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authorEric W. Biederman <ebiederm@xmission.com>2012-01-06 04:07:15 -0800
committerEric W. Biederman <ebiederm@xmission.com>2012-01-24 16:37:54 -0800
commit1f87f0b52b1d6581168cb80f86746bc4df918d01 (patch)
tree73576c0872c61c526ade225d6441a6610beb666b /fs/proc
parentde4e83bd6b5e16d491ec068cd22801d5d063b07a (diff)
sysctl: Move the implementation into fs/proc/proc_sysctl.c
Move the core sysctl code from kernel/sysctl.c and kernel/sysctl_check.c into fs/proc/proc_sysctl.c. Currently sysctl maintenance is hampered by the sysctl implementation being split across 3 files with artificial layering between them. Consolidate the entire sysctl implementation into 1 file so that it is easier to see what is going on and hopefully allowing for simpler maintenance. For functions that are now only used in fs/proc/proc_sysctl.c remove their declarations from sysctl.h and make them static in fs/proc/proc_sysctl.c Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/internal.h3
-rw-r--r--fs/proc/proc_sysctl.c622
2 files changed, 625 insertions, 0 deletions
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 292577531ad..3b5ecd960d6 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -10,12 +10,15 @@
*/
#include <linux/proc_fs.h>
+struct ctl_table_header;
extern struct proc_dir_entry proc_root;
#ifdef CONFIG_PROC_SYSCTL
extern int proc_sys_init(void);
+extern void sysctl_head_put(struct ctl_table_header *head);
#else
static inline void proc_sys_init(void) { }
+static inline void sysctl_head_put(struct ctl_table_header *head) { }
#endif
#ifdef CONFIG_NET
extern int proc_net_init(void);
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 9d29d28af57..06e6f10ee8e 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -7,6 +7,7 @@
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/namei.h>
+#include <linux/module.h>
#include "internal.h"
static const struct dentry_operations proc_sys_dentry_operations;
@@ -24,6 +25,209 @@ void proc_sys_poll_notify(struct ctl_table_poll *poll)
wake_up_interruptible(&poll->wait);
}
+static struct ctl_table root_table[1];
+static struct ctl_table_root sysctl_table_root;
+static struct ctl_table_header root_table_header = {
+ {{.count = 1,
+ .ctl_table = root_table,
+ .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}},
+ .root = &sysctl_table_root,
+ .set = &sysctl_table_root.default_set,
+};
+static struct ctl_table_root sysctl_table_root = {
+ .root_list = LIST_HEAD_INIT(sysctl_table_root.root_list),
+ .default_set.list = LIST_HEAD_INIT(root_table_header.ctl_entry),
+};
+
+static DEFINE_SPINLOCK(sysctl_lock);
+
+/* called under sysctl_lock */
+static int use_table(struct ctl_table_header *p)
+{
+ if (unlikely(p->unregistering))
+ return 0;
+ p->used++;
+ return 1;
+}
+
+/* called under sysctl_lock */
+static void unuse_table(struct ctl_table_header *p)
+{
+ if (!--p->used)
+ if (unlikely(p->unregistering))
+ complete(p->unregistering);
+}
+
+/* called under sysctl_lock, will reacquire if has to wait */
+static void start_unregistering(struct ctl_table_header *p)
+{
+ /*
+ * if p->used is 0, nobody will ever touch that entry again;
+ * we'll eliminate all paths to it before dropping sysctl_lock
+ */
+ if (unlikely(p->used)) {
+ struct completion wait;
+ init_completion(&wait);
+ p->unregistering = &wait;
+ spin_unlock(&sysctl_lock);
+ wait_for_completion(&wait);
+ spin_lock(&sysctl_lock);
+ } else {
+ /* anything non-NULL; we'll never dereference it */
+ p->unregistering = ERR_PTR(-EINVAL);
+ }
+ /*
+ * do not remove from the list until nobody holds it; walking the
+ * list in do_sysctl() relies on that.
