[PATCH v3 15/16] ima: Move dentries into ima_namespace

[Stefan Berger <stefanb@xxxxxxxxxxxxx>]

Move the dentries into the ima_namespace for reuse by virtualized
SecurityFS. Implement function freeing the dentries in order of
files and symlinks before directories.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
---
 include/linux/ima.h             | 13 ++++++
 security/integrity/ima/ima_fs.c | 72 ++++++++++++++++++---------------
 2 files changed, 52 insertions(+), 33 deletions(-)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 889e9c70cbfb..bfb978a7f8d5 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -220,6 +220,17 @@ struct ima_h_table {
 	struct hlist_head queue[IMA_MEASURE_HTABLE_SIZE];
 };
 
+enum {
+	IMAFS_DENTRY_DIR = 0,
+	IMAFS_DENTRY_SYMLINK,
+	IMAFS_DENTRY_BINARY_RUNTIME_MEASUREMENTS,
+	IMAFS_DENTRY_ASCII_RUNTIME_MEASUREMENTS,
+	IMAFS_DENTRY_RUNTIME_MEASUREMENTS_COUNT,
+	IMAFS_DENTRY_VIOLATIONS,
+	IMAFS_DENTRY_IMA_POLICY,
+	IMAFS_DENTRY_LAST
+};
+
 struct ima_namespace {
 	struct kref kref;
 	struct user_namespace *user_ns;
@@ -266,6 +277,8 @@ struct ima_namespace {
 	struct mutex ima_write_mutex;
 	unsigned long ima_fs_flags;
 	int valid_policy;
+
+	struct dentry *dentry[IMAFS_DENTRY_LAST];
 };
 
 extern struct ima_namespace init_ima_ns;
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 68f2e58c3917..c2a886c00ac2 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -359,14 +359,6 @@ static ssize_t ima_write_policy(struct file *file, const char __user *buf,
 	return result;
 }
 
-static struct dentry *ima_dir;
-static struct dentry *ima_symlink;
-static struct dentry *binary_runtime_measurements;
-static struct dentry *ascii_runtime_measurements;
-static struct dentry *runtime_measurements_count;
-static struct dentry *violations;
-static struct dentry *ima_policy;
-
 enum ima_fs_flags {
 	IMA_FS_BUSY,
 };
@@ -436,8 +428,8 @@ static int ima_release_policy(struct inode *inode, struct file *file)
 
 	ima_update_policy(ns);
 #if !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY)
-	securityfs_remove(ima_policy);
-	ima_policy = NULL;
+	securityfs_remove(ns->dentry[IMAFS_DENTRY_IMA_POLICY]);
+	ns->dentry[IMAFS_DENTRY_IMA_POLICY] = NULL;
 #elif defined(CONFIG_IMA_WRITE_POLICY)
 	clear_bit(IMA_FS_BUSY, &ns->ima_fs_flags);
 #elif defined(CONFIG_IMA_READ_POLICY)
@@ -454,58 +446,72 @@ static const struct file_operations ima_measure_policy_ops = {
 	.llseek = generic_file_llseek,
 };
 
-int __init ima_fs_init(void)
+static void ima_fs_ns_free_dentries(struct ima_namespace *ns)
 {
-	ima_dir = securityfs_create_dir("ima", integrity_dir);
-	if (IS_ERR(ima_dir))
+	int i;
+
+	for (i = IMAFS_DENTRY_LAST - 1; i >= 0; i--)
+		securityfs_remove(ns->dentry[i]);
+
+	memset(ns->dentry, 0, sizeof(ns->dentry));
+}
+
+static int __init ima_fs_ns_init(struct user_namespace *user_ns)
+{
+	struct ima_namespace *ns = user_ns->ima_ns;
+	struct dentry *ima_dir;
+
+	ns->dentry[IMAFS_DENTRY_DIR] = securityfs_create_dir("ima", integrity_dir);
+	if (IS_ERR(ns->dentry[IMAFS_DENTRY_DIR]))
 		return -1;
+	ima_dir = ns->dentry[IMAFS_DENTRY_DIR];
 
-	ima_symlink = securityfs_create_symlink("ima", NULL, "integrity/ima",
-						NULL);
-	if (IS_ERR(ima_symlink))
+	ns->dentry[IMAFS_DENTRY_SYMLINK] =
+	    securityfs_create_symlink("ima", NULL, "integrity/ima", NULL);
+	if (IS_ERR(ns->dentry[IMAFS_DENTRY_SYMLINK]))
 		goto out;
 
-	binary_runtime_measurements =
+	ns->dentry[IMAFS_DENTRY_BINARY_RUNTIME_MEASUREMENTS] =
 	    securityfs_create_file("binary_runtime_measurements",
 				   S_IRUSR | S_IRGRP, ima_dir, NULL,
 				   &ima_measurements_ops);
-	if (IS_ERR(binary_runtime_measurements))
+	if (IS_ERR(ns->dentry[IMAFS_DENTRY_BINARY_RUNTIME_MEASUREMENTS]))
 		goto out;
 
-	ascii_runtime_measurements =
+	ns->dentry[IMAFS_DENTRY_ASCII_RUNTIME_MEASUREMENTS] =
 	    securityfs_create_file("ascii_runtime_measurements",
 				   S_IRUSR | S_IRGRP, ima_dir, NULL,
 				   &ima_ascii_measurements_ops);
-	if (IS_ERR(ascii_runtime_measurements))
+	if (IS_ERR(ns->dentry[IMAFS_DENTRY_ASCII_RUNTIME_MEASUREMENTS]))
 		goto out;
 
-	runtime_measurements_count =
+	ns->dentry[IMAFS_DENTRY_RUNTIME_MEASUREMENTS_COUNT] =
 	    securityfs_create_file("runtime_measurements_count",
 				   S_IRUSR | S_IRGRP, ima_dir, NULL,
 				   &ima_measurements_count_ops);
-	if (IS_ERR(runtime_measurements_count))
+	if (IS_ERR(ns->dentry[IMAFS_DENTRY_RUNTIME_MEASUREMENTS_COUNT]))
 		goto out;
 
-	violations =
+	ns->dentry[IMAFS_DENTRY_VIOLATIONS] =
 	    securityfs_create_file("violations", S_IRUSR | S_IRGRP,
 				   ima_dir, NULL, &ima_htable_violations_ops);
-	if (IS_ERR(violations))
+	if (IS_ERR(ns->dentry[IMAFS_DENTRY_VIOLATIONS]))
 		goto out;
 
-	ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS,
+	ns->dentry[IMAFS_DENTRY_IMA_POLICY] =
+	    securityfs_create_file("policy", POLICY_FILE_FLAGS,
 					    ima_dir, NULL,
 					    &ima_measure_policy_ops);
-	if (IS_ERR(ima_policy))
+	if (IS_ERR(ns->dentry[IMAFS_DENTRY_IMA_POLICY]))
 		goto out;
 
 	return 0;
 out:
-	securityfs_remove(violations);
-	securityfs_remove(runtime_measurements_count);
-	securityfs_remove(ascii_runtime_measurements);
-	securityfs_remove(binary_runtime_measurements);
-	securityfs_remove(ima_symlink);
-	securityfs_remove(ima_dir);
-	securityfs_remove(ima_policy);
+	ima_fs_ns_free_dentries(ns);
 	return -1;
 }
+
+int __init ima_fs_init(void)
+{
+	return ima_fs_ns_init(&init_user_ns);
+}
-- 
2.31.1