not been populated. +In these cases, a locally-administered unicast MAC address will be randomly generated and returned via the .Ar hwaddr parameter. diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c index 303e31490eb1..9784f3bfc23b 100644 --- a/sys/kern/kern_jail.c +++ b/sys/kern/kern_jail.c @@ -76,7 +76,6 @@ __FBSDID("$FreeBSD$"); #include <security/mac/mac_framework.h> -#define DEFAULT_HOSTUUID "00000000-0000-0000-0000-000000000000" #define PRISON0_HOSTUUID_MODULE "hostuuid" MALLOC_DEFINE(M_PRISON, "prison", "Prison structures"); diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c index 01c2d2f7b3e8..7eb46df8281a 100644 --- a/sys/net/if_ethersubr.c +++ b/sys/net/if_ethersubr.c @@ -1443,6 +1443,11 @@ ether_gen_addr(struct ifnet *ifp, struct ether_addr *hwaddr) char jailname[MAXHOSTNAMELEN]; getcredhostuuid(curthread->td_ucred, uuid, sizeof(uuid)); + if (strncmp(uuid, DEFAULT_HOSTUUID, sizeof(uuid)) == 0) { + /* Fall back to a random mac address. */ + goto rando; + } + /* If each (vnet) jail would also have a unique hostuuid this would not * be necessary. */ getjailname(curthread->td_ucred, jailname, sizeof(jailname)); @@ -1450,9 +1455,7 @@ ether_gen_addr(struct ifnet *ifp, struct ether_addr *hwaddr) jailname); if (sz < 0) { /* Fall back to a random mac address. */ - arc4rand(hwaddr, sizeof(*hwaddr), 0); - hwaddr->octet[0] = 0x02; - return; + goto rando; } SHA1Init(&ctx); @@ -1467,6 +1470,14 @@ ether_gen_addr(struct ifnet *ifp, struct ether_addr *hwaddr) hwaddr->octet[i] = addr >> ((ETHER_ADDR_LEN - i - 1) * 8) & 0xFF; } + + return; +rando: + arc4rand(hwaddr, sizeof(*hwaddr), 0); + /* Unicast */ + hwaddr->octet[0] &= 0xFE; + /* Locally administered. */ + hwaddr->octet[0] |= 0x02; } DECLARE_MODULE(ether, ether_mod, SI_SUB_INIT_IF, SI_ORDER_ANY); diff --git a/sys/sys/jail.h b/sys/sys/jail.h index c9d4c65e4d9e..76ed377e3f06 100644 --- a/sys/sys/jail.h +++ b/sys/sys/jail.h @@ -140,6 +140,7 @@ MALLOC_DECLARE(M_PRISON); #include <sys/osd.h> #define HOSTUUIDLEN 64 +#define DEFAULT_HOSTUUID "00000000-0000-0000-0000-000000000000" #define OSRELEASELEN 32 struct racct; _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/dev-commits-src-all To unsubscribe, send any mail to "[email protected]"
