[PATCH] sanitize proc_sysctl
* keep references to ctl_table_head and ctl_table in /proc/sys inodes
* grab the former during operations, use the latter for access to
entry if that succeeds
* have ->d_compare() check if table should be seen for one who does lookup;
that allows us to avoid flipping inodes - if we have the same name resolve
to different things, we'll just keep several dentries and ->d_compare()
will reject the wrong ones.
* have ->lookup() and ->readdir() scan the table of our inode first, then
walk all ctl_table_header and scan ->attached_by for those that are
attached to our directory.
* implement ->getattr().
* get rid of insane amounts of tree-walking
* get rid of the need to know dentry in ->permission() and of the contortions
induced by that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index b37f25d..8bb03f0 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -17,6 +17,7 @@
#include <linux/init.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
+#include <linux/sysctl.h>
#include <asm/system.h>
#include <asm/uaccess.h>
@@ -65,6 +66,8 @@
module_put(de->owner);
de_put(de);
}
+ if (PROC_I(inode)->sysctl)
+ sysctl_head_put(PROC_I(inode)->sysctl);
clear_inode(inode);
}
@@ -84,6 +87,8 @@
ei->fd = 0;
ei->op.proc_get_link = NULL;
ei->pde = NULL;
+ ei->sysctl = NULL;
+ ei->sysctl_entry = NULL;
inode = &ei->vfs_inode;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
return inode;
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 5acc001..fa1ec24 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -10,149 +10,110 @@
static struct dentry_operations proc_sys_dentry_operations;
static const struct file_operations proc_sys_file_operations;
static const struct inode_operations proc_sys_inode_operations;
+static const struct file_operations proc_sys_dir_file_operations;
+static const struct inode_operations proc_sys_dir_operations;
-static void proc_sys_refresh_inode(struct inode *inode, struct ctl_table *table)
-{
- /* Refresh the cached information bits in the inode */
- if (table) {
- inode->i_uid = 0;
- inode->i_gid = 0;
- inode->i_mode = table->mode;
- if (table->proc_handler) {
- inode->i_mode |= S_IFREG;
- inode->i_nlink = 1;
- } else {
- inode->i_mode |= S_IFDIR;
- inode->i_nlink = 0; /* It is too hard to figure out */
- }
- }
-}
-
-static struct inode *proc_sys_make_inode(struct inode *dir, struct ctl_table *table)
+static struct inode *proc_sys_make_inode(struct super_block *sb,
+ struct ctl_table_header *head, struct ctl_table *table)
{
struct inode *inode;
- struct proc_inode *dir_ei, *ei;
- int depth;
+ struct proc_inode *ei;
- inode = new_inode(dir->i_sb);
+ inode = new_inode(sb);
if (!inode)
goto out;
- /* A directory is always one deeper than it's parent */
- dir_ei = PROC_I(dir);
- depth = dir_ei->fd + 1;
-
+ sysctl_head_get(head);
ei = PROC_I(inode);
- ei->fd = depth;
+ ei->sysctl = head;
+ ei->sysctl_entry = table;
+
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
- inode->i_op = &proc_sys_inode_operations;
- inode->i_fop = &proc_sys_file_operations;
inode->i_flags |= S_PRIVATE; /* tell selinux to ignore this inode */
- proc_sys_refresh_inode(inode, table);
+ inode->i_mode = table->mode;
+ if (!table->child) {
+ inode->i_mode |= S_IFREG;
+ inode->i_op = &proc_sys_inode_operations;
+ inode->i_fop = &proc_sys_file_operations;
+ } else {
+ inode->i_mode |= S_IFDIR;
+ inode->i_nlink = 0;
+ inode->i_op = &proc_sys_dir_operations;
+ inode->i_fop = &proc_sys_dir_file_operations;
+ }
out:
return inode;
}
-static struct dentry *proc_sys_ancestor(struct dentry *dentry, int depth)
-{
- for (;;) {
- struct proc_inode *ei;
-
- ei = PROC_I(dentry->d_inode);
- if (ei->fd == depth)
- break; /* found */
-
- dentry = dentry->d_parent;
- }
- return dentry;
-}
-
-static struct ctl_table *proc_sys_lookup_table_one(struct ctl_table *table,
- struct qstr *name)
+static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name)
{
int len;
- for ( ; table->ctl_name || table->procname; table++) {
+ for ( ; p->ctl_name || p->procname; p++) {
- if (!table->procname)
+ if (!p->procname)
continue;
- len = strlen(table->procname);
+ len = strlen(p->procname);
if (len != name->len)
continue;
- if (memcmp(table->procname, name->name, len) != 0)
