diff options
| author | Cong Wang <cong.wang@bytedance.com> | 2021-02-11 11:34:10 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-02-11 18:14:19 -0800 |
| commit | 3b23a32a63219f51a5298bc55a65ecee866e79d0 (patch) | |
| tree | 79f9a923b4679addfc28e39340e9834b922f7e40 /net/core/dev_ioctl.c | |
| parent | 7867299cde34e9c2d2c676f2a384a9d5853b914d (diff) | |
net: fix dev_ifsioc_locked() race condition
dev_ifsioc_locked() is called with only RCU read lock, so when
there is a parallel writer changing the mac address, it could
get a partially updated mac address, as shown below:
Thread 1 Thread 2
// eth_commit_mac_addr_change()
memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
// dev_ifsioc_locked()
memcpy(ifr->ifr_hwaddr.sa_data,
dev->dev_addr,...);
Close this race condition by guarding them with a RW semaphore,
like netdev_get_name(). We can not use seqlock here as it does not
allow blocking. The writers already take RTNL anyway, so this does
not affect the slow path. To avoid bothering existing
dev_set_mac_address() callers in drivers, introduce a new wrapper
just for user-facing callers on ioctl and rtnetlink paths.
Note, bonding also changes slave mac addresses but that requires
a separate patch due to the complexity of bonding code.
Fixes: 3710becf8a58 ("net: RCU locking for simple ioctl()")
Reported-by: "Gong, Sishuai" <sishuai@purdue.edu>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/dev_ioctl.c')
| -rw-r--r-- | net/core/dev_ioctl.c | 20 |
1 files changed, 7 insertions, 13 deletions
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c index db8a0ff86f36..478d032f34ac 100644 --- a/net/core/dev_ioctl.c +++ b/net/core/dev_ioctl.c @@ -123,17 +123,6 @@ static int dev_ifsioc_locked(struct net *net, struct ifreq *ifr, unsigned int cm ifr->ifr_mtu = dev->mtu; return 0; - case SIOCGIFHWADDR: - if (!dev->addr_len) - memset(ifr->ifr_hwaddr.sa_data, 0, - sizeof(ifr->ifr_hwaddr.sa_data)); - else - memcpy(ifr->ifr_hwaddr.sa_data, dev->dev_addr, - min(sizeof(ifr->ifr_hwaddr.sa_data), - (size_t)dev->addr_len)); - ifr->ifr_hwaddr.sa_family = dev->type; - return 0; - case SIOCGIFSLAVE: err = -EINVAL; break; @@ -274,7 +263,7 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, unsigned int cmd) case SIOCSIFHWADDR: if (dev->addr_len > sizeof(struct sockaddr)) return -EINVAL; - return dev_set_mac_address(dev, &ifr->ifr_hwaddr, NULL); + return dev_set_mac_address_user(dev, &ifr->ifr_hwaddr, NULL); case SIOCSIFHWBROADCAST: if (ifr->ifr_hwaddr.sa_family != dev->type) @@ -418,6 +407,12 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c */ switch (cmd) { + case SIOCGIFHWADDR: + dev_load(net, ifr->ifr_name); + ret = dev_get_mac_address(&ifr->ifr_hwaddr, net, ifr->ifr_name); + if (colon) + *colon = ':'; + return ret; /* * These ioctl calls: * - can be done by all. @@ -427,7 +422,6 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c case SIOCGIFFLAGS: case SIOCGIFMETRIC: case SIOCGIFMTU: - case SIOCGIFHWADDR: case SIOCGIFSLAVE: case SIOCGIFMAP: case SIOCGIFINDEX: |