1 files changed, 73 insertions, 39 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 327dbc3acefc..92f909a2e8f7 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -230,9 +230,22 @@ static inline u32 cred_sid(const struct cred *cred)
 }
 
 /*
+ * get the subjective security ID of a task
+ */
+static inline u32 task_sid_subj(const struct task_struct *task)
+{
+	u32 sid;
+
+	rcu_read_lock();
+	sid = cred_sid(rcu_dereference(task->cred));
+	rcu_read_unlock();
+	return sid;
+}
+
+/*
  * get the objective security ID of a task
  */
-static inline u32 task_sid(const struct task_struct *task)
+static inline u32 task_sid_obj(const struct task_struct *task)
 {
 	u32 sid;
 
@@ -242,6 +255,29 @@ static inline u32 task_sid(const struct task_struct *task)
 	return sid;
 }
 
+/*
+ * get the security ID of a task for use with binder
+ */
+static inline u32 task_sid_binder(const struct task_struct *task)
+{
+	/*
+	 * In many case where this function is used we should be using the
+	 * task's subjective SID, but we can't reliably access the subjective
+	 * creds of a task other than our own so we must use the objective
+	 * creds/SID, which are safe to access.  The downside is that if a task
+	 * is temporarily overriding it's creds it will not be reflected here;
+	 * however, it isn't clear that binder would handle that case well
+	 * anyway.
+	 *
+	 * If this ever changes and we can safely reference the subjective
+	 * creds/SID of another task, this function will make it easier to
+	 * identify the various places where we make use of the task SIDs in
+	 * the binder code.  It is also likely that we will need to adjust
+	 * the main drivers/android binder code as well.
+	 */
+	return task_sid_obj(task);
+}
+
 static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dentry);
 
 /*
@@ -2035,11 +2071,8 @@ static inline u32 open_file_to_av(struct file *file)
 
 static int selinux_binder_set_context_mgr(struct task_struct *mgr)
 {
-	u32 mysid = current_sid();
-	u32 mgrsid = task_sid(mgr);
-
 	return avc_has_perm(&selinux_state,
-			    mysid, mgrsid, SECCLASS_BINDER,
+			    current_sid(), task_sid_binder(mgr), SECCLASS_BINDER,
 			    BINDER__SET_CONTEXT_MGR, NULL);
 }
 
@@ -2047,8 +2080,7 @@ static int selinux_binder_transaction(struct task_struct *from,
 				      struct task_struct *to)
 {
 	u32 mysid = current_sid();
-	u32 fromsid = task_sid(from);
-	u32 tosid = task_sid(to);
+	u32 fromsid = task_sid_binder(from);
 	int rc;
 
 	if (mysid != fromsid) {
@@ -2059,19 +2091,16 @@ static int selinux_binder_transaction(struct task_struct *from,
 			return rc;
 	}
 
-	return avc_has_perm(&selinux_state,
-			    fromsid, tosid, SECCLASS_BINDER, BINDER__CALL,
-			    NULL);
+	return avc_has_perm(&selinux_state, fromsid, task_sid_binder(to),
+			    SECCLASS_BINDER, BINDER__CALL, NULL);
 }
 
 static int selinux_binder_transfer_binder(struct task_struct *from,
 					  struct task_struct *to)
 {
-	u32 fromsid = task_sid(from);
-	u32 tosid = task_sid(to);
-
 	return avc_has_perm(&selinux_state,
-			    fromsid, tosid, SECCLASS_BINDER, BINDER__TRANSFER,
+			    task_sid_binder(from), task_sid_binder(to),
+			    SECCLASS_BINDER, BINDER__TRANSFER,
 			    NULL);
 }
 
@@ -2079,7 +2108,7 @@ static int selinux_binder_transfer_file(struct task_struct *from,
 					struct task_struct *to,
 					struct file *file)
 {
-	u32 sid = task_sid(to);
+	u32 sid = task_sid_binder(to);
 	struct file_security_struct *fsec = selinux_file(file);
 	struct dentry *dentry = file->f_path.dentry;
 	struct inode_security_struct *isec;
@@ -2115,10 +2144,10 @@ static int selinux_binder_transfer_file(struct task_struct *from,
 }
 
 static int selinux_ptrace_access_check(struct task_struct *child,
-				     unsigned int mode)
+				       unsigned int mode)
 {
 	u32 sid = current_sid();
-	u32 csid = task_sid(child);
+	u32 csid = task_sid_obj(child);
 
 	if (mode & PTRACE_MODE_READ)
 		return avc_has_perm(&selinux_state,
@@ -2131,15 +2160,15 @@ static int selinux_ptrace_access_check(struct task_struct *child,
 static int selinux_ptrace_traceme(struct task_struct *parent)
 {
 	return avc_has_perm(&selinux_state,
-			    task_sid(parent), current_sid(), SECCLASS_PROCESS,
-			    PROCESS__PTRACE, NULL);
+			    task_sid_subj(parent), task_sid_obj(current),
+			    SECCLASS_PROCESS, PROCESS__PTRACE, NULL);
 }
 
 static int selinux_capget(struct task_struct *target, kernel_cap_t *effective,
 			  kernel_cap_t *inheritable, kernel_cap_t *permitted)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(target), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(target), SECCLASS_PROCESS,
 			    PROCESS__GETCAP, NULL);
 }
 
