This patch converts devcgroup_access_write() from a raw file handler
into a handler for the cgroup write_string() method. This allows some
boilerplate copying/locking/checking to be removed and simplifies the
cleanup path, since these functions are performed by the cgroups
framework before calling the handler.
Signed-off-by: Paul Menage <menage at google.com>
---
security/device_cgroup.c | 79 +++++++++++++----------------------------------
1 file changed, 22 insertions(+), 57 deletions(-)
Index: cgroup-2.6.25-mm1/security/device_cgroup.c
===================================================================
--- cgroup-2.6.25-mm1.orig/security/device_cgroup.c
+++ cgroup-2.6.25-mm1/security/device_cgroup.c
@@ -323,14 +323,14 @@ static int parent_has_perm(struct cgroup
* 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_access_write(struct cgroup *cgroup,
+ struct cftype *cft,
+ char *buffer)
{
struct cgroup *cur_cgroup;
struct dev_cgroup *devcgroup, *cur_devcgroup;
int filetype = cft->private;
- char *buffer, *b;
+ char *b;
int retval = 0, count;
struct dev_whitelist_item wh;
@@ -341,22 +341,6 @@ static ssize_t devcgroup_access_write(st
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;
- }
-
memset(&wh, 0, sizeof(wh));
b = buffer;
@@ -372,14 +356,11 @@ static ssize_t devcgroup_access_write(st
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;
@@ -391,13 +372,10 @@ static ssize_t devcgroup_access_write(st
b++;
}
} else {
- retval = -EINVAL;
- goto out2;
- }
- if (*b != ':') {
- retval = -EINVAL;
- goto out2;
+ return -EINVAL;
}
+ if (*b != ':')
+ return -EINVAL;
b++;
/* read minor */
@@ -411,13 +389,10 @@ static ssize_t devcgroup_access_write(st
b++;
}
} 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':
@@ -434,8 +409,7 @@ static ssize_t devcgroup_access_write(st
count = 3;
break;
default:
- retval = -EINVAL;
- goto out2;
+ return -EINVAL;
}
}
@@ -444,38 +418,29 @@ handle:
switch (filetype) {
case DEVCG_ALLOW:
if (!parent_has_perm(cgroup, &wh))
- retval = -EPERM;
- else
- retval = dev_whitelist_add(devcgroup, &wh);
- break;
+ return -EPERM;
+ return dev_whitelist_add(devcgroup, &wh);
case DEVCG_DENY:
dev_whitelist_rm(devcgroup, &wh);
break;
default:
- retval = -EINVAL;
- goto out2;
+ return -EINVAL;
}
-
- if (retval == 0)
- retval = nbytes;
-
-out2:
- cgroup_unlock();
-out1:
- kfree(buffer);
- return retval;
+ return 0;
}
static struct cftype dev_cgroup_files[] = {
{
.name = "allow",
- .write = devcgroup_access_write,
+ .write_string = devcgroup_access_write,
.private = DEVCG_ALLOW,
+ .lockmode = CFT_LOCK_CGL_WRITE,
},
{
.name = "deny",
- .write = devcgroup_access_write,
+ .write_string = devcgroup_access_write,
.private = DEVCG_DENY,
+ .lockmode = CFT_LOCK_CGL_WRITE,
},
{
.name = "list",
--
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