+ */
+ list_del_init(&p->ctl_entry);
+}
+
+static void sysctl_head_get(struct ctl_table_header *head)
+{
+ spin_lock(&sysctl_lock);
+ head->count++;
+ spin_unlock(&sysctl_lock);
+}
+
+void sysctl_head_put(struct ctl_table_header *head)
+{
+ spin_lock(&sysctl_lock);
+ if (!--head->count)
+ kfree_rcu(head, rcu);
+ spin_unlock(&sysctl_lock);
+}
+
+static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
+{
+ if (!head)
+ BUG();
+ spin_lock(&sysctl_lock);
+ if (!use_table(head))
+ head = ERR_PTR(-ENOENT);
+ spin_unlock(&sysctl_lock);
+ return head;
+}
+
+static void sysctl_head_finish(struct ctl_table_header *head)
+{
+ if (!head)
+ return;
+ spin_lock(&sysctl_lock);
+ unuse_table(head);
+ spin_unlock(&sysctl_lock);
+}
+
+static struct ctl_table_set *
+lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
+{
+ struct ctl_table_set *set = &root->default_set;
+ if (root->lookup)
+ set = root->lookup(root, namespaces);
+ return set;
+}
+
+static struct list_head *
+lookup_header_list(struct ctl_table_root *root, struct nsproxy *namespaces)
+{
+ struct ctl_table_set *set = lookup_header_set(root, namespaces);
+ return &set->list;
+}
+
+static 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;
+ }
+ tmp = &root_table_header.ctl_entry;
+ for (;;) {
+ head = list_entry(tmp, struct ctl_table_header, ctl_entry);
+
+ if (!use_table(head))
+ goto next;
+ spin_unlock(&sysctl_lock);
+ return head;
+ next:
+ root = head->root;
+ tmp = tmp->next;
+ 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;
+}
+
+static 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);
+}
+
+/*
+ * sysctl_perm does NOT grant the superuser all rights automatically, because
+ * some sysctl variables are readonly even to root.
+ */
+
+static int test_perm(int mode, int op)
+{
+ if (!current_euid())
+ mode >>= 6;
+ else if (in_egroup_p(0))
+ mode >>= 3;
+ if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
+ return 0;
+ return -EACCES;
+}
+
+static int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
+{
+ int mode;
+
+ if (root->permissions)
+ mode = root->permissions(root, current->nsproxy, table);
+ else
+ mode = table->mode;
+
+ return test_perm(mode, op);
+}
+
+static void sysctl_set_parent(struct ctl_table *parent, struct ctl_table *table)
+{
+ for (; table->procname; table++) {
+ table->parent = parent;
+ if (table->child)
+ sysctl_set_parent(table, table->child);
+ }
+}
+
+
static struct inode *proc_sys_make_inode(struct super_block *sb,
struct ctl_table_header *head, struct ctl_table *table)
{
@@ -435,6 +639,21 @@ static int proc_sys_delete(const struct dentry *dentry)
return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
}
+static int sysctl_is_seen(struct ctl_table_header *p)
+{
+ struct ctl_table_set *set = p->set;
+ int res;
+ spin_lock(&sysctl_lock);
+ if (p->unregistering)
+ res = 0;
+ else if (!set->is_seen)
+ res = 1;
+ else
+ res = set->is_seen(set);
+ spin_unlock(&sysctl_lock);
+ return res;
+}
+
static int proc_sys_compare(const struct dentry *parent,
const struct inode *pinode,
const struct dentry *dentry, const struct inode *inode,
@@ -460,6 +679,409 @@ static const struct dentry_operations proc_sys_dentry_operations = {
.d_compare = proc_sys_compare,
};
+static struct ctl_table *is_branch_in(struct ctl_table *branch,
