kernel.git/net/sched/act_api.c, branch linux-5.11.y

Revert "net: sched: bump refcount for new action in ACT replace mode"

2021-04-14T06:47:26Z

commit 4ba86128ba077fbb7d86516ae24ed642e6c3adef upstream. This reverts commit 6855e8213e06efcaf7c02a15e12b1ae64b9a7149. Following commit in series fixes the issue without introducing regression in error rollback of tcf_action_destroy(). Signed-off-by: Vlad Buslov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: sched: bump refcount for new action in ACT replace mode

2021-04-14T06:47:25Z

commit 6855e8213e06efcaf7c02a15e12b1ae64b9a7149 upstream. Currently, action creation using ACT API in replace mode is buggy. When invoking for non-existent action index 42, tc action replace action bpf obj foo.o sec index 42 kernel creates the action, fills up the netlink response, and then just deletes the action after notifying userspace. tc action show action bpf doesn't list the action. This happens due to the following sequence when ovr = 1 (replace mode) is enabled: tcf_idr_check_alloc is used to atomically check and either obtain reference for existing action at index, or reserve the index slot using a dummy entry (ERR_PTR(-EBUSY)). This is necessary as pointers to these actions will be held after dropping the idrinfo lock, so bumping the reference count is necessary as we need to insert the actions, and notify userspace by dumping their attributes. Finally, we drop the reference we took using the tcf_action_put_many call in tcf_action_add. However, for the case where a new action is created due to free index, its refcount remains one. This when paired with the put_many call leads to the kernel setting up the action, notifying userspace of its creation, and then tearing it down. For existing actions, the refcount is still held so they remain unaffected. Fortunately due to rtnl_lock serialization requirement, such an action with refcount == 1 will not be concurrently deleted by anything else, at best CLS API can move its refcount up and down by binding to it after it has been published from tcf_idr_insert_many. Since refcount is atleast one until put_many call, CLS API cannot delete it. Also __tcf_action_put release path already ensures deterministic outcome (either new action will be created or existing action will be reused in case CLS API tries to bind to action concurrently) due to idr lock serialization. We fix this by making refcount of newly created actions as 2 in ACT API replace mode. A relaxed store will suffice as visibility is ensured only after the tcf_idr_insert_many call. Note that in case of creation or overwriting using CLS API only (i.e. bind = 1), overwriting existing action object is not allowed, and any such request is silently ignored (without error). The refcount bump that occurs in tcf_idr_check_alloc call there for existing action will pair with tcf_exts_destroy call made from the owner module for the same action. In case of action creation, there is no existing action, so no tcf_exts_destroy callback happens. This means no code changes for CLS API. Fixes: cae422f379f3 ("net: sched: use reference counting action init") Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: sched: fix err handler in tcf_action_init()

2021-04-14T06:47:16Z

[ Upstream commit b3650bf76a32380d4d80a3e21b5583e7303f216c ] With recent changes that separated action module load from action initialization tcf_action_init() function error handling code was modified to manually release the loaded modules if loading/initialization of any further action in same batch failed. For the case when all modules successfully loaded and some of the actions were initialized before one of them failed in init handler. In this case for all previous actions the module will be released twice by the error handler: First time by the loop that manually calls module_put() for all ops, and second time by the action destroy code that puts the module after destroying the action. Reproduction: $ sudo tc actions add action simple sdata \"2\" index 2 $ sudo tc actions add action simple sdata \"1\" index 1 \ action simple sdata \"2\" index 2 RTNETLINK answers: File exists We have an error talking to the kernel $ sudo tc actions ls action simple total acts 1 action order 0: Simple <"2"> index 2 ref 1 bind 0 $ sudo tc actions flush action simple $ sudo tc actions ls action simple $ sudo tc actions add action simple sdata \"2\" index 2 Error: Failed to load TC action module. We have an error talking to the kernel $ lsmod | grep simple act_simple 20480 -1 Fix the issue by modifying module reference counting handling in action initialization code: - Get module reference in tcf_idr_create() and put it in tcf_idr_release() instead of taking over the reference held by the caller. - Modify users of tcf_action_init_1() to always release the module reference which they obtain before calling init function instead of assuming that created action takes over the reference. - Finally, modify tcf_action_init_1() to not release the module reference when overwriting existing action as this is no longer necessary since both upper and lower layers obtain and manage their own module references independently. Fixes: d349f9976868 ("net_sched: fix RTNL deadlock again caused by request_module()") Suggested-by: Cong Wang Signed-off-by: Vlad Buslov Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

