[linux.git] / fs / xattr.c

/*
  File: fs/xattr.c

  Extended attribute handling.

  Copyright (C) 2001 by Andreas Gruenbacher <[email protected]>
  Copyright (C) 2001 SGI - Silicon Graphics, Inc <[email protected]>
  Copyright (c) 2004 Red Hat, Inc., James Morris <[email protected]>
 */
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/xattr.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/module.h>
#include <linux/fsnotify.h>
#include <linux/audit.h>
#include <asm/uaccess.h>


/*
 * Check permissions for extended attribute access.  This is a bit complicated
 * because different namespaces have very different rules.
 */
static int
xattr_permission(struct inode *inode, const char *name, int mask)
{
	/*
	 * We can never set or remove an extended attribute on a read-only
	 * filesystem  or on an immutable / append-only inode.
	 */
	if (mask & MAY_WRITE) {
		if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
			return -EPERM;
	}

	/*
	 * No restriction for security.* and system.* from the VFS.  Decision
	 * on these is left to the underlying filesystem / security module.
	 */
	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
	    !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return 0;

	/*
	 * The trusted.* namespace can only be accessed by a privileged user.
	 */
	if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
		return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);

	/* In user.* namespace, only regular files and directories can have
	 * extended attributes. For sticky directories, only the owner and
	 * privileged user can write attributes.
	 */
	if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
		if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
			return -EPERM;
		if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
		    (mask & MAY_WRITE) && !is_owner_or_cap(inode))
			return -EPERM;
	}

	return inode_permission(inode, mask);
}

int
vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
		size_t size, int flags)
{
	struct inode *inode = dentry->d_inode;
	int error;

	error = xattr_permission(inode, name, MAY_WRITE);
	if (error)
		return error;

	mutex_lock(&inode->i_mutex);
	error = security_inode_setxattr(dentry, name, value, size, flags);
	if (error)
		goto out;
	error = -EOPNOTSUPP;
	if (inode->i_op->setxattr) {
		error = inode->i_op->setxattr(dentry, name, value, size, flags);
		if (!error) {
			fsnotify_xattr(dentry);
			security_inode_post_setxattr(dentry, name, value,
						     size, flags);
		}
	} else if (!strncmp(name, XATTR_SECURITY_PREFIX,
				XATTR_SECURITY_PREFIX_LEN)) {
		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
		error = security_inode_setsecurity(inode, suffix, value,
						   size, flags);
		if (!error)
			fsnotify_xattr(dentry);
	}
out:
	mutex_unlock(&inode->i_mutex);
	return error;
}
EXPORT_SYMBOL_GPL(vfs_setxattr);

ssize_t
xattr_getsecurity(struct inode *inode, const char *name, void *value,
			size_t size)
{
	void *buffer = NULL;
	ssize_t len;

	if (!value || !size) {
		len = security_inode_getsecurity(inode, name, &buffer, false);
		goto out_noalloc;
	}

	len = security_inode_getsecurity(inode, name, &buffer, true);
	if (len < 0)
		return len;
	if (size < len) {
		len = -ERANGE;
		goto out;
	}
	memcpy(value, buffer, len);
out:
	security_release_secctx(buffer, len);
out_noalloc:
	return len;
}
EXPORT_SYMBOL_GPL(xattr_getsecurity);

ssize_t
vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
{
	struct inode *inode = dentry->d_inode;
	int error;

	error = xattr_permission(inode, name, MAY_READ);
	if (error)
		return error;

	error = security_inode_getxattr(dentry, name);
	if (error)
		return error;

	if (!strncmp(name, XATTR_SECURITY_PREFIX,
				XATTR_SECURITY_PREFIX_LEN)) {
		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
		int ret = xattr_getsecurity(inode, suffix, value, size);
		/*
		 * Only overwrite the return value if a security module
		 * is actually active.
		 */
		if (ret == -EOPNOTSUPP)
			goto nolsm;
		return ret;
	}
nolsm:
	if (inode->i_op->getxattr)
		error = inode->i_op->getxattr(dentry, name, value, size);
	else
		error = -EOPNOTSUPP;

	return error;
}
EXPORT_SYMBOL_GPL(vfs_getxattr);

