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Fix rt_ifa selection during loopback route insertion process.

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Currently such routes are added with a link-level IFA, which is
  plain wrong. Only after the insertion they get fixed by the special
  link_rtrequest() ifa handler. This behaviour complicates routing code
  and makes ifa selection more complex.
Streamline this process by explicitly moving link_rtrequest() logic
  to the pre-insertion rt_getifa_fib() ifa selector. Avoid calling all
  this logic in the loopback route case by explicitly specifying
  proper rt_ifa inside the ifa_maintain_loopback_route().§

MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D20076
This commit is contained in:
Alexander V. Chernikov 2019-05-19 21:49:56 +00:00
parent 980bde5834
commit 2ad7ed6e4a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=347982
2 changed files with 54 additions and 43 deletions
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46
sys/net/if.c
View File

@ -264,7 +264,6 @@ static void if_route(struct ifnet *, int flag, int fam);
static int if_setflag(struct ifnet *, int, int, int *, int);
static int if_transmit(struct ifnet *ifp, struct mbuf *m);
static void if_unroute(struct ifnet *, int flag, int fam);
static void link_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
static int if_delmulti_locked(struct ifnet *, struct ifmultiaddr *, int);
static void do_link_state_change(void *, int);
static int if_getgroup(struct ifgroupreq *, struct ifnet *);
@ -862,7 +861,6 @@ if_attach_internal(struct ifnet *ifp, int vmove, struct if_clone *ifc)
sdl->sdl_type = ifp->if_type;
ifp->if_addr = ifa;
ifa->ifa_ifp = ifp;
ifa->ifa_rtrequest = link_rtrequest;
ifa->ifa_addr = (struct sockaddr *)sdl;
sdl = (struct sockaddr_dl *)(socksize + (caddr_t)sdl);
ifa->ifa_netmask = (struct sockaddr *)sdl;
@ -1892,6 +1890,7 @@ static int
ifa_maintain_loopback_route(int cmd, const char *otype, struct ifaddr *ifa,
struct sockaddr *ia)
{
struct epoch_tracker et;
int error;
struct rt_addrinfo info;
struct sockaddr_dl null_sdl;
@ -1902,6 +1901,16 @@ ifa_maintain_loopback_route(int cmd, const char *otype, struct ifaddr *ifa,
bzero(&info, sizeof(info));
if (cmd != RTM_DELETE)
info.rti_ifp = V_loif;
if (cmd == RTM_ADD) {
/* explicitly specify (loopback) ifa */
if (info.rti_ifp != NULL) {
NET_EPOCH_ENTER(et);
info.rti_ifa = ifaof_ifpforaddr(ifa->ifa_addr, info.rti_ifp);
if (info.rti_ifa != NULL)
ifa_ref(info.rti_ifa);
NET_EPOCH_EXIT(et);
}
}
info.rti_flags = ifa->ifa_flags | RTF_HOST | RTF_STATIC | RTF_PINNED;
info.rti_info[RTAX_DST] = ia;
info.rti_info[RTAX_GATEWAY] = (struct sockaddr *)&null_sdl;
@ -2210,39 +2219,6 @@ ifa_preferred(struct ifaddr *cur, struct ifaddr *next)
((*carp_master_p)(next) && !(*carp_master_p)(cur))));
}
#include <net/if_llatbl.h>
/*
* Default action when installing a route with a Link Level gateway.
* Lookup an appropriate real ifa to point to.
* This should be moved to /sys/net/link.c eventually.
*/
static void
link_rtrequest(int cmd, struct rtentry *rt, struct rt_addrinfo *info)
{
struct epoch_tracker et;
struct ifaddr *ifa, *oifa;
struct sockaddr *dst;
struct ifnet *ifp;
if (cmd != RTM_ADD || ((ifa = rt->rt_ifa) == NULL) ||
((ifp = ifa->ifa_ifp) == NULL) || ((dst = rt_key(rt)) == NULL))
return;
NET_EPOCH_ENTER(et);
ifa = ifaof_ifpforaddr(dst, ifp);
if (ifa) {
oifa = rt->rt_ifa;
if (oifa != ifa) {
ifa_free(oifa);
ifa_ref(ifa);
}
rt->rt_ifa = ifa;
if (ifa->ifa_rtrequest && ifa->ifa_rtrequest != link_rtrequest)
ifa->ifa_rtrequest(cmd, rt, info);
}
NET_EPOCH_EXIT(et);
}
struct sockaddr_dl *
link_alloc_sdl(size_t size, int flags)
{

