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ipv6: Check GATEWAY in rtm_to_fib6_multipath_config().

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In ip6_route_multipath_add(), we call rt6_qualify_for_ecmp() for each
entry.  If it returns false, the request fails.

rt6_qualify_for_ecmp() returns false if either of the conditions below
is true:

  1. f6i->fib6_flags has RTF_ADDRCONF
  2. f6i->nh is not NULL
  3. f6i->fib6_nh->fib_nh_gw_family is AF_UNSPEC

1 is unnecessary because rtm_to_fib6_config() never sets RTF_ADDRCONF
to cfg->fc_flags.

2. is equivalent with cfg->fc_nh_id.

3. can be replaced by checking RTF_GATEWAY in the base and each multipath
entry because AF_INET6 is set to f6i->fib6_nh->fib_nh_gw_family only when
cfg.fc_is_fdb is true or RTF_GATEWAY is set, but the former is always
false.

These checks do not require RCU and can be done earlier.

Let's perform the equivalent checks in rtm_to_fib6_multipath_config().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250418000443.43734-5-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Kuniyuki Iwashima 2025-04-17 17:03:45 -07:00 committed by Paolo Abeni
parent fa76c1674f
commit e6f497955f
1 changed files with 9 additions and 7 deletions
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16
net/ipv6/route.c
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@ -5031,6 +5031,7 @@ static int rtm_to_fib6_multipath_config(struct fib6_config *cfg,
}
do {
bool has_gateway = cfg->fc_flags & RTF_GATEWAY;
int attrlen = rtnh_attrlen(rtnh);
if (attrlen > 0) {
@ -5044,9 +5045,17 @@ static int rtm_to_fib6_multipath_config(struct fib6_config *cfg,
"Invalid IPv6 address in RTA_GATEWAY");
return -EINVAL;
}
has_gateway = true;
}
}
if (newroute && (cfg->fc_nh_id || !has_gateway)) {
NL_SET_ERR_MSG(extack,
"Device only routes can not be added for IPv6 using the multipath API.");
return -EINVAL;
}
rtnh = rtnh_next(rtnh, &remaining);
} while (rtnh_ok(rtnh, remaining));
@ -5388,13 +5397,6 @@ static int ip6_route_multipath_add(struct fib6_config *cfg,
rt = NULL;
goto cleanup;
}
if (!rt6_qualify_for_ecmp(rt)) {
err = -EINVAL;
NL_SET_ERR_MSG(extack,
"Device only routes can not be added for IPv6 using the multipath API.");
fib6_info_release(rt);
goto cleanup;
}
rt->fib6_nh->fib_nh_weight = rtnh->rtnh_hops + 1;