ssize_t
vfs_listxattr(struct dentry *d, char *list, size_t size)
{
	ssize_t error;

	error = security_inode_listxattr(d);
	if (error)
		return error;
	error = -EOPNOTSUPP;
	if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
		error = d->d_inode->i_op->listxattr(d, list, size);
	} else {
		error = security_inode_listsecurity(d->d_inode, list, size);
		if (size && error > size)
			error = -ERANGE;
	}
	return error;
}
EXPORT_SYMBOL_GPL(vfs_listxattr);

int
vfs_removexattr(struct dentry *dentry, const char *name)
{
	struct inode *inode = dentry->d_inode;
	int error;

	if (!inode->i_op->removexattr)
		return -EOPNOTSUPP;

	error = xattr_permission(inode, name, MAY_WRITE);
	if (error)
		return error;

	error = security_inode_removexattr(dentry, name);
	if (error)
		return error;

	mutex_lock(&inode->i_mutex);
	error = inode->i_op->removexattr(dentry, name);
	mutex_unlock(&inode->i_mutex);

	if (!error)
		fsnotify_xattr(dentry);
	return error;
}
EXPORT_SYMBOL_GPL(vfs_removexattr);


/*
 * Extended attribute SET operations
 */
static long
setxattr(struct dentry *d, const char __user *name, const void __user *value,
	 size_t size, int flags)
{
	int error;
	void *kvalue = NULL;
	char kname[XATTR_NAME_MAX + 1];

	if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
		return -EINVAL;

	error = strncpy_from_user(kname, name, sizeof(kname));
	if (error == 0 || error == sizeof(kname))
		error = -ERANGE;
	if (error < 0)
		return error;

	if (size) {
		if (size > XATTR_SIZE_MAX)
			return -E2BIG;
		kvalue = kmalloc(size, GFP_KERNEL);
		if (!kvalue)
			return -ENOMEM;
		if (copy_from_user(kvalue, value, size)) {
			kfree(kvalue);
			return -EFAULT;
		}
	}

	error = vfs_setxattr(d, kname, kvalue, size, flags);
	kfree(kvalue);
	return error;
}

asmlinkage long
sys_setxattr(const char __user *pathname, const char __user *name,
	     const void __user *value, size_t size, int flags)
{
	struct path path;
	int error;

	error = user_path(pathname, &path);
	if (error)
		return error;
	error = mnt_want_write(path.mnt);
	if (!error) {
		error = setxattr(path.dentry, name, value, size, flags);
		mnt_drop_write(path.mnt);
	}
	path_put(&path);
	return error;
}

asmlinkage long
sys_lsetxattr(const char __user *pathname, const char __user *name,
	      const void __user *value, size_t size, int flags)
{
	struct path path;
	int error;

	error = user_lpath(pathname, &path);
	if (error)
		return error;
	error = mnt_want_write(path.mnt);
	if (!error) {
		error = setxattr(path.dentry, name, value, size, flags);
		mnt_drop_write(path.mnt);
	}
	path_put(&path);
	return error;
}

asmlinkage long
sys_fsetxattr(int fd, const char __user *name, const void __user *value,
	      size_t size, int flags)
{
	struct file *f;
	struct dentry *dentry;
	int error = -EBADF;

	f = fget(fd);
	if (!f)
		return error;
	dentry = f->f_path.dentry;
	audit_inode(NULL, dentry);
	error = mnt_want_write(f->f_path.mnt);
	if (!error) {
		error = setxattr(dentry, name, value, size, flags);
		mnt_drop_write(f->f_path.mnt);
	}
	fput(f);
	return error;
}

