Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wirel...

[~andy/linux] / security / device_cgroup.c

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 44dfc415a379afc9c327388664e949bfcc855bcb..842c254396dbe8ab2a54fd566b37d29ce6fd4d8b 100644 (file)
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -42,7 +42,10 @@ struct dev_exception_item {
 struct dev_cgroup {
        struct cgroup_subsys_state css;
        struct list_head exceptions;
-       bool deny_all;
+       enum {
+               DEVCG_DEFAULT_ALLOW,
+               DEVCG_DEFAULT_DENY,
+       } behavior;
 };
 
 static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
@@ -182,13 +185,13 @@ static struct cgroup_subsys_state *devcgroup_create(struct cgroup *cgroup)
        parent_cgroup = cgroup->parent;
 
        if (parent_cgroup == NULL)
-               dev_cgroup->deny_all = false;
+               dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW;
        else {
                parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup);
                mutex_lock(&devcgroup_mutex);
                ret = dev_exceptions_copy(&dev_cgroup->exceptions,
                                          &parent_dev_cgroup->exceptions);
-               dev_cgroup->deny_all = parent_dev_cgroup->deny_all;
+               dev_cgroup->behavior = parent_dev_cgroup->behavior;
                mutex_unlock(&devcgroup_mutex);
                if (ret) {
                        kfree(dev_cgroup);
@@ -260,7 +263,7 @@ static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft,
         * - List the exceptions in case the default policy is to deny
         * This way, the file remains as a "whitelist of devices"
         */
-       if (devcgroup->deny_all == false) {
+       if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) {
                set_access(acc, ACC_MASK);
                set_majmin(maj, ~0);
                set_majmin(min, ~0);
@@ -314,12 +317,12 @@ static int may_access(struct dev_cgroup *dev_cgroup,
         * In two cases we'll consider this new exception valid:
         * - the dev cgroup has its default policy to allow + exception list:
         *   the new exception should *not* match any of the exceptions
-        *   (!deny_all, !match)
+        *   (behavior == DEVCG_DEFAULT_ALLOW, !match)
         * - the dev cgroup has its default policy to deny + exception list:
         *   the new exception *should* match the exceptions
-        *   (deny_all, match)
+        *   (behavior == DEVCG_DEFAULT_DENY, match)
         */
-       if (dev_cgroup->deny_all == match)
+       if ((dev_cgroup->behavior == DEVCG_DEFAULT_DENY) == match)
                return 1;
        return 0;
 }
@@ -341,6 +344,17 @@ static int parent_has_perm(struct dev_cgroup *childcg,
        return may_access(parent, ex);
 }
 
+/**
+ * may_allow_all - checks if it's possible to change the behavior to
+ *                allow based on parent's rules.
+ * @parent: device cgroup's parent
+ * returns: != 0 in case it's allowed, 0 otherwise
+ */
+static inline int may_allow_all(struct dev_cgroup *parent)
+{
+       return parent->behavior == DEVCG_DEFAULT_ALLOW;
+}
+
 /*
  * Modify the exception list using allow/deny rules.
  * CAP_SYS_ADMIN is needed for this.  It's at least separate from CAP_MKNOD
@@ -358,9 +372,11 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                                   int filetype, const char *buffer)
 {
        const char *b;
-       char *endp;
-       int count;
+       char temp[12];          /* 11 + 1 characters needed for a u32 */
+       int count, rc;
        struct dev_exception_item ex;
+       struct cgroup *p = devcgroup->css.cgroup;
+       struct dev_cgroup *parent = cgroup_to_devcgroup(p->parent);
 
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
@@ -372,14 +388,18 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
        case 'a':
                switch (filetype) {
                case DEVCG_ALLOW:
-                       if (!parent_has_perm(devcgroup, &ex))
+                       if (!may_allow_all(parent))
                                return -EPERM;
                        dev_exception_clean(devcgroup);
-                       devcgroup->deny_all = false;
+                       rc = dev_exceptions_copy(&devcgroup->exceptions,
+                                                &parent->exceptions);
+                       if (rc)
+                               return rc;
+                       devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
                        break;
                case DEVCG_DENY:
                        dev_exception_clean(devcgroup);
-                       devcgroup->deny_all = true;
+                       devcgroup->behavior = DEVCG_DEFAULT_DENY;
                        break;
                default:
                        return -EINVAL;
@@ -402,8 +422,16 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                ex.major = ~0;
                b++;
        } else if (isdigit(*b)) {
-               ex.major = simple_strtoul(b, &endp, 10);
-               b = endp;
+               memset(temp, 0, sizeof(temp));
+               for (count = 0; count < sizeof(temp) - 1; count++) {
+                       temp[count] = *b;
+                       b++;
+                       if (!isdigit(*b))
+                               break;
+               }
+               rc = kstrtou32(temp, 10, &ex.major);
+               if (rc)
+                       return -EINVAL;
        } else {
                return -EINVAL;
        }
@@ -416,8 +444,16 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                ex.minor = ~0;
                b++;
        } else if (isdigit(*b)) {
-               ex.minor = simple_strtoul(b, &endp, 10);
-               b = endp;
+               memset(temp, 0, sizeof(temp));
+               for (count = 0; count < sizeof(temp) - 1; count++) {
+                       temp[count] = *b;
+                       b++;
+                       if (!isdigit(*b))
+                               break;
+               }
+               rc = kstrtou32(temp, 10, &ex.minor);
+               if (rc)
+                       return -EINVAL;
        } else {
                return -EINVAL;
        }
@@ -452,7 +488,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                 * an matching exception instead. And be silent about it: we
                 * don't want to break compatibility
                 */
-               if (devcgroup->deny_all == false) {
+               if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) {
                        dev_exception_rm(devcgroup, &ex);
                        return 0;
                }
@@ -463,7 +499,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                 * an matching exception instead. And be silent about it: we
                 * don't want to break compatibility
                 */
-               if (devcgroup->deny_all == true) {
+               if (devcgroup->behavior == DEVCG_DEFAULT_DENY) {
                        dev_exception_rm(devcgroup, &ex);
                        return 0;
                }
@@ -533,10 +569,10 @@ struct cgroup_subsys devices_subsys = {
  *
  * returns 0 on success, -EPERM case the operation is not permitted
  */
-static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup,
-                                       short type, u32 major, u32 minor,
+static int __devcgroup_check_permission(short type, u32 major, u32 minor,
                                        short access)
 {
+       struct dev_cgroup *dev_cgroup;
        struct dev_exception_item ex;
        int rc;
 
@@ -547,6 +583,7 @@ static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup,
        ex.access = access;
 
        rcu_read_lock();
+       dev_cgroup = task_devcgroup(current);
        rc = may_access(dev_cgroup, &ex);
        rcu_read_unlock();
 
@@ -558,7 +595,6 @@ static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup,
 
 int __devcgroup_inode_permission(struct inode *inode, int mask)
 {
-       struct dev_cgroup *dev_cgroup = task_devcgroup(current);
        short type, access = 0;
 
        if (S_ISBLK(inode->i_mode))
@@ -570,13 +606,12 @@ int __devcgroup_inode_permission(struct inode *inode, int mask)
        if (mask & MAY_READ)
                access |= ACC_READ;
 
-       return __devcgroup_check_permission(dev_cgroup, type, imajor(inode),
-                                           iminor(inode), access);
+       return __devcgroup_check_permission(type, imajor(inode), iminor(inode),
+                       access);
 }
 
 int devcgroup_inode_mknod(int mode, dev_t dev)
 {
-       struct dev_cgroup *dev_cgroup = task_devcgroup(current);
        short type;
 
        if (!S_ISBLK(mode) && !S_ISCHR(mode))
@@ -587,7 +622,7 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
        else
                type = DEV_CHAR;
 
-       return __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
-                                           MINOR(dev), ACC_MKNOD);
+       return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev),
+                       ACC_MKNOD);
 
 }