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Separately locate external interfaces for IPv4 and IPv6

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Now that the back end allows passt/pasta to use different external
interfaces for IPv4 and IPv6, use that to do the right thing in the case
that the host has IPv4 and IPv6 connectivity via different interfaces.
If the user hasn't explicitly chosen an interface, separately search for
a suitable external interface for each protocol.

As a bonus, this substantially simplifies the external interface probe.  It
also eliminates a subtle confusing case where in some circumstances we
would pick the first interface in interface index order, and sometimes in
order of routes returned from netlink.  On some network configurations that
could cause tests to fail, because the logic in the tests was subtly
different (it always used route order).

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
David Gibson 2022-07-22 15:31:13 +10:00 committed by Stefano Brivio
parent 3eaf9f5320
commit 06abfcf6d9
7 changed files with 33 additions and 80 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
conf.c
View File

@ -630,8 +630,23 @@ static void conf_ip(struct ctx *c)
v4 = v6 = IP_VERSION_PROBE;
}
if (!c->ifi4 && !c->ifi6)
c->ifi4 = c->ifi6 = nl_get_ext_if(&v4, &v6);
if (v4 != IP_VERSION_DISABLED) {
if (!c->ifi4)
c->ifi4 = nl_get_ext_if(AF_INET);
if (!c->ifi4) {
warn("No external routable interface for IPv4");
v4 = IP_VERSION_DISABLED;
}
}
if (v6 != IP_VERSION_DISABLED) {
if (!c->ifi6)
c->ifi6 = nl_get_ext_if(AF_INET6);
if (!c->ifi6) {
warn("No external routable interface for IPv6");
v6 = IP_VERSION_DISABLED;
}
}
if (v4 != IP_VERSION_DISABLED) {
if (!c->gw4)

79
netlink.c
View File

@ -126,13 +126,13 @@ static int nl_req(int ns, char *buf, const void *req, ssize_t len)
}
/**
* nl_get_ext_if() - Get interface index supporting IP versions being probed
* @v4: Probe IPv4 support, set to ENABLED or DISABLED on return
* @v6: Probe IPv4 support, set to ENABLED or DISABLED on return
* nl_get_ext_if() - Get interface index supporting IP version being probed
* @af: Address family (AF_INET or AF_INET6) to look for connectivity
* for.
*
* Return: interface index, 0 if not found
*/
unsigned int nl_get_ext_if(int *v4, int *v6)
unsigned int nl_get_ext_if(sa_family_t af)
{
struct { struct nlmsghdr nlh; struct rtmsg rtm; } req = {
.nlh.nlmsg_type = RTM_GETROUTE,
@ -143,32 +143,14 @@ unsigned int nl_get_ext_if(int *v4, int *v6)
.rtm.rtm_table = RT_TABLE_MAIN,
.rtm.rtm_scope = RT_SCOPE_UNIVERSE,
.rtm.rtm_type = RTN_UNICAST,
.rtm.rtm_family = af,
};
unsigned int i, first_v4 = 0, first_v6 = 0;
uint8_t has_v4[PAGE_SIZE * 8 / 8] = { 0 }; /* See __dev_alloc_name() */
uint8_t has_v6[PAGE_SIZE * 8 / 8] = { 0 }; /* in kernel */
struct nlmsghdr *nh;
struct rtattr *rta;
struct rtmsg *rtm;
char buf[BUFSIZ];
long *word, tmp;
uint8_t *vmap;
ssize_t n;
size_t na;
int *v;
if (*v4 == IP_VERSION_PROBE) {
v = v4;
req.rtm.rtm_family = AF_INET;
vmap = has_v4;
} else if (*v6 == IP_VERSION_PROBE) {
v6:
v = v6;
req.rtm.rtm_family = AF_INET6;
vmap = has_v6;
} else {
return 0;
}
if ((n = nl_req(0, buf, &req, sizeof(req))) < 0)
return 0;
@ -178,7 +160,7 @@ v6:
for ( ; NLMSG_OK(nh, n); nh = NLMSG_NEXT(nh, n)) {
rtm = (struct rtmsg *)NLMSG_DATA(nh);
if (rtm->rtm_dst_len || rtm->rtm_family != req.rtm.rtm_family)
if (rtm->rtm_dst_len || rtm->rtm_family != af)
continue;
for (rta = RTM_RTA(rtm), na = RTM_PAYLOAD(nh); RTA_OK(rta, na);
@ -190,57 +172,10 @@ v6:
ifi = *(unsigned int *)RTA_DATA(rta);
if (*v4 == IP_VERSION_DISABLED ||
*v6 == IP_VERSION_DISABLED) {
*v = IP_VERSION_ENABLED;
return ifi;
}
if (v == v4 && !first_v4)
first_v4 = ifi;
if (v == v6 && !first_v6)
first_v6 = ifi;
bitmap_set(vmap, ifi);
return ifi;
}
}
if (v == v4 && *v6 == IP_VERSION_PROBE) {
req.nlh.nlmsg_seq = nl_seq++;
goto v6;
}
word = (long *)has_v4;
for (i = 0; i < ARRAY_SIZE(has_v4) / sizeof(long); i++, word++) {
tmp = *word;
while ((n = ffsl(tmp))) {
int ifi = i * sizeof(long) * 8 + n - 1;
if (!first_v4)
first_v4 = ifi;
tmp &= ~(1UL << (n - 1));
if (bitmap_isset(has_v6, ifi)) {
*v4 = *v6 = IP_VERSION_ENABLED;
return ifi;
}
}
}
if (first_v4) {
*v4 = IP_VERSION_ENABLED;
*v6 = IP_VERSION_DISABLED;
return first_v4;
}
if (first_v6) {
*v4 = IP_VERSION_DISABLED;
*v6 = IP_VERSION_ENABLED;
return first_v6;
}
err("No external routable interface for any IP protocol");
return 0;
}

