/*
- * dev_cgroup.c - device cgroup subsystem
+ * device_cgroup.c - device cgroup subsystem
*
* Copyright 2007 IBM Corp
*/
#include <linux/list.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
+#include <linux/rcupdate.h>
+#include <linux/mutex.h>
#define ACC_MKNOD 1
#define ACC_READ 2
#define DEV_CHAR 2
#define DEV_ALL 4 /* this represents all devices */
+static DEFINE_MUTEX(devcgroup_mutex);
+
/*
* whitelist locking rules:
- * cgroup_lock() cannot be taken under dev_cgroup->lock.
- * dev_cgroup->lock can be taken with or without cgroup_lock().
- *
- * modifications always require cgroup_lock
- * modifications to a list which is visible require the
- * dev_cgroup->lock *and* cgroup_lock()
- * walking the list requires dev_cgroup->lock or cgroup_lock().
- *
- * reasoning: dev_whitelist_copy() needs to kmalloc, so needs
- * a mutex, which the cgroup_lock() is. Since modifying
- * a visible list requires both locks, either lock can be
- * taken for walking the list.
+ * hold devcgroup_mutex for update/read.
+ * hold rcu_read_lock() for read.
*/
struct dev_whitelist_item {
struct dev_cgroup {
struct cgroup_subsys_state css;
struct list_head whitelist;
- spinlock_t lock;
};
static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
struct cgroup_subsys devices_subsys;
static int devcgroup_can_attach(struct cgroup_subsys *ss,
- struct cgroup *new_cgroup, struct task_struct *task)
+ struct cgroup *new_cgroup, struct task_struct *task,
+ bool threadgroup)
{
if (current != task && !capable(CAP_SYS_ADMIN))
return -EPERM;
}
/*
- * called under cgroup_lock()
+ * called under devcgroup_mutex
*/
static int dev_whitelist_copy(struct list_head *dest, struct list_head *orig)
{
struct dev_whitelist_item *wh, *tmp, *new;
list_for_each_entry(wh, orig, list) {
- new = kmalloc(sizeof(*wh), GFP_KERNEL);
+ new = kmemdup(wh, sizeof(*wh), GFP_KERNEL);
if (!new)
goto free_and_exit;
- new->major = wh->major;
- new->minor = wh->minor;
- new->type = wh->type;
- new->access = wh->access;
list_add_tail(&new->list, dest);
}
/* Stupid prototype - don't bother combining existing entries */
/*
- * called under cgroup_lock()
- * since the list is visible to other tasks, we need the spinlock also
+ * called under devcgroup_mutex
*/
static int dev_whitelist_add(struct dev_cgroup *dev_cgroup,
struct dev_whitelist_item *wh)
{
struct dev_whitelist_item *whcopy, *walk;
- whcopy = kmalloc(sizeof(*whcopy), GFP_KERNEL);
+ whcopy = kmemdup(wh, sizeof(*wh), GFP_KERNEL);
if (!whcopy)
return -ENOMEM;
- memcpy(whcopy, wh, sizeof(*whcopy));
- spin_lock(&dev_cgroup->lock);
list_for_each_entry(walk, &dev_cgroup->whitelist, list) {
if (walk->type != wh->type)
continue;
if (whcopy != NULL)
list_add_tail_rcu(&whcopy->list, &dev_cgroup->whitelist);
- spin_unlock(&dev_cgroup->lock);
return 0;
}
}
/*
- * called under cgroup_lock()
- * since the list is visible to other tasks, we need the spinlock also
+ * called under devcgroup_mutex
*/
static void dev_whitelist_rm(struct dev_cgroup *dev_cgroup,
struct dev_whitelist_item *wh)
{
struct dev_whitelist_item *walk, *tmp;
- spin_lock(&dev_cgroup->lock);
list_for_each_entry_safe(walk, tmp, &dev_cgroup->whitelist, list) {
if (walk->type == DEV_ALL)
goto remove;
call_rcu(&walk->rcu, whitelist_item_free);
}
}
- spin_unlock(&dev_cgroup->lock);
}
/*
list_add(&wh->list, &dev_cgroup->whitelist);
} else {
parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup);
+ mutex_lock(&devcgroup_mutex);
ret = dev_whitelist_copy(&dev_cgroup->whitelist,
&parent_dev_cgroup->whitelist);
+ mutex_unlock(&devcgroup_mutex);
if (ret) {
kfree(dev_cgroup);
return ERR_PTR(ret);
}
}
- spin_lock_init(&dev_cgroup->lock);
return &dev_cgroup->css;
}
* does the access granted to dev_cgroup c contain the access
* requested in whitelist item refwh.
* return 1 if yes, 0 if no.
- * call with c->lock held
+ * call with devcgroup_mutex held
*/
static int may_access_whitelist(struct dev_cgroup *c,
struct dev_whitelist_item *refwh)
{
struct cgroup *pcg = childcg->css.cgroup->parent;
struct dev_cgroup *parent;
- int ret;
if (!pcg)
return 1;
parent = cgroup_to_devcgroup(pcg);
- spin_lock(&parent->lock);
- ret = may_access_whitelist(parent, wh);
- spin_unlock(&parent->lock);
- return ret;
+ return may_access_whitelist(parent, wh);
}
/*
static int devcgroup_update_access(struct dev_cgroup *devcgroup,
int filetype, const char *buffer)
{
- struct dev_cgroup *cur_devcgroup;
const char *b;
char *endp;
- int retval = 0, count;
+ int count;
struct dev_whitelist_item wh;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- cur_devcgroup = task_devcgroup(current);
-
memset(&wh, 0, sizeof(wh));
b = buffer;
}
handle:
- retval = 0;
switch (filetype) {
case DEVCG_ALLOW:
if (!parent_has_perm(devcgroup, &wh))
const char *buffer)
{
int retval;
- if (!cgroup_lock_live_group(cgrp))
- return -ENODEV;
+
+ mutex_lock(&devcgroup_mutex);
retval = devcgroup_update_access(cgroup_to_devcgroup(cgrp),
cft->private, buffer);
- cgroup_unlock();
+ mutex_unlock(&devcgroup_mutex);
return retval;
}
list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
if (wh->type & DEV_ALL)
- goto acc_check;
+ goto found;
if ((wh->type & DEV_BLOCK) && !S_ISBLK(inode->i_mode))
continue;
if ((wh->type & DEV_CHAR) && !S_ISCHR(inode->i_mode))
continue;
if (wh->minor != ~0 && wh->minor != iminor(inode))
continue;
-acc_check:
+
if ((mask & MAY_WRITE) && !(wh->access & ACC_WRITE))
continue;
if ((mask & MAY_READ) && !(wh->access & ACC_READ))
continue;
+found:
rcu_read_unlock();
return 0;
}
struct dev_cgroup *dev_cgroup;
struct dev_whitelist_item *wh;
+ if (!S_ISBLK(mode) && !S_ISCHR(mode))
+ return 0;
+
rcu_read_lock();
dev_cgroup = task_devcgroup(current);
- list_for_each_entry(wh, &dev_cgroup->whitelist, list) {
+ list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
if (wh->type & DEV_ALL)
- goto acc_check;
+ goto found;
if ((wh->type & DEV_BLOCK) && !S_ISBLK(mode))
continue;
if ((wh->type & DEV_CHAR) && !S_ISCHR(mode))
continue;
if (wh->minor != ~0 && wh->minor != MINOR(dev))
continue;
-acc_check:
+
if (!(wh->access & ACC_MKNOD))
continue;
+found:
rcu_read_unlock();
return 0;
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff