kernel/linux.git/net/bridge/br_ioctl.c, branch v6.6.148

net: Remove RTNL dance for SIOCBRADDIF and SIOCBRDELIF.

2026-01-11T14:22:25+00:00

commit ed3ba9b6e280e14cc3148c1b226ba453f02fa76c upstream. SIOCBRDELIF is passed to dev_ioctl() first and later forwarded to br_ioctl_call(), which causes unnecessary RTNL dance and the splat below [0] under RTNL pressure. Let's say Thread A is trying to detach a device from a bridge and Thread B is trying to remove the bridge. In dev_ioctl(), Thread A bumps the bridge device's refcnt by netdev_hold() and releases RTNL because the following br_ioctl_call() also re-acquires RTNL. In the race window, Thread B could acquire RTNL and try to remove the bridge device. Then, rtnl_unlock() by Thread B will release RTNL and wait for netdev_put() by Thread A. Thread A, however, must hold RTNL after the unlock in dev_ifsioc(), which may take long under RTNL pressure, resulting in the splat by Thread B. Thread A (SIOCBRDELIF) Thread B (SIOCBRDELBR) ---------------------- ---------------------- sock_ioctl sock_ioctl `- sock_do_ioctl `- br_ioctl_call `- dev_ioctl `- br_ioctl_stub |- rtnl_lock | |- dev_ifsioc ' ' |- dev = __dev_get_by_name(...) |- netdev_hold(dev, ...) . / |- rtnl_unlock ------. | | |- br_ioctl_call `---> |- rtnl_lock Race | | `- br_ioctl_stub |- br_del_bridge Window | | | |- dev = __dev_get_by_name(...) | | | May take long | `- br_dev_delete(dev, ...) | | | under RTNL pressure | `- unregister_netdevice_queue(dev, ...) | | | | `- rtnl_unlock \ | |- rtnl_lock <-' `- netdev_run_todo | |- ... `- netdev_run_todo | `- rtnl_unlock |- __rtnl_unlock | |- netdev_wait_allrefs_any |- netdev_put(dev, ...) <----------------' Wait refcnt decrement and log splat below To avoid blocking SIOCBRDELBR unnecessarily, let's not call dev_ioctl() for SIOCBRADDIF and SIOCBRDELIF. In the dev_ioctl() path, we do the following: 1. Copy struct ifreq by get_user_ifreq in sock_do_ioctl() 2. Check CAP_NET_ADMIN in dev_ioctl() 3. Call dev_load() in dev_ioctl() 4. Fetch the master dev from ifr.ifr_name in dev_ifsioc() 3. can be done by request_module() in br_ioctl_call(), so we move 1., 2., and 4. to br_ioctl_stub(). Note that 2. is also checked later in add_del_if(), but it's better performed before RTNL. SIOCBRADDIF and SIOCBRDELIF have been processed in dev_ioctl() since the pre-git era, and there seems to be no specific reason to process them there. [0]: unregister_netdevice: waiting for wpan3 to become free. Usage count = 2 ref_tracker: wpan3@ffff8880662d8608 has 1/1 users at __netdev_tracker_alloc include/linux/netdevice.h:4282 [inline] netdev_hold include/linux/netdevice.h:4311 [inline] dev_ifsioc+0xc6a/0x1160 net/core/dev_ioctl.c:624 dev_ioctl+0x255/0x10c0 net/core/dev_ioctl.c:826 sock_do_ioctl+0x1ca/0x260 net/socket.c:1213 sock_ioctl+0x23a/0x6c0 net/socket.c:1318 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x1a4/0x210 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: 893b19587534 ("net: bridge: fix ioctl locking") Reported-by: syzkaller Reported-by: yan kang Reported-by: yue sun Closes: https://lore.kernel.org/netdev/SY8P300MB0421225D54EB92762AE8F0F2A1D32@SY8P300MB0421.AUSP300.PROD.OUTLOOK.COM/ Signed-off-by: Kuniyuki Iwashima Acked-by: Stanislav Fomichev Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20250316192851.19781-1-kuniyu@amazon.com Signed-off-by: Paolo Abeni [cascardo: fixed conflict at dev_ifsioc] Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Greg Kroah-Hartman

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2021-12-31T14:35:40+00:00

Alexei Starovoitov says: ==================== pull-request: bpf-next 2021-12-30 The following pull-request contains BPF updates for your *net-next* tree. We've added 72 non-merge commits during the last 20 day(s) which contain a total of 223 files changed, 3510 insertions(+), 1591 deletions(-). The main changes are: 1) Automatic setrlimit in libbpf when bpf is memcg's in the kernel, from Andrii. 2) Beautify and de-verbose verifier logs, from Christy. 3) Composable verifier types, from Hao. 4) bpf_strncmp helper, from Hou. 5) bpf.h header dependency cleanup, from Jakub. 6) get_func_[arg|ret|arg_cnt] helpers, from Jiri. 7) Sleepable local storage, from KP. 8) Extend kfunc with PTR_TO_CTX, PTR_TO_MEM argument support, from Kumar. ==================== Signed-off-by: David S. Miller

net: Don't include filter.h from net/sock.h

2021-12-29T16:48:14+00:00

sock.h is pretty heavily used (5k objects rebuilt on x86 after it's touched). We can drop the include of filter.h from it and add a forward declaration of struct sk_filter instead. This decreases the number of rebuilt objects when bpf.h is touched from ~5k to ~1k. There's a lot of missing includes this was masking. Primarily in networking tho, this time. Signed-off-by: Jakub Kicinski Signed-off-by: Alexei Starovoitov Acked-by: Marc Kleine-Budde Acked-by: Florian Fainelli Acked-by: Nikolay Aleksandrov Acked-by: Stefano Garzarella Link: https://lore.kernel.org/bpf/20211229004913.513372-1-kuba@kernel.org