/*
 * Extended attribute GET operations
 */
static ssize_t
getxattr(struct dentry *d, const char __user *name, void __user *value,
	 size_t size)
{
	ssize_t error;
	void *kvalue = NULL;
	char kname[XATTR_NAME_MAX + 1];

	error = strncpy_from_user(kname, name, sizeof(kname));
	if (error == 0 || error == sizeof(kname))
		error = -ERANGE;
	if (error < 0)
		return error;

	if (size) {
		if (size > XATTR_SIZE_MAX)
			size = XATTR_SIZE_MAX;
		kvalue = kzalloc(size, GFP_KERNEL);
		if (!kvalue)
			return -ENOMEM;
	}

	error = vfs_getxattr(d, kname, kvalue, size);
	if (error > 0) {
		if (size && copy_to_user(value, kvalue, error))
			error = -EFAULT;
	} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
		/* The file system tried to returned a value bigger
		   than XATTR_SIZE_MAX bytes. Not possible. */
		error = -E2BIG;
	}
	kfree(kvalue);
	return error;
}

asmlinkage ssize_t
sys_getxattr(const char __user *pathname, const char __user *name,
	     void __user *value, size_t size)
{
	struct path path;
	ssize_t error;

	error = user_path(pathname, &path);
	if (error)
		return error;
	error = getxattr(path.dentry, name, value, size);
	path_put(&path);
	return error;
}

asmlinkage ssize_t
sys_lgetxattr(const char __user *pathname, const char __user *name, void __user *value,
	      size_t size)
{
	struct path path;
	ssize_t error;

	error = user_lpath(pathname, &path);
	if (error)
		return error;
	error = getxattr(path.dentry, name, value, size);
	path_put(&path);
	return error;
}

asmlinkage ssize_t
sys_fgetxattr(int fd, const char __user *name, void __user *value, size_t size)
{
	struct file *f;
	ssize_t error = -EBADF;

	f = fget(fd);
	if (!f)
		return error;
	audit_inode(NULL, f->f_path.dentry);
	error = getxattr(f->f_path.dentry, name, value, size);
	fput(f);
	return error;
}

/*
 * Extended attribute LIST operations
 */
static ssize_t
listxattr(struct dentry *d, char __user *list, size_t size)
{
	ssize_t error;
	char *klist = NULL;

	if (size) {
		if (size > XATTR_LIST_MAX)
			size = XATTR_LIST_MAX;
		klist = kmalloc(size, GFP_KERNEL);
		if (!klist)
			return -ENOMEM;
	}

	error = vfs_listxattr(d, klist, size);
	if (error > 0) {
		if (size && copy_to_user(list, klist, error))
			error = -EFAULT;
	} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
		/* The file system tried to returned a list bigger
		   than XATTR_LIST_MAX bytes. Not possible. */
		error = -E2BIG;
	}
	kfree(klist);
	return error;
}

asmlinkage ssize_t
sys_listxattr(const char __user *pathname, char __user *list, size_t size)
{
	struct path path;
	ssize_t error;

	error = user_path(pathname, &path);
	if (error)
		return error;
	error = listxattr(path.dentry, list, size);
	path_put(&path);
	return error;
}

asmlinkage ssize_t
sys_llistxattr(const char __user *pathname, char __user *list, size_t size)
{
	struct path path;
	ssize_t error;

	error = user_lpath(pathname, &path);
	if (error)
		return error;
	error = listxattr(path.dentry, list, size);
	path_put(&path);
	return error;
}

asmlinkage ssize_t
sys_flistxattr(int fd, char __user *list, size_t size)
{
	struct file *f;
	ssize_t error = -EBADF;

	f = fget(fd);
	if (!f)
		return error;
	audit_inode(NULL, f->f_path.dentry);
	error = listxattr(f->f_path.dentry, list, size);
	fput(f);
	return error;
}

/*
 * Extended attribute REMOVE operations
 */
static long
removexattr(struct dentry *d, const char __user *name)
{
	int error;
	char kname[XATTR_NAME_MAX + 1];

	error = strncpy_from_user(kname, name, sizeof(kname));
	if (error == 0 || error == sizeof(kname))
		error = -ERANGE;
	if (error < 0)
		return error;

	return vfs_removexattr(d, kname);
}

asmlinkage long
sys_removexattr(const char __user *pathname, const char __user *name)
{
	struct path path;
	int error;

	error = user_path(pathname, &path);
	if (error)
		return error;
	error = mnt_want_write(path.mnt);
	if (!error) {
		error = removexattr(path.dentry, name);
		mnt_drop_write(path.mnt);
	}
	path_put(&path);
	return error;
}

asmlinkage long
sys_lremovexattr(const char __user *pathname, const char __user *name)
{
	struct path path;
	int error;