+ struct ctl_table *table)
+{
+ struct ctl_table *p;
+ const char *s = branch->procname;
+
+ /* branch should have named subdirectory as its first element */
+ if (!s || !branch->child)
+ return NULL;
+
+ /* ... and nothing else */
+ if (branch[1].procname)
+ return NULL;
+
+ /* table should contain subdirectory with the same name */
+ for (p = table; p->procname; p++) {
+ if (!p->child)
+ continue;
+ if (p->procname && strcmp(p->procname, s) == 0)
+ return p;
+ }
+ return NULL;
+}
+
+/* see if attaching q to p would be an improvement */
+static void try_attach(struct ctl_table_header *p, struct ctl_table_header *q)
+{
+ struct ctl_table *to = p->ctl_table, *by = q->ctl_table;
+ struct ctl_table *next;
+ int is_better = 0;
+ int not_in_parent = !p->attached_by;
+
+ while ((next = is_branch_in(by, to)) != NULL) {
+ if (by == q->attached_by)
+ is_better = 1;
+ if (to == p->attached_by)
+ not_in_parent = 1;
+ by = by->child;
+ to = next->child;
+ }
+
+ if (is_better && not_in_parent) {
+ q->attached_by = by;
+ q->attached_to = to;
+ q->parent = p;
+ }
+}
+
+#ifdef CONFIG_SYSCTL_SYSCALL_CHECK
+static int sysctl_depth(struct ctl_table *table)
+{
+ struct ctl_table *tmp;
+ int depth;
+
+ depth = 0;
+ for (tmp = table; tmp->parent; tmp = tmp->parent)
+ depth++;
+
+ return depth;
+}
+
+static struct ctl_table *sysctl_parent(struct ctl_table *table, int n)
+{
+ int i;
+
+ for (i = 0; table && i < n; i++)
+ table = table->parent;
+
+ return table;
+}
+
+
+static void sysctl_print_path(struct ctl_table *table)
+{
+ struct ctl_table *tmp;
+ int depth, i;
+ depth = sysctl_depth(table);
+ if (table->procname) {
+ for (i = depth; i >= 0; i--) {
+ tmp = sysctl_parent(table, i);
+ printk("/%s", tmp->procname?tmp->procname:"");
+ }
+ }
+ printk(" ");
+}
+
+static struct ctl_table *sysctl_check_lookup(struct nsproxy *namespaces,
+ struct ctl_table *table)
+{
+ struct ctl_table_header *head;
+ struct ctl_table *ref, *test;
+ int depth, cur_depth;
+
+ depth = sysctl_depth(table);
+
+ for (head = __sysctl_head_next(namespaces, NULL); head;
+ head = __sysctl_head_next(namespaces, head)) {
+ cur_depth = depth;
+ ref = head->ctl_table;
+repeat:
+ test = sysctl_parent(table, cur_depth);
+ for (; ref->procname; ref++) {
+ int match = 0;
+ if (cur_depth && !ref->child)
+ continue;
+
+ if (test->procname && ref->procname &&
+ (strcmp(test->procname, ref->procname) == 0))
+ match++;
+
+ if (match) {
+ if (cur_depth != 0) {
+ cur_depth--;
+ ref = ref->child;
+ goto repeat;
+ }
+ goto out;
+ }
+ }
+ }
+ ref = NULL;
+out:
+ sysctl_head_finish(head);
+ return ref;
+}
+
+static void set_fail(const char **fail, struct ctl_table *table, const char *str)
+{
+ if (*fail) {
+ printk(KERN_ERR "sysctl table check failed: ");
+ sysctl_print_path(table);
+ printk(" %s\n", *fail);
+ dump_stack();
+ }
+ *fail = str;
+}
+
+static void sysctl_check_leaf(struct nsproxy *namespaces,
+ struct ctl_table *table, const char **fail)
+{
+ struct ctl_table *ref;
+
+ ref = sysctl_check_lookup(namespaces, table);
+ if (ref && (ref != table))
+ set_fail(fail, table, "Sysctl already exists");
+}
+
+static int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *table)
+{
+ int error = 0;
+ for (; table->procname; table++) {
+ const char *fail = NULL;
+
+ if (table->parent) {
