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path: root/fs/proc/proc_sysctl.c
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-rw-r--r--fs/proc/proc_sysctl.c397
1 files changed, 295 insertions, 102 deletions
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index a78556514a8..ec54a57c469 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -32,26 +32,26 @@ static struct ctl_table root_table[] = {
},
{ }
};
-static struct ctl_table_root sysctl_table_root;
-static struct ctl_dir sysctl_root_dir = {
- .header = {
+static struct ctl_table_root sysctl_table_root = {
+ .default_set.list = LIST_HEAD_INIT(sysctl_table_root.default_set.dir.header.ctl_entry),
+ .default_set.dir.header = {
{{.count = 1,
.nreg = 1,
.ctl_table = root_table,
.ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}},
+ .ctl_table_arg = root_table,
.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(sysctl_root_dir.header.ctl_entry),
- .default_set.root = &sysctl_table_root,
-};
static DEFINE_SPINLOCK(sysctl_lock);
static void drop_sysctl_table(struct ctl_table_header *header);
+static int sysctl_follow_link(struct ctl_table_header **phead,
+ struct ctl_table **pentry, struct nsproxy *namespaces);
+static int insert_links(struct ctl_table_header *head);
+static void put_links(struct ctl_table_header *header);
static void sysctl_print_dir(struct ctl_dir *dir)
{
@@ -76,9 +76,9 @@ static int namecmp(const char *name1, int len1, const char *name2, int len2)
}
static struct ctl_table *find_entry(struct ctl_table_header **phead,
- struct ctl_table_set *set, struct ctl_dir *dir,
- const char *name, int namelen)
+ struct ctl_dir *dir, const char *name, int namelen)
{
+ struct ctl_table_set *set = dir->header.set;
struct ctl_table_header *head;
struct ctl_table *entry;
@@ -119,11 +119,21 @@ static void erase_header(struct ctl_table_header *head)
list_del_init(&head->ctl_entry);
}
-static void insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
+static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
{
+ int err;
+
+ dir->header.nreg++;
header->parent = dir;
- header->parent->header.nreg++;
+ err = insert_links(header);
+ if (err)
+ goto fail_links;
list_add_tail(&header->ctl_entry, &header->set->list);
+ return 0;
+fail_links:
+ header->parent = NULL;
+ drop_sysctl_table(&dir->header);
+ return err;
}
/* called under sysctl_lock */
@@ -212,72 +222,39 @@ lookup_header_set(struct ctl_table_root *root, struct nsproxy *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 *lookup_entry(struct ctl_table_header **phead,
struct ctl_dir *dir,
const char *name, int namelen)
{
struct ctl_table_header *head;
struct ctl_table *entry;
- struct ctl_table_root *root;
- struct ctl_table_set *set;
spin_lock(&sysctl_lock);
- root = &sysctl_table_root;
- do {
- set = lookup_header_set(root, current->nsproxy);
- entry = find_entry(&head, set, dir, name, namelen);
- if (entry && use_table(head))
- *phead = head;
- else
- entry = NULL;
- root = list_entry(root->root_list.next,
- struct ctl_table_root, root_list);
- } while (!entry && root != &sysctl_table_root);
+ entry = find_entry(&head, dir, name, namelen);
+ if (entry && use_table(head))
+ *phead = head;
+ else
+ entry = NULL;
spin_unlock(&sysctl_lock);
return entry;
}
static struct ctl_table_header *next_usable_entry(struct ctl_dir *dir,
- struct ctl_table_root *root, struct list_head *tmp)
+ struct list_head *tmp)
{
- struct nsproxy *namespaces = current->nsproxy;
- struct list_head *header_list;