net: sched: fix action overwrite reference counting

2021-04-14T06:47:13Z

commit 87c750e8c38bce706eb32e4d8f1e3402f2cebbd4 upstream. Action init code increments reference counter when it changes an action. This is the desired behavior for cls API which needs to obtain action reference for every classifier that points to action. However, act API just needs to change the action and releases the reference before returning. This sequence breaks when the requested action doesn't exist, which causes act API init code to create new action with specified index, but action is still released before returning and is deleted (unless it was referenced concurrently by cls API). Reproduction: $ sudo tc actions ls action gact $ sudo tc actions change action gact drop index 1 $ sudo tc actions ls action gact Extend tcf_action_init() to accept 'init_res' array and initialize it with action->ops->init() result. In tcf_action_add() remove pointers to created actions from actions array before passing it to tcf_action_put_many(). Fixes: cae422f379f3 ("net: sched: use reference counting action init") Reported-by: Kumar Kartikeya Dwivedi Signed-off-by: Vlad Buslov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net_sched: fix RTNL deadlock again caused by request_module()

2021-03-04T11:15:44Z

commit d349f997686887906b1183b5be96933c5452362a upstream. tcf_action_init_1() loads tc action modules automatically with request_module() after parsing the tc action names, and it drops RTNL lock and re-holds it before and after request_module(). This causes a lot of troubles, as discovered by syzbot, because we can be in the middle of batch initializations when we create an array of tc actions. One of the problem is deadlock: CPU 0 CPU 1 rtnl_lock(); for (...) { tcf_action_init_1(); -> rtnl_unlock(); -> request_module(); rtnl_lock(); for (...) { tcf_action_init_1(); -> tcf_idr_check_alloc(); // Insert one action into idr, // but it is not committed until // tcf_idr_insert_many(), then drop // the RTNL lock in the _next_ // iteration -> rtnl_unlock(); -> rtnl_lock(); -> a_o->init(); -> tcf_idr_check_alloc(); // Now waiting for the same index // to be committed -> request_module(); -> rtnl_lock() // Now waiting for RTNL lock } rtnl_unlock(); } rtnl_unlock(); This is not easy to solve, we can move the request_module() before this loop and pre-load all the modules we need for this netlink message and then do the rest initializations. So the loop breaks down to two now: for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) { struct tc_action_ops *a_o; a_o = tc_action_load_ops(name, tb[i]...); ops[i - 1] = a_o; } for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) { act = tcf_action_init_1(ops[i - 1]...); } Although this looks serious, it only has been reported by syzbot, so it seems hard to trigger this by humans. And given the size of this patch, I'd suggest to make it to net-next and not to backport to stable. This patch has been tested by syzbot and tested with tdc.py by me. Fixes: 0fedc63fadf0 ("net_sched: commit action insertions together") Reported-and-tested-by: syzbot+82752bc5331601cf4899@syzkaller.appspotmail.com Reported-and-tested-by: syzbot+b3b63b6bff456bd95294@syzkaller.appspotmail.com Reported-by: syzbot+ba67b12b1ca729912834@syzkaller.appspotmail.com Cc: Jiri Pirko Signed-off-by: Cong Wang Tested-by: Jamal Hadi Salim Acked-by: Jamal Hadi Salim Link: https://lore.kernel.org/r/20210117005657.14810-1-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: sched: fix police ext initialization