+ if (!table->parent->procname)
+ set_fail(&fail, table, "Parent without procname");
+ }
+ if (table->child) {
+ if (table->data)
+ set_fail(&fail, table, "Directory with data?");
+ if (table->maxlen)
+ set_fail(&fail, table, "Directory with maxlen?");
+ if ((table->mode & (S_IRUGO|S_IXUGO)) != table->mode)
+ set_fail(&fail, table, "Writable sysctl directory");
+ if (table->proc_handler)
+ set_fail(&fail, table, "Directory with proc_handler");
+ if (table->extra1)
+ set_fail(&fail, table, "Directory with extra1");
+ if (table->extra2)
+ set_fail(&fail, table, "Directory with extra2");
+ } else {
+ if ((table->proc_handler == proc_dostring) ||
+ (table->proc_handler == proc_dointvec) ||
+ (table->proc_handler == proc_dointvec_minmax) ||
+ (table->proc_handler == proc_dointvec_jiffies) ||
+ (table->proc_handler == proc_dointvec_userhz_jiffies) ||
+ (table->proc_handler == proc_dointvec_ms_jiffies) ||
+ (table->proc_handler == proc_doulongvec_minmax) ||
+ (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
+ if (!table->data)
+ set_fail(&fail, table, "No data");
+ if (!table->maxlen)
+ set_fail(&fail, table, "No maxlen");
+ }
+#ifdef CONFIG_PROC_SYSCTL
+ if (!table->proc_handler)
+ set_fail(&fail, table, "No proc_handler");
+#endif
+ sysctl_check_leaf(namespaces, table, &fail);
+ }
+ if (table->mode > 0777)
+ set_fail(&fail, table, "bogus .mode");
+ if (fail) {
+ set_fail(&fail, table, NULL);
+ error = -EINVAL;
+ }
+ if (table->child)
+ error |= sysctl_check_table(namespaces, table->child);
+ }
+ return error;
+}
+#endif /* CONFIG_SYSCTL_SYSCALL_CHECK */
+
+/**
+ * __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
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * The members of the &struct ctl_table structure are used as follows:
+ *
+ * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
+ * enter a sysctl file
+ *
+ * data - a pointer to data for use by proc_handler
+ *
+ * maxlen - the maximum size in bytes of the data
+ *
+ * mode - the file permissions for the /proc/sys file, and for sysctl(2)
+ *
+ * child - a pointer to the child sysctl table if this entry is a directory, or
+ * %NULL.
+ *
+ * proc_handler - the text handler routine (described below)
+ *
+ * de - for internal use by the sysctl routines
+ *
+ * extra1, extra2 - extra pointers usable by the proc handler routines
+ *
+ * Leaf nodes in the sysctl tree will be represented by a single file
+ * under /proc; non-leaf nodes will be represented by directories.
+ *
+ * sysctl(2) can automatically manage read and write requests through
+ * the sysctl table. The data and maxlen fields of the ctl_table
+ * struct enable minimal validation of the values being written to be
+ * performed, and the mode field allows minimal authentication.
+ *
+ * There must be a proc_handler routine for any terminal nodes
+ * mirrored under /proc/sys (non-terminals are handled by a built-in
+ * directory handler). Several default handlers are available to
+ * cover common cases -
+ *
+ * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
+ * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
+ * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
+ *
+ * It is the handler's job to read the input buffer from user memory
+ * and process it. The handler should return 0 on success.