+ if (memcmp(p->procname, name->name, len) != 0)
continue;
/* I have a match */
- return table;
+ return p;
}
return NULL;
}
-static struct ctl_table *proc_sys_lookup_table(struct dentry *dentry,
- struct ctl_table *table)
+struct ctl_table_header *grab_header(struct inode *inode)
{
- struct dentry *ancestor;
- struct proc_inode *ei;
- int depth, i;
-
- ei = PROC_I(dentry->d_inode);
- depth = ei->fd;
-
- if (depth == 0)
- return table;
-
- for (i = 1; table && (i <= depth); i++) {
- ancestor = proc_sys_ancestor(dentry, i);
- table = proc_sys_lookup_table_one(table, &ancestor->d_name);
- if (table)
- table = table->child;
- }
- return table;
-
-}
-static struct ctl_table *proc_sys_lookup_entry(struct dentry *dparent,
- struct qstr *name,
- struct ctl_table *table)
-{
- table = proc_sys_lookup_table(dparent, table);
- if (table)
- table = proc_sys_lookup_table_one(table, name);
- return table;
-}
-
-static struct ctl_table *do_proc_sys_lookup(struct dentry *parent,
- struct qstr *name,
- struct ctl_table_header **ptr)
-{
- struct ctl_table_header *head;
- struct ctl_table *table = NULL;
-
- for (head = sysctl_head_next(NULL); head;
- head = sysctl_head_next(head)) {
- table = proc_sys_lookup_entry(parent, name, head->ctl_table);
- if (table)
- break;
- }
- *ptr = head;
- return table;
+ if (PROC_I(inode)->sysctl)
+ return sysctl_head_grab(PROC_I(inode)->sysctl);
+ else
+ return sysctl_head_next(NULL);
}
static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
- struct ctl_table_header *head;
+ struct ctl_table_header *head = grab_header(dir);
+ struct ctl_table *table = PROC_I(dir)->sysctl_entry;
+ struct ctl_table_header *h = NULL;
+ struct qstr *name = &dentry->d_name;
+ struct ctl_table *p;
struct inode *inode;
- struct dentry *err;
- struct ctl_table *table;
+ struct dentry *err = ERR_PTR(-ENOENT);
- err = ERR_PTR(-ENOENT);
- table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
- if (!table)
+ if (IS_ERR(head))
+ return ERR_CAST(head);
+
+ if (table && !table->child) {
+ WARN_ON(1);
+ goto out;
+ }
+
+ table = table ? table->child : head->ctl_table;
+
+ p = find_in_table(table, name);
+ if (!p) {
+ for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
+ if (h->attached_to != table)
+ continue;
+ p = find_in_table(h->attached_by, name);
+ if (p)
+ break;
+ }
+ }
+
+ if (!p)
goto out;
err = ERR_PTR(-ENOMEM);
- inode = proc_sys_make_inode(dir, table);
+ inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
+ if (h)
+ sysctl_head_finish(h);
+
if (!inode)
goto out;
@@ -168,22 +129,14 @@
static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
size_t count, loff_t *ppos, int write)
{
- struct dentry *dentry = filp->f_dentry;
- struct ctl_table_header *head;
- struct ctl_table *table;
+ struct inode *inode = filp->f_path.dentry->d_inode;
+ struct ctl_table_header *head = grab_header(inode);
+ struct ctl_table *table = PROC_I(inode)->sysctl_entry;
ssize_t error;
size_t res;
- table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
- /* Has the sysctl entry disappeared on us? */
- error = -ENOENT;
- if (!table)
- goto out;
-
- /* Has the sysctl entry been replaced by a directory? */
- error = -EISDIR;
- if (!table->proc_handler)
- goto out;
+ if (IS_ERR(head))
+ return PTR_ERR(head);
/*
* At this point we know that the sysctl was not unregistered
@@ -193,6 +146,11 @@
if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
goto out;
+ /* if that can happen at all, it should be -EINVAL, not -EISDIR */
+ error = -EINVAL;
+ if (!table->proc_handler)
+ goto out;
+
/* careful: calling conventions are nasty here */
res = count;
error = table->proc_handler(table, write, filp, buf, &res, ppos);
@@ -218,82 +176,86 @@
static int proc_sys_fill_cache(struct file *filp, void *dirent,
- filldir_t filldir, struct ctl_table *table)
+ filldir_t filldir,
+ struct ctl_table_header *head,
+ struct ctl_table *table)
{
- struct ctl_table_header *head;
- struct ctl_table *child_table = NULL;
struct dentry *child, *dir = filp->f_path.dentry;
struct inode *inode;
struct qstr qname;
ino_t ino = 0;
unsigned type = DT_UNKNOWN;
- int ret;
qname.name = table->procname;
qname.len = strlen(table->procname);
qname.hash = full_name_hash(qname.name, qname.len);
- /* Suppress duplicates.
