kernel/linux.git/net/sched/sch_api.c, branch v6.6

net/sched: fix a qdisc modification with ambiguous command request

2023-08-23T08:44:48+00:00

When replacing an existing root qdisc, with one that is of the same kind, the request boils down to essentially a parameterization change i.e not one that requires allocation and grafting of a new qdisc. syzbot was able to create a scenario which resulted in a taprio qdisc replacing an existing taprio qdisc with a combination of NLM_F_CREATE, NLM_F_REPLACE and NLM_F_EXCL leading to create and graft scenario. The fix ensures that only when the qdisc kinds are different that we should allow a create and graft, otherwise it goes into the "change" codepath. While at it, fix the code and comments to improve readability. While syzbot was able to create the issue, it did not zone on the root cause. Analysis from Vladimir Oltean helped narrow it down. v1->V2 changes: - remove "inline" function definition (Vladmir) - remove extrenous braces in branches (Vladmir) - change inline function names (Pedro) - Run tdc tests (Victor) v2->v3 changes: - dont break else/if (Simon) Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+a3618a167af2021433cd@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/20230816225759.g25x76kmgzya2gei@skbuf/T/ Tested-by: Vladimir Oltean Tested-by: Victor Nogueira Reviewed-by: Pedro Tammela Reviewed-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Signed-off-by: David S. Miller

net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting

2023-06-14T08:31:39+00:00

mini_Qdisc_pair::p_miniq is a double pointer to mini_Qdisc, initialized in ingress_init() to point to net_device::miniq_ingress. ingress Qdiscs access this per-net_device pointer in mini_qdisc_pair_swap(). Similar for clsact Qdiscs and miniq_egress. Unfortunately, after introducing RTNL-unlocked RTM_{NEW,DEL,GET}TFILTER requests (thanks Hillf Danton for the hint), when replacing ingress or clsact Qdiscs, for example, the old Qdisc ("@old") could access the same miniq_{in,e}gress pointer(s) concurrently with the new Qdisc ("@new"), causing race conditions [1] including a use-after-free bug in mini_qdisc_pair_swap() reported by syzbot: BUG: KASAN: slab-use-after-free in mini_qdisc_pair_swap+0x1c2/0x1f0 net/sched/sch_generic.c:1573 Write of size 8 at addr ffff888045b31308 by task syz-executor690/14901 ... Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:319 print_report mm/kasan/report.c:430 [inline] kasan_report+0x11c/0x130 mm/kasan/report.c:536 mini_qdisc_pair_swap+0x1c2/0x1f0 net/sched/sch_generic.c:1573 tcf_chain_head_change_item net/sched/cls_api.c:495 [inline] tcf_chain0_head_change.isra.0+0xb9/0x120 net/sched/cls_api.c:509 tcf_chain_tp_insert net/sched/cls_api.c:1826 [inline] tcf_chain_tp_insert_unique net/sched/cls_api.c:1875 [inline] tc_new_tfilter+0x1de6/0x2290 net/sched/cls_api.c:2266 ... @old and @new should not affect each other. In other words, @old should never modify miniq_{in,e}gress after @new, and @new should not update @old's RCU state. Fixing without changing sch_api.c turned out to be difficult (please refer to Closes: for discussions). Instead, make sure @new's first call always happen after @old's last call (in {ingress,clsact}_destroy()) has finished: In qdisc_graft(), return -EBUSY if @old has any ongoing filter requests, and call qdisc_destroy() for @old before grafting @new. Introduce qdisc_refcount_dec_if_one() as the counterpart of qdisc_refcount_inc_nz() used for filter requests. Introduce a non-static version of qdisc_destroy() that does a TCQ_F_BUILTIN check, just like qdisc_put() etc. Depends on patch "net/sched: Refactor qdisc_graft() for ingress and clsact Qdiscs". [1] To illustrate, the syzkaller reproducer adds ingress Qdiscs under TC_H_ROOT (no longer possible after commit c7cfbd115001 ("net/sched: sch_ingress: Only create under TC_H_INGRESS")) on eth0 that has 8 transmission queues: Thread 1 creates ingress Qdisc A (containing mini Qdisc a1 and a2), then adds a flower filter X to A. Thread 2 creates another ingress Qdisc B (containing mini Qdisc b1 and b2) to replace A, then adds a flower filter Y to B. Thread 1 A's refcnt Thread 2 RTM_NEWQDISC (A, RTNL-locked) qdisc_create(A) 1 qdisc_graft(A) 9 RTM_NEWTFILTER (X, RTNL-unlocked) __tcf_qdisc_find(A) 10 tcf_chain0_head_change(A) mini_qdisc_pair_swap(A) (1st) | | RTM_NEWQDISC (B, RTNL-locked) RCU sync 2 qdisc_graft(B) | 1 notify_and_destroy(A) | tcf_block_release(A) 0 RTM_NEWTFILTER (Y, RTNL-unlocked) qdisc_destroy(A) tcf_chain0_head_change(B) tcf_chain0_head_change_cb_del(A) mini_qdisc_pair_swap(B) (2nd) mini_qdisc_pair_swap(A) (3rd) | ... ... Here, B calls mini_qdisc_pair_swap(), pointing eth0->miniq_ingress to its mini Qdisc, b1. Then, A calls mini_qdisc_pair_swap() again during ingress_destroy(), setting eth0->miniq_ingress to NULL, so ingress packets on eth0 will not find filter Y in sch_handle_ingress(). This is just one of the possible consequences of concurrently accessing miniq_{in,e}gress pointers. Fixes: 7a096d579e8e ("net: sched: ingress: set 'unlocked' flag for Qdisc ops") Fixes: 87f373921c4e ("net: sched: ingress: set 'unlocked' flag for clsact Qdisc ops") Reported-by: syzbot+b53a9c0d1ea4ad62da8b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/r/0000000000006cf87705f79acf1a@google.com/ Cc: Hillf Danton Cc: Vlad Buslov Signed-off-by: Peilin Ye Acked-by: Jamal Hadi Salim Signed-off-by: Paolo Abeni

