netdev - [PATCH bpf-next] libbpf: fix bpf_object name determination for bpf_object__open

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Message-ID: <20191122003527.551556-1-andriin@fb.com>
Date:   Thu, 21 Nov 2019 16:35:27 -0800
From:   Andrii Nakryiko <andriin@...com>
To:     <bpf@...r.kernel.org>, <netdev@...r.kernel.org>, <ast@...com>,
        <daniel@...earbox.net>
CC:     <andrii.nakryiko@...il.com>, <kernel-team@...com>,
        Andrii Nakryiko <andriin@...com>
Subject: [PATCH bpf-next] libbpf: fix bpf_object name determination for bpf_object__open_file()

If bpf_object__open_file() gets path like "some/dir/obj.o", it should derive
BPF object's name as "obj" (unless overriden through opts->object_name).
Instead, due to using `path` as a fallback value for opts->obj_name, path is
used as is for object name, so for above example BPF object's name will be
verbatim "some/dir/obj", which leads to all sorts of troubles, especially when
internal maps are concern (they are using up to 8 characters of object name).
Fix that by ensuring object_name stays NULL, unless overriden.

Fixes: 291ee02b5e40 ("libbpf: Refactor bpf_object__open APIs to use common opts")
Signed-off-by: Andrii Nakryiko <andriin@...com>
---
 tools/lib/bpf/libbpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a4e250a369c6..e1698461c6b3 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3940,7 +3940,7 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
 	if (!OPTS_VALID(opts, bpf_object_open_opts))
 		return ERR_PTR(-EINVAL);

-	obj_name = OPTS_GET(opts, object_name, path);
+	obj_name = OPTS_GET(opts, object_name, NULL);
 	if (obj_buf) {
 		if (!obj_name) {
 			snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
-- 
2.17.1