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
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=334094
@ -53,10 +53,14 @@
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/hash.h>
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#include <sys/jail.h>
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#include <sys/kernel.h>
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#include <sys/libkern.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/module.h>
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#include <sys/proc.h>
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#include <sys/refcount.h>
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#include <sys/queue.h>
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#include <sys/smp.h>
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@ -713,6 +717,9 @@ epair_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
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struct ifnet *ifp;
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char *dp;
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int error, unit, wildcard;
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uint64_t hostid;
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uint32_t key[3];
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uint32_t hash;
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uint8_t eaddr[ETHER_ADDR_LEN]; /* 00:00:00:00:00:00 */
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/*
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@ -724,14 +731,12 @@ epair_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
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if (params) {
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scb = (struct epair_softc *)params;
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ifp = scb->ifp;
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/* Assign a hopefully unique, locally administered etheraddr. */
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eaddr[0] = 0x02;
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eaddr[3] = (ifp->if_index >> 8) & 0xff;
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eaddr[4] = ifp->if_index & 0xff;
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/* Copy epairNa etheraddr and change the last byte. */
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memcpy(eaddr, scb->oifp->if_hw_addr, ETHER_ADDR_LEN);
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eaddr[5] = 0x0b;
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ether_ifattach(ifp, eaddr);
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/* Correctly set the name for the cloner list. */
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strlcpy(name, scb->ifp->if_xname, len);
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strlcpy(name, ifp->if_xname, len);
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return (0);
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}
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@ -835,10 +840,21 @@ epair_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
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ifp->if_init = epair_init;
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if_setsendqlen(ifp, ifqmaxlen);
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if_setsendqready(ifp);
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/* Assign a hopefully unique, locally administered etheraddr. */
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/*
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* Calculate the etheraddr hashing the hostid and the
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* interface index. The result would be hopefully unique
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*/
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getcredhostid(curthread->td_ucred, (unsigned long *)&hostid);
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if (hostid == 0)
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arc4rand(&hostid, sizeof(hostid), 0);
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key[0] = (uint32_t)ifp->if_index;
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key[1] = (uint32_t)(hostid & 0xffffffff);
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key[2] = (uint32_t)((hostid >> 32) & 0xfffffffff);
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hash = jenkins_hash32(key, 3, 0);
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eaddr[0] = 0x02;
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eaddr[3] = (ifp->if_index >> 8) & 0xff;
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eaddr[4] = ifp->if_index & 0xff;
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memcpy(&eaddr[1], &hash, 4);
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eaddr[5] = 0x0a;
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ether_ifattach(ifp, eaddr);
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sca->if_qflush = ifp->if_qflush;
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