+ struct ctl_table_set *set = dir->header.set;
struct ctl_table_header *head;
- goto next;
- for (;;) {
+ for (tmp = tmp->next; tmp != &set->list; tmp = tmp->next) {
head = list_entry(tmp, struct ctl_table_header, ctl_entry);
- root = head->root;
if (head->parent != dir ||
!head->ctl_table->procname ||
!use_table(head))
- goto next;
-
- return head;
- next:
- 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;
+ return head;
}
-out:
return NULL;
}
@@ -288,8 +265,7 @@ static void first_entry(struct ctl_dir *dir,
struct ctl_table *entry = NULL;
spin_lock(&sysctl_lock);
- head = next_usable_entry(dir, &sysctl_table_root,
- &sysctl_table_root.default_set.list);
+ head = next_usable_entry(dir, &dir->header.set->list);
spin_unlock(&sysctl_lock);
if (head)
entry = head->ctl_table;
@@ -306,7 +282,7 @@ static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentr
if (!entry->procname) {
spin_lock(&sysctl_lock);
unuse_table(head);
- head = next_usable_entry(head->parent, head->root, &head->ctl_entry);
+ head = next_usable_entry(head->parent, &head->ctl_entry);
spin_unlock(&sysctl_lock);
if (head)
entry = head->ctl_table;
@@ -317,9 +293,6 @@ static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentr
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);
}
/*
@@ -386,7 +359,7 @@ static struct ctl_table_header *grab_header(struct inode *inode)
{
struct ctl_table_header *head = PROC_I(inode)->sysctl;
if (!head)
- head = &sysctl_root_dir.header;
+ head = &sysctl_table_root.default_set.dir.header;
return sysctl_head_grab(head);
}
@@ -400,6 +373,7 @@ static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
struct inode *inode;
struct dentry *err = ERR_PTR(-ENOENT);
struct ctl_dir *ctl_dir;
+ int ret;
if (IS_ERR(head))
return ERR_CAST(head);
@@ -410,6 +384,11 @@ static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
if (!p)
goto out;
+ ret = sysctl_follow_link(&h, &p, current->nsproxy);
+ err = ERR_PTR(ret);
+ if (ret)
+ goto out;
+
err = ERR_PTR(-ENOMEM);
inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
if (h)
@@ -547,6 +526,25 @@ static int proc_sys_fill_cache(struct file *filp, void *dirent,
return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
}
+static int proc_sys_link_fill_cache(struct file *filp, void *dirent,
+ filldir_t filldir,
+ struct ctl_table_header *head,
+ struct ctl_table *table)
+{
+ int err, ret = 0;
+ head = sysctl_head_grab(head);
+
+ /* It is not an error if we can not follow the link ignore it */
+ err = sysctl_follow_link(&head, &table, current->nsproxy);
+ if (err)
+ goto out;
+
+ ret = proc_sys_fill_cache(filp, dirent, filldir, head, table);
+out:
+ sysctl_head_finish(head);
+ return ret;
+}
+
static int scan(struct ctl_table_header *head, ctl_table *table,
unsigned long *pos, struct file *file,
void *dirent, filldir_t filldir)
@@ -556,7 +554,10 @@ static int scan(struct ctl_table_header *head, ctl_table *table,
if ((*pos)++ < file->f_pos)
return 0;
- res = proc_sys_fill_cache(file, dirent, filldir, head, table);
+ if (unlikely(S_ISLNK(table->mode)))
+ res = proc_sys_link_fill_cache(file, dirent, filldir, head, table);
+ else
+ res = proc_sys_fill_cache(file, dirent, filldir, head, table);
if (res == 0)
file->f_pos = *pos;
@@ -757,13 +758,13 @@ static const struct dentry_operations proc_sys_dentry_operations = {
.d_compare = proc_sys_compare,
};
-static struct ctl_dir *find_subdir(struct ctl_table_set *set, struct ctl_dir *dir,
- const char *name, int namelen)
