[PATCH security-next v4 29/32] LSM: Introduce enum lsm_order
From: Kees Cook <hidden>
Date: 2018-10-02 01:04:37
Also in:
linux-arch, linux-doc, lkml
Subsystem:
security subsystem, the rest · Maintainers:
Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
In preparation for distinguishing the "capability" LSM from other LSMs, it must be ordered first. This introduces LSM_ORDER_MUTABLE for the general LSMs, LSM_ORDER_FIRST for capabilities, and LSM_ORDER_LAST for anything that must run last (e.g. Landlock may use this in the future). Signed-off-by: Kees Cook <redacted> Reviewed-by: Casey Schaufler <casey@schaufler-ca.com> --- include/linux/lsm_hooks.h | 7 +++++++ security/security.c | 18 ++++++++++++++++-- 2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 63a6caaee8e6..62bc230826e0 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h@@ -2041,8 +2041,15 @@ extern void security_add_hooks(struct security_hook_list *hooks, int count, #define LSM_FLAG_LEGACY_MAJOR BIT(0) +enum lsm_order { + LSM_ORDER_FIRST = -1, /* This is only for capabilities. */ + LSM_ORDER_MUTABLE = 0, + LSM_ORDER_LAST, +}; + struct lsm_info { const char *name; /* Required. */ + enum lsm_order order; /* Optional: default is LSM_ORDER_MUTABLE */ unsigned long flags; /* Optional: flags describing LSM */ int *enabled; /* Optional: set based on CONFIG_LSM_ENABLE */ int (*init)(void); /* Required. */
diff --git a/security/security.c b/security/security.c
index 44c23d23158e..dac379518e60 100644
--- a/security/security.c
+++ b/security/security.c@@ -140,7 +140,8 @@ static void __init parse_lsm_order(const char *order, const char *origin) bool found = false; for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { - if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0 && + if (lsm->order == LSM_ORDER_MUTABLE && + (lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0 && strcmp(lsm->name, name) == 0) { append_ordered_lsm(lsm, origin); found = true;
@@ -158,6 +159,12 @@ static void __init prepare_lsm_order(void) { struct lsm_info *lsm; + /* LSM_ORDER_FIRST is always first. */ + for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { + if (lsm->order == LSM_ORDER_FIRST) + append_ordered_lsm(lsm, "first"); + } + /* Parse order from commandline, if present. */ parse_lsm_order(chosen_lsm_order, "cmdline");
@@ -166,9 +173,16 @@ static void __init prepare_lsm_order(void) /* Add any missing LSMs, in link order. */ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { - if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0) + if (lsm->order == LSM_ORDER_MUTABLE && + (lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0) append_ordered_lsm(lsm, "link-time"); } + + /* LSM_ORDER_LAST is always last. */ + for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { + if (lsm->order == LSM_ORDER_LAST) + append_ordered_lsm(lsm, "last"); + } } /* Is an LSM allowed to be initialized? */
--
2.17.1