kernel/linux.git/net/core/netclassid_cgroup.c, branch v6.12.80

cgroup, netclassid: on modifying netclassid in cgroup, only consider the main process.

2023-10-16T23:36:53+00:00

When modifying netclassid, the command("echo 0x100001 > net_cls.classid") will take more time on many threads of one process, because the process create many fds. for example, one process exists 28000 fds and 60000 threads, echo command will task 45 seconds. Now, we only consider the main process when exec "iterate_fd", and the time is about 52 milliseconds. Signed-off-by: Liansen Zhai Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20231012090330.29636-1-zhailiansen@kuaishou.com Signed-off-by: Jakub Kicinski

core: Variable type completion

2022-08-31T08:40:34+00:00

'unsigned int' is better than 'unsigned'. Signed-off-by: Xin Gao Signed-off-by: David S. Miller

bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode

2021-09-13T23:35:58+00:00

Fix cgroup v1 interference when non-root cgroup v2 BPF programs are used. Back in the days, commit bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup") embedded per-socket cgroup information into sock->sk_cgrp_data and in order to save 8 bytes in struct sock made both mutually exclusive, that is, when cgroup v1 socket tagging (e.g. net_cls/net_prio) is used, then cgroup v2 falls back to the root cgroup in sock_cgroup_ptr() (&cgrp_dfl_root.cgrp). The assumption made was "there is no reason to mix the two and this is in line with how legacy and v2 compatibility is handled" as stated in bd1060a1d671. However, with Kubernetes more widely supporting cgroups v2 as well nowadays, this assumption no longer holds, and the possibility of the v1/v2 mixed mode with the v2 root fallback being hit becomes a real security issue. Many of the cgroup v2 BPF programs are also used for policy enforcement, just to pick _one_ example, that is, to programmatically deny socket related system calls like connect(2) or bind(2). A v2 root fallback would implicitly cause a policy bypass for the affected Pods. In production environments, we have recently seen this case due to various circumstances: i) a different 3rd party agent and/or ii) a container runtime such as [0] in the user's environment configuring legacy cgroup v1 net_cls tags, which triggered implicitly mentioned root fallback. Another case is Kubernetes projects like kind [1] which create Kubernetes nodes in a container and also add cgroup namespaces to the mix, meaning programs which are attached to the cgroup v2 root of the cgroup namespace get attached to a non-root cgroup v2 path from init namespace point of view. And the latter's root is out of reach for agents on a kind Kubernetes node to configure. Meaning, any entity on the node setting cgroup v1 net_cls tag will trigger the bypass despite cgroup v2 BPF programs attached to the namespace root. Generally, this mutual exclusiveness does not hold anymore in today's user environments and makes cgroup v2 usage from BPF side fragile and unreliable. This fix adds proper struct cgroup pointer for the cgroup v2 case to struct sock_cgroup_data in order to address these issues; this implicitly also fixes the tradeoffs being made back then with regards to races and refcount leaks as stated in bd1060a1d671, and removes the fallback, so that cgroup v2 BPF programs always operate as expected. [0] https://github.com/nestybox/sysbox/ [1] https://kind.sigs.k8s.io/ Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup") Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Acked-by: Stanislav Fomichev Acked-by: Tejun Heo Link: https://lore.kernel.org/bpf/20210913230759.2313-1-daniel@iogearbox.net

net: Remove the err argument from sock_from_file

2020-12-04T21:32:40+00:00

Currently, the sock_from_file prototype takes an "err" pointer that is either not set or set to -ENOTSOCK IFF the returned socket is NULL. This makes the error redundant and it is ignored by a few callers. This patch simplifies the API by letting callers deduce the error based on whether the returned socket is NULL or not. Suggested-by: Al Viro Signed-off-by: Florent Revest Signed-off-by: Daniel Borkmann Reviewed-by: KP Singh Link: https://lore.kernel.org/bpf/20201204113609.1850150-1-revest@google.com

cgroup, netclassid: remove double cond_resched

2020-04-21T22:44:30+00:00

Commit 018d26fcd12a ("cgroup, netclassid: periodically release file_lock on classid") added a second cond_resched to write_classid indirectly by update_classid_task. Remove the one in write_classid. Signed-off-by: Jiri Slaby Cc: Dmitry Yakunin Cc: Konstantin Khlebnikov Cc: David S. Miller Signed-off-by: David S. Miller

