mm: extract do_pages_move() out of sys_move_pages()
[linux-2.6.git] / security / device_cgroup.c
index baf348834b66c003758246427a98907d38f78c14..46f23971f7e4208d9487cbb9cf477790a8fb378a 100644 (file)
@@ -41,6 +41,7 @@ struct dev_whitelist_item {
        short type;
        short access;
        struct list_head list;
+       struct rcu_head rcu;
 };
 
 struct dev_cgroup {
@@ -59,6 +60,11 @@ static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup)
        return css_to_devcgroup(cgroup_subsys_state(cgroup, devices_subsys_id));
 }
 
+static inline struct dev_cgroup *task_devcgroup(struct task_struct *task)
+{
+       return css_to_devcgroup(task_subsys_state(task, devices_subsys_id));
+}
+
 struct cgroup_subsys devices_subsys;
 
 static int devcgroup_can_attach(struct cgroup_subsys *ss,
@@ -128,11 +134,19 @@ static int dev_whitelist_add(struct dev_cgroup *dev_cgroup,
        }
 
        if (whcopy != NULL)
-               list_add_tail(&whcopy->list, &dev_cgroup->whitelist);
+               list_add_tail_rcu(&whcopy->list, &dev_cgroup->whitelist);
        spin_unlock(&dev_cgroup->lock);
        return 0;
 }
 
+static void whitelist_item_free(struct rcu_head *rcu)
+{
+       struct dev_whitelist_item *item;
+
+       item = container_of(rcu, struct dev_whitelist_item, rcu);
+       kfree(item);
+}
+
 /*
  * called under cgroup_lock()
  * since the list is visible to other tasks, we need the spinlock also
@@ -156,8 +170,8 @@ static void dev_whitelist_rm(struct dev_cgroup *dev_cgroup,
 remove:
                walk->access &= ~wh->access;
                if (!walk->access) {
-                       list_del(&walk->list);
-                       kfree(walk);
+                       list_del_rcu(&walk->list);
+                       call_rcu(&walk->rcu, whitelist_item_free);
                }
        }
        spin_unlock(&dev_cgroup->lock);
@@ -188,7 +202,7 @@ static struct cgroup_subsys_state *devcgroup_create(struct cgroup_subsys *ss,
                }
                wh->minor = wh->major = ~0;
                wh->type = DEV_ALL;
-               wh->access = ACC_MKNOD | ACC_READ | ACC_WRITE;
+               wh->access = ACC_MASK;
                list_add(&wh->list, &dev_cgroup->whitelist);
        } else {
                parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup);
@@ -222,7 +236,7 @@ static void devcgroup_destroy(struct cgroup_subsys *ss,
 #define DEVCG_DENY 2
 #define DEVCG_LIST 3
 
-#define MAJMINLEN 10
+#define MAJMINLEN 13
 #define ACCLEN 4
 
 static void set_access(char *acc, short access)
@@ -250,11 +264,10 @@ static char type_to_char(short type)
 
 static void set_majmin(char *str, unsigned m)
 {
-       memset(str, 0, MAJMINLEN);
        if (m == ~0)
-               sprintf(str, "*");
+               strcpy(str, "*");
        else
-               snprintf(str, MAJMINLEN, "%d", m);
+               sprintf(str, "%u", m);
 }
 
 static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft,
@@ -264,15 +277,15 @@ static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft,
        struct dev_whitelist_item *wh;
        char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN];
 
-       spin_lock(&devcgroup->lock);
-       list_for_each_entry(wh, &devcgroup->whitelist, list) {
+       rcu_read_lock();
+       list_for_each_entry_rcu(wh, &devcgroup->whitelist, list) {
                set_access(acc, wh->access);
                set_majmin(maj, wh->major);
                set_majmin(min, wh->minor);
                seq_printf(m, "%c %s:%s %s\n", type_to_char(wh->type),
                           maj, min, acc);
        }
-       spin_unlock(&devcgroup->lock);
+       rcu_read_unlock();
 
        return 0;
 }
@@ -300,7 +313,7 @@ static int may_access_whitelist(struct dev_cgroup *c,
                        continue;
                if (whitem->minor != ~0 && whitem->minor != refwh->minor)
                        continue;
-               if (refwh->access & (~(whitem->access | ACC_MASK)))
+               if (refwh->access & (~whitem->access))
                        continue;
                return 1;
        }
@@ -312,10 +325,10 @@ static int may_access_whitelist(struct dev_cgroup *c,
  * when adding a new allow rule to a device whitelist, the rule
  * must be allowed in the parent device
  */
-static int parent_has_perm(struct cgroup *childcg,
+static int parent_has_perm(struct dev_cgroup *childcg,
                                  struct dev_whitelist_item *wh)
 {
-       struct cgroup *pcg = childcg->parent;
+       struct cgroup *pcg = childcg->css.cgroup->parent;
        struct dev_cgroup *parent;
        int ret;
 
