ACK: [SRU][R][PATCH 1/1] UBUNTU: SAUCE: Revert "bpf: Verifier support for sleepable tracepoint programs"

[Edoardo Canepa]

Acked-by: Edoardo Canepa <edoardo.canepa at canonical.com>

On 9/1/26 19:18, Alice C. Munduruca via kernel-team wrote:
> BugLink: https://bugs.launchpad.net/bugs/2165872
>
> This reverts commit 2946e2f49e86d17c3b2fc8ba57de4b39dd5b58f4.
>
> This commit was picked up by upstream stable linux-7.1.y in order to
> simplify the cherry-pick for commit 5b038319be44 ("bpf: Reject sleepable
> BPF_LSM_CGROUP programs at load time"), however the other patches in the
> series, which are required for a non-regressing bpf subsystem, were not
> also added. As a result, remove this superfluous breaking change and
> simply retain the changes for rejetcting sleepable BPF_LSM_CGROUP
> programs.
>
> Signed-off-by: Alice C. Munduruca <alice.munduruca at canonical.com>
> ---
>   kernel/bpf/syscall.c  |  5 -----
>   kernel/bpf/verifier.c | 13 ++-----------
>   2 files changed, 2 insertions(+), 16 deletions(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index c531555cc2d9..4f4a61cbd813 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -4311,11 +4311,6 @@ static int bpf_raw_tp_link_attach(struct bpf_prog *prog,
>   	if (!btp)
>   		return -ENOENT;
>   
> -	if (prog->sleepable && !tracepoint_is_faultable(btp->tp)) {
> -		bpf_put_raw_tracepoint(btp);
> -		return -EINVAL;
> -	}
> -
>   	link = kzalloc_obj(*link, GFP_USER);
>   	if (!link) {
>   		err = -ENOMEM;
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index d4e38697a704..22ea58b98a8c 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -25205,12 +25205,6 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
>   		btp = bpf_get_raw_tracepoint(tname);
>   		if (!btp)
>   			return -EINVAL;
> -		if (prog->sleepable && !tracepoint_is_faultable(btp->tp)) {
> -			bpf_log(log, "Sleepable program cannot attach to non-faultable tracepoint %s\n",
> -				tname);
> -			bpf_put_raw_tracepoint(btp);
> -			return -EINVAL;
> -		}
>   		fname = kallsyms_lookup((unsigned long)btp->bpf_func, NULL, NULL, NULL,
>   					trace_symbol);
>   		bpf_put_raw_tracepoint(btp);
> @@ -25432,7 +25426,6 @@ static bool can_be_sleepable(struct bpf_prog *prog)
>   		case BPF_MODIFY_RETURN:
>   		case BPF_TRACE_ITER:
>   		case BPF_TRACE_FSESSION:
> -		case BPF_TRACE_RAW_TP:
>   			return true;
>   		default:
>   			return false;
> @@ -25442,9 +25435,7 @@ static bool can_be_sleepable(struct bpf_prog *prog)
>   		return prog->expected_attach_type != BPF_LSM_CGROUP;
>   
>   	return prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ ||
> -	       prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
> -	       prog->type == BPF_PROG_TYPE_RAW_TRACEPOINT ||
> -	       prog->type == BPF_PROG_TYPE_TRACEPOINT;
> +	       prog->type == BPF_PROG_TYPE_STRUCT_OPS;
>   }
>   
>   static int check_attach_btf_id(struct bpf_verifier_env *env)
> @@ -25466,7 +25457,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
>   	}
>   
>   	if (prog->sleepable && !can_be_sleepable(prog)) {
> -		verbose(env, "Program of this type cannot be sleepable\n");
> +		verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable\n");
>   		return -EINVAL;
>   	}
>   
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