diff mbox series

[v4,2/8] LSM: Maintain a table of LSM attribute data

Message ID 20221229233454.43880-3-casey@schaufler-ca.com
State New
Headers
Series LSM: Three basic syscalls |

Commit Message

Casey Schaufler Dec. 29, 2022, 11:34 p.m. UTC 
  As LSMs are registered add their lsm_id pointers to a table.
This will be used later for attribute reporting.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/security.h | 18 ++++++++++++++++++
 security/security.c      | 18 ++++++++++++++++++
 2 files changed, 36 insertions(+)

Comments

Liu, Yujie Jan. 2, 2023, 4:06 p.m. UTC | #1 
Greeting,

FYI, we noticed UBSAN:array-index-out-of-bounds_in_security/security.c due to commit (built with gcc-11):

commit: 541d81106c1f677b6140c5eb894dda23b6422614 ("[PATCH v4 2/8] LSM: Maintain a table of LSM attribute data")
url: https://github.com/intel-lab-lkp/linux/commits/Casey-Schaufler/LSM-Maintain-a-table-of-LSM-attribute-data/20221230-083536
base: https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git 03c4c7f88709fac0e20b6a48357c73d6fc50e544
patch link: https://lore.kernel.org/all/20221229233454.43880-3-casey@schaufler-ca.com/
patch subject: [PATCH v4 2/8] LSM: Maintain a table of LSM attribute data

in testcase: boot

on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


[  335.323207][    T0] UBSAN: array-index-out-of-bounds in security/security.c:529:13
[  335.324261][    T0] index 4 is out of range for type 'lsm_id *[4]'
[  335.324964][    T0] CPU: 0 PID: 0 Comm: swapper Not tainted 6.2.0-rc1-00003-g541d81106c1f #1
[  335.325955][    T0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-5 04/01/2014
[  335.327092][    T0] Call Trace:
[  335.327472][    T0]  <TASK>
[ 335.327802][ T0] dump_stack_lvl (??:?) 
[ 335.328350][ T0] ubsan_epilogue (ubsan.c:?) 
[ 335.328350][ T0] __ubsan_handle_out_of_bounds (??:?) 
[ 335.328350][ T0] ? __register_sysctl_paths (??:?) 
[ 335.328350][ T0] security_add_hooks (??:?) 
[ 335.328350][ T0] safesetid_security_init (lsm.c:?) 
[ 335.328350][ T0] initialize_lsm (security.c:?) 
[ 335.328350][ T0] ordered_lsm_init (security.c:?) 
[ 335.328350][ T0] security_init (??:?) 
[ 335.328350][ T0] start_kernel (??:?) 
[ 335.328350][ T0] secondary_startup_64_no_verify (??:?) 
[  335.328350][    T0]  </TASK>
[  335.328356][    T0] ================================================================================
[  335.329401][    T0] Kernel panic - not syncing: security_add_hooks Too many LSMs registered.
[  335.330386][    T0] CPU: 0 PID: 0 Comm: swapper Not tainted 6.2.0-rc1-00003-g541d81106c1f #1
[  335.331405][    T0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-5 04/01/2014
[  335.332607][    T0] Call Trace:
[  335.332957][    T0]  <TASK>
[ 335.333282][ T0] dump_stack_lvl (??:?) 
[ 335.333799][ T0] panic (??:?) 
[ 335.334242][ T0] security_add_hooks (??:?) 
[ 335.334793][ T0] safesetid_security_init (lsm.c:?) 
[ 335.335426][ T0] initialize_lsm (security.c:?) 
[ 335.335920][ T0] ordered_lsm_init (security.c:?) 
[ 335.336458][ T0] security_init (??:?) 
[ 335.337004][ T0] start_kernel (??:?) 
[ 335.337510][ T0] secondary_startup_64_no_verify (??:?) 
[  335.338178][    T0]  </TASK>


If you fix the issue, kindly add following tag
| Reported-by: kernel test robot <yujie.liu@intel.com>
| Link: https://lore.kernel.org/oe-lkp/202301022326.638b5c49-yujie.liu@intel.com


To reproduce:

        # build kernel
	cd linux
	cp config-6.2.0-rc1-00003-g541d81106c1f .config
	make HOSTCC=gcc-11 CC=gcc-11 ARCH=x86_64 olddefconfig prepare modules_prepare bzImage modules
	make HOSTCC=gcc-11 CC=gcc-11 ARCH=x86_64 INSTALL_MOD_PATH=<mod-install-dir> modules_install
	cd <mod-install-dir>
	find lib/ | cpio -o -H newc --quiet | gzip > modules.cgz


        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> -m modules.cgz job-script # job-script is attached in this email

        # if come across any failure that blocks the test,
        # please remove ~/.lkp and /lkp dir to run from a clean state.
diff mbox series

Patch

diff --git a/include/linux/security.h b/include/linux/security.h
index 5b67f208f7de..e70d546acf3d 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -139,6 +139,24 @@  enum lockdown_reason {
 
 extern const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1];
 
+/* The capability module is accounted for by CONFIG_SECURITY */
+#define LSMID_ENTRIES ( \
+	(IS_ENABLED(CONFIG_SECURITY) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_SELINUX) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_SMACK) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_TOMOYO) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_IMA) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_APPARMOR) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_YAMA) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_LOADPIN) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_SAFESETID) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_LOCKDOWN) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0) + \
+	(IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0))
+
+extern u32 lsm_active_cnt;
+extern struct lsm_id *lsm_idlist[];
+
 /* These functions are in security/commoncap.c */
 extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
 		       int cap, unsigned int opts);
diff --git a/security/security.c b/security/security.c
index 07a8fe7f92bf..4acb14500bc3 100644
--- a/security/security.c
+++ b/security/security.c
@@ -28,6 +28,7 @@ 
 #include <linux/backing-dev.h>
 #include <linux/string.h>
 #include <linux/msg.h>
+#include <uapi/linux/lsm.h>
 #include <net/flow.h>
 
 #define MAX_LSM_EVM_XATTR	2
@@ -341,6 +342,12 @@  static void __init report_lsm_order(void)
 	pr_cont("\n");
 }
 
+/*
+ * Current index to use while initializing the lsm id list.
+ */
+u32 lsm_active_cnt __lsm_ro_after_init;
+struct lsm_id *lsm_idlist[LSMID_ENTRIES] __lsm_ro_after_init;
+
 static void __init ordered_lsm_init(void)
 {
 	struct lsm_info **lsm;
@@ -388,6 +395,7 @@  static void __init ordered_lsm_init(void)
 	for (lsm = ordered_lsms; *lsm; lsm++)
 		initialize_lsm(*lsm);
 
+	init_debug("lsm count            = %d\n", lsm_active_cnt);
 	kfree(ordered_lsms);
 }
 
@@ -513,6 +521,16 @@  void __init security_add_hooks(struct security_hook_list *hooks, int count,
 {
 	int i;
 
+	/*
+	 * A security module may call security_add_hooks() more
+	 * than once. Landlock is one such case.
+	 */
+	if (lsm_active_cnt == 0 || lsm_idlist[lsm_active_cnt -1] != lsmid)
+		lsm_idlist[lsm_active_cnt++] = lsmid;
+
+	if (lsm_active_cnt > LSMID_ENTRIES)
+		panic("%s Too many LSMs registered.\n", __func__);
+
 	for (i = 0; i < count; i++) {
 		hooks[i].lsmid = lsmid;
 		hlist_add_tail_rcu(&hooks[i].list, hooks[i].head);