arp: Get dev after calling arp_req_(delete|set|get)().
authorKuniyuki Iwashima <kuniyu@amazon.com>
Tue, 30 Apr 2024 01:58:11 +0000 (18:58 -0700)
committerJakub Kicinski <kuba@kernel.org>
Thu, 2 May 2024 01:37:07 +0000 (18:37 -0700)
commita428bfc77a4dd4ba19b7646e887fa655fcfee5a0
tree13874acf4864cc6ca1562982870427cd204af3e4
parent51e9ba48d48786da89d2695be9a1cab40b2afc31
arp: Get dev after calling arp_req_(delete|set|get)().

arp_ioctl() holds rtnl_lock() first regardless of cmd (SIOCDARP,
SIOCSARP, and SIOCGARP) to get net_device by __dev_get_by_name()
and copy dev->name safely.

In the SIOCGARP path, arp_req_get() calls neigh_lookup(), which
looks up a neighbour entry under RCU.

We will extend the RCU section not to take rtnl_lock() and instead
use dev_get_by_name_rcu() for SIOCGARP.

As a preparation, let's move __dev_get_by_name() into another
function and call it from arp_req_delete(), arp_req_set(), and
arp_req_get().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240430015813.71143-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net/ipv4/arp.c