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Subject[v2 073/115] sysctl: group root-specific operations
Date
No functional change, just moved stuff around.

->lookup was not moved to _ops because we'll get rid of it later.

This makes ctl_table_set occupy less space (the pointer to is_seen),
and that will means N*sizeof(void*) saved for N network
namespaces, but I don't that will impress anyone.

Signed-off-by: Lucian Adrian Grijincu <lucian.grijincu@gmail.com>
---
fs/proc/proc_sysctl.c | 4 ++--
include/linux/sysctl.h | 26 +++++++++++++++++++-------
kernel/sysctl.c | 25 ++++++++++++++-----------
net/sysctl_net.c | 20 ++++++++++++++------
4 files changed, 49 insertions(+), 26 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 125b679..55c9bd1 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -131,7 +131,7 @@ 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->root->ctl_ops, table, write ? MAY_WRITE : MAY_READ))
goto out;

/* if that can happen at all, it should be -EINVAL, not -EISDIR */
@@ -305,7 +305,7 @@ static int proc_sys_permission(struct inode *inode, int mask,unsigned int flags)
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);
+ error = sysctl_perm(head->root->ctl_ops, table, mask);

sysctl_unuse_header(head);
return error;
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 1af4ed5..8209d75 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -934,22 +934,21 @@ enum

/* For the /proc/sys support */
struct ctl_table;
+struct ctl_table_header;
+struct ctl_table_group_ops;
struct nsproxy;
struct ctl_table_root;

struct ctl_table_set {
struct list_head list;
struct ctl_table_set *parent;
- int (*is_seen)(struct ctl_table_set *);
};

extern __init int sysctl_init(void);

extern void setup_sysctl_set(struct ctl_table_set *p,
- struct ctl_table_set *parent,
- int (*is_seen)(struct ctl_table_set *));
+ struct ctl_table_set *parent);

-struct ctl_table_header;

/* get/put a reference to this header that
* will be/was embedded in a procfs proc_inode */
@@ -962,8 +961,8 @@ extern struct ctl_table_header *sysctl_use_next_header(struct ctl_table_header *
extern struct ctl_table_header *__sysctl_use_next_header(struct nsproxy *namespaces,
struct ctl_table_header *prev);
extern void sysctl_unuse_header(struct ctl_table_header *prev);
-extern int sysctl_perm(struct ctl_table_root *root,
- struct ctl_table *table, int op);
+extern int sysctl_perm(const struct ctl_table_group_ops *ops,
+ struct ctl_table *table, int op);

typedef struct ctl_table ctl_table;

@@ -1029,12 +1028,25 @@ struct ctl_table
void *extra2;
};

+struct ctl_table_group_ops {
+ /* some sysctl entries are visible only in some situations.
+ * E.g.: /proc/sys/net/ipv4/conf/eth0/ is only visible in the
+ * netns in which that eth0 interface lives.
+ *
+ * If this hook is not set, then all the sysctl entries in
+ * this set are always visible. */
+ int (*is_seen)(struct ctl_table_set *set);
+
+ /* hook to alter permissions for some sysctl nodes at runtime */
+ int (*permissions)(struct ctl_table *table);
+};
+
struct ctl_table_root {
struct list_head root_list;
struct ctl_table_set default_set;
struct ctl_table_set *(*lookup)(struct ctl_table_root *root,
struct nsproxy *namespaces);
- int (*permissions)(struct ctl_table *table);
+ const struct ctl_table_group_ops *ctl_ops;
};

/* struct ctl_table_header is used to maintain dynamic lists of
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6e4e32b..0f00b87 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -197,6 +197,9 @@ static int sysrq_sysctl_handler(ctl_table *table, int write,

