1 files changed, 255 insertions, 125 deletions

diff --git a/kernel/capability.c b/kernel/capability.c
index cfbe44299488..33e51e78c2d8 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -115,11 +115,229 @@ static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
 	return 0;
 }
 
+#ifndef CONFIG_SECURITY_FILE_CAPABILITIES
+
+/*
+ * Without filesystem capability support, we nominally support one process
+ * setting the capabilities of another
+ */
+static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
+				     kernel_cap_t *pIp, kernel_cap_t *pPp)
+{
+	struct task_struct *target;
+	int ret;
+
+	spin_lock(&task_capability_lock);
+	read_lock(&tasklist_lock);
+
+	if (pid && pid != task_pid_vnr(current)) {
+		target = find_task_by_vpid(pid);
+		if (!target) {
+			ret = -ESRCH;
+			goto out;
+		}
+	} else
+		target = current;
+
+	ret = security_capget(target, pEp, pIp, pPp);
+
+out:
+	read_unlock(&tasklist_lock);
+	spin_unlock(&task_capability_lock);
+
+	return ret;
+}
+
+/*
+ * cap_set_pg - set capabilities for all processes in a given process
+ * group.  We call this holding task_capability_lock and tasklist_lock.
+ */
+static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective,
+			     kernel_cap_t *inheritable,
+			     kernel_cap_t *permitted)
+{
+	struct task_struct *g, *target;
+	int ret = -EPERM;
+	int found = 0;
+	struct pid *pgrp;
+
+	spin_lock(&task_capability_lock);
+	read_lock(&tasklist_lock);
+
+	pgrp = find_vpid(pgrp_nr);
+	do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
+		target = g;
+		while_each_thread(g, target) {
+			if (!security_capset_check(target, effective,
+						   inheritable, permitted)) {
+				security_capset_set(target, effective,
+						    inheritable, permitted);
+				ret = 0;
+			}
+			found = 1;
+		}
+	} while_each_pid_task(pgrp, PIDTYPE_PGID, g);
+
+	read_unlock(&tasklist_lock);
+	spin_unlock(&task_capability_lock);
+
+	if (!found)
+		ret = 0;
+	return ret;
+}
+
+/*
+ * cap_set_all - set capabilities for all processes other than init
+ * and self.  We call this holding task_capability_lock and tasklist_lock.
+ */
+static inline int cap_set_all(kernel_cap_t *effective,
+			      kernel_cap_t *inheritable,
+			      kernel_cap_t *permitted)
+{
+	struct task_struct *g, *target;
+	int ret = -EPERM;
+	int found = 0;
+
+	spin_lock(&task_capability_lock);
+	read_lock(&tasklist_lock);
+
+	do_each_thread(g, target) {
+		if (target == current
+		    || is_container_init(target->group_leader))
+			continue;
+		found = 1;
+		if (security_capset_check(target, effective, inheritable,
+					  permitted))
+			continue;
+		ret = 0;
+		security_capset_set(target, effective, inheritable, permitted);
+	} while_each_thread(g, target);
+
+	read_unlock(&tasklist_lock);
+	spin_unlock(&task_capability_lock);
+
+	if (!found)
+		ret = 0;
+
+	return ret;
+}
+
+/*
+ * Given the target pid does not refer to the current process we
+ * need more elaborate support... (This support is not present when
+ * filesystem capabilities are configured.)
+ */
+static inline int do_sys_capset_other_tasks(pid_t pid, kernel_cap_t *effective,
+					    kernel_cap_t *inheritable,
+					    kernel_cap_t *permitted)
+{
+	struct task_struct *target;
+	int ret;
+
+	if (!capable(CAP_SETPCAP))
+		return -EPERM;
+
+	if (pid == -1)	          /* all procs other than current and init */
+		return cap_set_all(effective, inheritable, permitted);
+
+	else if (pid < 0)                    /* all procs in process group */
+		return cap_set_pg(-pid, effective, inheritable, permitted);
+
+	/* target != current */
+	spin_lock(&task_capability_lock);
+	read_lock(&tasklist_lock);
+
+	target = find_task_by_vpid(pid);
+	if (!target)
+		ret = -ESRCH;
+	else {
+		ret = security_capset_check(target, effective, inheritable,
+					    permitted);
+
+		/* having verified that the proposed changes are legal,
+		   we now put them into effect. */
+		if (!ret)
+			security_capset_set(target, effective, inheritable,
+					    permitted);
+	}
+
+	read_unlock(&tasklist_lock);
+	spin_unlock(&task_capability_lock);
+
+	return ret;
+}
+
+#else /* ie., def CONFIG_SECURITY_FILE_CAPABILITIES */
+
+/*
+ * If we have configured with filesystem capability support, then the
+ * only thing that can change the capabilities of the current process
+ * is the current process. As such, we can't be in this code at the
+ * same time as we are in the process of setting capabilities in this
+ * process. The net result is that we can limit our use of locks to
+ * when we are reading the caps of another process.
+ */
+static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
+				     kernel_cap_t *pIp, kernel_cap_t *pPp)
+{
+	int ret;
+
+	if (pid && (pid != task_pid_vnr(current))) {
+		struct task_struct *target;
+
+		spin_lock(&task_capability_lock);
+		read_lock(&tasklist_lock);
+
+		target = find_task_by_vpid(pid);
+		if (!target)
+			ret = -ESRCH;
+		else
+			ret = security_capget(target, pEp, pIp, pPp);
+
+		read_unlock(&tasklist_lock);
+		spin_unlock(&task_capability_lock);
+	} else
+		ret = security_capget(current, pEp, pIp, pPp);
+
+	return ret;
+}
+
 /*
- * For sys_getproccap() and sys_setproccap(), any of the three
- * capability set pointers may be NULL -- indicating that that set is
- * uninteresting and/or not to be changed.
+ * With filesystem capability support configured, the kernel does not
+ * permit the changing of capabilities in one process by another
+ * process. (CAP_SETPCAP has much less broad semantics when configured
+ * this way.)
  */
+static inline int do_sys_capset_other_tasks(pid_t pid,
+					    kernel_cap_t *effective,
+					    kernel_cap_t *inheritable,
+					    kernel_cap_t *permitted)
+{
+	return -EPERM;
+}
+
+#endif /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
+
+/*
+ * Atomically modify the effective capabilities returning the original
+ * value. No permission check is performed here - it is assumed that the
+ * caller is permitted to set the desired effective capabilities.
+ */
+kernel_cap_t cap_set_effective(const kernel_cap_t pE_new)
+{
+	kernel_cap_t pE_old;
+
+	spin_lock(&task_capability_lock);
+
+	pE_old = current->cap_effective;
+	current->cap_effective = pE_new;
+
+	spin_unlock(&task_capability_lock);
+
+	return pE_old;
+}
+
+EXPORT_SYMBOL(cap_set_effective);
 