net/sched: Refactor qdisc_graft() for ingress and clsact Qdiscs

2023-06-14T08:31:39+00:00

Grafting ingress and clsact Qdiscs does not need a for-loop in qdisc_graft(). Refactor it. No functional changes intended. Tested-by: Pedro Tammela Acked-by: Jamal Hadi Salim Reviewed-by: Jamal Hadi Salim Reviewed-by: Vlad Buslov Signed-off-by: Peilin Ye Signed-off-by: Paolo Abeni

net: sched: add rcu annotations around qdisc->qdisc_sleeping

2023-06-07T09:25:39+00:00

syzbot reported a race around qdisc->qdisc_sleeping [1] It is time we add proper annotations to reads and writes to/from qdisc->qdisc_sleeping. [1] BUG: KCSAN: data-race in dev_graft_qdisc / qdisc_lookup_rcu read to 0xffff8881286fc618 of 8 bytes by task 6928 on cpu 1: qdisc_lookup_rcu+0x192/0x2c0 net/sched/sch_api.c:331 __tcf_qdisc_find+0x74/0x3c0 net/sched/cls_api.c:1174 tc_get_tfilter+0x18f/0x990 net/sched/cls_api.c:2547 rtnetlink_rcv_msg+0x7af/0x8c0 net/core/rtnetlink.c:6386 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503 ___sys_sendmsg net/socket.c:2557 [inline] __sys_sendmsg+0x1e3/0x270 net/socket.c:2586 __do_sys_sendmsg net/socket.c:2595 [inline] __se_sys_sendmsg net/socket.c:2593 [inline] __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd write to 0xffff8881286fc618 of 8 bytes by task 6912 on cpu 0: dev_graft_qdisc+0x4f/0x80 net/sched/sch_generic.c:1115 qdisc_graft+0x7d0/0xb60 net/sched/sch_api.c:1103 tc_modify_qdisc+0x712/0xf10 net/sched/sch_api.c:1693 rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6395 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503 ___sys_sendmsg net/socket.c:2557 [inline] __sys_sendmsg+0x1e3/0x270 net/socket.c:2586 __do_sys_sendmsg net/socket.c:2595 [inline] __se_sys_sendmsg net/socket.c:2593 [inline] __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 6912 Comm: syz-executor.5 Not tainted 6.4.0-rc3-syzkaller-00190-g0d85b27b0cc6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/16/2023 Fixes: 3a7d0d07a386 ("net: sched: extend Qdisc with rcu") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Vlad Buslov Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller

net: sched: wrap tc_skip_wrapper with CONFIG_RETPOLINE

2023-06-04T14:49:06+00:00

This patch fixes the following sparse warning: net/sched/sch_api.c:2305:1: sparse: warning: symbol 'tc_skip_wrapper' was not declared. Should it be static? No functional change intended. Signed-off-by: Min-Hua Chen Acked-by: Pedro Tammela Signed-off-by: David S. Miller

net: sched: fix NULL pointer dereference in mq_attach

2023-05-31T06:31:40+00:00

When use the following command to test: 1)ip link add bond0 type bond 2)ip link set bond0 up 3)tc qdisc add dev bond0 root handle ffff: mq 4)tc qdisc replace dev bond0 parent ffff:fff1 handle ffff: mq The kernel reports NULL pointer dereference issue. The stack information is as follows: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Internal error: Oops: 0000000096000006 [#1] SMP Modules linked in: pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : mq_attach+0x44/0xa0 lr : qdisc_graft+0x20c/0x5cc sp : ffff80000e2236a0 x29: ffff80000e2236a0 x28: ffff0000c0e59d80 x27: ffff0000c0be19c0 x26: ffff0000cae3e800 x25: 0000000000000010 x24: 00000000fffffff1 x23: 0000000000000000 x22: ffff0000cae3e800 x21: ffff0000c9df4000 x20: ffff0000c9df4000 x19: 0000000000000000 x18: ffff80000a934000 x17: ffff8000f5b56000 x16: ffff80000bb08000 x15: 0000000000000000 x14: 0000000000000000 x13: 6b6b6b6b6b6b6b6b x12: 6b6b6b6b00000001 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : ffff0000c0be0730 x7 : bbbbbbbbbbbbbbbb x6 : 0000000000000008 x5 : ffff0000cae3e864 x4 : 0000000000000000 x3 : 0000000000000001 x2 : 0000000000000001 x1 : ffff8000090bc23c x0 : 0000000000000000 Call trace: mq_attach+0x44/0xa0 qdisc_graft+0x20c/0x5cc tc_modify_qdisc+0x1c4/0x664 rtnetlink_rcv_msg+0x354/0x440 netlink_rcv_skb+0x64/0x144 rtnetlink_rcv+0x28/0x34 netlink_unicast+0x1e8/0x2a4 netlink_sendmsg+0x308/0x4a0 sock_sendmsg+0x64/0xac ____sys_sendmsg+0x29c/0x358 ___sys_sendmsg+0x90/0xd0 __sys_sendmsg+0x7c/0xd0 __arm64_sys_sendmsg+0x2c/0x38 invoke_syscall+0x54/0x114 el0_svc_common.constprop.1+0x90/0x174 do_el0_svc+0x3c/0xb0 el0_svc+0x24/0xec el0t_64_sync_handler+0x90/0xb4 el0t_64_sync+0x174/0x178 This is because when mq is added for the first time, qdiscs in mq is set to NULL in mq_attach(). Therefore, when replacing mq after adding mq, we need to initialize qdiscs in the mq before continuing to graft. Otherwise, it will couse NULL pointer dereference issue in mq_attach(). And the same issue will occur in the attach functions of mqprio, taprio and htb. ffff:fff1 means that the repalce qdisc is ingress. Ingress does not allow any qdisc to be attached. Therefore, ffff:fff1 is incorrectly used, and the command should be dropped. Fixes: 6ec1c69a8f64 ("net_sched: add classful multiqueue dummy scheduler") Signed-off-by: Zhengchao Shao Tested-by: Peilin Ye Acked-by: Jamal Hadi Salim Link: https://lore.kernel.org/r/20230527093747.3583502-1-shaozhengchao@huawei.com Signed-off-by: Jakub Kicinski