2
netlink.h
View File

@ -7,7 +7,7 @@
#define NETLINK_H
int nl_sock_init(const struct ctx *c);
unsigned int nl_get_ext_if(int *v4, int *v6);
unsigned int nl_get_ext_if(sa_family_t af);
void nl_route(int ns, unsigned int ifi, sa_family_t af, void *gw);
void nl_addr(int ns, unsigned int ifi, sa_family_t af,
void *addr, int *prefix_len, void *addr_l);

3
test/dhcp/passt
View File

@ -17,6 +17,7 @@ htools ip jq sed tr head
test Interface name
gout IFNAME ip -j link show | jq -rM '.[] | select(.link_type == "ether").ifname'
hout HOST_IFNAME ip -j -4 route show|jq -rM '[.[] | select(.dst == "default").dev] | .[0]'
hout HOST_IFNAME6 ip -j -6 route show|jq -rM '[.[] | select(.dst == "default").dev] | .[0]'
check [ -n "__IFNAME__" ]
test DHCP: address
@ -49,7 +50,7 @@ check [ "__SEARCH__" = "__HOST_SEARCH__" ]
test DHCPv6: address
guest /sbin/dhclient -6 __IFNAME__
gout ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.prefixlen == 128).local'
hout HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME__").addr_info[] | select(.scope == "global").local'
hout HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local'
check [ "__ADDR6__" = "__HOST_ADDR6__" ]
test DHCPv6: route

3
test/dhcp/pasta
View File

@ -35,8 +35,9 @@ check [ __MTU__ = 65520 ]
test DHCPv6: address
ns /sbin/dhclient -6 --no-pid __IFNAME__
hout HOST_IFNAME6 ip -j -6 route show|jq -rM '[.[] | select(.dst == "default").dev] | .[0]'
nsout ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.prefixlen == 128).local'
hout HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global").local'
hout HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local'
check [ __ADDR6__ = __HOST_ADDR6__ ]
test DHCPv6: route

4
test/ndp/passt
View File

@ -17,13 +17,13 @@ htools ip jq sipcalc grep cut
test Interface name
gout IFNAME ip -j link show | jq -rM '.[] | select(.link_type == "ether").ifname'
guest ip link set dev __IFNAME__ up && sleep 2
hout HOST_IFNAME ip -j -4 route show|jq -rM '.[] | select(.dst == "default").dev'
hout HOST_IFNAME6 ip -j -6 route show|jq -rM '.[] | select(.dst == "default").dev'
check [ -n "__IFNAME__" ]
test SLAAC: prefix
gout ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .prefixlen == 64).local'
gout PREFIX6 sipcalc __ADDR6__/64 | grep prefix | cut -d' ' -f4
hout HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME__").addr_info[] | select(.scope == "global").local'
hout HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local'
hout HOST_PREFIX6 sipcalc __HOST_ADDR6__/64 | grep prefix | cut -d' ' -f4
check [ "__PREFIX6__" = "__HOST_PREFIX6__" ]

3
test/two_guests/basic
View File

@ -19,6 +19,7 @@ test Interface names
g1out IFNAME1 ip -j link show | jq -rM '.[] | select(.link_type == "ether").ifname'
g2out IFNAME2 ip -j link show | jq -rM '.[] | select(.link_type == "ether").ifname'
hout HOST_IFNAME ip -j -4 route show|jq -rM '[.[] | select(.dst == "default").dev] | .[0]'
hout HOST_IFNAME6 ip -j -6 route show|jq -rM '[.[] | select(.dst == "default").dev] | .[0]'
check [ -n "__IFNAME1__" ]
check [ -n "__IFNAME2__" ]
@ -40,7 +41,7 @@ guest1 /sbin/dhclient -6 __IFNAME1__
guest2 /sbin/dhclient -6 __IFNAME2__
g1out ADDR1_6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME1__").addr_info[] | select(.prefixlen == 128).local'
g2out ADDR2_6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME2__").addr_info[] | select(.prefixlen == 128).local'
hout HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME__").addr_info[] | select(.scope == "global").local'
hout HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local'
check [ "__ADDR1_6__" = "__HOST_ADDR6__" ]
check [ "__ADDR2_6__" = "__HOST_ADDR6__" ]