	error = user_lpath(pathname, &path);
	if (error)
		return error;
	error = mnt_want_write(path.mnt);
	if (!error) {
		error = removexattr(path.dentry, name);
		mnt_drop_write(path.mnt);
	}
	path_put(&path);
	return error;
}

asmlinkage long
sys_fremovexattr(int fd, const char __user *name)
{
	struct file *f;
	struct dentry *dentry;
	int error = -EBADF;

	f = fget(fd);
	if (!f)
		return error;
	dentry = f->f_path.dentry;
	audit_inode(NULL, dentry);
	error = mnt_want_write(f->f_path.mnt);
	if (!error) {
		error = removexattr(dentry, name);
		mnt_drop_write(f->f_path.mnt);
	}
	fput(f);
	return error;
}


static const char *
strcmp_prefix(const char *a, const char *a_prefix)
{
	while (*a_prefix && *a == *a_prefix) {
		a++;
		a_prefix++;
	}
	return *a_prefix ? NULL : a;
}

/*
 * In order to implement different sets of xattr operations for each xattr
 * prefix with the generic xattr API, a filesystem should create a
 * null-terminated array of struct xattr_handler (one for each prefix) and
 * hang a pointer to it off of the s_xattr field of the superblock.
 *
 * The generic_fooxattr() functions will use this list to dispatch xattr
 * operations to the correct xattr_handler.
 */
#define for_each_xattr_handler(handlers, handler)		\
		for ((handler) = *(handlers)++;			\
			(handler) != NULL;			\
			(handler) = *(handlers)++)

/*
 * Find the xattr_handler with the matching prefix.
 */
static struct xattr_handler *
xattr_resolve_name(struct xattr_handler **handlers, const char **name)
{
	struct xattr_handler *handler;

	if (!*name)
		return NULL;

	for_each_xattr_handler(handlers, handler) {
		const char *n = strcmp_prefix(*name, handler->prefix);
		if (n) {
			*name = n;
			break;
		}
	}
	return handler;
}

/*
 * Find the handler for the prefix and dispatch its get() operation.
 */
ssize_t
generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
{
	struct xattr_handler *handler;
	struct inode *inode = dentry->d_inode;

	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
	if (!handler)
		return -EOPNOTSUPP;
	return handler->get(inode, name, buffer, size);
}

/*
 * Combine the results of the list() operation from every xattr_handler in the
 * list.
 */
ssize_t
generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
{
	struct inode *inode = dentry->d_inode;
	struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr;
	unsigned int size = 0;

	if (!buffer) {
		for_each_xattr_handler(handlers, handler)
			size += handler->list(inode, NULL, 0, NULL, 0);
	} else {
		char *buf = buffer;

		for_each_xattr_handler(handlers, handler) {
			size = handler->list(inode, buf, buffer_size, NULL, 0);
			if (size > buffer_size)
				return -ERANGE;
			buf += size;
			buffer_size -= size;
		}
		size = buf - buffer;
	}
	return size;
}

/*
 * Find the handler for the prefix and dispatch its set() operation.
 */
int
generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
{
	struct xattr_handler *handler;
	struct inode *inode = dentry->d_inode;

	if (size == 0)
		value = "";  /* empty EA, do not remove */
	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
	if (!handler)
		return -EOPNOTSUPP;
	return handler->set(inode, name, value, size, flags);
}

/*
 * Find the handler for the prefix and dispatch its set() operation to remove
 * any associated extended attribute.
 */
int
generic_removexattr(struct dentry *dentry, const char *name)
{
	struct xattr_handler *handler;
	struct inode *inode = dentry->d_inode;

	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
	if (!handler)
		return -EOPNOTSUPP;
	return handler->set(inode, name, NULL, 0, XATTR_REPLACE);
}

