netdev - [PATCH bpf-next 4/4] bpftool: use libbpf_[get|put]_bpf

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Date:   Tue, 25 Jun 2019 11:23:03 -0700
From:   Song Liu <songliubraving@...com>
To:     <netdev@...r.kernel.org>, <bpf@...r.kernel.org>
CC:     <ast@...nel.org>, <daniel@...earbox.net>, <kernel-team@...com>,
        Song Liu <songliubraving@...com>
Subject: [PATCH bpf-next 4/4] bpftool: use libbpf_[get|put]_bpf_permission()

This patch calls libbpf_[get|put]_bpf_permission() from bpftool. This
allows users with access to /dev/bpf to perform operations like root.

Signed-off-by: Song Liu <songliubraving@...com>
---
 tools/bpf/bpftool/feature.c | 2 +-
 tools/bpf/bpftool/main.c    | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
index d672d9086fff..f7f43b91ce96 100644
--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -583,7 +583,7 @@ static int do_probe(int argc, char **argv)
 	/* Detection assumes user has sufficient privileges (CAP_SYS_ADMIN).
 	 * Let's approximate, and restrict usage to root user only.
 	 */
-	if (geteuid()) {
+	if (!libbpf_get_bpf_permission()) {
 		p_err("please run this command as root user");
 		return -1;
 	}
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 4879f6395c7e..f9146d7d8fc5 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -390,6 +390,10 @@ int main(int argc, char **argv)
 	if (argc < 0)
 		usage();
 
+	if (!libbpf_get_bpf_permission()) {
+		p_err("cannot get permission to access bpf() syscall");
+		usage();
+	}
 	ret = cmd_select(cmds, argc, argv, do_help);
 
 	if (json_output)
@@ -400,5 +404,6 @@ int main(int argc, char **argv)
 		delete_pinned_obj_table(&map_table);
 	}
 
+	libbpf_put_bpf_permission();
 	return ret;
 }
-- 
2.17.1