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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>
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parent
a428bfc77a
commit
0840556e5a
2 changed files with 24 additions and 4 deletions
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@ -3136,6 +3136,7 @@ struct net_device *netdev_get_by_name(struct net *net, const char *name,
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netdevice_tracker *tracker, gfp_t gfp);
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netdevice_tracker *tracker, gfp_t gfp);
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struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);
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struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);
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struct net_device *dev_get_by_napi_id(unsigned int napi_id);
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struct net_device *dev_get_by_napi_id(unsigned int napi_id);
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void netdev_copy_name(struct net_device *dev, char *name);
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static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
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static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
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unsigned short type,
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unsigned short type,
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@ -940,6 +940,18 @@ struct net_device *dev_get_by_napi_id(unsigned int napi_id)
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}
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}
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EXPORT_SYMBOL(dev_get_by_napi_id);
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EXPORT_SYMBOL(dev_get_by_napi_id);
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static DEFINE_SEQLOCK(netdev_rename_lock);
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void netdev_copy_name(struct net_device *dev, char *name)
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{
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unsigned int seq;
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do {
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seq = read_seqbegin(&netdev_rename_lock);
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strscpy(name, dev->name, IFNAMSIZ);
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} while (read_seqretry(&netdev_rename_lock, seq));
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}
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/**
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/**
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* netdev_get_name - get a netdevice name, knowing its ifindex.
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* netdev_get_name - get a netdevice name, knowing its ifindex.
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* @net: network namespace
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* @net: network namespace
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@ -951,7 +963,6 @@ int netdev_get_name(struct net *net, char *name, int ifindex)
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struct net_device *dev;
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struct net_device *dev;
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int ret;
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int ret;
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down_read(&devnet_rename_sem);
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rcu_read_lock();
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rcu_read_lock();
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dev = dev_get_by_index_rcu(net, ifindex);
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dev = dev_get_by_index_rcu(net, ifindex);
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@ -960,12 +971,11 @@ int netdev_get_name(struct net *net, char *name, int ifindex)
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goto out;
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goto out;
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}
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}
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strcpy(name, dev->name);
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netdev_copy_name(dev, name);
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ret = 0;
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ret = 0;
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out:
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out:
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rcu_read_unlock();
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rcu_read_unlock();
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up_read(&devnet_rename_sem);
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return ret;
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return ret;
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}
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}
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@ -1217,7 +1227,10 @@ int dev_change_name(struct net_device *dev, const char *newname)
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memcpy(oldname, dev->name, IFNAMSIZ);
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memcpy(oldname, dev->name, IFNAMSIZ);
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write_seqlock(&netdev_rename_lock);
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err = dev_get_valid_name(net, dev, newname);
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err = dev_get_valid_name(net, dev, newname);
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write_sequnlock(&netdev_rename_lock);
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if (err < 0) {
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if (err < 0) {
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up_write(&devnet_rename_sem);
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up_write(&devnet_rename_sem);
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return err;
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return err;
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@ -1257,7 +1270,9 @@ int dev_change_name(struct net_device *dev, const char *newname)
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if (err >= 0) {
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if (err >= 0) {
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err = ret;
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err = ret;
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down_write(&devnet_rename_sem);
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down_write(&devnet_rename_sem);
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write_seqlock(&netdev_rename_lock);
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memcpy(dev->name, oldname, IFNAMSIZ);
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memcpy(dev->name, oldname, IFNAMSIZ);
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write_sequnlock(&netdev_rename_lock);
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memcpy(oldname, newname, IFNAMSIZ);
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memcpy(oldname, newname, IFNAMSIZ);
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WRITE_ONCE(dev->name_assign_type, old_assign_type);
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WRITE_ONCE(dev->name_assign_type, old_assign_type);
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old_assign_type = NET_NAME_RENAMED;
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old_assign_type = NET_NAME_RENAMED;
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@ -11403,8 +11418,12 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net,
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dev_net_set(dev, net);
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dev_net_set(dev, net);
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dev->ifindex = new_ifindex;
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dev->ifindex = new_ifindex;
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if (new_name[0]) /* Rename the netdev to prepared name */
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if (new_name[0]) {
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/* Rename the netdev to prepared name */
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write_seqlock(&netdev_rename_lock);
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strscpy(dev->name, new_name, IFNAMSIZ);
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strscpy(dev->name, new_name, IFNAMSIZ);
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write_sequnlock(&netdev_rename_lock);
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}
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/* Fixup kobjects */
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/* Fixup kobjects */
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dev_set_uevent_suppress(&dev->dev, 1);
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dev_set_uevent_suppress(&dev->dev, 1);
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