- * Only fill a directory entry if it is the value that
- * an ordinary lookup of that name returns. Hide all
- * others.
- *
- * If we ever cache this translation in the dcache
- * I should do a dcache lookup first. But for now
- * it is just simpler not to.
- */
- ret = 0;
- child_table = do_proc_sys_lookup(dir, &qname, &head);
- sysctl_head_finish(head);
- if (child_table != table)
- return 0;
-
child = d_lookup(dir, &qname);
if (!child) {
- struct dentry *new;
- new = d_alloc(dir, &qname);
- if (new) {
- inode = proc_sys_make_inode(dir->d_inode, table);
- if (!inode)
- child = ERR_PTR(-ENOMEM);
- else {
- new->d_op = &proc_sys_dentry_operations;
- d_add(new, inode);
+ child = d_alloc(dir, &qname);
+ if (child) {
+ inode = proc_sys_make_inode(dir->d_sb, head, table);
+ if (!inode) {
+ dput(child);
+ return -ENOMEM;
+ } else {
+ child->d_op = &proc_sys_dentry_operations;
+ d_add(child, inode);
}
- if (child)
- dput(new);
- else
- child = new;
+ } else {
+ return -ENOMEM;
}
}
- if (!child || IS_ERR(child) || !child->d_inode)
- goto end_instantiate;
inode = child->d_inode;
- if (inode) {
- ino = inode->i_ino;
- type = inode->i_mode >> 12;
- }
+ ino = inode->i_ino;
+ type = inode->i_mode >> 12;
dput(child);
-end_instantiate:
- if (!ino)
- ino= find_inode_number(dir, &qname);
- if (!ino)
- ino = 1;
- return filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
+ return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
+}
+
+static int scan(struct ctl_table_header *head, ctl_table *table,
+ unsigned long *pos, struct file *file,
+ void *dirent, filldir_t filldir)
+{
+
+ for (; table->ctl_name || table->procname; table++, (*pos)++) {
+ int res;
+
+ /* Can't do anything without a proc name */
+ if (!table->procname)
+ continue;
+
+ if (*pos < file->f_pos)
+ continue;
+
+ res = proc_sys_fill_cache(file, dirent, filldir, head, table);
+ if (res)
+ return res;
+
+ file->f_pos = *pos + 1;
+ }
+ return 0;
}
static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
- struct dentry *dentry = filp->f_dentry;
+ struct dentry *dentry = filp->f_path.dentry;
struct inode *inode = dentry->d_inode;
- struct ctl_table_header *head = NULL;
- struct ctl_table *table;
+ struct ctl_table_header *head = grab_header(inode);
+ struct ctl_table *table = PROC_I(inode)->sysctl_entry;
+ struct ctl_table_header *h = NULL;
unsigned long pos;
- int ret;
+ int ret = -EINVAL;
- ret = -ENOTDIR;
- if (!S_ISDIR(inode->i_mode))
+ if (IS_ERR(head))
+ return PTR_ERR(head);
+
+ if (table && !table->child) {
+ WARN_ON(1);
goto out;
+ }
+
+ table = table ? table->child : head->ctl_table;
ret = 0;
/* Avoid a switch here: arm builds fail with missing __cmpdi2 */
@@ -311,30 +273,17 @@
}
pos = 2;
- /* - Find each instance of the directory
- * - Read all entries in each instance
- * - Before returning an entry to user space lookup the entry
- * by name and if I find a different entry don't return
- * this one because it means it is a buried dup.
- * For sysctl this should only happen for directory entries.
- */
- for (head = sysctl_head_next(NULL); head; head = sysctl_head_next(head)) {
- table = proc_sys_lookup_table(dentry, head->ctl_table);
+ ret = scan(head, table, &pos, filp, dirent, filldir);
+ if (ret)
+ goto out;
- if (!table)
+ for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
+ if (h->attached_to != table)
continue;
-
- for (; table->ctl_name || table->procname; table++, pos++) {
- /* Can't do anything without a proc name */
- if (!table->procname)
- continue;
-
- if (pos < filp->f_pos)
- continue;
-
- if (proc_sys_fill_cache(filp, dirent, filldir, table) < 0)
- goto out;
- filp->f_pos = pos + 1;
+ ret = scan(h, h->attached_by, &pos, filp, dirent, filldir);
+ if (ret) {
+ sysctl_head_finish(h);
+ break;
}
}
ret = 1;
@@ -349,47 +298,18 @@
* sysctl entries that are not writeable,
* are _NOT_ writeable, capabilities or not.