+static struct ctl_dir *find_subdir(struct ctl_dir *dir,
+ const char *name, int namelen)
{
struct ctl_table_header *head;
struct ctl_table *entry;
- entry = find_entry(&head, set, dir, name, namelen);
+ entry = find_entry(&head, dir, name, namelen);
if (!entry)
return ERR_PTR(-ENOENT);
if (S_ISDIR(entry->mode))
@@ -772,7 +773,7 @@ static struct ctl_dir *find_subdir(struct ctl_table_set *set, struct ctl_dir *di
}
static struct ctl_dir *new_dir(struct ctl_table_set *set,
- const char *name, int namelen)
+ const char *name, int namelen)
{
struct ctl_table *table;
struct ctl_dir *new;
@@ -789,22 +790,19 @@ static struct ctl_dir *new_dir(struct ctl_table_set *set,
new_name[namelen] = '\0';
table[0].procname = new_name;
table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
- init_header(&new->header, set->root, set, table);
+ init_header(&new->header, set->dir.header.root, set, table);
return new;
}
-static struct ctl_dir *get_subdir(struct ctl_table_set *set,
- struct ctl_dir *dir, const char *name, int namelen)
+static struct ctl_dir *get_subdir(struct ctl_dir *dir,
+ const char *name, int namelen)
{
+ struct ctl_table_set *set = dir->header.set;
struct ctl_dir *subdir, *new = NULL;
spin_lock(&sysctl_lock);
- subdir = find_subdir(dir->header.set, dir, name, namelen);
- if (!IS_ERR(subdir))
- goto found;
- if ((PTR_ERR(subdir) == -ENOENT) && set != dir->header.set)
- subdir = find_subdir(set, dir, name, namelen);
+ subdir = find_subdir(dir, name, namelen);
if (!IS_ERR(subdir))
goto found;
if (PTR_ERR(subdir) != -ENOENT)
@@ -817,13 +815,14 @@ static struct ctl_dir *get_subdir(struct ctl_table_set *set,
if (!new)
goto failed;
- subdir = find_subdir(set, dir, name, namelen);
+ subdir = find_subdir(dir, name, namelen);
if (!IS_ERR(subdir))
goto found;
if (PTR_ERR(subdir) != -ENOENT)
goto failed;
- insert_header(dir, &new->header);
+ if (insert_header(dir, &new->header))
+ goto failed;
subdir = new;
found:
subdir->header.nreg++;
@@ -841,6 +840,57 @@ failed:
return subdir;
}
+static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
+{
+ struct ctl_dir *parent;
+ const char *procname;
+ if (!dir->header.parent)
+ return &set->dir;
+ parent = xlate_dir(set, dir->header.parent);
+ if (IS_ERR(parent))
+ return parent;
+ procname = dir->header.ctl_table[0].procname;
+ return find_subdir(parent, procname, strlen(procname));
+}
+
+static int sysctl_follow_link(struct ctl_table_header **phead,
+ struct ctl_table **pentry, struct nsproxy *namespaces)
+{
+ struct ctl_table_header *head;
+ struct ctl_table_root *root;
+ struct ctl_table_set *set;
+ struct ctl_table *entry;
+ struct ctl_dir *dir;
+ int ret;
+
+ /* Get out quickly if not a link */
+ if (!S_ISLNK((*pentry)->mode))
+ return 0;
+
+ ret = 0;
+ spin_lock(&sysctl_lock);
+ root = (*pentry)->data;
+ set = lookup_header_set(root, namespaces);
+ dir = xlate_dir(set, (*phead)->parent);
+ if (IS_ERR(dir))
+ ret = PTR_ERR(dir);
+ else {
+ const char *procname = (*pentry)->procname;
+ head = NULL;
+ entry = find_entry(&head, dir, procname, strlen(procname));
+ ret = -ENOENT;
+ if (entry && use_table(head)) {
+ unuse_table(*phead);
+ *phead = head;
+ *pentry = entry;
+ ret = 0;
+ }
+ }
+
+ spin_unlock(&sysctl_lock);
+ return ret;
+}
+
static int sysctl_check_table_dups(const char *path, struct ctl_table *old,
struct ctl_table *table)
{
@@ -859,30 +909,21 @@ static int sysctl_check_table_dups(const char *path, struct ctl_table *old,
return error;
}
-static int sysctl_check_dups(struct nsproxy *namespaces,
