linux/net/core/rtnetlink.c, branch v6.13

rtnetlink: Try the outer netns attribute in rtnl_get_peer_net().

2024-12-18T01:54:18Z

Xiao Liang reported that the cited commit changed netns handling in newlink() of netkit, veth, and vxcan. Before the patch, if we don't find a netns attribute in the peer device attributes, we tried to find another netns attribute in the outer netlink attributes by passing it to rtnl_link_get_net(). Let's restore the original behaviour. Fixes: 48327566769a ("rtnetlink: fix double call of rtnl_link_get_net_ifla()") Reported-by: Xiao Liang Closes: https://lore.kernel.org/netdev/CABAhCORBVVU8P6AHcEkENMj+gD2d3ce9t=A_o48E0yOQp8_wUQ@mail.gmail.com/#t Signed-off-by: Kuniyuki Iwashima Tested-by: Xiao Liang Link: https://patch.msgid.link/20241216110432.51488-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

rtnetlink: fix error code in rtnl_newlink()

2024-12-08T02:25:09Z

If rtnl_get_peer_net() fails, then propagate the error code. Don't return success. Fixes: 48327566769a ("rtnetlink: fix double call of rtnl_link_get_net_ifla()") Signed-off-by: Dan Carpenter Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/a2d20cd4-387a-4475-887c-bb7d0e88e25a@stanley.mountain Signed-off-by: Jakub Kicinski

rtnetlink: fix double call of rtnl_link_get_net_ifla()

2024-12-03T10:29:29Z

Currently rtnl_link_get_net_ifla() gets called twice when we create peer devices, once in rtnl_add_peer_net() and once in each ->newlink() implementation. This looks safer, however, it leads to a classic Time-of-Check to Time-of-Use (TOCTOU) bug since IFLA_NET_NS_PID is very dynamic. And because of the lack of checking error pointer of the second call, it also leads to a kernel crash as reported by syzbot. Fix this by getting rid of the second call, which already becomes redudant after Kuniyuki's work. We have to propagate the result of the first rtnl_link_get_net_ifla() down to each ->newlink(). Reported-by: syzbot+21ba4d5adff0b6a7cfc6@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=21ba4d5adff0b6a7cfc6 Fixes: 0eb87b02a705 ("veth: Set VETH_INFO_PEER to veth_link_ops.peer_type.") Fixes: 6b84e558e95d ("vxcan: Set VXCAN_INFO_PEER to vxcan_link_ops.peer_type.") Fixes: fefd5d082172 ("netkit: Set IFLA_NETKIT_PEER_INFO to netkit_link_ops.peer_type.") Cc: Kuniyuki Iwashima Signed-off-by: Cong Wang Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20241129212519.825567-1-xiyou.wangcong@gmail.com Signed-off-by: Paolo Abeni

rtnetlink: fix rtnl_dump_ifinfo() error path

2024-11-25T00:43:13Z

syzbot found that rtnl_dump_ifinfo() could return with a lock held [1] Move code around so that rtnl_link_ops_put() and put_net() can be called at the end of this function. [1] WARNING: lock held when returning to user space! 6.12.0-rc7-syzkaller-01681-g38f83a57aa8e #0 Not tainted syz-executor399/5841 is leaving the kernel with locks still held! 1 lock held by syz-executor399/5841: #0: ffffffff8f46c2a0 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #0: ffffffff8f46c2a0 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8f46c2a0 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x22/0x250 net/core/rtnetlink.c:555 Fixes: 43c7ce69d28e ("rtnetlink: Protect struct rtnl_link_ops with SRCU.") Reported-by: syzbot Signed-off-by: Eric Dumazet Reviewed-by: Joe Damato Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20241121194105.3632507-1-edumazet@google.com Signed-off-by: Jakub Kicinski

ndo_fdb_del: Add a parameter to report whether notification was sent

2024-11-16T00:39:18Z

In a similar fashion to ndo_fdb_add, which was covered in the previous patch, add the bool *notified argument to ndo_fdb_del. Callees that send a notification on their own set the flag to true. Signed-off-by: Petr Machata Reviewed-by: Amit Cohen Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/06b1acf4953ef0a5ed153ef1f32d7292044f2be6.1731589511.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski

ndo_fdb_add: Add a parameter to report whether notification was sent

2024-11-16T00:39:18Z

Currently when FDB entries are added to or deleted from a VXLAN netdevice, the VXLAN driver emits one notification, including the VXLAN-specific attributes. The core however always sends a notification as well, a generic one. Thus two notifications are unnecessarily sent for these operations. A similar situation comes up with bridge driver, which also emits notifications on its own: # ip link add name vx type vxlan id 1000 dstport 4789 # bridge monitor fdb & [1] 1981693 # bridge fdb add de:ad:be:ef:13:37 dev vx self dst 192.0.2.1 de:ad:be:ef:13:37 dev vx dst 192.0.2.1 self permanent de:ad:be:ef:13:37 dev vx self permanent In order to prevent this duplicity, add a paremeter to ndo_fdb_add, bool *notified. The flag is primed to false, and if the callee sends a notification on its own, it sets it to true, thus informing the core that it should not generate another notification. Signed-off-by: Petr Machata Reviewed-by: Amit Cohen Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/cbf6ae8195e85cbf922f8058ce4eba770f3b71ed.1731589511.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski

rtnetlink: Register rtnl_dellink() and rtnl_setlink() with RTNL_FLAG_DOIT_PERNET_WIP.

2024-11-12T01:26:52Z

Currently, rtnl_setlink() and rtnl_dellink() cannot be fully converted to per-netns RTNL due to a lack of handling peer/lower/upper devices in different netns. For example, when we change a device in rtnl_setlink() and need to propagate that to its upper devices, we want to avoid acquiring all netns locks, for which we do not know the upper limit. The same situation happens when we remove a device. rtnl_dellink() could be transformed to remove a single device in the requested netns and delegate other devices to per-netns work, and rtnl_setlink() might be ? Until we come up with a better idea, let's use a new flag RTNL_FLAG_DOIT_PERNET_WIP for rtnl_dellink() and rtnl_setlink(). This will unblock converting RTNL users where such devices are not related. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Nikolay Aleksandrov Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20241108004823.29419-11-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

rtnetlink: Convert RTM_NEWLINK to per-netns RTNL.

2024-11-12T01:26:52Z

Now, we are ready to convert rtnl_newlink() to per-netns RTNL; rtnl_link_ops is protected by SRCU and netns is prefetched in rtnl_newlink(). Let's register rtnl_newlink() with RTNL_FLAG_DOIT_PERNET and push RTNL down as rtnl_nets_lock(). Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20241108004823.29419-10-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

rtnetlink: Add peer_type in struct rtnl_link_ops.

2024-11-12T01:26:52Z

In ops->newlink(), veth, vxcan, and netkit call rtnl_link_get_net() with a net pointer, which is the first argument of ->newlink(). rtnl_link_get_net() could return another netns based on IFLA_NET_NS_PID and IFLA_NET_NS_FD in the peer device's attributes. We want to get it and fill rtnl_nets->nets[] in advance in rtnl_newlink() for per-netns RTNL. All of the three get the peer netns in the same way: 1. Call rtnl_nla_parse_ifinfomsg() 2. Call ops->validate() (vxcan doesn't have) 3. Call rtnl_link_get_net_tb() Let's add a new field peer_type to struct rtnl_link_ops and prefetch netns in the peer ifla to add it to rtnl_nets in rtnl_newlink(). Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20241108004823.29419-6-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

rtnetlink: Introduce struct rtnl_nets and helpers.

2024-11-12T01:26:51Z

rtnl_newlink() needs to hold 3 per-netns RTNL: 2 for a new device and 1 for its peer. We will add rtnl_nets_lock() later, which performs the nested locking based on struct rtnl_nets, which has an array of struct net pointers. rtnl_nets_add() adds a net pointer to the array and sorts it so that rtnl_nets_lock() can simply acquire per-netns RTNL from array[0] to [2]. Before calling rtnl_nets_add(), get_net() must be called for the net, and rtnl_nets_destroy() will call put_net() for each. Let's apply the helpers to rtnl_newlink(). When CONFIG_DEBUG_NET_SMALL_RTNL is disabled, we do not call rtnl_net_lock() thus do not care about the array order, so rtnl_net_cmp_locks() returns -1 so that the loop in rtnl_nets_add() can be optimised to NOP. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20241108004823.29419-5-kuniyu@amazon.com Signed-off-by: Jakub Kicinski