[PATCH v5 bpf-next 2/4] bpf: allow bpf_d_path in sleepable bpf_iter program

From: Song Liu <songliubraving@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <linux-mm@kvack.org>
Cc: <ast@kernel.org>, <daniel@iogearbox.net>, <kernel-team@fb.com>,
	<akpm@linux-foundation.org>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>
Subject: [PATCH v5 bpf-next 2/4] bpf: allow bpf_d_path in sleepable bpf_iter program
Date: Mon, 8 Feb 2021 14:52:53 -0800	[thread overview]
Message-ID: <20210208225255.3089073-3-songliubraving@fb.com> (raw)
In-Reply-To: <20210208225255.3089073-1-songliubraving@fb.com>

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.

Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Song Liu <songliubraving@fb.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 6c0018abe68a0..1f3becd4435ae 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