2021-03-04T11:15:44Z

commit 396d7f23adf9e8c436dd81a69488b5b6a865acf8 upstream. When police action is created by cls API tcf_exts_validate() first conditional that calls tcf_action_init_1() directly, the action idr is not updated according to latest changes in action API that require caller to commit newly created action to idr with tcf_idr_insert_many(). This results such action not being accessible through act API and causes crash reported by syzbot: ================================================================== BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:71 [inline] BUG: KASAN: null-ptr-deref in atomic_read include/asm-generic/atomic-instrumented.h:27 [inline] BUG: KASAN: null-ptr-deref in __tcf_idr_release net/sched/act_api.c:178 [inline] BUG: KASAN: null-ptr-deref in tcf_idrinfo_destroy+0x129/0x1d0 net/sched/act_api.c:598 Read of size 4 at addr 0000000000000010 by task kworker/u4:5/204 CPU: 0 PID: 204 Comm: kworker/u4:5 Not tainted 5.11.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 __kasan_report mm/kasan/report.c:400 [inline] kasan_report.cold+0x5f/0xd5 mm/kasan/report.c:413 check_memory_region_inline mm/kasan/generic.c:179 [inline] check_memory_region+0x13d/0x180 mm/kasan/generic.c:185 instrument_atomic_read include/linux/instrumented.h:71 [inline] atomic_read include/asm-generic/atomic-instrumented.h:27 [inline] __tcf_idr_release net/sched/act_api.c:178 [inline] tcf_idrinfo_destroy+0x129/0x1d0 net/sched/act_api.c:598 tc_action_net_exit include/net/act_api.h:151 [inline] police_exit_net+0x168/0x360 net/sched/act_police.c:390 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:190 cleanup_net+0x4ea/0xb10 net/core/net_namespace.c:604 process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 ================================================================== Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 204 Comm: kworker/u4:5 Tainted: G B 5.11.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 panic+0x306/0x73d kernel/panic.c:231 end_report+0x58/0x5e mm/kasan/report.c:100 __kasan_report mm/kasan/report.c:403 [inline] kasan_report.cold+0x67/0xd5 mm/kasan/report.c:413 check_memory_region_inline mm/kasan/generic.c:179 [inline] check_memory_region+0x13d/0x180 mm/kasan/generic.c:185 instrument_atomic_read include/linux/instrumented.h:71 [inline] atomic_read include/asm-generic/atomic-instrumented.h:27 [inline] __tcf_idr_release net/sched/act_api.c:178 [inline] tcf_idrinfo_destroy+0x129/0x1d0 net/sched/act_api.c:598 tc_action_net_exit include/net/act_api.h:151 [inline] police_exit_net+0x168/0x360 net/sched/act_police.c:390 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:190 cleanup_net+0x4ea/0xb10 net/core/net_namespace.c:604 process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Kernel Offset: disabled Fix the issue by calling tcf_idr_insert_many() after successful action initialization. Fixes: 0fedc63fadf0 ("net_sched: commit action insertions together") Reported-by: syzbot+151e3e714d34ae4ce7e8@syzkaller.appspotmail.com Signed-off-by: Vlad Buslov Reviewed-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net/sched: sch_frag: add generic packet fragment support.

2020-11-27T22:36:02Z

Currently kernel tc subsystem can do conntrack in cat_ct. But when several fragment packets go through the act_ct, function tcf_ct_handle_fragments will defrag the packets to a big one. But the last action will redirect mirred to a device which maybe lead the reassembly big packet over the mtu of target device. This patch add support for a xmit hook to mirred, that gets executed before xmiting the packet. Then, when act_ct gets loaded, it configs that hook. The frag xmit hook maybe reused by other modules. Signed-off-by: wenxu Acked-by: Cong Wang Acked-by: Jamal Hadi Salim Signed-off-by: Jakub Kicinski

net: sched: alias action flags with TCA_ACT_ prefix

2020-11-25T20:34:44Z

Currently both filter and action flags use same "TCA_" prefix which makes them hard to distinguish to code and confusing for users. Create aliases for existing action flags constants with "TCA_ACT_" prefix. Signed-off-by: Vlad Buslov Link: https://lore.kernel.org/r/20201124164054.893168-1-vlad@buslov.dev Signed-off-by: Jakub Kicinski

treewide: rename nla_strlcpy to nla_strscpy.

2020-11-16T16:08:54Z

Calls to nla_strlcpy are now replaced by calls to nla_strscpy which is the new name of this function. Signed-off-by: Francis Laniel Reviewed-by: Kees Cook Signed-off-by: Jakub Kicinski

Modify return value of nla_strlcpy to match that of strscpy.

2020-11-16T16:08:54Z

nla_strlcpy now returns -E2BIG if src was truncated when written to dst. It also returns this error value if dstsize is 0 or higher than INT_MAX. For example, if src is "foo\0" and dst is 3 bytes long, the result will be: 1. "foG" after memcpy (G means garbage). 2. "fo\0" after memset. 3. -E2BIG is returned because src was not completely written into dst. The callers of nla_strlcpy were modified to take into account this modification. Signed-off-by: Francis Laniel Reviewed-by: Kees Cook Signed-off-by: Jakub Kicinski