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authorKuniyuki Iwashima <kuniyu@amazon.com>2024-04-29 18:58:12 -0700
committerJakub Kicinski <kuba@kernel.org>2024-05-01 18:37:07 -0700
commit0840556e5a3a331b6932ef17dd4bc94445df3297 (patch)
treecb33bf3e2a686696f6db4ce268fe77c5f3c9836c /net/core
parenta428bfc77a4dd4ba19b7646e887fa655fcfee5a0 (diff)
net: Protect dev->name by seqlock.
We will convert ioctl(SIOCGARP) to RCU, and then we need to copy dev->name which is currently protected by rtnl_lock(). This patch does the following: 1) Add seqlock netdev_rename_lock to protect dev->name 2) Add netdev_copy_name() that copies dev->name to buffer under netdev_rename_lock 3) Use netdev_copy_name() in netdev_get_name() and drop devnet_rename_sem Suggested-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/netdev/CANn89iJEWs7AYSJqGCUABeVqOCTkErponfZdT5kV-iD=-SajnQ@mail.gmail.com/ Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://lore.kernel.org/r/20240430015813.71143-7-kuniyu@amazon.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/dev.c27
1 files changed, 23 insertions, 4 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index cd7ba50eac15..e02d2363347e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -940,6 +940,18 @@ struct net_device *dev_get_by_napi_id(unsigned int napi_id)
}
EXPORT_SYMBOL(dev_get_by_napi_id);
+static DEFINE_SEQLOCK(netdev_rename_lock);
+
+void netdev_copy_name(struct net_device *dev, char *name)
+{
+ unsigned int seq;
+
+ do {
+ seq = read_seqbegin(&netdev_rename_lock);
+ strscpy(name, dev->name, IFNAMSIZ);
+ } while (read_seqretry(&netdev_rename_lock, seq));
+}
+
/**
* netdev_get_name - get a netdevice name, knowing its ifindex.
* @net: network namespace
@@ -951,7 +963,6 @@ int netdev_get_name(struct net *net, char *name, int ifindex)
struct net_device *dev;
int ret;
- down_read(&devnet_rename_sem);
rcu_read_lock();
dev = dev_get_by_index_rcu(net, ifindex);
@@ -960,12 +971,11 @@ int netdev_get_name(struct net *net, char *name, int ifindex)
goto out;
}
- strcpy(name, dev->name);
+ netdev_copy_name(dev, name);
ret = 0;
out:
rcu_read_unlock();
- up_read(&devnet_rename_sem);
return ret;
}
@@ -1217,7 +1227,10 @@ int dev_change_name(struct net_device *dev, const char *newname)
memcpy(oldname, dev->name, IFNAMSIZ);
+ write_seqlock(&netdev_rename_lock);
err = dev_get_valid_name(net, dev, newname);
+ write_sequnlock(&netdev_rename_lock);
+
if (err < 0) {
up_write(&devnet_rename_sem);
return err;
@@ -1257,7 +1270,9 @@ rollback:
if (err >= 0) {
err = ret;
down_write(&devnet_rename_sem);
+ write_seqlock(&netdev_rename_lock);
memcpy(dev->name, oldname, IFNAMSIZ);
+ write_sequnlock(&netdev_rename_lock);
memcpy(oldname, newname, IFNAMSIZ);
WRITE_ONCE(dev->name_assign_type, old_assign_type);
old_assign_type = NET_NAME_RENAMED;
@@ -11403,8 +11418,12 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net,
dev_net_set(dev, net);
dev->ifindex = new_ifindex;
- if (new_name[0]) /* Rename the netdev to prepared name */
+ if (new_name[0]) {
+ /* Rename the netdev to prepared name */
+ write_seqlock(&netdev_rename_lock);
strscpy(dev->name, new_name, IFNAMSIZ);
+ write_sequnlock(&netdev_rename_lock);
+ }
/* Fixup kobjects */
dev_set_uevent_suppress(&dev->dev, 1);