- struct ctl_dir *dir,
+static int sysctl_check_dups(struct ctl_dir *dir,
const char *path, struct ctl_table *table)
{
- struct ctl_table_root *root;
struct ctl_table_set *set;
struct ctl_table_header *head;
int error = 0;
- root = &sysctl_table_root;
- do {
- set = lookup_header_set(root, namespaces);
-
- list_for_each_entry(head, &set->list, ctl_entry) {
- if (head->unregistering)
- continue;
- if (head->parent != dir)
- continue;
- error = sysctl_check_table_dups(path, head->ctl_table,
- table);
- }
- root = list_entry(root->root_list.next,
- struct ctl_table_root, root_list);
- } while (root != &sysctl_table_root);
+ set = dir->header.set;
+ list_for_each_entry(head, &set->list, ctl_entry) {
+ if (head->unregistering)
+ continue;
+ if (head->parent != dir)
+ continue;
+ error = sysctl_check_table_dups(path, head->ctl_table, table);
+ }
return error;
}
@@ -932,6 +973,115 @@ static int sysctl_check_table(const char *path, struct ctl_table *table)
return err;
}
+static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
+ struct ctl_table_root *link_root)
+{
+ struct ctl_table *link_table, *entry, *link;
+ struct ctl_table_header *links;
+ char *link_name;
+ int nr_entries, name_bytes;
+
+ name_bytes = 0;
+ nr_entries = 0;
+ for (entry = table; entry->procname; entry++) {
+ nr_entries++;
+ name_bytes += strlen(entry->procname) + 1;
+ }
+
+ links = kzalloc(sizeof(struct ctl_table_header) +
+ sizeof(struct ctl_table)*(nr_entries + 1) +
+ name_bytes,
+ GFP_KERNEL);
+
+ if (!links)
+ return NULL;
+
+ link_table = (struct ctl_table *)(links + 1);
+ link_name = (char *)&link_table[nr_entries + 1];
+
+ for (link = link_table, entry = table; entry->procname; link++, entry++) {
+ int len = strlen(entry->procname) + 1;
+ memcpy(link_name, entry->procname, len);
+ link->procname = link_name;
+ link->mode = S_IFLNK|S_IRWXUGO;
+ link->data = link_root;
+ link_name += len;
+ }
+ init_header(links, dir->header.root, dir->header.set, link_table);
+ links->nreg = nr_entries;
+
+ return links;
+}
+
+static bool get_links(struct ctl_dir *dir,
+ struct ctl_table *table, struct ctl_table_root *link_root)
+{
+ struct ctl_table_header *head;
+ struct ctl_table *entry, *link;
+
+ /* Are there links available for every entry in table? */
+ for (entry = table; entry->procname; entry++) {
+ const char *procname = entry->procname;
+ link = find_entry(&head, dir, procname, strlen(procname));
+ if (!link)
+ return false;
+ if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
+ continue;
+ if (S_ISLNK(link->mode) && (link->data == link_root))
+ continue;
+ return false;
+ }
+
+ /* The checks passed. Increase the registration count on the links */
+ for (entry = table; entry->procname; entry++) {
+ const char *procname = entry->procname;
+ link = find_entry(&head, dir, procname, strlen(procname));
+ head->nreg++;
+ }
+ return true;
+}
+
+static int insert_links(struct ctl_table_header *head)
+{
+ struct ctl_table_set *root_set = &sysctl_table_root.default_set;
+ struct ctl_dir *core_parent = NULL;
+ struct ctl_table_header *links;
+ int err;
+
+ if (head->set == root_set)
+ return 0;
+
+ core_parent = xlate_dir(root_set, head->parent);
+ if (IS_ERR(core_parent))
+ return 0;
+
+ if (get_links(core_parent, head->ctl_table, head->root))
+ return 0;
+
+ core_parent->header.nreg++;
+ spin_unlock(&sysctl_lock);
+
+ links = new_links(core_parent, head->ctl_table, head->root);
+
+ spin_lock(&sysctl_lock);
+ err = -ENOMEM;
+ if (!links)
+ goto out;
+
+ err = 0;
