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Repair special-casing of EEXIST for Linux/SITNL route install

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The code in sitnl_route_set() used to treat "route can not be installed
because it already exists" (EEXIST) as "not an error".

This is arguably a reasonable approach, but needs to handled higher
up - if the low level add_route() function say "no error", we will try
to remove that route later on in delete_route(), possibly removing
someone else's "already existing" route then.

So:
 - remove special case in sitnl_route_set()
 - do not pass NLM_F_REPLACE flag to sitnl_route_set() call - this would
   cause netlink to just replace existing routes, never return EEXIST
   (see "man netlink(7)")
 - add detailed return code handling to add_route(), assign "2" on
"-EEXIST"
   (and log appropriate message).

(Note: sitnl_route_set() is a common function for sitnl route add and
delete, but EEXIST can not happen on delete - so this change has no
impact for the "delete" case)

v2: use RTA_ macros, also adjust add_route_ipv6()

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Selva Nair <selva.nair@gmail.com>
Message-Id: <20230118074633.27586-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26046.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
This commit is contained in:
Gert Doering 2023-01-18 08:46:33 +01:00
parent 328cc40c83
commit adc54f483b
2 changed files with 19 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
src/openvpn/networking_sitnl.c
View file

@ -944,10 +944,6 @@ sitnl_route_set(int cmd, uint32_t flags, int ifindex, sa_family_t af_family,
}
ret = sitnl_send(&req.n, 0, 0, NULL, NULL);
if (ret == -EEXIST)
{
ret = 0;
}
err:
return ret;
}
@ -1177,7 +1173,7 @@ sitnl_route_add(const char *iface, sa_family_t af_family, const void *dst,
scope = RT_SCOPE_LINK;
}
return sitnl_route_set(RTM_NEWROUTE, NLM_F_CREATE | NLM_F_REPLACE, ifindex,
return sitnl_route_set(RTM_NEWROUTE, NLM_F_CREATE, ifindex,
af_family, dst, prefixlen, gw, table, metric, scope,
RTPROT_BOOT, RTN_UNICAST);
}

24
src/openvpn/route.c
View file

@ -1599,8 +1599,14 @@ add_route(struct route_ipv4 *r,
}
status = RTA_SUCCESS;
if (net_route_v4_add(ctx, &r->network, netmask_to_netbits2(r->netmask),
&r->gateway, iface, 0, metric) < 0)
int ret = net_route_v4_add(ctx, &r->network, netmask_to_netbits2(r->netmask),
&r->gateway, iface, 0, metric);
if (ret == -EEXIST)
{
msg(D_ROUTE, "NOTE: Linux route add command failed because route exists");
status = RTA_EEXIST;
}
else if (ret < 0)
{
msg(M_WARN, "ERROR: Linux route add command failed");
status = RTA_ERROR;
@ -1963,11 +1969,17 @@ add_route_ipv6(struct route_ipv6 *r6, const struct tuntap *tt,
}
status = RTA_SUCCESS;
if (net_route_v6_add(ctx, &r6->network, r6->netbits,
gateway_needed ? &r6->gateway : NULL, device, 0,
metric) < 0)
int ret = net_route_v6_add(ctx, &r6->network, r6->netbits,
gateway_needed ? &r6->gateway : NULL,
device, 0, metric);
if (ret == -EEXIST)
{
msg(M_WARN, "ERROR: Linux IPv6 route can't be added");
msg(D_ROUTE, "NOTE: Linux route add command failed because route exists");
status = RTA_EEXIST;
}
else if (ret < 0)
{
msg(M_WARN, "ERROR: Linux route add command failed");
status = RTA_ERROR;
}