net: bridge: Get SIOCGIFBR/SIOCSIFBR ioctl working in compat mode

2021-12-27T12:31:57+00:00

In compat mode SIOC{G,S}IFBR ioctls were only supporting BRCTL_GET_VERSION returning an artificially version to spur userland tool to use SIOCDEVPRIVATE instead. But some userland tools ignore that and use SIOC{G,S}IFBR unconditionally as seen with busybox's brctl. Example of non working 32-bit brctl with CONFIG_COMPAT=y: $ brctl show brctl: SIOCGIFBR: Invalid argument Example of fixed 32-bit brctl with CONFIG_COMPAT=y: $ brctl show bridge name bridge id STP enabled interfaces br0 Signed-off-by: Remi Pommarel Co-developed-by: Arnd Bergmann Signed-off-by: Arnd Bergmann Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

net: bridge: fix ioctl old_deviceless bridge argument

2021-12-23T17:53:50+00:00

Commit 561d8352818f ("bridge: use ndo_siocdevprivate") changed the source and destination arguments of copy_{to,from}_user in bridge's old_deviceless() from args[1] to uarg breaking SIOC{G,S}IFBR ioctls. Commit cbd7ad29a507 ("net: bridge: fix ioctl old_deviceless bridge argument") fixed only BRCTL_{ADD,DEL}_BRIDGES commands leaving BRCTL_GET_BRIDGES one untouched. The fixes BRCTL_GET_BRIDGES as well and has been tested with busybox's brctl. Example of broken brctl: $ brctl show bridge name bridge id STP enabled interfaces brctl: can't get bridge name for index 0: No such device or address Example of fixed brctl: $ brctl show bridge name bridge id STP enabled interfaces br0 8000.000000000000 no Fixes: 561d8352818f ("bridge: use ndo_siocdevprivate") Signed-off-by: Remi Pommarel Reviewed-by: Arnd Bergmann Acked-by: Nikolay Aleksandrov Link: https://lore.kernel.org/all/20211223153139.7661-2-repk@triplefau.lt/ Signed-off-by: Jakub Kicinski

net: make use of helper netif_is_bridge_master()

2021-10-16T14:02:56+00:00

Make use of netdev helper functions to improve code readability. Replace 'dev->priv_flags & IFF_EBRIDGE' with netif_is_bridge_master(dev). Signed-off-by: Kyungrok Chung Reviewed-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

net: bridge: Use array_size() helper in copy_to_user()

2021-09-29T10:32:14+00:00

Use array_size() helper instead of the open-coded version in copy_to_user(). These sorts of multiplication factors need to be wrapped in array_size(). Link: https://github.com/KSPP/linux/issues/160 Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller

net: bridge: fix ioctl old_deviceless bridge argument

2021-08-05T10:36:59+00:00

Commit ad2f99aedf8f ("net: bridge: move bridge ioctls out of .ndo_do_ioctl") changed the source of the argument copy in bridge's old_deviceless() from args[1] (user ptr to device name) to uarg (ptr to ioctl arguments) causing wrong device name to be used. Example (broken, bridge exists but is up): $ brctl delbr bridge bridge bridge doesn't exist; can't delete it Example (working): $ brctl delbr bridge bridge bridge is still up; can't delete it Fixes: ad2f99aedf8f ("net: bridge: move bridge ioctls out of .ndo_do_ioctl") Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

net: bridge: fix ioctl locking

2021-08-05T10:36:59+00:00

Before commit ad2f99aedf8f ("net: bridge: move bridge ioctls out of .ndo_do_ioctl") the bridge ioctl calls were divided in two parts: one was deviceless called by sock_ioctl and didn't expect rtnl to be held, the other was with a device called by dev_ifsioc() and expected rtnl to be held. After the commit above they were united in a single ioctl stub, but it didn't take care of the locking expectations. For sock_ioctl now we acquire (1) br_ioctl_mutex, (2) rtnl and for dev_ifsioc we acquire (1) rtnl, (2) br_ioctl_mutex The fix is to get a refcnt on the netdev for dev_ifsioc calls and drop rtnl then to reacquire it in the bridge ioctl stub after br_ioctl_mutex has been acquired. That will avoid playing locking games and make the rules straight-forward: we always take br_ioctl_mutex first, and then rtnl. Reported-by: syzbot+34fe5894623c4ab1b379@syzkaller.appspotmail.com Fixes: ad2f99aedf8f ("net: bridge: move bridge ioctls out of .ndo_do_ioctl") Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

net: bridge: move bridge ioctls out of .ndo_do_ioctl

2021-07-27T19:11:45+00:00

Working towards obsoleting the .ndo_do_ioctl operation entirely, stop passing the SIOCBRADDIF/SIOCBRDELIF device ioctl commands into this callback. My first attempt was to add another ndo_siocbr() callback, but as there is only a single driver that takes these commands and there is already a hook mechanism to call directly into this driver, extend this hook instead, and use it for both the deviceless and the device specific ioctl commands. Cc: Roopa Prabhu Cc: Nikolay Aleksandrov Cc: bridge@lists.linux-foundation.org Signed-off-by: Arnd Bergmann Signed-off-by: David S. Miller