From: Mickaël Salaün <m...@linux.microsoft.com> Add a new option CONFIG_LSM_AUTO to enable users to delegate default LSM stacking order to kernel developers. This enable to keep a consistent order of enabled LSM when changing the LSM selection, especially when a new LSM is added to the kernel.
CONFIG_LSM depends on !CONFIG_LSM_AUTO, which is backward compatible and gives the opportunity to users to select CONFIG_LSM_AUTO with a make oldconfig. CONFIG_LSM and CONFIG_LSM_AUTO depend on CONFIG_SECURITY, which makes sense because an LSM depends on the security framework. Cc: Casey Schaufler <ca...@schaufler-ca.com> Cc: James Morris <jmor...@namei.org> Cc: Kees Cook <keesc...@chromium.org> Cc: Serge E. Hallyn <se...@hallyn.com> Signed-off-by: Mickaël Salaün <m...@linux.microsoft.com> Link: https://lore.kernel.org/r/20210222150608.808146-2-...@digikod.net --- Changes since v2: * Revamp without virtual dependencies but a new option to automatically enable all selected LSMs. Changes since v1: * Add CONFIG_SECURITY as a dependency of CONFIG_LSM. This prevent an error when building without any LSMs. --- security/Kconfig | 19 +++++++++++++++++++ security/security.c | 26 +++++++++++++++++++++++++- 2 files changed, 44 insertions(+), 1 deletion(-) diff --git a/security/Kconfig b/security/Kconfig index 7561f6f99f1d..fae083e9867d 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -243,6 +243,7 @@ source "security/integrity/Kconfig" choice prompt "First legacy 'major LSM' to be initialized" + depends on SECURITY default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX default DEFAULT_SECURITY_SMACK if SECURITY_SMACK default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO @@ -275,8 +276,26 @@ choice endchoice +config LSM_AUTO + bool "Automatically enable all selected LSMs at boot" + depends on SECURITY + default y + help + This automatically configure the build-time selected LSMs to be + enabled at boot unless the "lsm=" parameter is provided. + + If this option is not selected, it will be required to configure and + maintained a static list of enabled LSMs that may become inconsistent + with future user configuration. Indeed, this list will not be + automatically upgraded when selecting a new (future) LSM, e.g. with + make oldconfig. + + If you are unsure how to answer this question, answer Y. + +# This lists should be synchronized with LSM_ORDER defined in security/security.c . config LSM string "Ordered list of enabled LSMs" + depends on SECURITY && !LSM_AUTO default "lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK default "lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR default "lockdown,yama,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO diff --git a/security/security.c b/security/security.c index 401663b5b70e..defa1d2c40a3 100644 --- a/security/security.c +++ b/security/security.c @@ -82,7 +82,31 @@ static struct lsm_blob_sizes blob_sizes __lsm_ro_after_init; static __initdata const char *chosen_lsm_order; static __initdata const char *chosen_major_lsm; -static __initconst const char * const builtin_lsm_order = CONFIG_LSM; +#ifdef CONFIG_LSM +#define LSM_ORDER CONFIG_LSM +#else + +/* + * This lists should be synchronized with the default values of CONFIG_LSM + * defined in security/Kconfig . + */ +#define LSM_ORDER_PRE "lockdown,yama,loadpin,safesetid,integrity," + +#if defined(CONFIG_DEFAULT_SECURITY_SMACK) +#define LSM_ORDER LSM_ORDER_PRE "smack,selinux,tomoyo,apparmor,bpf" +#elif defined(CONFIG_DEFAULT_SECURITY_APPARMOR) +#define LSM_ORDER LSM_ORDER_PRE "apparmor,selinux,smack,tomoyo,bpf" +#elif defined(CONFIG_DEFAULT_SECURITY_TOMOYO) +#define LSM_ORDER LSM_ORDER_PRE "tomoyo,bpf" +#elif defined(CONFIG_DEFAULT_SECURITY_DAC) +#define LSM_ORDER LSM_ORDER_PRE "bpf" +#else +#define LSM_ORDER LSM_ORDER_PRE "selinux,smack,tomoyo,apparmor,bpf" +#endif + +#endif /* CONFIG_LSM */ + +static __initconst const char * const builtin_lsm_order = LSM_ORDER; /* Ordered list of LSMs to initialize. */ static __initdata struct lsm_info **ordered_lsms; -- 2.30.0
