[PATCH security-next v4 20/32] LSM: Refactor "security=" in terms of enable/disable
From: Kees Cook <hidden>
Date: 2018-10-02 01:05:03
Also in:
linux-arch, linux-doc, lkml
Subsystem:
security subsystem, the rest · Maintainers:
Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
For what are marked as the Legacy Major LSMs, make them effectively exclusive when selected on the "security=" boot parameter, to handle the future case of when a previously major LSMs become non-exclusive (e.g. when TOMOYO starts blob-sharing). Signed-off-by: Kees Cook <redacted> Reviewed-by: Casey Schaufler <casey@schaufler-ca.com> --- security/security.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/security/security.c b/security/security.c
index 455ba2767965..d7132c181ea6 100644
--- a/security/security.c
+++ b/security/security.c@@ -103,14 +103,6 @@ static bool __init lsm_allowed(struct lsm_info *lsm) if (!is_enabled(lsm)) return false; - /* Skip major-specific checks if not a major LSM. */ - if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0) - return true; - - /* Disabled if this LSM isn't the chosen one. */ - if (strcmp(lsm->name, chosen_major_lsm) != 0) - return false; - return true; }
@@ -188,8 +180,24 @@ static void __init prepare_lsm_enable(void) parse_lsm_enable(chosen_lsm_enable, set_enabled, true); parse_lsm_enable(chosen_lsm_disable, set_enabled, false); + /* Process "security=", if given. */ if (!chosen_major_lsm) chosen_major_lsm = CONFIG_DEFAULT_SECURITY; + if (chosen_major_lsm) { + struct lsm_info *lsm; + + /* + * To match the original "security=" behavior, this + * explicitly does NOT fallback to another Legacy Major + * if the selected one was separately disabled: disable + * all non-matching Legacy Major LSMs. + */ + for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { + if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) && + strcmp(lsm->name, chosen_major_lsm) != 0) + set_enabled(lsm, false); + } + } } /**
--
2.17.1