EXPORT_SYMBOL(generic_getxattr);
EXPORT_SYMBOL(generic_listxattr);
EXPORT_SYMBOL(generic_setxattr);
EXPORT_SYMBOL(generic_removexattr);
Commit	Line	Data
1da177e4 LT	1	/*
	2	File: fs/xattr.c
	3
	4	Extended attribute handling.
	5
	6	Copyright (C) 2001 by Andreas Gruenbacher <[email protected]>
	7	Copyright (C) 2001 SGI - Silicon Graphics, Inc <[email protected]>
	8	Copyright (c) 2004 Red Hat, Inc., James Morris <[email protected]>
	9	*/
	10	#include <linux/fs.h>
	11	#include <linux/slab.h>
1da177e4 LT	12	#include <linux/file.h>
1da177e4 LT	13	#include <linux/xattr.h>
18f335af	14	#include <linux/mount.h>
1da177e4 LT	15	#include <linux/namei.h>
	16	#include <linux/security.h>
	17	#include <linux/syscalls.h>
	18	#include <linux/module.h>
0eeca283	19	#include <linux/fsnotify.h>
73241ccc	20	#include <linux/audit.h>
1da177e4 LT	21	#include <asm/uaccess.h>
1da177e4 LT	22
5be196e5	23
e0ad7b07	24	/*
	25	* Check permissions for extended attribute access. This is a bit complicated
	26	* because different namespaces have very different rules.
	27	*/
	28	static int
	29	xattr_permission(struct inode inode, const char name, int mask)
	30	{
	31	/*
	32	* We can never set or remove an extended attribute on a read-only
	33	* filesystem or on an immutable / append-only inode.
	34	*/
	35	if (mask & MAY_WRITE) {
e0ad7b07	36	if (IS_IMMUTABLE(inode) \|\| IS_APPEND(inode))
	37	return -EPERM;
	38	}
	39
	40	/*
	41	* No restriction for security.* and system.* from the VFS. Decision
	42	* on these is left to the underlying filesystem / security module.
	43	*/
	44	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) \|\|
	45	!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
	46	return 0;
	47
	48	/*
f1f2d871	49	* The trusted.* namespace can only be accessed by a privileged user.
e0ad7b07	50	*/
	51	if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
	52	return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);
	53
f1f2d871 AG	54	/* In user.* namespace, only regular files and directories can have
	55	* extended attributes. For sticky directories, only the owner and
	56	* privileged user can write attributes.
	57	*/
e0ad7b07	58	if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
f1f2d871 AG	59	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
	60	return -EPERM;
	61	if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
3bd858ab	62	(mask & MAY_WRITE) && !is_owner_or_cap(inode))
e0ad7b07	63	return -EPERM;
	64	}
	65
f419a2e3	66	return inode_permission(inode, mask);
e0ad7b07	67	}
e0ad7b07	68
5be196e5	69	int
8f0cfa52	70	vfs_setxattr(struct dentry dentry, const char name, const void *value,
5be196e5 CH	71	size_t size, int flags)
	72	{
	73	struct inode *inode = dentry->d_inode;
	74	int error;
	75
e0ad7b07	76	error = xattr_permission(inode, name, MAY_WRITE);
	77	if (error)
	78	return error;
	79
5be196e5 CH	80	mutex_lock(&inode->i_mutex);
	81	error = security_inode_setxattr(dentry, name, value, size, flags);
	82	if (error)
	83	goto out;
	84	error = -EOPNOTSUPP;
	85	if (inode->i_op->setxattr) {
	86	error = inode->i_op->setxattr(dentry, name, value, size, flags);
	87	if (!error) {
	88	fsnotify_xattr(dentry);
	89	security_inode_post_setxattr(dentry, name, value,
	90	size, flags);
	91	}
	92	} else if (!strncmp(name, XATTR_SECURITY_PREFIX,
e0ad7b07	93	XATTR_SECURITY_PREFIX_LEN)) {
e0ad7b07	94	const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