+ *
+ * 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(
+ struct ctl_table_root *root,
+ struct nsproxy *namespaces,
+ const struct ctl_path *path, struct ctl_table *table)
+{
+ struct ctl_table_header *header;
+ struct ctl_table *new, **prevp;
+ unsigned int n, npath;
+ struct ctl_table_set *set;
+
+ /* Count the path components */
+ for (npath = 0; path[npath].procname; ++npath)
+ ;
+
+ /*
+ * For each path component, allocate a 2-element ctl_table array.
+ * The first array element will be filled with the sysctl entry
+ * for this, the second will be the sentinel (procname == 0).
+ *
+ * We allocate everything in one go so that we don't have to
+ * worry about freeing additional memory in unregister_sysctl_table.
+ */
+ header = kzalloc(sizeof(struct ctl_table_header) +
+ (2 * npath * sizeof(struct ctl_table)), GFP_KERNEL);
+ if (!header)
+ return NULL;
+
+ new = (struct ctl_table *) (header + 1);
+
+ /* Now connect the dots */
+ prevp = &header->ctl_table;
+ for (n = 0; n < npath; ++n, ++path) {
+ /* Copy the procname */
+ new->procname = path->procname;
+ new->mode = 0555;
+
+ *prevp = new;
+ prevp = &new->child;
+
+ new += 2;
+ }
+ *prevp = table;
+ header->ctl_table_arg = table;
+
+ INIT_LIST_HEAD(&header->ctl_entry);
+ header->used = 0;
+ header->unregistering = NULL;
+ header->root = root;
+ sysctl_set_parent(NULL, header->ctl_table);
+ header->count = 1;
+#ifdef CONFIG_SYSCTL_SYSCALL_CHECK
+ if (sysctl_check_table(namespaces, header->ctl_table)) {
+ kfree(header);
+ return NULL;
+ }
+#endif
+ spin_lock(&sysctl_lock);
+ header->set = lookup_header_set(root, namespaces);
+ header->attached_by = header->ctl_table;
+ header->attached_to = root_table;
+ header->parent = &root_table_header;
+ for (set = header->set; set; set = set->parent) {
+ struct ctl_table_header *p;
+ list_for_each_entry(p, &set->list, ctl_entry) {
+ if (p->unregistering)
+ continue;
+ try_attach(p, header);
+ }
+ }
+ header->parent->count++;
+ list_add_tail(&header->ctl_entry, &header->set->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);
+}
+EXPORT_SYMBOL(register_sysctl_paths);
+
+/**
+ * register_sysctl_table - register a sysctl table hierarchy
+ * @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_table(struct ctl_table *table)
+{
+ static const struct ctl_path null_path[] = { {} };
+
+ return register_sysctl_paths(null_path, table);
+}
+EXPORT_SYMBOL(register_sysctl_table);
+
+/**
+ * unregister_sysctl_table - unregister a sysctl table hierarchy
+ * @header: the header returned from register_sysctl_table
+ *
+ * Unregisters the sysctl table and all children. proc entries may not
+ * actually be removed until they are no longer used by anyone.
+ */
+void unregister_sysctl_table(struct ctl_table_header * header)
+{
+ might_sleep();
+
+ if (header == NULL)
+ return;
+
+ spin_lock(&sysctl_lock);
+ start_unregistering(header);
+ if (!--header->parent->count) {
+ WARN_ON(1);
+ kfree_rcu(header->parent, rcu);
+ }
+ if (!--header->count)
+ kfree_rcu(header, rcu);
+ spin_unlock(&sysctl_lock);
+}
+EXPORT_SYMBOL(unregister_sysctl_table);
+
+void setup_sysctl_set(struct ctl_table_set *p,
+ struct ctl_table_set *parent,
+ int (*is_seen)(struct ctl_table_set *))
+{
+ INIT_LIST_HEAD(&p->list);
+ p->parent = parent ? parent : &sysctl_table_root.default_set;
+ p->is_seen = is_seen;
+}
+
+
int __init proc_sys_init(void)
{
struct proc_dir_entry *proc_sys_root;