@@ -2264,7 +2293,7 @@ static u32 ptrace_parent_sid(void)
 	rcu_read_lock();
 	tracer = ptrace_parent(current);
 	if (tracer)
-		sid = task_sid(tracer);
+		sid = task_sid_obj(tracer);
 	rcu_read_unlock();
 
 	return sid;
@@ -3976,7 +4005,7 @@ static int selinux_file_send_sigiotask(struct task_struct *tsk,
 				       struct fown_struct *fown, int signum)
 {
 	struct file *file;
-	u32 sid = task_sid(tsk);
+	u32 sid = task_sid_obj(tsk);
 	u32 perm;
 	struct file_security_struct *fsec;
 
@@ -4195,47 +4224,52 @@ static int selinux_kernel_load_data(enum kernel_load_data_id id, bool contents)
 static int selinux_task_setpgid(struct task_struct *p, pid_t pgid)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(p), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(p), SECCLASS_PROCESS,
 			    PROCESS__SETPGID, NULL);
 }
 
 static int selinux_task_getpgid(struct task_struct *p)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(p), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(p), SECCLASS_PROCESS,
 			    PROCESS__GETPGID, NULL);
 }
 
 static int selinux_task_getsid(struct task_struct *p)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(p), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(p), SECCLASS_PROCESS,
 			    PROCESS__GETSESSION, NULL);
 }
 
-static void selinux_task_getsecid(struct task_struct *p, u32 *secid)
+static void selinux_task_getsecid_subj(struct task_struct *p, u32 *secid)
+{
+	*secid = task_sid_subj(p);
+}
+
+static void selinux_task_getsecid_obj(struct task_struct *p, u32 *secid)
 {
-	*secid = task_sid(p);
+	*secid = task_sid_obj(p);
 }
 
 static int selinux_task_setnice(struct task_struct *p, int nice)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(p), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(p), SECCLASS_PROCESS,
 			    PROCESS__SETSCHED, NULL);
 }
 
 static int selinux_task_setioprio(struct task_struct *p, int ioprio)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(p), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(p), SECCLASS_PROCESS,
 			    PROCESS__SETSCHED, NULL);
 }
 
 static int selinux_task_getioprio(struct task_struct *p)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(p), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(p), SECCLASS_PROCESS,
 			    PROCESS__GETSCHED, NULL);
 }
 
@@ -4266,7 +4300,7 @@ static int selinux_task_setrlimit(struct task_struct *p, unsigned int resource,
 	   upon context transitions.  See selinux_bprm_committing_creds. */
 	if (old_rlim->rlim_max != new_rlim->rlim_max)
 		return avc_has_perm(&selinux_state,
-				    current_sid(), task_sid(p),
+				    current_sid(), task_sid_obj(p),
 				    SECCLASS_PROCESS, PROCESS__SETRLIMIT, NULL);
 
 	return 0;
@@ -4275,21 +4309,21 @@ static int selinux_task_setrlimit(struct task_struct *p, unsigned int resource,
 static int selinux_task_setscheduler(struct task_struct *p)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(p), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(p), SECCLASS_PROCESS,
 			    PROCESS__SETSCHED, NULL);
 }
 
 static int selinux_task_getscheduler(struct task_struct *p)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(p), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(p), SECCLASS_PROCESS,
 			    PROCESS__GETSCHED, NULL);
 }
 
 static int selinux_task_movememory(struct task_struct *p)
 {
 	return avc_has_perm(&selinux_state,
-			    current_sid(), task_sid(p), SECCLASS_PROCESS,
+			    current_sid(), task_sid_obj(p), SECCLASS_PROCESS,
 			    PROCESS__SETSCHED, NULL);
 }
 
@@ -4308,14 +4342,14 @@ static int selinux_task_kill(struct task_struct *p, struct kernel_siginfo *info,
 	else
 		secid = cred_sid(cred);
 	return avc_has_perm(&selinux_state,
-			    secid, task_sid(p), SECCLASS_PROCESS, perm, NULL);
+			    secid, task_sid_obj(p), SECCLASS_PROCESS, perm, NULL);
 }
 
 static void selinux_task_to_inode(struct task_struct *p,
 				  struct inode *inode)
 {
 	struct inode_security_struct *isec = selinux_inode(inode);
-	u32 sid = task_sid(p);
+	u32 sid = task_sid_obj(p);
 
 	spin_lock(&isec->lock);
 	isec->sclass = inode_mode_to_security_class(inode->i_mode);
@@ -6208,7 +6242,7 @@ static int selinux_msg_queue_msgrcv(struct kern_ipc_perm *msq, struct msg_msg *m
 	struct ipc_security_struct *isec;
 	struct msg_security_struct *msec;
 	struct common_audit_data ad;
-	u32 sid = task_sid(target);
+	u32 sid = task_sid_subj(target);
 	int rc;
 
 	isec = selinux_ipc(msq);
@@ -7205,8 +7239,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),
 	LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),
 	LSM_HOOK_INIT(task_getsid, selinux_task_getsid),
-	LSM_HOOK_INIT(task_getsecid_subj, selinux_task_getsecid),
-	LSM_HOOK_INIT(task_getsecid_obj, selinux_task_getsecid),
+	LSM_HOOK_INIT(task_getsecid_subj, selinux_task_getsecid_subj),
+	LSM_HOOK_INIT(task_getsecid_obj, selinux_task_getsecid_obj),
 	LSM_HOOK_INIT(task_setnice, selinux_task_setnice),
 	LSM_HOOK_INIT(task_setioprio, selinux_task_setioprio),
 	LSM_HOOK_INIT(task_getioprio, selinux_task_getioprio),