From 5e214f2e43e453d862ebbbd2a4f7ee3fe650f209 Mon Sep 17 00:00:00 2001 From: Connor O'Brien Date: Wed, 23 Feb 2022 01:28:14 +0000 Subject: bpf: Add config to allow loading modules with BTF mismatches 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 Suggested-by: Michal Suchánek Signed-off-by: Connor O'Brien Signed-off-by: Daniel Borkmann Acked-by: Shung-Hsi Yu Acked-by: Song Liu Link: https://lore.kernel.org/bpf/CAADnVQJ+OVPnBz8z3vNu8gKXX42jCUqfuvhWAyCQDu8N_yqqwQ@mail.gmail.com Link: https://lore.kernel.org/bpf/20220223012814.1898677-1-connoro@google.com --- kernel/bpf/btf.c | 3 ++- lib/Kconfig.debug | 10 ++++++++++ 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 0890e56e8b08..b472cf0c8fdb 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -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); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 1555da672275..72ca4684beda 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -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 -- cgit v1.2.3