diff mbox series

[net-next,v2,2/3] devlink: call peernet2id_alloc() with net pointer under RCU read lock

Message ID 20231010091323.195451-3-jiri@resnulli.us (mailing list archive)
State Deferred
Delegated to: Netdev Maintainers
Headers show
Series devlink: don't take instance lock for nested handle put | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1363 this patch: 1363
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 1387 this patch: 1387
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1388 this patch: 1388
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 27 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Jiri Pirko Oct. 10, 2023, 9:13 a.m. UTC 
From: Jiri Pirko <jiri@nvidia.com>

peernet2id_alloc() allows to be called lockless with peer net pointer
obtained in RCU critical section and makes sure to return ns ID if net
namespaces is not being removed concurrently. Benefit from
read_pnet_rcu() helper addition, use it to obtain net pointer under RCU
read lock and pass it to peernet2id_alloc() to get ns ID.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
v1->v2:
- moved the netns related bits from the next patch
- fixed the code using RCU to avoid use after free of peer net struct
---
 net/devlink/netlink.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c
index 499304d9de49..809bfc3ba8c4 100644
--- a/net/devlink/netlink.c
+++ b/net/devlink/netlink.c
@@ -86,18 +86,24 @@  int devlink_nl_put_nested_handle(struct sk_buff *msg, struct net *net,
 				 struct devlink *devlink, int attrtype)
 {
 	struct nlattr *nested_attr;
+	struct net *devl_net;
 
 	nested_attr = nla_nest_start(msg, attrtype);
 	if (!nested_attr)
 		return -EMSGSIZE;
 	if (devlink_nl_put_handle(msg, devlink))
 		goto nla_put_failure;
-	if (!net_eq(net, devlink_net(devlink))) {
-		int id = peernet2id_alloc(net, devlink_net(devlink),
-					  GFP_KERNEL);
 
+	rcu_read_lock();
+	devl_net = read_pnet_rcu(&devlink->_net);
+	if (!net_eq(net, devl_net)) {
+		int id = peernet2id_alloc(net, devl_net, GFP_ATOMIC);
+
+		rcu_read_unlock();
 		if (nla_put_s32(msg, DEVLINK_ATTR_NETNS_ID, id))
 			return -EMSGSIZE;
+	} else {
+		rcu_read_unlock();
 	}
 
 	nla_nest_end(msg, nested_attr);