@@ -341,39 +354,19 @@ static int parent_has_perm(struct cgroup *childcg,
  * new access is only allowed if you're in the top-level cgroup, or your
  * parent cgroup has the access you're asking for.
  */
-static ssize_t devcgroup_access_write(struct cgroup *cgroup, struct cftype *cft,
-                               struct file *file, const char __user *userbuf,
-                               size_t nbytes, loff_t *ppos)
+static int devcgroup_update_access(struct dev_cgroup *devcgroup,
+                                  int filetype, const char *buffer)
 {
-       struct cgroup *cur_cgroup;
-       struct dev_cgroup *devcgroup, *cur_devcgroup;
-       int filetype = cft->private;
-       char *buffer, *b;
+       struct dev_cgroup *cur_devcgroup;
+       const char *b;
+       char *endp;
        int retval = 0, count;
        struct dev_whitelist_item wh;
 
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
 
-       devcgroup = cgroup_to_devcgroup(cgroup);
-       cur_cgroup = task_cgroup(current, devices_subsys.subsys_id);
-       cur_devcgroup = cgroup_to_devcgroup(cur_cgroup);
-
-       buffer = kmalloc(nbytes+1, GFP_KERNEL);
-       if (!buffer)
-               return -ENOMEM;
-
-       if (copy_from_user(buffer, userbuf, nbytes)) {
-               retval = -EFAULT;
-               goto out1;
-       }
-       buffer[nbytes] = 0;     /* nul-terminate */
-
-       cgroup_lock();
-       if (cgroup_is_removed(cgroup)) {
-               retval = -ENODEV;
-               goto out2;
-       }
+       cur_devcgroup = task_devcgroup(current);
 
        memset(&wh, 0, sizeof(wh));
        b = buffer;
@@ -382,6 +375,8 @@ static ssize_t devcgroup_access_write(struct cgroup *cgroup, struct cftype *cft,
        case 'a':
                wh.type = DEV_ALL;
                wh.access = ACC_MASK;
+               wh.major = ~0;
+               wh.minor = ~0;
                goto handle;
        case 'b':
                wh.type = DEV_BLOCK;
@@ -390,32 +385,23 @@ static ssize_t devcgroup_access_write(struct cgroup *cgroup, struct cftype *cft,
                wh.type = DEV_CHAR;
                break;
        default:
-               retval = -EINVAL;
-               goto out2;
+               return -EINVAL;
        }
        b++;
-       if (!isspace(*b)) {
-               retval = -EINVAL;
-               goto out2;
-       }
+       if (!isspace(*b))
+               return -EINVAL;
        b++;
        if (*b == '*') {
                wh.major = ~0;
                b++;
        } else if (isdigit(*b)) {
-               wh.major = 0;
-               while (isdigit(*b)) {
-                       wh.major = wh.major*10+(*b-'0');
-                       b++;
-               }
+               wh.major = simple_strtoul(b, &endp, 10);
+               b = endp;
        } else {
-               retval = -EINVAL;
-               goto out2;
-       }
-       if (*b != ':') {
-               retval = -EINVAL;
-               goto out2;
+               return -EINVAL;
        }
+       if (*b != ':')
+               return -EINVAL;
        b++;
 