5be196e5 CH	95	error = security_inode_setsecurity(inode, suffix, value,
	96	size, flags);
	97	if (!error)
	98	fsnotify_xattr(dentry);
	99	}
	100	out:
	101	mutex_unlock(&inode->i_mutex);
	102	return error;
	103	}
	104	EXPORT_SYMBOL_GPL(vfs_setxattr);
	105
42492594 DQ	106	ssize_t
	107	xattr_getsecurity(struct inode inode, const char name, void *value,
	108	size_t size)
	109	{
	110	void *buffer = NULL;
	111	ssize_t len;
	112
	113	if (!value \|\| !size) {
	114	len = security_inode_getsecurity(inode, name, &buffer, false);
	115	goto out_noalloc;
	116	}
	117
	118	len = security_inode_getsecurity(inode, name, &buffer, true);
	119	if (len < 0)
	120	return len;
	121	if (size < len) {
	122	len = -ERANGE;
	123	goto out;
	124	}
	125	memcpy(value, buffer, len);
	126	out:
	127	security_release_secctx(buffer, len);
	128	out_noalloc:
	129	return len;
	130	}
	131	EXPORT_SYMBOL_GPL(xattr_getsecurity);
	132
5be196e5	133	ssize_t
8f0cfa52	134	vfs_getxattr(struct dentry dentry, const char name, void *value, size_t size)
5be196e5 CH	135	{
	136	struct inode *inode = dentry->d_inode;
	137	int error;
	138
e0ad7b07	139	error = xattr_permission(inode, name, MAY_READ);
	140	if (error)
	141	return error;
	142
5be196e5 CH	143	error = security_inode_getxattr(dentry, name);
	144	if (error)
	145	return error;
	146
5be196e5	147	if (!strncmp(name, XATTR_SECURITY_PREFIX,
e0ad7b07	148	XATTR_SECURITY_PREFIX_LEN)) {
e0ad7b07	149	const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
42492594	150	int ret = xattr_getsecurity(inode, suffix, value, size);
5be196e5 CH	151	/*
	152	* Only overwrite the return value if a security module
	153	* is actually active.
	154	*/
4bea5805 DQ	155	if (ret == -EOPNOTSUPP)
	156	goto nolsm;
	157	return ret;
5be196e5	158	}
4bea5805 DQ	159	nolsm:
	160	if (inode->i_op->getxattr)
	161	error = inode->i_op->getxattr(dentry, name, value, size);
	162	else
	163	error = -EOPNOTSUPP;
5be196e5 CH	164
	165	return error;
	166	}
	167	EXPORT_SYMBOL_GPL(vfs_getxattr);
	168
659564c8 BN	169	ssize_t
	170	vfs_listxattr(struct dentry d, char list, size_t size)
	171	{
	172	ssize_t error;
	173
	174	error = security_inode_listxattr(d);
	175	if (error)
	176	return error;
	177	error = -EOPNOTSUPP;
	178	if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
	179	error = d->d_inode->i_op->listxattr(d, list, size);
	180	} else {
	181	error = security_inode_listsecurity(d->d_inode, list, size);
	182	if (size && error > size)
	183	error = -ERANGE;
	184	}
	185	return error;
	186	}
	187	EXPORT_SYMBOL_GPL(vfs_listxattr);
	188
5be196e5	189	int
8f0cfa52	190	vfs_removexattr(struct dentry dentry, const char name)
5be196e5 CH	191	{
	192	struct inode *inode = dentry->d_inode;
	193	int error;
	194
	195	if (!inode->i_op->removexattr)
	196	return -EOPNOTSUPP;
	197
e0ad7b07	198	error = xattr_permission(inode, name, MAY_WRITE);
	199	if (error)
	200	return error;
	201
5be196e5 CH	202	error = security_inode_removexattr(dentry, name);
	203	if (error)
	204	return error;
	205
	206	mutex_lock(&inode->i_mutex);
	207	error = inode->i_op->removexattr(dentry, name);
	208	mutex_unlock(&inode->i_mutex);
	209
	210	if (!error)
	211	fsnotify_xattr(dentry);
	212	return error;
	213	}
	214	EXPORT_SYMBOL_GPL(vfs_removexattr);
	215
	216
1da177e4 LT	217	/*
	218	* Extended attribute SET operations
	219	*/
	220	static long
