Merge tag 'integrity-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull integrity updates from Mimi Zohar:
 "Four integrity changes: two IMA-overlay updates, an integrity Kconfig
  cleanup, and a secondary keyring update"

* tag 'integrity-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  ima: detect changes to the backing overlay file
  certs: Only allow certs signed by keys on the builtin keyring
  integrity: fix indentation of config attributes
  ima: annotate iint mutex to avoid lockdep false positive warnings

5 files changed, 81 insertions, 34 deletions

diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig
index b6e074ac022730..3c45f4f3455fb6 100644
--- a/security/integrity/Kconfig
+++ b/security/integrity/Kconfig
@@ -34,10 +34,10 @@ config INTEGRITY_ASYMMETRIC_KEYS
 	bool "Enable asymmetric keys support"
 	depends on INTEGRITY_SIGNATURE
 	default n
-        select ASYMMETRIC_KEY_TYPE
-        select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
-        select CRYPTO_RSA
-        select X509_CERTIFICATE_PARSER
+	select ASYMMETRIC_KEY_TYPE
+	select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+	select CRYPTO_RSA
+	select X509_CERTIFICATE_PARSER
 	help
 	  This option enables digital signature verification using
 	  asymmetric keys.
@@ -53,14 +53,14 @@ config INTEGRITY_TRUSTED_KEYRING
 	   keyring.
 
 config INTEGRITY_PLATFORM_KEYRING
-        bool "Provide keyring for platform/firmware trusted keys"
-        depends on INTEGRITY_ASYMMETRIC_KEYS
-        depends on SYSTEM_BLACKLIST_KEYRING
-        help
-         Provide a separate, distinct keyring for platform trusted keys, which
-         the kernel automatically populates during initialization from values
-         provided by the platform for verifying the kexec'ed kerned image
-         and, possibly, the initramfs signature.
+	bool "Provide keyring for platform/firmware trusted keys"
+	depends on INTEGRITY_ASYMMETRIC_KEYS
+	depends on SYSTEM_BLACKLIST_KEYRING
+	help
+	  Provide a separate, distinct keyring for platform trusted keys, which
+	  the kernel automatically populates during initialization from values
+	  provided by the platform for verifying the kexec'ed kerned image
+	  and, possibly, the initramfs signature.
 
 config INTEGRITY_MACHINE_KEYRING
 	bool "Provide a keyring to which Machine Owner Keys may be added"
@@ -69,10 +69,10 @@ config INTEGRITY_MACHINE_KEYRING
 	depends on SYSTEM_BLACKLIST_KEYRING
 	depends on LOAD_UEFI_KEYS || LOAD_PPC_KEYS
 	help
-	 If set, provide a keyring to which Machine Owner Keys (MOK) may
-	 be added. This keyring shall contain just MOK keys.  Unlike keys
-	 in the platform keyring, keys contained in the .machine keyring will
-	 be trusted within the kernel.
+	  If set, provide a keyring to which Machine Owner Keys (MOK) may
+	  be added. This keyring shall contain just MOK keys.  Unlike keys
+	  in the platform keyring, keys contained in the .machine keyring will
+	  be trusted within the kernel.
 
 config INTEGRITY_CA_MACHINE_KEYRING
 	bool "Enforce Machine Keyring CA Restrictions"
@@ -97,14 +97,14 @@ config INTEGRITY_CA_MACHINE_KEYRING_MAX
 	  .platform keyring.
 
 config LOAD_UEFI_KEYS
-       depends on INTEGRITY_PLATFORM_KEYRING
-       depends on EFI
-       def_bool y
+	depends on INTEGRITY_PLATFORM_KEYRING
+	depends on EFI
+	def_bool y
 
 config LOAD_IPL_KEYS
-       depends on INTEGRITY_PLATFORM_KEYRING
-       depends on S390
-       def_bool y
+	depends on INTEGRITY_PLATFORM_KEYRING
+	depends on S390
+	def_bool y
 
 config LOAD_PPC_KEYS
 	bool "Enable loading of platform and blacklisted keys for POWER"
diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index a462df827de2da..27ea19fb1f54c7 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -66,9 +66,32 @@ struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
 	return iint;
 }
 
