[PATCH security-next v2 19/26] LSM: Introduce CONFIG_LSM_ORDER
From: Kees Cook <hidden>
Date: 2018-09-20 16:24:03
Also in:
linux-arch, linux-doc, lkml
Subsystem:
security subsystem, the rest · Maintainers:
Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
This provides a way to declare LSM initialization order via Kconfig. Signed-off-by: Kees Cook <redacted> --- security/Kconfig | 11 +++++++++++ security/security.c | 38 +++++++++++++++++++++++++++++++++++--- 2 files changed, 46 insertions(+), 3 deletions(-)
diff --git a/security/Kconfig b/security/Kconfig
index 27d8b2688f75..de8202886c1d 100644
--- a/security/Kconfig
+++ b/security/Kconfig@@ -276,5 +276,16 @@ config DEFAULT_SECURITY default "apparmor" if DEFAULT_SECURITY_APPARMOR default "" if DEFAULT_SECURITY_DAC +config LSM_ORDER + string "Default initialization order of builtin LSMs" + default "integrity" + help + A comma-separated list of LSMs, in initialization order. + Any LSMs left off this list will be link-order initialized + after any listed LSMs. Any LSMs listed here but not built in + the kernel will be ignored. + + If unsure, leave this as the default. + endmenu
diff --git a/security/security.c b/security/security.c
index 2541a512a0f7..063ee2466e58 100644
--- a/security/security.c
+++ b/security/security.c@@ -44,6 +44,8 @@ char *lsm_names; /* Boot-time LSM user choice */ static __initdata const char *chosen_major_lsm; +static __initconst const char * const builtin_lsm_order = CONFIG_LSM_ORDER; + /* Ordered list of LSMs to initialize. */ static __initdata struct lsm_info **ordered_lsms;
@@ -108,14 +110,44 @@ static void __init append_ordered_lsm(struct lsm_info *lsm, const char *from) (!lsm->enabled || *lsm->enabled) ? "en" : "dis"); } -/* Populate ordered LSMs list from hard-coded list of LSMs. */ +/* Populate ordered LSMs list from given string. */ +static void __init parse_lsm_order(const char *order, const char *origin) +{ + struct lsm_info *lsm; + char *sep, *name, *next; + + sep = kstrdup(order, GFP_KERNEL); + next = sep; + /* Walk the list, looking for matching LSMs. */ + while ((name = strsep(&next, ",")) != NULL) { + bool found = false; + + for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { + if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0 && + strcmp(lsm->name, name) == 0) { + append_ordered_lsm(lsm, origin); + found = true; + } + } + + if (!found) + init_debug("%s ignored: %s\n", origin, name); + } + kfree(sep); +} + +/* Populate ordered LSMs list from builtin list of LSMs. */ static void __init prepare_lsm_order(void) { struct lsm_info *lsm; + /* Parse order from builtin list. */ + parse_lsm_order(builtin_lsm_order, "builtin"); + + /* Add any missing LSMs, in link order. */ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { - if (strcmp(lsm->name, "integrity") == 0) - append_ordered_lsm(lsm, "builtin"); + if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0) + append_ordered_lsm(lsm, "link-time"); } }
--
2.17.1