diff options
| author | Andrii Nakryiko <andrii@kernel.org> | 2020-11-09 17:19:31 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-11-10 15:25:53 -0800 |
| commit | 36e68442d1afd4f720704ee1ea8486331507e834 (patch) | |
| tree | ad526ed86159e5d24b2a741c954f620c4987b157 /kernel/module.c | |
| parent | 5f9ae91f7c0dbbc4195e2a6c8eedcaeb5b9e4cbb (diff) | |
bpf: Load and verify kernel module BTFs
Add kernel module listener that will load/validate and unload module BTF.
Module BTFs gets ID generated for them, which makes it possible to iterate
them with existing BTF iteration API. They are given their respective module's
names, which will get reported through GET_OBJ_INFO API. They are also marked
as in-kernel BTFs for tooling to distinguish them from user-provided BTFs.
Also, similarly to vmlinux BTF, kernel module BTFs are exposed through
sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space
tools to inspect module BTF contents and dump their types with existing tools:
[vmuser@archvm bpf]$ ls -la /sys/kernel/btf
total 0
drwxr-xr-x 2 root root 0 Nov 4 19:46 .
drwxr-xr-x 13 root root 0 Nov 4 19:46 ..
...
-r--r--r-- 1 root root 888 Nov 4 19:46 irqbypass
-r--r--r-- 1 root root 100225 Nov 4 19:46 kvm
-r--r--r-- 1 root root 35401 Nov 4 19:46 kvm_intel
-r--r--r-- 1 root root 120 Nov 4 19:46 pcspkr
-r--r--r-- 1 root root 399 Nov 4 19:46 serio_raw
-r--r--r-- 1 root root 4094095 Nov 4 19:46 vmlinux
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/bpf/20201110011932.3201430-5-andrii@kernel.org
Diffstat (limited to 'kernel/module.c')
| -rw-r--r-- | kernel/module.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/kernel/module.c b/kernel/module.c index a4fa44a652a7..f2996b02ab2e 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -380,6 +380,35 @@ static void *section_objs(const struct load_info *info, return (void *)info->sechdrs[sec].sh_addr; } +/* Find a module section: 0 means not found. Ignores SHF_ALLOC flag. */ +static unsigned int find_any_sec(const struct load_info *info, const char *name) +{ + unsigned int i; + + for (i = 1; i < info->hdr->e_shnum; i++) { + Elf_Shdr *shdr = &info->sechdrs[i]; + if (strcmp(info->secstrings + shdr->sh_name, name) == 0) + return i; + } + return 0; +} + +/* + * Find a module section, or NULL. Fill in number of "objects" in section. + * Ignores SHF_ALLOC flag. + */ +static __maybe_unused void *any_section_objs(const struct load_info *info, + const char *name, + size_t object_size, + unsigned int *num) +{ + unsigned int sec = find_any_sec(info, name); + + /* Section 0 has sh_addr 0 and sh_size 0. */ + *num = info->sechdrs[sec].sh_size / object_size; + return (void *)info->sechdrs[sec].sh_addr; +} + /* Provided by the linker */ extern const struct kernel_symbol __start___ksymtab[]; extern const struct kernel_symbol __stop___ksymtab[]; @@ -3250,6 +3279,9 @@ static int find_module_sections(struct module *mod, struct load_info *info) sizeof(*mod->bpf_raw_events), &mod->num_bpf_raw_events); #endif +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES + mod->btf_data = any_section_objs(info, ".BTF", 1, &mod->btf_data_size); +#endif #ifdef CONFIG_JUMP_LABEL mod->jump_entries = section_objs(info, "__jump_table", sizeof(*mod->jump_entries), |