*/
- struct ctl_table_header *head;
- struct ctl_table *table;
- struct dentry *dentry;
- int mode;
- int depth;
+ struct ctl_table_header *head = grab_header(inode);
+ struct ctl_table *table = PROC_I(inode)->sysctl_entry;
int error;
- head = NULL;
- depth = PROC_I(inode)->fd;
+ if (IS_ERR(head))
+ return PTR_ERR(head);
- /* First check the cached permissions, in case we don't have
- * enough information to lookup the sysctl table entry.
- */
- error = -EACCES;
- mode = inode->i_mode;
+ 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);
- if (current->euid == 0)
- mode >>= 6;
- else if (in_group_p(0))
- mode >>= 3;
-
- if ((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)
- error = 0;
-
- /* If we can't get a sysctl table entry the permission
- * checks on the cached mode will have to be enough.
- */
- if (!nd || !depth)
- goto out;
-
- dentry = nd->path.dentry;
- table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
-
- /* If the entry does not exist deny permission */
- error = -EACCES;
- if (!table)
- goto out;
-
- /* Use the permissions on the sysctl table entry */
- error = sysctl_perm(head->root, table, mask);
-out:
sysctl_head_finish(head);
return error;
}
@@ -409,33 +329,70 @@
return error;
}
-/* I'm lazy and don't distinguish between files and directories,
- * until access time.
- */
+static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+{
+ struct inode *inode = dentry->d_inode;
+ struct ctl_table_header *head = grab_header(inode);
+ struct ctl_table *table = PROC_I(inode)->sysctl_entry;
+
+ if (IS_ERR(head))
+ return PTR_ERR(head);
+
+ generic_fillattr(inode, stat);
+ if (table)
+ stat->mode = (stat->mode & S_IFMT) | table->mode;
+
+ sysctl_head_finish(head);
+ return 0;
+}
+
static const struct file_operations proc_sys_file_operations = {
.read = proc_sys_read,
.write = proc_sys_write,
+};
+
+static const struct file_operations proc_sys_dir_file_operations = {
.readdir = proc_sys_readdir,
};
static const struct inode_operations proc_sys_inode_operations = {
+ .permission = proc_sys_permission,
+ .setattr = proc_sys_setattr,
+ .getattr = proc_sys_getattr,
+};
+
+static const struct inode_operations proc_sys_dir_operations = {
.lookup = proc_sys_lookup,
.permission = proc_sys_permission,
.setattr = proc_sys_setattr,
+ .getattr = proc_sys_getattr,
};
static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
{
- struct ctl_table_header *head;
- struct ctl_table *table;
- table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
- proc_sys_refresh_inode(dentry->d_inode, table);
- sysctl_head_finish(head);
- return !!table;
+ return !PROC_I(dentry->d_inode)->sysctl->unregistering;
+}
+
+static int proc_sys_delete(struct dentry *dentry)
+{
+ return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
+}
+
+static int proc_sys_compare(struct dentry *dir, struct qstr *qstr,
+ struct qstr *name)
+{
+ struct dentry *dentry = container_of(qstr, struct dentry, d_name);
+ if (qstr->len != name->len)
+ return 1;
+ if (memcmp(qstr->name, name->name, name->len))
+ return 1;
+ return !sysctl_is_seen(PROC_I(dentry->d_inode)->sysctl);
}
static struct dentry_operations proc_sys_dentry_operations = {
.d_revalidate = proc_sys_revalidate,
+ .d_delete = proc_sys_delete,
+ .d_compare = proc_sys_compare,
};
static struct proc_dir_entry *proc_sys_root;
@@ -443,8 +400,8 @@
int proc_sys_init(void)
{
proc_sys_root = proc_mkdir("sys", NULL);
- proc_sys_root->proc_iops = &proc_sys_inode_operations;
- proc_sys_root->proc_fops = &proc_sys_file_operations;
+ proc_sys_root->proc_iops = &proc_sys_dir_operations;
+ proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
proc_sys_root->nlink = 0;
return 0;
}