This is a note to let you know that I've just added the patch titled bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD and PERF_BPF_EVENT_PROG_UNLOAD to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bpf-restore-the-ebpf-program-id-for-bpf_audit_unload-and-perf_bpf_event_prog_unload.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From ef01f4e25c1760920e2c94f1c232350277ace69b Mon Sep 17 00:00:00 2001 From: Paul Moore <paul@xxxxxxxxxxxxxx> Date: Fri, 6 Jan 2023 10:43:59 -0500 Subject: bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD and PERF_BPF_EVENT_PROG_UNLOAD From: Paul Moore <paul@xxxxxxxxxxxxxx> commit ef01f4e25c1760920e2c94f1c232350277ace69b upstream. When changing the ebpf program put() routines to support being called from within IRQ context the program ID was reset to zero prior to calling the perf event and audit UNLOAD record generators, which resulted in problems as the ebpf program ID was bogus (always zero). This patch addresses this problem by removing an unnecessary call to bpf_prog_free_id() in __bpf_prog_offload_destroy() and adjusting __bpf_prog_put() to only call bpf_prog_free_id() after audit and perf have finished their bpf program unload tasks in bpf_prog_put_deferred(). For the record, no one can determine, or remember, why it was necessary to free the program ID, and remove it from the IDR, prior to executing bpf_prog_put_deferred(); regardless, both Stanislav and Alexei agree that the approach in this patch should be safe. It is worth noting that when moving the bpf_prog_free_id() call, the do_idr_lock parameter was forced to true as the ebpf devs determined this was the correct as the do_idr_lock should always be true. The do_idr_lock parameter will be removed in a follow-up patch, but it was kept here to keep the patch small in an effort to ease any stable backports. I also modified the bpf_audit_prog() logic used to associate the AUDIT_BPF record with other associated records, e.g. @ctx != NULL. Instead of keying off the operation, it now keys off the execution context, e.g. '!in_irg && !irqs_disabled()', which is much more appropriate and should help better connect the UNLOAD operations with the associated audit state (other audit records). Cc: stable@xxxxxxxxxxxxxxx Fixes: d809e134be7a ("bpf: Prepare bpf_prog_put() to be called from irq context.") Reported-by: Burn Alting <burn.alting@xxxxxxxxxxxx> Reported-by: Jiri Olsa <olsajiri@xxxxxxxxx> Suggested-by: Stanislav Fomichev <sdf@xxxxxxxxxx> Suggested-by: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx> Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230106154400.74211-1-paul@xxxxxxxxxxxxxx Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/bpf/offload.c | 3 --- kernel/bpf/syscall.c | 6 ++---- 2 files changed, 2 insertions(+), 7 deletions(-) --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -216,9 +216,6 @@ static void __bpf_prog_offload_destroy(s if (offload->dev_state) offload->offdev->ops->destroy(prog); - /* Make sure BPF_PROG_GET_NEXT_ID can't find this dead program */ - bpf_prog_free_id(prog, true); - list_del_init(&offload->offloads); kfree(offload); prog->aux->offload = NULL; --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1695,7 +1695,7 @@ static void bpf_audit_prog(const struct return; if (audit_enabled == AUDIT_OFF) return; - if (op == BPF_AUDIT_LOAD) + if (!in_irq() && !irqs_disabled()) ctx = audit_context(); ab = audit_log_start(ctx, GFP_ATOMIC, AUDIT_BPF); if (unlikely(!ab)) @@ -1790,6 +1790,7 @@ static void bpf_prog_put_deferred(struct prog = aux->prog; perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_UNLOAD, 0); bpf_audit_prog(prog, BPF_AUDIT_UNLOAD); + bpf_prog_free_id(prog, true); __bpf_prog_put_noref(prog, true); } @@ -1798,9 +1799,6 @@ static void __bpf_prog_put(struct bpf_pr struct bpf_prog_aux *aux = prog->aux; if (atomic64_dec_and_test(&aux->refcnt)) { - /* bpf_prog_free_id() must be called first */ - bpf_prog_free_id(prog, do_idr_lock); - if (in_irq() || irqs_disabled()) { INIT_WORK(&aux->work, bpf_prog_put_deferred); schedule_work(&aux->work); Patches currently in stable-queue which might be from paul@xxxxxxxxxxxxxx are queue-5.15/bpf-restore-the-ebpf-program-id-for-bpf_audit_unload-and-perf_bpf_event_prog_unload.patch