-static void iint_free(struct integrity_iint_cache *iint)
+#define IMA_MAX_NESTING (FILESYSTEM_MAX_STACK_DEPTH+1)
+
+/*
+ * It is not clear that IMA should be nested at all, but as long is it measures
+ * files both on overlayfs and on underlying fs, we need to annotate the iint
+ * mutex to avoid lockdep false positives related to IMA + overlayfs.
+ * See ovl_lockdep_annotate_inode_mutex_key() for more details.
+ */
+static inline void iint_lockdep_annotate(struct integrity_iint_cache *iint,
+					 struct inode *inode)
+{
+#ifdef CONFIG_LOCKDEP
+	static struct lock_class_key iint_mutex_key[IMA_MAX_NESTING];
+
+	int depth = inode->i_sb->s_stack_depth;
+
+	if (WARN_ON_ONCE(depth < 0 || depth >= IMA_MAX_NESTING))
+		depth = 0;
+
+	lockdep_set_class(&iint->mutex, &iint_mutex_key[depth]);
+#endif
+}
+
+static void iint_init_always(struct integrity_iint_cache *iint,
+			     struct inode *inode)
 {
-	kfree(iint->ima_hash);
 	iint->ima_hash = NULL;
 	iint->version = 0;
 	iint->flags = 0UL;
@@ -80,6 +103,14 @@ static void iint_free(struct integrity_iint_cache *iint)
 	iint->ima_creds_status = INTEGRITY_UNKNOWN;
 	iint->evm_status = INTEGRITY_UNKNOWN;
 	iint->measured_pcrs = 0;
+	mutex_init(&iint->mutex);
+	iint_lockdep_annotate(iint, inode);
+}
+
+static void iint_free(struct integrity_iint_cache *iint)
+{
+	kfree(iint->ima_hash);
+	mutex_destroy(&iint->mutex);
 	kmem_cache_free(iint_cache, iint);
 }
 
@@ -104,6 +135,8 @@ struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
 	if (!iint)
 		return NULL;
 
+	iint_init_always(iint, inode);
+
 	write_lock(&integrity_iint_lock);
 
 	p = &integrity_iint_tree.rb_node;
@@ -153,25 +186,18 @@ void integrity_inode_free(struct inode *inode)
 	iint_free(iint);
 }
 
-static void init_once(void *foo)
+static void iint_init_once(void *foo)
 {
 	struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo;
 
 	memset(iint, 0, sizeof(*iint));
-	iint->ima_file_status = INTEGRITY_UNKNOWN;
-	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
-	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
-	iint->ima_read_status = INTEGRITY_UNKNOWN;
-	iint->ima_creds_status = INTEGRITY_UNKNOWN;
-	iint->evm_status = INTEGRITY_UNKNOWN;
-	mutex_init(&iint->mutex);
 }
 
 static int __init integrity_iintcache_init(void)
 {
 	iint_cache =
 	    kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
-			      0, SLAB_PANIC, init_once);
+			      0, SLAB_PANIC, iint_init_once);
 	return 0;
 }
 DEFINE_LSM(integrity) = {
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 452e80b541e544..597ea0c4d72f78 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -243,6 +243,7 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
 {
 	const char *audit_cause = "failed";
 	struct inode *inode = file_inode(file);
+	struct inode *real_inode = d_real_inode(file_dentry(file));
 	const char *filename = file->f_path.dentry->d_name.name;
 	struct ima_max_digest_data hash;
 	struct kstat stat;
@@ -302,6 +303,10 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
 	iint->ima_hash = tmpbuf;
 	memcpy(iint->ima_hash, &hash, length);
 	iint->version = i_version;
+	if (real_inode != inode) {
+		iint->real_ino = real_inode->i_ino;
+		iint->real_dev = real_inode->i_sb->s_dev;
+	}
 
 	/* Possibly temporary failure due to type of read (eg. O_DIRECT) */
 	if (!result)
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 365db0e43d7c22..cc1217ac2c6faf 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -25,6 +25,7 @@
 #include <linux/xattr.h>
 #include <linux/ima.h>
 #include <linux/fs.h>
+#include <linux/iversion.h>
 
 #include "ima.h"
 
@@ -207,7 +208,7 @@ static int process_measurement(struct file *file, const struct cred *cred,
 			       u32 secid, char *buf, loff_t size, int mask,
 			       enum ima_hooks func)
 {
-	struct inode *inode = file_inode(file);
+	struct inode *backing_inode, *inode = file_inode(file);
 	struct integrity_iint_cache *iint = NULL;
 	struct ima_template_desc *template_desc = NULL;
 	char *pathbuf = NULL;
@@ -284,6 +285,19 @@ static int process_measurement(struct file *file, const struct cred *cred,
 		iint->measured_pcrs = 0;
 	}
 
+	/* Detect and re-evaluate changes made to the backing file. */
+	backing_inode = d_real_inode(file_dentry(file));
+	if (backing_inode != inode &&
+	    (action & IMA_DO_MASK) && (iint->flags & IMA_DONE_MASK)) {
+		if (!IS_I_VERSION(backing_inode) ||
+		    backing_inode->i_sb->s_dev != iint->real_dev ||
+		    backing_inode->i_ino != iint->real_ino ||
+		    !inode_eq_iversion(backing_inode, iint->version)) {
+			iint->flags &= ~IMA_DONE_MASK;
+			iint->measured_pcrs = 0;
+		}
+	}
+
 	/* Determine if already appraised/measured based on bitmask
 	 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
 	 *  IMA_AUDIT, IMA_AUDITED)
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index d7553c93f5c0d0..9561db7cf6b42c 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -164,6 +164,8 @@ struct integrity_iint_cache {
 	unsigned long flags;
 	unsigned long measured_pcrs;
 	unsigned long atomic_flags;
+	unsigned long real_ino;
+	dev_t real_dev;
 	enum integrity_status ima_file_status:4;
 	enum integrity_status ima_mmap_status:4;
 	enum integrity_status ima_bprm_status:4;