kernel-ark/fs/devpts/inode.c
Stephen Smalley f549d6c18c [PATCH] Generic VFS fallback for security xattrs
This patch modifies the VFS setxattr, getxattr, and listxattr code to fall
back to the security module for security xattrs if the filesystem does not
support xattrs natively.  This allows security modules to export the incore
inode security label information to userspace even if the filesystem does
not provide xattr storage, and eliminates the need to individually patch
various pseudo filesystem types to provide such access.  The patch removes
the existing xattr code from devpts and tmpfs as it is then no longer
needed.

The patch restructures the code flow slightly to reduce duplication between
the normal path and the fallback path, but this should only have one
user-visible side effect - a program may get -EACCES rather than
-EOPNOTSUPP if policy denied access but the filesystem didn't support the
operation anyway.  Note that the post_setxattr hook call is not needed in
the fallback case, as the inode_setsecurity hook call handles the incore
inode security state update directly.  In contrast, we do call fsnotify in
both cases.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-05 00:05:52 -07:00

222 lines
5.0 KiB
C

/* -*- linux-c -*- --------------------------------------------------------- *
*
* linux/fs/devpts/inode.c
*
* Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
*
* This file is part of the Linux kernel and is made available under
* the terms of the GNU General Public License, version 2, or at your
* option, any later version, incorporated herein by reference.
*
* ------------------------------------------------------------------------- */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/tty.h>
#include <linux/devpts_fs.h>
#define DEVPTS_SUPER_MAGIC 0x1cd1
static struct vfsmount *devpts_mnt;
static struct dentry *devpts_root;
static struct {
int setuid;
int setgid;
uid_t uid;
gid_t gid;
umode_t mode;
} config = {.mode = 0600};
static int devpts_remount(struct super_block *sb, int *flags, char *data)
{
int setuid = 0;
int setgid = 0;
uid_t uid = 0;
gid_t gid = 0;
umode_t mode = 0600;
char *this_char;
this_char = NULL;
while ((this_char = strsep(&data, ",")) != NULL) {
int n;
char dummy;
if (!*this_char)
continue;
if (sscanf(this_char, "uid=%i%c", &n, &dummy) == 1) {
setuid = 1;
uid = n;
} else if (sscanf(this_char, "gid=%i%c", &n, &dummy) == 1) {
setgid = 1;
gid = n;
} else if (sscanf(this_char, "mode=%o%c", &n, &dummy) == 1)
mode = n & ~S_IFMT;
else {
printk("devpts: called with bogus options\n");
return -EINVAL;
}
}
config.setuid = setuid;
config.setgid = setgid;
config.uid = uid;
config.gid = gid;
config.mode = mode;
return 0;
}
static struct super_operations devpts_sops = {
.statfs = simple_statfs,
.remount_fs = devpts_remount,
};
static int
devpts_fill_super(struct super_block *s, void *data, int silent)
{
struct inode * inode;
s->s_blocksize = 1024;
s->s_blocksize_bits = 10;
s->s_magic = DEVPTS_SUPER_MAGIC;
s->s_op = &devpts_sops;
s->s_time_gran = 1;
inode = new_inode(s);
if (!inode)
goto fail;
inode->i_ino = 1;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
inode->i_blocks = 0;
inode->i_blksize = 1024;
inode->i_uid = inode->i_gid = 0;
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inode->i_nlink = 2;
devpts_root = s->s_root = d_alloc_root(inode);
if (s->s_root)
return 0;
printk("devpts: get root dentry failed\n");
iput(inode);
fail:
return -ENOMEM;
}
static struct super_block *devpts_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
return get_sb_single(fs_type, flags, data, devpts_fill_super);
}
static struct file_system_type devpts_fs_type = {
.owner = THIS_MODULE,
.name = "devpts",
.get_sb = devpts_get_sb,
.kill_sb = kill_anon_super,
};
/*
* The normal naming convention is simply /dev/pts/<number>; this conforms
* to the System V naming convention
*/
static struct dentry *get_node(int num)
{
char s[12];
struct dentry *root = devpts_root;
down(&root->d_inode->i_sem);
return lookup_one_len(s, root, sprintf(s, "%d", num));
}
int devpts_pty_new(struct tty_struct *tty)
{
int number = tty->index;
struct tty_driver *driver = tty->driver;
dev_t device = MKDEV(driver->major, driver->minor_start+number);
struct dentry *dentry;
struct inode *inode = new_inode(devpts_mnt->mnt_sb);
/* We're supposed to be given the slave end of a pty */
BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
if (!inode)
return -ENOMEM;
inode->i_ino = number+2;
inode->i_blksize = 1024;
inode->i_uid = config.setuid ? config.uid : current->fsuid;
inode->i_gid = config.setgid ? config.gid : current->fsgid;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
init_special_inode(inode, S_IFCHR|config.mode, device);
inode->u.generic_ip = tty;
dentry = get_node(number);
if (!IS_ERR(dentry) && !dentry->d_inode)
d_instantiate(dentry, inode);
up(&devpts_root->d_inode->i_sem);
return 0;
}
struct tty_struct *devpts_get_tty(int number)
{
struct dentry *dentry = get_node(number);
struct tty_struct *tty;
tty = NULL;
if (!IS_ERR(dentry)) {
if (dentry->d_inode)
tty = dentry->d_inode->u.generic_ip;
dput(dentry);
}
up(&devpts_root->d_inode->i_sem);
return tty;
}
void devpts_pty_kill(int number)
{
struct dentry *dentry = get_node(number);
if (!IS_ERR(dentry)) {
struct inode *inode = dentry->d_inode;
if (inode) {
inode->i_nlink--;
d_delete(dentry);
dput(dentry);
}
dput(dentry);
}
up(&devpts_root->d_inode->i_sem);
}
static int __init init_devpts_fs(void)
{
int err = register_filesystem(&devpts_fs_type);
if (!err) {
devpts_mnt = kern_mount(&devpts_fs_type);
if (IS_ERR(devpts_mnt))
err = PTR_ERR(devpts_mnt);
}
return err;
}
static void __exit exit_devpts_fs(void)
{
unregister_filesystem(&devpts_fs_type);
mntput(devpts_mnt);
}
module_init(init_devpts_fs)
module_exit(exit_devpts_fs)
MODULE_LICENSE("GPL");