[RFC,04/10] TOMOYO: Abstract the cred security blob

Commit Message

Casey Schaufler July 11, 2016, 7:30 p.m. UTC

Subject: [PATCH RFC 04/10] TOMOYO: Abstract the cred security blob

Abstract reading the credential security blob.
Remove abstraction when writing the credential security blob.
There is no change in the behavior of the code.

Signed-off-by: Casey Schaufler <[e-mail]>
---
 security/tomoyo/common.h        | 16 ++++++++++++++--
 security/tomoyo/securityfs_if.c |  9 ++++++---
 security/tomoyo/tomoyo.c        | 17 ++++++++++++-----
 3 files changed, 32 insertions(+), 10 deletions(-)


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Patch

diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h
index 361e7a2..82be05d 100644
--- a/security/tomoyo/common.h
+++ b/security/tomoyo/common.h
@@ -28,6 +28,7 @@ 
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/un.h>
+#include <linux/lsm_hooks.h>
 #include <net/sock.h>
 #include <net/af_unix.h>
 #include <net/ip.h>
@@ -1196,13 +1197,24 @@  static inline void tomoyo_put_group(struct tomoyo_group *group)
 }
 
 /**
+ * tomoyo_cred - Get a pointer to the tomoyo cred security blob
+ * @cred - the relevant cred
+ *
+ * Returns pointer to the tomoyo cred blob.
+ */
+static inline struct tomoyo_domain_info *tomoyo_cred(const struct cred *cred)
+{
+	return cred->security;
+}
+
+/**
  * tomoyo_domain - Get "struct tomoyo_domain_info" for current thread.
  *
  * Returns pointer to "struct tomoyo_domain_info" for current thread.
  */
 static inline struct tomoyo_domain_info *tomoyo_domain(void)
 {
-	return current_cred()->security;
+	return tomoyo_cred(current_cred());
 }
 
 /**
@@ -1215,7 +1227,7 @@  static inline struct tomoyo_domain_info *tomoyo_domain(void)
 static inline struct tomoyo_domain_info *tomoyo_real_domain(struct task_struct
 							    *task)
 {
-	return task_cred_xxx(task, security);
+	return tomoyo_cred(get_task_cred(task));
 }
 
 /**
diff --git a/security/tomoyo/securityfs_if.c b/security/tomoyo/securityfs_if.c
index 06ab41b1..e22f2c6 100644
--- a/security/tomoyo/securityfs_if.c
+++ b/security/tomoyo/securityfs_if.c
@@ -70,8 +70,9 @@  static ssize_t tomoyo_write_self(struct file *file, const char __user *buf,
 				if (!cred) {
 					error = -ENOMEM;
 				} else {
-					struct tomoyo_domain_info *old_domain =
-						cred->security;
+					struct tomoyo_domain_info *old_domain;
+
+					old_domain = tomoyo_cred(cred);
 					cred->security = new_domain;
 					atomic_inc(&new_domain->users);
 					atomic_dec(&old_domain->users);
@@ -233,10 +234,12 @@  static void __init tomoyo_create_entry(const char *name, const umode_t mode,
  */
 static int __init tomoyo_initerface_init(void)
 {
+	struct tomoyo_domain_info *domain;
 	struct dentry *tomoyo_dir;
 
+	domain = tomoyo_cred(current_cred());
 	/* Don't create securityfs entries unless registered. */
-	if (current_cred()->security != &tomoyo_kernel_domain)
+	if (domain != &tomoyo_kernel_domain)
 		return 0;
 
 	tomoyo_dir = securityfs_create_dir("tomoyo", NULL);
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index edc52d6..353c935 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -33,7 +33,9 @@  static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
 			       gfp_t gfp)
 {
-	struct tomoyo_domain_info *domain = old->security;
+	struct tomoyo_domain_info *domain;
+
+	domain = tomoyo_cred(old);
 	new->security = domain;
 	if (domain)
 		atomic_inc(&domain->users);
@@ -58,7 +60,9 @@  static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
  */
 static void tomoyo_cred_free(struct cred *cred)
 {
-	struct tomoyo_domain_info *domain = cred->security;
+	struct tomoyo_domain_info *domain;
+
+	domain = tomoyo_cred(cred);
 	if (domain)
 		atomic_dec(&domain->users);
 }
@@ -72,6 +76,8 @@  static void tomoyo_cred_free(struct cred *cred)
  */
 static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
 {
+	struct tomoyo_domain_info *domain;
+
 	/*
 	 * Do only if this function is called for the first time of an execve
 	 * operation.
@@ -92,8 +98,8 @@  static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
 	 * stored inside "bprm->cred->security" will be acquired later inside
 	 * tomoyo_find_next_domain().
 	 */
-	atomic_dec(&((struct tomoyo_domain_info *)
-		     bprm->cred->security)->users);
+	domain = tomoyo_cred(bprm->cred);
+	atomic_dec(&domain->users);
 	/*
 	 * Tell tomoyo_bprm_check_security() is called for the first time of an
 	 * execve operation.
@@ -111,8 +117,9 @@  static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
  */
 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
 {
-	struct tomoyo_domain_info *domain = bprm->cred->security;
+	struct tomoyo_domain_info *domain;
 
+	domain = tomoyo_cred(bprm->cred);
 	/*
 	 * Execute permission is checked against pathname passed to do_execve()
 	 * using current domain.