 /**
  * sys_capget - get the capabilities of a given process.
@@ -134,7 +352,6 @@ asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
 {
 	int ret = 0;
 	pid_t pid;
-	struct task_struct *target;
 	unsigned tocopy;
 	kernel_cap_t pE, pI, pP;
 
@@ -148,23 +365,7 @@ asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
 	if (pid < 0)
 		return -EINVAL;
 
-	spin_lock(&task_capability_lock);
-	read_lock(&tasklist_lock);
-
-	if (pid && pid != task_pid_vnr(current)) {
-		target = find_task_by_vpid(pid);
-		if (!target) {
-			ret = -ESRCH;
-			goto out;
-		}
-	} else
-		target = current;
-
-	ret = security_capget(target, &pE, &pI, &pP);
-
-out:
-	read_unlock(&tasklist_lock);
-	spin_unlock(&task_capability_lock);
+	ret = cap_get_target_pid(pid, &pE, &pI, &pP);
 
 	if (!ret) {
 		struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
@@ -195,7 +396,6 @@ out:
 		 * before modification is attempted and the application
 		 * fails.
 		 */
-
 		if (copy_to_user(dataptr, kdata, tocopy
 				 * sizeof(struct __user_cap_data_struct))) {
 			return -EFAULT;
@@ -205,70 +405,8 @@ out:
 	return ret;
 }
 
