Re: [PATCH] network: Increase max route size when checking IPv6 forwarding
On 1/21/23 01:58, Brooks Swinnerton wrote:
In d9ee51e, virNetDevIPCheckIPv6Forwarding was updated to walk the
contents of /proc/net/ipv6_route so that it could check to see if the
RTF_ADDRCONF was set on any IPv6 routes to ultimately determine if
enabling forwarding would result in an error due to accept_ra=1 being
set on the interface.
The implementation added in that commit limited the number of routes
that could be read from /proc/net/ipv6_route to 100_000, each with 150
characters. This is problematic for machines that have a full IPv6
routing table, as the IPv6 routing table has now grown to over 160_000
(it was closer to 100_000 at the time of that commit).
This patch increases the maximum route size from 100_000 to 1_000_000.
While a million routes is somewhat arbitrary, it's meant to be a value
that can be supported for the forseeable future. APNIC, one of the five
regional internet registries, recently published a forecast of IPv6
table growth which anticipates a worst-case growth to 1_000_000 in
January of 2029.
Not to mention that 150 chars long line is expectation that's not always
met. For interfaces with sufficiently long names we can get longer lines:
# tail -n1 /proc/net/ipv6_route | wc -c
156
But I agree, ~143MiB ought to be enough for everyone :-)
Signed-off-by: Brooks Swinnerton <bswinnerton(a)gmail.com>
---
src/util/virnetdevip.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Michal Privoznik <mprivozn(a)redhat.com>
and pushed. Congratulations on your first libvirt contribution!
Michal