[PATCH v5 10/38] LSM: Refactor "security=" in terms of enable/disable
From: Casey Schaufler <casey@schaufler-ca.com>
Date: 2018-11-26 23:34:15
Also in:
linux-fsdevel, 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 | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/security/security.c b/security/security.c
index f4a7b7d52d71..a7889885585e 100644
--- a/security/security.c
+++ b/security/security.c@@ -129,14 +129,6 @@ 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; }
@@ -164,8 +156,28 @@ static void __init ordered_lsm_parse(const char *order, const char *origin) struct lsm_info *lsm; char *sep, *name, *next; + /* Process "security=", if given. */ if (!chosen_major_lsm) chosen_major_lsm = CONFIG_DEFAULT_SECURITY; + if (chosen_major_lsm) { + struct lsm_info *major; + + /* + * 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 (major = __start_lsm_info; major < __end_lsm_info; + major++) { + if ((major->flags & LSM_FLAG_LEGACY_MAJOR) && + strcmp(major->name, chosen_major_lsm) != 0) { + set_enabled(major, false); + init_debug("security=%s disabled: %s\n", + chosen_major_lsm, major->name); + } + } + } sep = kstrdup(order, GFP_KERNEL); next = sep;
--
2.14.5