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. */ + arc4rand(hwaddr, sizeof(*hwaddr), 0); + hwaddr->octet[0] = 0x02; + return; + } + SHA1Init(&ctx); SHA1Update(&ctx, buf, sz); SHA1Final(digest, &ctx); + free(buf, M_TEMP); addr = ((digest[0] << 16) | (digest[1] << 8) | digest[2]) & OUI_FREEBSD_GENERATED_MASK; Modified: head/sys/sys/jail.h ============================================================================== --- head/sys/sys/jail.h Sat Apr 18 03:14:16 2020 (r360067) +++ head/sys/sys/jail.h Sat Apr 18 07:50:30 2020 (r360068) @@ -382,6 +382,7 @@ void getcredhostname(struct ucred *, char *, size_t); void getcreddomainname(struct ucred *, char *, size_t); void getcredhostuuid(struct ucred *, char *, size_t); void getcredhostid(struct ucred *, unsigned long *); +void getjailname(struct ucred *cred, char *name, size_t len); void prison0_init(void); int prison_allow(struct ucred *, unsigned); int prison_check(struct ucred *cred1, struct ucred *cred2); _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