51
sys/net/route.c
View File

@ -1276,12 +1276,14 @@ rt_notifydelete(struct rtentry *rt, struct rt_addrinfo *info)
/*
* Look up rt_addrinfo for a specific fib. Note that if rti_ifa is defined,
* it will be referenced so the caller must free it.
*
* Assume basic consistency checks are executed by callers:
* RTAX_DST exists, if RTF_GATEWAY is set, RTAX_GATEWAY exists as well.
*/
int
rt_getifa_fib(struct rt_addrinfo *info, u_int fibnum)
{
struct epoch_tracker et;
struct ifaddr *ifa;
int needref, error;
/*
@ -1291,21 +1293,54 @@ rt_getifa_fib(struct rt_addrinfo *info, u_int fibnum)
error = 0;
needref = (info->rti_ifa == NULL);
NET_EPOCH_ENTER(et);
/* If we have interface specified by the ifindex in the address, use it */
if (info->rti_ifp == NULL && ifpaddr != NULL &&
ifpaddr->sa_family == AF_LINK &&
(ifa = ifa_ifwithnet(ifpaddr, 0, fibnum)) != NULL) {
info->rti_ifp = ifa->ifa_ifp;
ifpaddr->sa_family == AF_LINK) {
const struct sockaddr_dl *sdl = (const struct sockaddr_dl *)ifpaddr;
if (sdl->sdl_index != 0)
info->rti_ifp = ifnet_byindex_locked(sdl->sdl_index);
}
/*
* If we have source address specified, try to find it
* TODO: avoid enumerating all ifas on all interfaces.
*/
if (info->rti_ifa == NULL && ifaaddr != NULL)
info->rti_ifa = ifa_ifwithaddr(ifaaddr);
if (info->rti_ifa == NULL) {
struct sockaddr *sa;
sa = ifaaddr != NULL ? ifaaddr :
(gateway != NULL ? gateway : dst);
if (sa != NULL && info->rti_ifp != NULL)
/*
* Most common use case for the userland-supplied routes.
*
* Choose sockaddr to select ifa.
* -- if ifp is set --
* Order of preference:
* 1) IFA address
* 2) gateway address
* Note: for interface routes link-level gateway address
* is specified to indicate the interface index without
* specifying RTF_GATEWAY. In this case, ignore gateway
* Note: gateway AF may be different from dst AF. In this case,
* ignore gateway
* 3) final destination.
* 4) if all of these fails, try to get at least link-level ifa.
* -- else --
* try to lookup gateway or dst in the routing table to get ifa
*/
if (info->rti_info[RTAX_IFA] != NULL)
sa = info->rti_info[RTAX_IFA];
else if ((info->rti_flags & RTF_GATEWAY) != 0 &&
gateway->sa_family == dst->sa_family)
sa = gateway;
else
sa = dst;
if (info->rti_ifp != NULL) {
info->rti_ifa = ifaof_ifpforaddr(sa, info->rti_ifp);
else if (dst != NULL && gateway != NULL)
/* Case 4 */
if (info->rti_ifa == NULL && gateway != NULL)
info->rti_ifa = ifaof_ifpforaddr(gateway, info->rti_ifp);
} else if (dst != NULL && gateway != NULL)
info->rti_ifa = ifa_ifwithroute(flags, dst, gateway,
fibnum);
else if (sa != NULL)