1 files changed, 221 insertions, 117 deletions

diff --git a/kernel/capability.c b/kernel/capability.c
index 901e0fdc3fff..0101e847603e 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -115,11 +115,208 @@ 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;
+}
+
 /*
- * 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.
+ * 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;
+}
+
+/*
+ * 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
@@ -155,7 +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;
 
@@ -169,23 +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];
@@ -216,7 +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;
@@ -226,70 +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,
@@ -313,7 +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;
 
@@ -324,9 +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;
@@ -344,40 +457,31 @@ 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;
 }