Date: Wed, 23 May 2018 13:10:58 +0000 (UTC) From: Luca Pizzamiglio <pizzamig@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r334094 - head/sys/net Message-ID: <201805231310.w4NDAwJn031430@repo.freebsd.org>
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Author: pizzamig (ports committer) Date: Wed May 23 13:10:57 2018 New Revision: 334094 URL: https://svnweb.freebsd.org/changeset/base/334094 Log: Improve MAC address uniqueness on if_epair(4). As reported in PR184149, it can happen that epair devices can have the same MAC address. This solution is based on a 32-bit hash, obtained combining the if_index of the a interface and the hostid. If the hostid is zero, a random number is used. PR: 184149 Reviewed by: wollman, eugen Approved by: cognet Differential Revision: https://reviews.freebsd.org/D15329 Modified: head/sys/net/if_epair.c Modified: head/sys/net/if_epair.c ============================================================================== --- head/sys/net/if_epair.c Wed May 23 12:10:16 2018 (r334093) +++ head/sys/net/if_epair.c Wed May 23 13:10:57 2018 (r334094) @@ -53,10 +53,14 @@ __FBSDID("$FreeBSD$"); #include <sys/param.h> +#include <sys/hash.h> +#include <sys/jail.h> #include <sys/kernel.h> +#include <sys/libkern.h> #include <sys/malloc.h> #include <sys/mbuf.h> #include <sys/module.h> +#include <sys/proc.h> #include <sys/refcount.h> #include <sys/queue.h> #include <sys/smp.h> @@ -713,6 +717,9 @@ epair_clone_create(struct if_clone *ifc, char *name, s struct ifnet *ifp; char *dp; int error, unit, wildcard; + uint64_t hostid; + uint32_t key[3]; + uint32_t hash; uint8_t eaddr[ETHER_ADDR_LEN]; /* 00:00:00:00:00:00 */ /* @@ -724,14 +731,12 @@ epair_clone_create(struct if_clone *ifc, char *name, s if (params) { scb = (struct epair_softc *)params; ifp = scb->ifp; - /* Assign a hopefully unique, locally administered etheraddr. */ - eaddr[0] = 0x02; - eaddr[3] = (ifp->if_index >> 8) & 0xff; - eaddr[4] = ifp->if_index & 0xff; + /* Copy epairNa etheraddr and change the last byte. */ + memcpy(eaddr, scb->oifp->if_hw_addr, ETHER_ADDR_LEN); eaddr[5] = 0x0b; ether_ifattach(ifp, eaddr); /* Correctly set the name for the cloner list. */ - strlcpy(name, scb->ifp->if_xname, len); + strlcpy(name, ifp->if_xname, len); return (0); } @@ -835,10 +840,21 @@ epair_clone_create(struct if_clone *ifc, char *name, s ifp->if_init = epair_init; if_setsendqlen(ifp, ifqmaxlen); if_setsendqready(ifp); - /* Assign a hopefully unique, locally administered etheraddr. */ + + /* + * Calculate the etheraddr hashing the hostid and the + * interface index. The result would be hopefully unique + */ + getcredhostid(curthread->td_ucred, (unsigned long *)&hostid); + if (hostid == 0) + arc4rand(&hostid, sizeof(hostid), 0); + key[0] = (uint32_t)ifp->if_index; + key[1] = (uint32_t)(hostid & 0xffffffff); + key[2] = (uint32_t)((hostid >> 32) & 0xfffffffff); + hash = jenkins_hash32(key, 3, 0); + eaddr[0] = 0x02; - eaddr[3] = (ifp->if_index >> 8) & 0xff; - eaddr[4] = ifp->if_index & 0xff; + memcpy(&eaddr[1], &hash, 4); eaddr[5] = 0x0a; ether_ifattach(ifp, eaddr); sca->if_qflush = ifp->if_qflush;
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