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From: Casey Schaufler <casey@schaufler-ca.com>
To: jmorris@namei.org, linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, selinux@vger.kernel.org
Cc: john.johansen@canonical.com, keescook@chromium.org,
	penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com,
	linux-fsdevel@vger.kernel.org, sds@tycho.nsa.gov,
	adobriyan@gmail.com, mic@digikod.net, s.mesoraca16@gmail.com,
	casey@schaufler-ca.com
Subject: [PATCH v5 10/38] LSM: Refactor "security=" in terms of enable/disable
Date: Tue, 11 Dec 2018 14:42:46 -0800
Message-ID: <20181211224314.22412-11-casey@schaufler-ca.com> (raw)
In-Reply-To: <20181211224314.22412-1-casey@schaufler-ca.com>

From: Kees Cook <keescook@chromium.org>

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 <keescook@chromium.org>
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


  parent reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-11 22:42 [PATCH v5 00/38] LSM: Module stacking for SARA and Landlock Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 01/38] LSM: Introduce LSM_FLAG_LEGACY_MAJOR Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 02/38] LSM: Provide separate ordered initialization Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 03/38] LSM: Plumb visibility into optional "enabled" state Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 04/38] LSM: Lift LSM selection out of individual LSMs Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 05/38] LSM: Build ordered list of LSMs to initialize Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 06/38] LSM: Introduce CONFIG_LSM Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 07/38] LSM: Introduce "lsm=" for boottime LSM selection Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 08/38] LSM: Tie enabling logic to presence in ordered list Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 09/38] LSM: Prepare for reorganizing "security=" logic Casey Schaufler
2018-12-11 22:42 ` Casey Schaufler [this message]
2018-12-11 22:42 ` [PATCH v5 11/38] LSM: Separate idea of "major" LSM from "exclusive" LSM Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 12/38] apparmor: Remove SECURITY_APPARMOR_BOOTPARAM_VALUE Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 13/38] selinux: Remove SECURITY_SELINUX_BOOTPARAM_VALUE Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 14/38] LSM: Add all exclusive LSMs to ordered initialization Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 15/38] LSM: Split LSM preparation from initialization Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 16/38] LoadPin: Initialize as ordered LSM Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 17/38] Yama: " Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 18/38] LSM: Introduce enum lsm_order Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 19/38] capability: Initialize as LSM_ORDER_FIRST Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 20/38] procfs: add smack subdir to attrs Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 21/38] Smack: Abstract use of cred security blob Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 22/38] SELinux: " Casey Schaufler
2018-12-11 22:42 ` [PATCH v5 23/38] SELinux: Remove cred security blob poisoning Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 24/38] SELinux: Remove unused selinux_is_enabled Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 25/38] AppArmor: Abstract use of cred security blob Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 26/38] TOMOYO: " Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 27/38] Infrastructure management of the " Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 28/38] SELinux: Abstract use of file " Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 29/38] Smack: " Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 30/38] LSM: Infrastructure management of the file security Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 31/38] SELinux: Abstract use of inode security blob Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 32/38] Smack: " Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 33/38] LSM: Infrastructure management of the inode security Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 34/38] LSM: Infrastructure management of the task security Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 35/38] SELinux: Abstract use of ipc security blobs Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 36/38] Smack: " Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 37/38] LSM: Infrastructure management of the ipc security blob Casey Schaufler
2018-12-12 16:05 ` [PATCH v5 38/38] TOMOYO: Update LSM flags to no longer be exclusive Casey Schaufler
  -- strict thread matches above, loose matches on Subject: below --
2018-11-26 23:22 [PATCH v5 00/38] LSM: Module stacking for SARA and Landlock Casey Schaufler
2018-11-26 23:34 ` [PATCH v5 10/38] LSM: Refactor "security=" in terms of enable/disable Casey Schaufler

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