Commit 54b8625c authored by John Fastabend's avatar John Fastabend Committed by Daniel Borkmann

bpf, libbpf: Add kernel version section parsing back

With commit "libbpf: stop enforcing kern_version,..." we removed the
kernel version section parsing in favor of querying for the kernel
using uname() and populating the version using the result of the
query. After this any version sections were simply ignored.

Unfortunately, the world of kernels is not so friendly. I've found some
customized kernels where uname() does not match the in kernel version.
To fix this so programs can load in this environment this patch adds
back parsing the section and if it exists uses the user specified
kernel version to override the uname() result. However, keep most the
kernel uname() discovery bits so users are not required to insert the
version except in these odd cases.

Fixes: 5e61f270 ("libbpf: stop enforcing kern_version, populate it for users")
Signed-off-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157140968634.9073.6407090804163937103.stgit@john-XPS-13-9370
parent 1f5343c0
......@@ -657,6 +657,21 @@ bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
return 0;
}
static int
bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
{
__u32 kver;
if (size != sizeof(kver)) {
pr_warning("invalid kver section in %s\n", obj->path);
return -LIBBPF_ERRNO__FORMAT;
}
memcpy(&kver, data, sizeof(kver));
obj->kern_version = kver;
pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
return 0;
}
static int compare_bpf_map(const void *_a, const void *_b)
{
const struct bpf_map *a = _a;
......@@ -1574,7 +1589,11 @@ static int bpf_object__elf_collect(struct bpf_object *obj, bool relaxed_maps)
if (err)
return err;
} else if (strcmp(name, "version") == 0) {
/* skip, we don't need it anymore */
err = bpf_object__init_kversion(obj,
data->d_buf,
data->d_size);
if (err)
return err;
} else if (strcmp(name, "maps") == 0) {
obj->efile.maps_shndx = idx;
} else if (strcmp(name, MAPS_ELF_SEC) == 0) {
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment