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sysctl: Pass useful parameters to sysctl permissions 

- Current is implicitly avaiable so passing current->nsproxy isn't useful.
- The ctl_table_header is needed to find how the sysctl table is connected
  to the rest of sysctl.
- ctl_table_root is avaiable in the ctl_table_header so no need to it.

With these changes it becomes possible to write a version of
net_sysctl_permission that takes into account the network namespace of
the sysctl table, an important feature in extending the user namespace.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric W. Biederman 2012-11-16 03:02:58 +00:00 committed by David S. Miller
parent d328b83682
commit 73f7ef4359
3 changed files with 7 additions and 8 deletions
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9
fs/proc/proc_sysctl.c
View File

@ -378,12 +378,13 @@ static int test_perm(int mode, int op)
return -EACCES;
}
static int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
{
struct ctl_table_root *root = head->root;
int mode;
if (root->permissions)
mode = root->permissions(root, current->nsproxy, table);
mode = root->permissions(head, table);
else
mode = table->mode;
@ -491,7 +492,7 @@ static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
* and won't be until we finish.
*/
error = -EPERM;
if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
goto out;
/* if that can happen at all, it should be -EINVAL, not -EISDIR */
@ -717,7 +718,7 @@ static int proc_sys_permission(struct inode *inode, int mask)
if (!table) /* global root - r-xr-xr-x */
error = mask & MAY_WRITE ? -EACCES : 0;
else /* Use the permissions on the sysctl table entry */
error = sysctl_perm(head->root, table, mask & ~MAY_NOT_BLOCK);
error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
sysctl_head_finish(head);
return error;

3
include/linux/sysctl.h
View File

@ -158,8 +158,7 @@ struct ctl_table_root {
struct ctl_table_set default_set;
struct ctl_table_set *(*lookup)(struct ctl_table_root *root,
struct nsproxy *namespaces);
int (*permissions)(struct ctl_table_root *root,
struct nsproxy *namespaces, struct ctl_table *table);
int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
};
/* struct ctl_path describes where in the hierarchy a table is added */

3
net/sysctl_net.c
View File

@ -38,8 +38,7 @@ static int is_seen(struct ctl_table_set *set)
}
/* Return standard mode bits for table entry. */
static int net_ctl_permissions(struct ctl_table_root *root,
struct nsproxy *nsproxy,
static int net_ctl_permissions(struct ctl_table_header *head,
struct ctl_table *table)
{
/* Allow network administrator to have same access as root. */