#endif

+/* uses default ops */
+static const struct ctl_table_group_ops root_table_group_ops = { };
+
static struct ctl_table root_table[];
static struct ctl_table_root sysctl_table_root;
static struct ctl_table_header root_table_header = {
@@ -206,7 +209,9 @@ static struct ctl_table_header root_table_header = {
.root = &sysctl_table_root,
.set = &sysctl_table_root.default_set,
};
+
static struct ctl_table_root sysctl_table_root = {
+ .ctl_ops = &root_table_group_ops,
.root_list = LIST_HEAD_INIT(sysctl_table_root.root_list),
.default_set.list = LIST_HEAD_INIT(root_table_header.ctl_entry),
};
@@ -1659,12 +1664,13 @@ static int test_perm(int mode, int op)
return -EACCES;
}

-int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
+int sysctl_perm(const struct ctl_table_group_ops *ops,
+ struct ctl_table *table, int op)
{
int mode;

- if (root->permissions)
- mode = root->permissions(table);
+ if (ops->permissions)
+ mode = ops->permissions(table);
else
mode = table->mode;

@@ -1950,26 +1956,24 @@ void unregister_sysctl_table(struct ctl_table_header * header)

int sysctl_is_seen(struct ctl_table_header *p)
{
- struct ctl_table_set *set = p->set;
+ const struct ctl_table_group_ops *ops = p->root->ctl_ops;
int res;
spin_lock(&sysctl_lock);
if (p->unregistering)
res = 0;
- else if (!set->is_seen)
+ else if (!ops->is_seen)
res = 1;
else
- res = set->is_seen(set);
+ res = ops->is_seen(p->set);
spin_unlock(&sysctl_lock);
return res;
}

void setup_sysctl_set(struct ctl_table_set *p,
- struct ctl_table_set *parent,
- int (*is_seen)(struct ctl_table_set *))
+ struct ctl_table_set *parent)
{
INIT_LIST_HEAD(&p->list);
p->parent = parent ? parent : &sysctl_table_root.default_set;
- p->is_seen = is_seen;
}

#else /* !CONFIG_SYSCTL */
@@ -1984,8 +1988,7 @@ void unregister_sysctl_table(struct ctl_table_header * table)
}

void setup_sysctl_set(struct ctl_table_set *p,
- struct ctl_table_set *parent,
- int (*is_seen)(struct ctl_table_set *))
+ struct ctl_table_set *parent)
{
}

diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index 1c0cb57..c0d7140 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -51,12 +51,17 @@ static int net_ctl_permissions(struct ctl_table *table)
return table->mode;
}

+static const struct ctl_table_group_ops net_sysctl_group_ops = {
+ .is_seen = is_seen,
+ .permissions = net_ctl_permissions,
+};
+
static struct ctl_table_root net_sysctl_root = {
.lookup = net_ctl_header_lookup,
- .permissions = net_ctl_permissions,
+ .ctl_ops = &net_sysctl_group_ops,
};

-static int net_ctl_ro_header_perms(ctl_table *table)
+static int net_ctl_ro_header_permissions(ctl_table *table)
{
if (net_eq(current->nsproxy->net_ns, &init_net))
return table->mode;
@@ -64,15 +69,18 @@ static int net_ctl_ro_header_perms(ctl_table *table)
return table->mode & ~0222;
}

+static const struct ctl_table_group_ops net_sysctl_ro_group_ops = {
+ .permissions = net_ctl_ro_header_permissions,
+};
+
static struct ctl_table_root net_sysctl_ro_root = {
- .permissions = net_ctl_ro_header_perms,
+ .ctl_ops = &net_sysctl_ro_group_ops,
};

static int __net_init sysctl_net_init(struct net *net)
{
setup_sysctl_set(&net->sysctls,
- &net_sysctl_ro_root.default_set,
- is_seen);
+ &net_sysctl_ro_root.default_set);
return 0;
}

@@ -93,7 +101,7 @@ static __init int net_sysctl_init(void)
if (ret)
goto out;
register_sysctl_root(&net_sysctl_root);
- setup_sysctl_set(&net_sysctl_ro_root.default_set, NULL, NULL);
+ setup_sysctl_set(&net_sysctl_ro_root.default_set, NULL);
register_sysctl_root(&net_sysctl_ro_root);
out:
return ret;
--
1.7.5.134.g1c08b


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