Merge tag 'integrity-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull IMA fixes from Mimi Zohar:

 - Instantiating the ima_file_truncate and ima_path_truncate LSM hooks
   resulted in configfs locking issues.

   configfs files should not be measured, appraised, or audited in the
   first place, so the builtin policies are updated to exclude them.

 - IMA audit messages include the filename, which could result in a page
   fault when the filename doesn't exist

 - Un-hide the IMA_MEASURE_PCR_IDX Kconfig prompt

* tag 'integrity-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  ima: allow users to specify the pcr index with IMA_MEASURE_PCR_IDX
  ima: Check for ERR_PTR from dentry_path() in validate_hash_algo()
  ima: don't measure/appraise files on configfs
  configfs: move CONFIGFS_MAGIC definition to magic.h

6 files changed, 18 insertions, 5 deletions

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 19258471b7b2..b8a763e4c9fb 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -108,6 +108,9 @@ Description:
 			# NSFS_MAGIC
 			dont_measure fsmagic=0x6e736673
 			dont_appraise fsmagic=0x6e736673
+			# CONFIGFS_MAGIC
+			dont_measure fsmagic=0x62656570
+			dont_appraise fsmagic=0x62656570
 
 			measure func=BPRM_CHECK
 			measure func=FILE_MMAP mask=MAY_EXEC
diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c
index 4929f3431189..d8cac1cbf3bd 100644
--- a/fs/configfs/mount.c
+++ b/fs/configfs/mount.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/fs.h>
+#include <linux/magic.h>
 #include <linux/module.h>
 #include <linux/mount.h>
 #include <linux/fs_context.h>
@@ -19,9 +20,6 @@
 #include <linux/configfs.h>
 #include "configfs_internal.h"
 
-/* Random magic number */
-#define CONFIGFS_MAGIC 0x62656570
-
 static struct vfsmount *configfs_mount = NULL;
 struct kmem_cache *configfs_dir_cachep;
 static int configfs_mnt_count = 0;
diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
index fd5f0e95648e..66a91c8b1cb9 100644
--- a/include/uapi/linux/magic.h
+++ b/include/uapi/linux/magic.h
@@ -8,6 +8,7 @@
 #define AUTOFS_SUPER_MAGIC	0x0187
 #define CEPH_SUPER_MAGIC	0x00c36400
 #define CODA_SUPER_MAGIC	0x73757245
+#define CONFIGFS_MAGIC		0x62656570	/* some random number */
 #define CRAMFS_MAGIC		0x28cd3d45	/* some random number */
 #define CRAMFS_MAGIC_WEND	0x453dcd28	/* magic number with the wrong endianess */
 #define DEBUGFS_MAGIC          0x64626720
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index b3a9f86809b0..72654cf797cd 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -46,12 +46,16 @@ config IMA_KEXEC
 
 config IMA_MEASURE_PCR_IDX
 	int
+	prompt "PCR Index for Aggregate" if EXPERT
 	range 8 14
 	default 10
 	help
 	  IMA_MEASURE_PCR_IDX determines the TPM PCR register index
 	  that IMA uses to maintain the integrity aggregate of the
-	  measurement list.  If unsure, use the default 10.
+	  measurement list. Most attestation tooling expects PCR 10.
+
+	  The default is almost always what you want. Only change this
+	  if you know what you are doing.
 
 config IMA_LSM_RULES
 	bool
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index ced2e131b061..b280488e15fc 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -748,6 +748,8 @@ static int validate_hash_algo(struct dentry *dentry,
 		return -EACCES;
 
 	path = dentry_path(dentry, pathbuf, PATH_MAX);
+	if (IS_ERR(path))
+		path = NULL;
 
 	integrity_audit_msg(AUDIT_INTEGRITY_DATA, d_inode(dentry), path,
 			    "set_data", errmsg, -EACCES, 0);
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index f79d07bb63c6..68d9a5e6c232 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -165,7 +165,10 @@ static struct ima_rule_entry dont_measure_rules[] __ro_after_init = {
 	{.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC,
 	 .flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
-	{.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}
+	{.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC,
+	 .flags = IMA_FSMAGIC},
+	{.action = DONT_MEASURE, .fsmagic = CONFIGFS_MAGIC,
+	 .flags = IMA_FSMAGIC}
 };
 
 static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
@@ -211,6 +214,8 @@ static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
 	{.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC},
+	{.action = DONT_APPRAISE, .fsmagic = CONFIGFS_MAGIC,
+	 .flags = IMA_FSMAGIC},
 #ifdef CONFIG_IMA_WRITE_POLICY
 	{.action = APPRAISE, .func = POLICY_CHECK,
 	.flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},