+ if (get_links(core_parent, head->ctl_table, head->root)) {
+ kfree(links);
+ goto out;
+ }
+
+ err = insert_header(core_parent, links);
+ if (err)
+ kfree(links);
+out:
+ drop_sysctl_table(&core_parent->header);
+ return err;
+}
+
/**
* __register_sysctl_table - register a leaf sysctl table
* @root: List of sysctl headers to register on
@@ -980,6 +1130,7 @@ struct ctl_table_header *__register_sysctl_table(
struct nsproxy *namespaces,
const char *path, struct ctl_table *table)
{
+ struct ctl_table_header *links = NULL;
struct ctl_table_header *header;
const char *name, *nextname;
struct ctl_table_set *set;
@@ -995,7 +1146,7 @@ struct ctl_table_header *__register_sysctl_table(
spin_lock(&sysctl_lock);
header->set = set = lookup_header_set(root, namespaces);
- dir = &sysctl_root_dir;
+ dir = &set->dir;
dir->header.nreg++;
spin_unlock(&sysctl_lock);
@@ -1012,22 +1163,28 @@ struct ctl_table_header *__register_sysctl_table(
if (namelen == 0)
continue;
- dir = get_subdir(set, dir, name, namelen);
+ dir = get_subdir(dir, name, namelen);
if (IS_ERR(dir))
goto fail;
}
+
spin_lock(&sysctl_lock);
- if (sysctl_check_dups(namespaces, dir, path, table))
+ if (sysctl_check_dups(dir, path, table))
+ goto fail_put_dir_locked;
+
+ if (insert_header(dir, header))
goto fail_put_dir_locked;
- insert_header(dir, header);
+
drop_sysctl_table(&dir->header);
spin_unlock(&sysctl_lock);
return header;
+
fail_put_dir_locked:
drop_sysctl_table(&dir->header);
spin_unlock(&sysctl_lock);
fail:
+ kfree(links);
kfree(header);
dump_stack();
return NULL;
@@ -1249,6 +1406,40 @@ struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
}
EXPORT_SYMBOL(register_sysctl_table);
+static void put_links(struct ctl_table_header *header)
+{
+ struct ctl_table_set *root_set = &sysctl_table_root.default_set;
+ struct ctl_table_root *root = header->root;
+ struct ctl_dir *parent = header->parent;
+ struct ctl_dir *core_parent;
+ struct ctl_table *entry;
+
+ if (header->set == root_set)
+ return;
+
+ core_parent = xlate_dir(root_set, parent);
+ if (IS_ERR(core_parent))
+ return;
+
+ for (entry = header->ctl_table; entry->procname; entry++) {
+ struct ctl_table_header *link_head;
+ struct ctl_table *link;
+ const char *name = entry->procname;
+
+ link = find_entry(&link_head, core_parent, name, strlen(name));
+ if (link &&
+ ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
+ (S_ISLNK(link->mode) && (link->data == root)))) {
+ drop_sysctl_table(link_head);
+ }
+ else {
+ printk(KERN_ERR "sysctl link missing during unregister: ");
+ sysctl_print_dir(parent);
+ printk(KERN_CONT "/%s\n", name);
+ }
+ }
+}
+
static void drop_sysctl_table(struct ctl_table_header *header)
{
struct ctl_dir *parent = header->parent;
@@ -1256,6 +1447,7 @@ static void drop_sysctl_table(struct ctl_table_header *header)
if (--header->nreg)
return;
+ put_links(header);
start_unregistering(header);
if (!--header->count)
kfree_rcu(header, rcu);
@@ -1301,13 +1493,14 @@ void unregister_sysctl_table(struct ctl_table_header * header)
}
EXPORT_SYMBOL(unregister_sysctl_table);
-void setup_sysctl_set(struct ctl_table_set *p,
+void setup_sysctl_set(struct ctl_table_set *set,
struct ctl_table_root *root,
int (*is_seen)(struct ctl_table_set *))
{
- INIT_LIST_HEAD(&p->list);
- p->root = root;
- p->is_seen = is_seen;
+ memset(set, sizeof(*set), 0);
+ INIT_LIST_HEAD(&set->list);
+ set->is_seen = is_seen;
+ init_header(&set->dir.header, root, set, root_table);
}
void retire_sysctl_set(struct ctl_table_set *set)