diff options
| author | Kuniyuki Iwashima <kuniyu@google.com> | 2026-06-19 21:27:20 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-06-22 18:37:36 -0700 |
| commit | b72f0db64205d9ce462038ba995d5d31eff32dc1 (patch) | |
| tree | 5e334d15166aed238d7e93956df95da27552e488 /include | |
| parent | 40529e58629baa9ce72143cb46cf1b3d2ca0d465 (diff) | |
| download | ath-b72f0db64205d9ce462038ba995d5d31eff32dc1.tar.gz | |
ipv4: fib: Don't ignore error route in local/main tables.
When CONFIG_IP_MULTIPLE_TABLES is enabled but no rule is added,
fib_lookup() performs route lookup directly on two tables.
Since the first lookup does not properly bail out, the result
of an error route in the merged local/main table could be
overwritten by another route in the default table:
# unshare -n
# ip link set lo up
# ip route add 192.168.0.0/24 dev lo table 253
# ip route add unreachable 192.168.0.0/24
# ip route get 192.168.0.1
192.168.0.1 dev lo table default uid 0
cache <local>
Once a random rule is added, the error route is respected:
# ip rule add table 0
# ip rule del table 0
# ip route get 192.168.0.1
RTNETLINK answers: No route to host
Let's fix the inconsistent behaviour.
Fixes: f4530fa574df ("ipv4: Avoid overhead when no custom FIB rules are installed.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260619212753.3367244-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/ip_fib.h | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h index a71a985056507..c63a3c4967ae6 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -374,7 +374,7 @@ static inline int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res, unsigned int flags) { struct fib_table *tb; - int err = -ENETUNREACH; + int err = -EAGAIN; flags |= FIB_LOOKUP_NOREF; if (net->ipv4.fib_has_custom_rules) @@ -388,17 +388,16 @@ static inline int fib_lookup(struct net *net, struct flowi4 *flp, if (tb) err = fib_table_lookup(tb, flp, res, flags); - if (!err) + if (err != -EAGAIN) goto out; tb = rcu_dereference_rtnl(net->ipv4.fib_default); if (tb) err = fib_table_lookup(tb, flp, res, flags); -out: if (err == -EAGAIN) err = -ENETUNREACH; - +out: rcu_read_unlock(); return err; |