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sysctl: Infrastructure for per namespace sysctls

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This patch implements the basic infrastructure for per namespace sysctls.

A list of lists of sysctl headers is added, allowing each namespace to have
it's own list of sysctl headers.

Each list of sysctl headers has a lookup function to find the first
sysctl header in the list, allowing the lists to have a per namespace
instance.

register_sysct_root is added to tell sysctl.c about additional
lists of sysctl_headers.  As all of the users are expected to be in
kernel no unregister function is provided.

sysctl_head_next is updated to walk through the list of lists.

__register_sysctl_paths is added to add a new sysctl table on
a non-default sysctl list.

The only intrusive part of this patch is propagating the information
to decided which list of sysctls to use for sysctl_check_table.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Daniel Lezcano <dlezcano@fr.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric W. Biederman
2007-11-30 23:54:00 +11:00
committed by David S. Miller
parent 23eb06de7d
commit e51b6ba077
3 changed files with 112 additions and 23 deletions
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93
kernel/sysctl.c
View File

@@ -157,8 +157,16 @@ static int proc_dointvec_taint(struct ctl_table *table, int write, struct file *
#endif
static struct ctl_table root_table[];
static struct ctl_table_header root_table_header =
{ root_table, LIST_HEAD_INIT(root_table_header.ctl_entry) };
static struct ctl_table_root sysctl_table_root;
static struct ctl_table_header root_table_header = {
.ctl_table = root_table,
.ctl_entry = LIST_HEAD_INIT(sysctl_table_root.header_list),
.root = &sysctl_table_root,
};
static struct ctl_table_root sysctl_table_root = {
.root_list = LIST_HEAD_INIT(sysctl_table_root.root_list),
.header_list = LIST_HEAD_INIT(root_table_header.ctl_entry),
};
static struct ctl_table kern_table[];
static struct ctl_table vm_table[];
@@ -1371,12 +1379,27 @@ void sysctl_head_finish(struct ctl_table_header *head)
spin_unlock(&sysctl_lock);
}
struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev)
static struct list_head *
lookup_header_list(struct ctl_table_root *root, struct nsproxy *namespaces)
{
struct list_head *header_list;
header_list = &root->header_list;
if (root->lookup)
header_list = root->lookup(root, namespaces);
return header_list;
}
struct ctl_table_header *__sysctl_head_next(struct nsproxy *namespaces,
struct ctl_table_header *prev)
{
struct ctl_table_root *root;
struct list_head *header_list;
struct ctl_table_header *head;
struct list_head *tmp;
spin_lock(&sysctl_lock);
if (prev) {
head = prev;
tmp = &prev->ctl_entry;
unuse_table(prev);
goto next;
@@ -1390,14 +1413,38 @@ struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev)
spin_unlock(&sysctl_lock);
return head;
next:
root = head->root;
tmp = tmp->next;
if (tmp == &root_table_header.ctl_entry)
break;
header_list = lookup_header_list(root, namespaces);
if (tmp != header_list)
continue;
do {
root = list_entry(root->root_list.next,
struct ctl_table_root, root_list);
if (root == &sysctl_table_root)
goto out;
header_list = lookup_header_list(root, namespaces);
} while (list_empty(header_list));
tmp = header_list->next;
}
out:
spin_unlock(&sysctl_lock);
return NULL;
}
struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev)
{
return __sysctl_head_next(current->nsproxy, prev);
}
void register_sysctl_root(struct ctl_table_root *root)
{
spin_lock(&sysctl_lock);
list_add_tail(&root->root_list, &sysctl_table_root.root_list);
spin_unlock(&sysctl_lock);
}
#ifdef CONFIG_SYSCTL_SYSCALL
int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *oldlenp,
void __user *newval, size_t newlen)
@@ -1554,14 +1601,16 @@ static __init int sysctl_init(void)
{
int err;
sysctl_set_parent(NULL, root_table);
err = sysctl_check_table(root_table);
err = sysctl_check_table(current->nsproxy, root_table);
return 0;
}
core_initcall(sysctl_init);
/**
* register_sysctl_paths - register a sysctl hierarchy
* __register_sysctl_paths - register a sysctl hierarchy
* @root: List of sysctl headers to register on
* @namespaces: Data to compute which lists of sysctl entries are visible
* @path: The path to the directory the sysctl table is in.
* @table: the top-level table structure
*
@@ -1629,9 +1678,12 @@ core_initcall(sysctl_init);
* This routine returns %NULL on a failure to register, and a pointer
* to the table header on success.
*/
struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
struct ctl_table *table)
struct ctl_table_header *__register_sysctl_paths(
struct ctl_table_root *root,
struct nsproxy *namespaces,
const struct ctl_path *path, struct ctl_table *table)
{
struct list_head *header_list;
struct ctl_table_header *header;
struct ctl_table *new, **prevp;
unsigned int n, npath;
@@ -1674,18 +1726,37 @@ struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
INIT_LIST_HEAD(&header->ctl_entry);
header->used = 0;
header->unregistering = NULL;
header->root = root;
sysctl_set_parent(NULL, header->ctl_table);
if (sysctl_check_table(header->ctl_table)) {
if (sysctl_check_table(namespaces, header->ctl_table)) {
kfree(header);
return NULL;
}
spin_lock(&sysctl_lock);
list_add_tail(&header->ctl_entry, &root_table_header.ctl_entry);
header_list = lookup_header_list(root, namespaces);
list_add_tail(&header->ctl_entry, header_list);
spin_unlock(&sysctl_lock);
return header;
}
/**
* register_sysctl_table_path - register a sysctl table hierarchy
* @path: The path to the directory the sysctl table is in.
* @table: the top-level table structure
*
* Register a sysctl table hierarchy. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
*
* See __register_sysctl_paths for more details.
*/
struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
struct ctl_table *table)
{
return __register_sysctl_paths(&sysctl_table_root, current->nsproxy,
path, table);
}
/**
* register_sysctl_table - register a sysctl table hierarchy
* @table: the top-level table structure