        /* read minor */
@@ -423,19 +409,13 @@ static ssize_t devcgroup_access_write(struct cgroup *cgroup, struct cftype *cft,
                wh.minor = ~0;
                b++;
        } else if (isdigit(*b)) {
-               wh.minor = 0;
-               while (isdigit(*b)) {
-                       wh.minor = wh.minor*10+(*b-'0');
-                       b++;
-               }
+               wh.minor = simple_strtoul(b, &endp, 10);
+               b = endp;
        } else {
-               retval = -EINVAL;
-               goto out2;
-       }
-       if (!isspace(*b)) {
-               retval = -EINVAL;
-               goto out2;
+               return -EINVAL;
        }
+       if (!isspace(*b))
+               return -EINVAL;
        for (b++, count = 0; count < 3; count++, b++) {
                switch (*b) {
                case 'r':
@@ -452,8 +432,7 @@ static ssize_t devcgroup_access_write(struct cgroup *cgroup, struct cftype *cft,
                        count = 3;
                        break;
                default:
-                       retval = -EINVAL;
-                       goto out2;
+                       return -EINVAL;
                }
        }
 
@@ -461,38 +440,39 @@ handle:
        retval = 0;
        switch (filetype) {
        case DEVCG_ALLOW:
-               if (!parent_has_perm(cgroup, &wh))
-                       retval = -EPERM;
-               else
-                       retval = dev_whitelist_add(devcgroup, &wh);
-               break;
+               if (!parent_has_perm(devcgroup, &wh))
+                       return -EPERM;
+               return dev_whitelist_add(devcgroup, &wh);
        case DEVCG_DENY:
                dev_whitelist_rm(devcgroup, &wh);
                break;
        default:
-               retval = -EINVAL;
-               goto out2;
+               return -EINVAL;
        }
+       return 0;
+}
 
-       if (retval == 0)
-               retval = nbytes;
-
-out2:
+static int devcgroup_access_write(struct cgroup *cgrp, struct cftype *cft,
+                                 const char *buffer)
+{
+       int retval;
+       if (!cgroup_lock_live_group(cgrp))
+               return -ENODEV;
+       retval = devcgroup_update_access(cgroup_to_devcgroup(cgrp),
+                                        cft->private, buffer);
        cgroup_unlock();
-out1:
-       kfree(buffer);
        return retval;
 }
 
 static struct cftype dev_cgroup_files[] = {
        {
                .name = "allow",
-               .write  = devcgroup_access_write,
+               .write_string  = devcgroup_access_write,
                .private = DEVCG_ALLOW,
        },
        {
                .name = "deny",
-               .write = devcgroup_access_write,
+               .write_string = devcgroup_access_write,
                .private = DEVCG_DENY,
        },
        {
@@ -528,13 +508,12 @@ int devcgroup_inode_permission(struct inode *inode, int mask)
                return 0;
        if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode))
                return 0;
-       dev_cgroup = css_to_devcgroup(task_subsys_state(current,
-                               devices_subsys_id));
-       if (!dev_cgroup)
-               return 0;
 
-       spin_lock(&dev_cgroup->lock);
-       list_for_each_entry(wh, &dev_cgroup->whitelist, list) {
+       rcu_read_lock();
+
+       dev_cgroup = task_devcgroup(current);
+
+       list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
                if (wh->type & DEV_ALL)
                        goto acc_check;
                if ((wh->type & DEV_BLOCK) && !S_ISBLK(inode->i_mode))
@@ -550,10 +529,11 @@ acc_check:
                        continue;
                if ((mask & MAY_READ) && !(wh->access & ACC_READ))
                        continue;
-               spin_unlock(&dev_cgroup->lock);
+               rcu_read_unlock();
                return 0;
        }
-       spin_unlock(&dev_cgroup->lock);
+
+       rcu_read_unlock();
 
        return -EPERM;
 }
@@ -563,12 +543,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
        struct dev_cgroup *dev_cgroup;
        struct dev_whitelist_item *wh;
 
-       dev_cgroup = css_to_devcgroup(task_subsys_state(current,
-                               devices_subsys_id));
-       if (!dev_cgroup)
-               return 0;
+       rcu_read_lock();
+
+       dev_cgroup = task_devcgroup(current);
 
-       spin_lock(&dev_cgroup->lock);
        list_for_each_entry(wh, &dev_cgroup->whitelist, list) {
                if (wh->type & DEV_ALL)
                        goto acc_check;
@@ -583,9 +561,11 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
 acc_check:
                if (!(wh->access & ACC_MKNOD))
                        continue;
-               spin_unlock(&dev_cgroup->lock);
+               rcu_read_unlock();
                return 0;
        }
-       spin_unlock(&dev_cgroup->lock);
+
+       rcu_read_unlock();
+
        return -EPERM;
 }