cgroup, netclassid: periodically release file_lock on classid updating

2020-03-10T01:13:39+00:00

In our production environment we have faced with problem that updating classid in cgroup with heavy tasks cause long freeze of the file tables in this tasks. By heavy tasks we understand tasks with many threads and opened sockets (e.g. balancers). This freeze leads to an increase number of client timeouts. This patch implements following logic to fix this issue: аfter iterating 1000 file descriptors file table lock will be released thus providing a time gap for socket creation/deletion. Now update is non atomic and socket may be skipped using calls: dup2(oldfd, newfd); close(oldfd); But this case is not typical. Moreover before this patch skip is possible too by hiding socket fd in unix socket buffer. New sockets will be allocated with updated classid because cgroup state is updated before start of the file descriptors iteration. So in common cases this patch has no side effects. Signed-off-by: Dmitry Yakunin Reviewed-by: Konstantin Khlebnikov Signed-off-by: David S. Miller

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

cgroup, netclassid: add a preemption point to write_classid

2018-10-23T19:58:17+00:00

We have seen a customer complaining about soft lockups on !PREEMPT kernel config with 4.4 based kernel [1072141.435366] NMI watchdog: BUG: soft lockup - CPU#21 stuck for 22s! [systemd:1] [1072141.444090] Modules linked in: mpt3sas raid_class binfmt_misc af_packet 8021q garp mrp stp llc xfs libcrc32c bonding iscsi_ibft iscsi_boot_sysfs msr ext4 crc16 jbd2 mbcache cdc_ether usbnet mii joydev hid_generic usbhid intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel ipmi_ssif mgag200 i2c_algo_bit ttm ipmi_devintf drbg ixgbe drm_kms_helper vxlan ansi_cprng ip6_udp_tunnel drm aesni_intel udp_tunnel aes_x86_64 iTCO_wdt syscopyarea ptp xhci_pci lrw iTCO_vendor_support pps_core gf128mul ehci_pci glue_helper sysfillrect mdio pcspkr sb_edac ablk_helper cryptd ehci_hcd sysimgblt xhci_hcd fb_sys_fops edac_core mei_me lpc_ich ses usbcore enclosure dca mfd_core ipmi_si mei i2c_i801 scsi_transport_sas usb_common ipmi_msghandler shpchp fjes wmi processor button acpi_pad btrfs xor raid6_pq sd_mod crc32c_intel megaraid_sas sg dm_multipath dm_mod scsi_dh_rdac scsi_dh_emc scsi_dh_alua scsi_mod md_mod autofs4 [1072141.444146] Supported: Yes [1072141.444149] CPU: 21 PID: 1 Comm: systemd Not tainted 4.4.121-92.80-default #1 [1072141.444150] Hardware name: LENOVO Lenovo System x3650 M5 -[5462P4U]- -[5462P4U]-/01GR451, BIOS -[TCE136H-2.70]- 06/13/2018 [1072141.444151] task: ffff880191bd0040 ti: ffff880191bd4000 task.ti: ffff880191bd4000 [1072141.444153] RIP: 0010:[] [] update_classid_sock+0x29/0x40 [1072141.444157] RSP: 0018:ffff880191bd7d58 EFLAGS: 00000286 [1072141.444158] RAX: ffff883b177cb7c0 RBX: 0000000000000000 RCX: 0000000000000000 [1072141.444159] RDX: 00000000000009c7 RSI: ffff880191bd7d5c RDI: ffff8822e29bb200 [1072141.444160] RBP: ffff883a72230980 R08: 0000000000000101 R09: 0000000000000000 [1072141.444161] R10: 0000000000000008 R11: f000000000000000 R12: ffffffff815229d0 [1072141.444162] R13: 0000000000000000 R14: ffff881fd0a47ac0 R15: ffff880191bd7f28 [1072141.444163] FS: 00007f3e2f1eb8c0(0000) GS:ffff882000340000(0000) knlGS:0000000000000000 [1072141.444164] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [1072141.444165] CR2: 00007f3e2f200000 CR3: 0000001ffea4e000 CR4: 00000000001606f0 [1072141.444166] Stack: [1072141.444166] ffffffa800000246 00000000000009c7 ffffffff8121d583 ffff8818312a05c0 [1072141.444168] ffff8818312a1100 ffff880197c3b280 ffff881861422858 ffffffffffffffea [1072141.444170] ffffffff81522b1c ffffffff81d0ca20 ffff8817fa17b950 ffff883fdd8121e0 [1072141.444171] Call Trace: [1072141.444179] [] iterate_fd+0x53/0x80 [1072141.444182] [] write_classid+0x4c/0x80 [1072141.444187] [] cgroup_file_write+0x9b/0x100 [1072141.444193] [] kernfs_fop_write+0x11b/0x150 [1072141.444198] [] __vfs_write+0x26/0x100 [1072141.444201] [] vfs_write+0x9d/0x190 [1072141.444203] [] SyS_write+0x42/0xa0 [1072141.444207] [] entry_SYSCALL_64_fastpath+0x1e/0xca [1072141.445490] DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x1e/0xca If a cgroup has many tasks with many open file descriptors then we would end up in a large loop without any rescheduling point throught the operation. Add cond_resched once per task. Signed-off-by: Michal Hocko Signed-off-by: Tejun Heo

cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS

2017-07-21T15:14:51+00:00

css_task_iter currently always walks all tasks. With the scheduled cgroup v2 thread support, the iterator would need to handle multiple types of iteration. As a preparation, add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS. If the flag is not specified, it walks all tasks as before. When asserted, the iterator only walks the group leaders. For now, the only user of the flag is cgroup v2 "cgroup.procs" file which no longer needs to skip non-leader tasks in cgroup_procs_next(). Note that cgroup v1 "cgroup.procs" can't use the group leader walk as v1 "cgroup.procs" doesn't mean "list all thread group leaders in the cgroup" but "list all thread group id's with any threads in the cgroup". While at it, update cgroup_procs_show() to use task_pid_vnr() instead of task_tgid_vnr(). As the iteration guarantees that the function only sees group leaders, this doesn't change the output and will allow sharing the function for thread iteration. Signed-off-by: Tejun Heo

cgroup, net_cls: iterate the fds of only the tasks which are being migrated

2017-03-22T17:32:46+00:00

The net_cls controller controls the classid field of each socket which is associated with the cgroup. Because the classid is per-socket attribute, when a task migrates to another cgroup or the configured classid of the cgroup changes, the controller needs to walk all sockets and update the classid value, which was implemented by 3b13758f51de ("cgroups: Allow dynamically changing net_classid"). While the approach is not scalable, migrating tasks which have a lot of fds attached to them is rare and the cost is born by the ones initiating the operations. However, for simplicity, both the migration and classid config change paths call update_classid() which scans all fds of all tasks in the target css. This is an overkill for the migration path which only needs to cover a much smaller subset of tasks which are actually getting migrated in. On cgroup v1, this can lead to unexpected scalability issues when one tries to migrate a task or process into a net_cls cgroup which already contains a lot of fds. Even if the migration traget doesn't have many to get scanned, update_classid() ends up scanning all fds in the target cgroup which can be extremely numerous. Unfortunately, on cgroup v2 which doesn't use net_cls, the problem is even worse. Before bfc2cf6f61fc ("cgroup: call subsys->*attach() only for subsystems which are actually affected by migration"), cgroup core would call the ->css_attach callback even for controllers which don't see actual migration to a different css. As net_cls is always disabled but still mounted on cgroup v2, whenever a process is migrated on the cgroup v2 hierarchy, net_cls sees identity migration from root to root and cgroup core used to call ->css_attach callback for those. The net_cls ->css_attach ends up calling update_classid() on the root net_cls css to which all processes on the system belong to as the controller isn't used. This makes any cgroup v2 migration O(total_number_of_fds_on_the_system) which is horrible and easily leads to noticeable stalls triggering RCU stall warnings and so on. The worst symptom is already fixed in upstream by bfc2cf6f61fc ("cgroup: call subsys->*attach() only for subsystems which are actually affected by migration"); however, backporting that commit is too invasive and we want to avoid other cases too. This patch updates net_cls's cgrp_attach() to iterate fds of only the processes which are actually getting migrated. This removes the surprising migration cost which is dependent on the total number of fds in the target cgroup. As this leaves write_classid() the only user of update_classid(), open-code the helper into write_classid(). Reported-by: David Goode Fixes: 3b13758f51de ("cgroups: Allow dynamically changing net_classid") Cc: stable@vger.kernel.org # v4.4+ Cc: Nina Schiff Cc: David S. Miller Signed-off-by: Tejun Heo Signed-off-by: David S. Miller