-/*
- * cap_set_pg - set capabilities for all processes in a given process
- * group.  We call this holding task_capability_lock and tasklist_lock.
- */
-static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective,
-			      kernel_cap_t *inheritable,
-			      kernel_cap_t *permitted)
-{
-	struct task_struct *g, *target;
-	int ret = -EPERM;
-	int found = 0;
-	struct pid *pgrp;
-
-	pgrp = find_vpid(pgrp_nr);
-	do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
-		target = g;
-		while_each_thread(g, target) {
-			if (!security_capset_check(target, effective,
-							inheritable,
-							permitted)) {
-				security_capset_set(target, effective,
-							inheritable,
-							permitted);
-				ret = 0;
-			}
-			found = 1;
-		}
-	} while_each_pid_task(pgrp, PIDTYPE_PGID, g);
-
-	if (!found)
-		ret = 0;
-	return ret;
-}
-
-/*
- * cap_set_all - set capabilities for all processes other than init
- * and self.  We call this holding task_capability_lock and tasklist_lock.
- */
-static inline int cap_set_all(kernel_cap_t *effective,
-			       kernel_cap_t *inheritable,
-			       kernel_cap_t *permitted)
-{
-     struct task_struct *g, *target;
-     int ret = -EPERM;
-     int found = 0;
-
-     do_each_thread(g, target) {
-             if (target == current || is_container_init(target->group_leader))
-                     continue;
-             found = 1;
-	     if (security_capset_check(target, effective, inheritable,
-						permitted))
-		     continue;
-	     ret = 0;
-	     security_capset_set(target, effective, inheritable, permitted);
-     } while_each_thread(g, target);
-
-     if (!found)
-	     ret = 0;
-     return ret;
-}
-
 /**
- * sys_capset - set capabilities for a process or a group of processes
+ * sys_capset - set capabilities for a process or (*) a group of processes
  * @header: pointer to struct that contains capability version and
  *	target pid data
  * @data: pointer to struct that contains the effective, permitted,
@@ -292,7 +430,6 @@ asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 	struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
 	unsigned i, tocopy;
 	kernel_cap_t inheritable, permitted, effective;
-	struct task_struct *target;
 	int ret;
 	pid_t pid;
 
@@ -303,9 +440,6 @@ asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 	if (get_user(pid, &header->pid))
 		return -EFAULT;
 
-	if (pid && pid != task_pid_vnr(current) && !capable(CAP_SETPCAP))
-		return -EPERM;
-
 	if (copy_from_user(&kdata, data, tocopy
 			   * sizeof(struct __user_cap_data_struct))) {
 		return -EFAULT;
@@ -323,55 +457,51 @@ asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 		i++;
 	}
 
-	spin_lock(&task_capability_lock);
-	read_lock(&tasklist_lock);
-
-	if (pid > 0 && pid != task_pid_vnr(current)) {
-		target = find_task_by_vpid(pid);
-		if (!target) {
-			ret = -ESRCH;
-			goto out;
-		}
-	} else
-		target = current;
-
-	ret = 0;
-
-	/* having verified that the proposed changes are legal,
-	   we now put them into effect. */
-	if (pid < 0) {
-		if (pid == -1)	/* all procs other than current and init */
-			ret = cap_set_all(&effective, &inheritable, &permitted);
+	if (pid && (pid != task_pid_vnr(current)))
+		ret = do_sys_capset_other_tasks(pid, &effective, &inheritable,
+						&permitted);
+	else {
+		/*
+		 * This lock is required even when filesystem
+		 * capability support is configured - it protects the
+		 * sys_capget() call from returning incorrect data in
+		 * the case that the targeted process is not the
+		 * current one.
+		 */
+		spin_lock(&task_capability_lock);
 
-		else		/* all procs in process group */
-			ret = cap_set_pg(-pid, &effective, &inheritable,
-					 &permitted);
-	} else {
-		ret = security_capset_check(target, &effective, &inheritable,
+		ret = security_capset_check(current, &effective, &inheritable,
 					    &permitted);
+		/*
+		 * Having verified that the proposed changes are
+		 * legal, we now put them into effect.
+		 */
 		if (!ret)
-			security_capset_set(target, &effective, &inheritable,
+			security_capset_set(current, &effective, &inheritable,
 					    &permitted);
+		spin_unlock(&task_capability_lock);
 	}
 
-out:
-	read_unlock(&tasklist_lock);
-	spin_unlock(&task_capability_lock);
 
 	return ret;
 }
 
-int __capable(struct task_struct *t, int cap)
+/**
+ * capable - Determine if the current task has a superior capability in effect
+ * @cap: The capability to be tested for
+ *
+ * Return true if the current task has the given superior capability currently
+ * available for use, false if not.
+ *
+ * This sets PF_SUPERPRIV on the task if the capability is available on the
+ * assumption that it's about to be used.
+ */
+int capable(int cap)
 {
-	if (security_capable(t, cap) == 0) {
-		t->flags |= PF_SUPERPRIV;
+	if (has_capability(current, cap)) {
+		current->flags |= PF_SUPERPRIV;
 		return 1;
 	}
 	return 0;
 }
-
-int capable(int cap)
-{
-	return __capable(current, cap);
-}
 EXPORT_SYMBOL(capable);