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-rw-r--r--security/device_cgroup.c158
1 files changed, 68 insertions, 90 deletions
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index ddd92cec78ed..7bd296cca041 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -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);
@@ -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, "%u", 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;
}
@@ -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;
@@ -392,32 +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 */
@@ -425,19 +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':
@@ -454,8 +432,7 @@ static ssize_t devcgroup_access_write(struct cgroup *cgroup, struct cftype *cft,
count = 3;
break;
default:
- retval = -EINVAL;
- goto out2;
+ return -EINVAL;
}
}
@@ -463,38 +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,
},
{
@@ -535,8 +513,8 @@ int devcgroup_inode_permission(struct inode *inode, int mask)
if (!dev_cgroup)
return 0;
- spin_lock(&dev_cgroup->lock);
- list_for_each_entry(wh, &dev_cgroup->whitelist, list) {
+ rcu_read_lock();
+ 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))
@@ -552,10 +530,10 @@ 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;
}
@@ -570,7 +548,7 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
if (!dev_cgroup)
return 0;
- spin_lock(&dev_cgroup->lock);
+ rcu_read_lock();
list_for_each_entry(wh, &dev_cgroup->whitelist, list) {
if (wh->type & DEV_ALL)
goto acc_check;
@@ -585,9 +563,9 @@ 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;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-30 03:38:29 +0100