[PATCH 3/4] sysctl: Infrastructure for per namespace sysctls

From: Eric W. Biederman
Date: Thu Nov 29 2007 - 12:59:36 EST

Next message: Adrian Bunk: "Re: 2.6.24-rc3-git4 build warnings"
Previous message: Miklos Szeredi: "Re: scheduling anomaly on uml (was: -rt doesn't compile for UML)"
In reply to: Eric W. Biederman: "[PATCH 2/4] sysctl: Remember the ctl_table we passed to register_sysctl_paths"
Next in thread: Eric W. Biederman: "[PATCH 4/4] net: Implement the per network namespace sysctl infrastructure"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

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@xxxxxxxxxxxx>
---
include/linux/sysctl.h | 16 ++++++++-
kernel/sysctl.c | 93 ++++++++++++++++++++++++++++++++++++++++++------
kernel/sysctl_check.c | 25 +++++++------
3 files changed, 111 insertions(+), 23 deletions(-)

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 8b2e9e0..cd1da5c 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -951,7 +951,9 @@ enum

/* For the /proc/sys support */
struct ctl_table;
+struct nsproxy;
extern struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev);
+extern struct ctl_table_header *__sysctl_head_next(struct nsproxy *namespaces, struct ctl_table_header *prev);
extern void sysctl_head_finish(struct ctl_table_header *prev);
extern int sysctl_perm(struct ctl_table *table, int op);

@@ -1055,6 +1057,13 @@ struct ctl_table
void *extra2;
};

+struct ctl_table_root {
+ struct list_head root_list;
+ struct list_head header_list;
+ struct list_head *(*lookup)(struct ctl_table_root *root,
+ struct nsproxy *namespaces);
+};
+
/* struct ctl_table_header is used to maintain dynamic lists of
struct ctl_table trees. */
struct ctl_table_header
@@ -1064,6 +1073,7 @@ struct ctl_table_header
int used;
struct completion *unregistering;
struct ctl_table *ctl_table_arg;
+ struct ctl_table_root *root;
};

/* struct ctl_path describes where in the hierarchy a table is added */
@@ -1073,12 +1083,16 @@ struct ctl_path
int ctl_name;
};

+void register_sysctl_root(struct ctl_table_root *root);
+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 ctl_table_header *register_sysctl_table(struct ctl_table * table);
struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
struct ctl_table *table);

void unregister_sysctl_table(struct ctl_table_header * table);
-int sysctl_check_table(struct ctl_table *table);
+int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *table);

#else /* __KERNEL__ */

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index effae87..ad4b709 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -156,8 +156,16 @@ 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[];
@@ -1300,12 +1308,27 @@ 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;
@@ -1319,14 +1342,38 @@ 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)
@@ -1483,14 +1530,16 @@ 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
*
@@ -1558,9 +1607,12 @@ 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;
@@ -1603,19 +1655,38 @@ 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
*
diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
index fdfca0d..2544852 100644
--- a/kernel/sysctl_check.c
+++ b/kernel/sysctl_check.c
@@ -1352,7 +1352,8 @@ static void sysctl_repair_table(struct ctl_table *table)
}
}

-static struct ctl_table *sysctl_check_lookup(struct ctl_table *table)
+static struct ctl_table *sysctl_check_lookup(struct nsproxy *namespaces,
+ struct ctl_table *table)
{
struct ctl_table_header *head;
struct ctl_table *ref, *test;
@@ -1360,8 +1361,8 @@ static struct ctl_table *sysctl_check_lookup(struct ctl_table *table)

depth = sysctl_depth(table);

- for (head = sysctl_head_next(NULL); head;
- head = sysctl_head_next(head)) {
+ for (head = __sysctl_head_next(namespaces, NULL); head;
+ head = __sysctl_head_next(namespaces, head)) {
cur_depth = depth;
ref = head->ctl_table;
repeat:
@@ -1406,13 +1407,14 @@ static void set_fail(const char **fail, struct ctl_table *table, const char *str
*fail = str;
}

-static int sysctl_check_dir(struct ctl_table *table)
+static int sysctl_check_dir(struct nsproxy *namespaces,
+ struct ctl_table *table)
{
struct ctl_table *ref;
int error;

error = 0;
- ref = sysctl_check_lookup(table);
+ ref = sysctl_check_lookup(namespaces, table);
if (ref) {
int match = 0;
if ((!table->procname && !ref->procname) ||
@@ -1437,11 +1439,12 @@ static int sysctl_check_dir(struct ctl_table *table)
return error;
}

-static void sysctl_check_leaf(struct ctl_table *table, const char **fail)
+static void sysctl_check_leaf(struct nsproxy *namespaces,
+ struct ctl_table *table, const char **fail)
{
struct ctl_table *ref;

- ref = sysctl_check_lookup(table);
+ ref = sysctl_check_lookup(namespaces, table);
if (ref && (ref != table))
set_fail(fail, table, "Sysctl already exists");
}
@@ -1465,7 +1468,7 @@ static void sysctl_check_bin_path(struct ctl_table *table, const char **fail)
}
}

-int sysctl_check_table(struct ctl_table *table)
+int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *table)
{
int error = 0;
for (; table->ctl_name || table->procname; table++) {
@@ -1495,7 +1498,7 @@ int sysctl_check_table(struct ctl_table *table)
set_fail(&fail, table, "Directory with extra1");
if (table->extra2)
set_fail(&fail, table, "Directory with extra2");
- if (sysctl_check_dir(table))
+ if (sysctl_check_dir(namespaces, table))
set_fail(&fail, table, "Inconsistent directory names");
} else {
if ((table->strategy == sysctl_data) ||
@@ -1544,7 +1547,7 @@ int sysctl_check_table(struct ctl_table *table)
if (!table->procname && table->proc_handler)
set_fail(&fail, table, "proc_handler without procname");
#endif
- sysctl_check_leaf(table, &fail);
+ sysctl_check_leaf(namespaces, table, &fail);
}
sysctl_check_bin_path(table, &fail);
if (fail) {
@@ -1552,7 +1555,7 @@ int sysctl_check_table(struct ctl_table *table)
error = -EINVAL;
}
if (table->child)
- error |= sysctl_check_table(table->child);
+ error |= sysctl_check_table(namespaces, table->child);
}
return error;
}
--
1.5.3.rc6.17.g1911

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Adrian Bunk: "Re: 2.6.24-rc3-git4 build warnings"
Previous message: Miklos Szeredi: "Re: scheduling anomaly on uml (was: -rt doesn't compile for UML)"
In reply to: Eric W. Biederman: "[PATCH 2/4] sysctl: Remember the ctl_table we passed to register_sysctl_paths"
Next in thread: Eric W. Biederman: "[PATCH 4/4] net: Implement the per network namespace sysctl infrastructure"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]