netdev - [PATCH bpf-next 2/4] bpf: allow bpf_d_path in sleepable bpf

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Date:   Fri, 11 Dec 2020 18:48:08 -0800
From:   Song Liu <songliubraving@...com>
To:     <bpf@...r.kernel.org>, <netdev@...r.kernel.org>
CC:     <ast@...nel.org>, <daniel@...earbox.net>, <andrii@...nel.org>,
        <john.fastabend@...il.com>, <kpsingh@...omium.org>,
        <kernel-team@...com>, Song Liu <songliubraving@...com>
Subject: [PATCH bpf-next 2/4] bpf: allow bpf_d_path in sleepable bpf_iter program

task_file and task_vma iter programs have access to file->f_path. Enable
bpf_d_path to print paths of these file.

bpf_iter programs are generally called in sleepable context. However, it
is still necessary to diffientiate sleepable and non-sleepable bpf_iter
programs: sleepable programs have access to bpf_d_path; non-sleepable
programs have access to bpf_spin_lock.

Signed-off-by: Song Liu <songliubraving@...com>
---
 kernel/trace/bpf_trace.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 52ddd217d6a19..839c654160d1b 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1191,6 +1191,11 @@ BTF_SET_END(btf_allowlist_d_path)
 
 static bool bpf_d_path_allowed(const struct bpf_prog *prog)
 {
+	if (prog->type == BPF_PROG_TYPE_TRACING &&
+	    prog->expected_attach_type == BPF_TRACE_ITER &&
+	    prog->aux->sleepable)
+		return true;
+
 	if (prog->type == BPF_PROG_TYPE_LSM)
 		return bpf_lsm_is_sleepable_hook(prog->aux->attach_btf_id);
 
-- 
2.24.1