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bpf: Add config to allow loading modules with BTF mismatches

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BTF mismatch can occur for a separately-built module even when the ABI is
otherwise compatible and nothing else would prevent successfully loading.

Add a new Kconfig to control how mismatches are handled. By default, preserve
the current behavior of refusing to load the module. If MODULE_ALLOW_BTF_MISMATCH
is enabled, load the module but ignore its BTF information.

Suggested-by: Yonghong Song <yhs@fb.com>
Suggested-by: Michal Suchánek <msuchanek@suse.de>
Signed-off-by: Connor O'Brien <connoro@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/CAADnVQJ+OVPnBz8z3vNu8gKXX42jCUqfuvhWAyCQDu8N_yqqwQ@mail.gmail.com
Link: https://lore.kernel.org/bpf/20220223012814.1898677-1-connoro@google.com
This commit is contained in:
Connor O'Brien 2022-02-23 01:28:14 +00:00 committed by Daniel Borkmann
parent dda7596c10
commit 5e214f2e43
2 changed files with 12 additions and 1 deletions
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3
kernel/bpf/btf.c
View File

@ -6398,7 +6398,8 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op,
pr_warn("failed to validate module [%s] BTF: %ld\n",
mod->name, PTR_ERR(btf));
kfree(btf_mod);
err = PTR_ERR(btf);
if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
err = PTR_ERR(btf);
goto out;
}
err = btf_alloc_id(btf);

10
lib/Kconfig.debug
View File

@ -339,6 +339,16 @@ config DEBUG_INFO_BTF_MODULES
help
Generate compact split BTF type information for kernel modules.
config MODULE_ALLOW_BTF_MISMATCH
bool "Allow loading modules with non-matching BTF type info"
depends on DEBUG_INFO_BTF_MODULES
help
For modules whose split BTF does not match vmlinux, load without
BTF rather than refusing to load. The default behavior with
module BTF enabled is to reject modules with such mismatches;
this option will still load module BTF where possible but ignore
it when a mismatch is found.
config GDB_SCRIPTS
bool "Provide GDB scripts for kernel debugging"
help