net/sched: Prohibit regrafting ingress or clsact Qdiscs

2023-05-31T06:31:05+00:00

Currently, after creating an ingress (or clsact) Qdisc and grafting it under TC_H_INGRESS (TC_H_CLSACT), it is possible to graft it again under e.g. a TBF Qdisc: $ ip link add ifb0 type ifb $ tc qdisc add dev ifb0 handle 1: root tbf rate 20kbit buffer 1600 limit 3000 $ tc qdisc add dev ifb0 clsact $ tc qdisc link dev ifb0 handle ffff: parent 1:1 $ tc qdisc show dev ifb0 qdisc tbf 1: root refcnt 2 rate 20Kbit burst 1600b lat 560.0ms qdisc clsact ffff: parent ffff:fff1 refcnt 2 ^^^^^^^^ clsact's refcount has increased: it is now grafted under both TC_H_CLSACT and 1:1. ingress and clsact Qdiscs should only be used under TC_H_INGRESS (TC_H_CLSACT). Prohibit regrafting them. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: 1f211a1b929c ("net, sched: add clsact qdisc") Tested-by: Pedro Tammela Acked-by: Jamal Hadi Salim Reviewed-by: Jamal Hadi Salim Reviewed-by: Vlad Buslov Signed-off-by: Peilin Ye Signed-off-by: Jakub Kicinski

net/sched: Reserve TC_H_INGRESS (TC_H_CLSACT) for ingress (clsact) Qdiscs

2023-05-31T06:31:05+00:00

Currently it is possible to add e.g. an HTB Qdisc under ffff:fff1 (TC_H_INGRESS, TC_H_CLSACT): $ ip link add name ifb0 type ifb $ tc qdisc add dev ifb0 parent ffff:fff1 htb $ tc qdisc add dev ifb0 clsact Error: Exclusivity flag on, cannot modify. $ drgn ... >>> ifb0 = netdev_get_by_name(prog, "ifb0") >>> qdisc = ifb0.ingress_queue.qdisc_sleeping >>> print(qdisc.ops.id.string_().decode()) htb >>> qdisc.flags.value_() # TCQ_F_INGRESS 2 Only allow ingress and clsact Qdiscs under ffff:fff1. Return -EINVAL for everything else. Make TCQ_F_INGRESS a static flag of ingress and clsact Qdiscs. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: 1f211a1b929c ("net, sched: add clsact qdisc") Tested-by: Pedro Tammela Acked-by: Jamal Hadi Salim Reviewed-by: Jamal Hadi Salim Reviewed-by: Vlad Buslov Signed-off-by: Peilin Ye Signed-off-by: Jakub Kicinski

net: sched: remove qdisc_watchdog->last_expires

2023-03-10T07:24:14+00:00

This field mirrors hrtimer softexpires, we can instead use the existing helpers. Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20230308182648.1150762-1-edumazet@google.com Signed-off-by: Jakub Kicinski

net/sched: fix error recovery in qdisc_create()

2023-02-13T09:51:59+00:00

If TCA_STAB attribute is malformed, qdisc_get_stab() returns an error, and we end up calling ops->destroy() while ops->init() has not been called yet. While we are at it, call qdisc_put_stab() after ops->destroy(). Fixes: 1f62879e3632 ("net/sched: make stab available before ops->init() call") Reported-by: syzbot+d44d88f1d11e6ca8576b@syzkaller.appspotmail.com Signed-off-by: Eric Dumazet Cc: Vladimir Oltean Cc: Kurt Kanzenbach Reviewed-by: Vladimir Oltean Signed-off-by: David S. Miller