[PATCH bpf] libbpf: Sanitise internal map names so they are not rejected by the kernel
From: Toke Høiland-Jørgensen <hidden>
Date: 2020-02-17 17:17:20
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
The kernel only accepts map names with alphanumeric characters, underscores
and periods in their name. However, the auto-generated internal map names
used by libbpf takes their prefix from the user-supplied BPF object name,
which has no such restriction. This can lead to "Invalid argument" errors
when trying to load a BPF program using global variables.
Fix this by sanitising the map names, replacing any non-allowed characters
with underscores.
Fixes: d859900c4c56 ("bpf, libbpf: support global data/bss/rodata sections")
Signed-off-by: Toke Høiland-Jørgensen <redacted>
---
tools/lib/bpf/libbpf.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 514b1a524abb..7469c7dcc15e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c@@ -24,6 +24,7 @@ #include <endian.h> #include <fcntl.h> #include <errno.h> +#include <ctype.h> #include <asm/unistd.h> #include <linux/err.h> #include <linux/kernel.h>
@@ -1283,7 +1284,7 @@ static size_t bpf_map_mmap_sz(const struct bpf_map *map) static char *internal_map_name(struct bpf_object *obj, enum libbpf_map_type type) { - char map_name[BPF_OBJ_NAME_LEN]; + char map_name[BPF_OBJ_NAME_LEN], *p; const char *sfx = libbpf_type_to_btf_name[type]; int sfx_len = max((size_t)7, strlen(sfx)); int pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1,
@@ -1292,6 +1293,11 @@ static char *internal_map_name(struct bpf_object *obj, snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name, sfx_len, libbpf_type_to_btf_name[type]); + /* sanitise map name to characters allowed by kernel */ + for (p = map_name; *p && p < map_name + sizeof(map_name); p++) + if (!isalnum(*p) && *p != '_' && *p != '.') + *p = '_'; + return strdup(map_name); }
--
2.25.0