8f0cfa52	221	setxattr(struct dentry d, const char __user name, const void __user *value,
1da177e4 LT	222	size_t size, int flags)
	223	{
	224	int error;
	225	void *kvalue = NULL;
	226	char kname[XATTR_NAME_MAX + 1];
	227
	228	if (flags & ~(XATTR_CREATE\|XATTR_REPLACE))
	229	return -EINVAL;
	230
	231	error = strncpy_from_user(kname, name, sizeof(kname));
	232	if (error == 0 \|\| error == sizeof(kname))
	233	error = -ERANGE;
	234	if (error < 0)
	235	return error;
	236
	237	if (size) {
	238	if (size > XATTR_SIZE_MAX)
	239	return -E2BIG;
	240	kvalue = kmalloc(size, GFP_KERNEL);
	241	if (!kvalue)
	242	return -ENOMEM;
	243	if (copy_from_user(kvalue, value, size)) {
	244	kfree(kvalue);
	245	return -EFAULT;
	246	}
	247	}
	248
5be196e5	249	error = vfs_setxattr(d, kname, kvalue, size, flags);
f99d49ad	250	kfree(kvalue);
1da177e4 LT	251	return error;
	252	}
	253
	254	asmlinkage long
2d8f3038	255	sys_setxattr(const char __user pathname, const char __user name,
8f0cfa52	256	const void __user *value, size_t size, int flags)
1da177e4	257	{
2d8f3038	258	struct path path;
1da177e4 LT	259	int error;
1da177e4 LT	260
2d8f3038	261	error = user_path(pathname, &path);
1da177e4 LT	262	if (error)
1da177e4 LT	263	return error;
2d8f3038	264	error = mnt_want_write(path.mnt);
18f335af	265	if (!error) {
2d8f3038 AV	266	error = setxattr(path.dentry, name, value, size, flags);
2d8f3038 AV	267	mnt_drop_write(path.mnt);
18f335af	268	}
2d8f3038	269	path_put(&path);
1da177e4 LT	270	return error;
	271	}
	272
	273	asmlinkage long
2d8f3038	274	sys_lsetxattr(const char __user pathname, const char __user name,
8f0cfa52	275	const void __user *value, size_t size, int flags)
1da177e4	276	{
2d8f3038	277	struct path path;
1da177e4 LT	278	int error;
1da177e4 LT	279
2d8f3038	280	error = user_lpath(pathname, &path);
1da177e4 LT	281	if (error)
1da177e4 LT	282	return error;
2d8f3038	283	error = mnt_want_write(path.mnt);
18f335af	284	if (!error) {
2d8f3038 AV	285	error = setxattr(path.dentry, name, value, size, flags);
2d8f3038 AV	286	mnt_drop_write(path.mnt);
18f335af	287	}
2d8f3038	288	path_put(&path);
1da177e4 LT	289	return error;
	290	}
	291
	292	asmlinkage long
8f0cfa52	293	sys_fsetxattr(int fd, const char __user name, const void __user value,
1da177e4 LT	294	size_t size, int flags)
	295	{
	296	struct file *f;
73241ccc	297	struct dentry *dentry;
1da177e4 LT	298	int error = -EBADF;
	299
	300	f = fget(fd);
	301	if (!f)
	302	return error;
0f7fc9e4	303	dentry = f->f_path.dentry;
5a190ae6	304	audit_inode(NULL, dentry);
18f335af DH	305	error = mnt_want_write(f->f_path.mnt);
	306	if (!error) {
	307	error = setxattr(dentry, name, value, size, flags);
	308	mnt_drop_write(f->f_path.mnt);
	309	}
1da177e4 LT	310	fput(f);
	311	return error;
	312	}
	313
	314	/*
	315	* Extended attribute GET operations
	316	*/
	317	static ssize_t
8f0cfa52 DH	318	getxattr(struct dentry d, const char __user name, void __user *value,
8f0cfa52 DH	319	size_t size)
1da177e4 LT	320	{
	321	ssize_t error;
	322	void *kvalue = NULL;
	323	char kname[XATTR_NAME_MAX + 1];
	324
	325	error = strncpy_from_user(kname, name, sizeof(kname));
	326	if (error == 0 \|\| error == sizeof(kname))
	327	error = -ERANGE;
	328	if (error < 0)
	329	return error;
	330
	331	if (size) {
	332	if (size > XATTR_SIZE_MAX)
	333	size = XATTR_SIZE_MAX;
d381d8a9	334	kvalue = kzalloc(size, GFP_KERNEL);
1da177e4 LT	335	if (!kvalue)
	336	return -ENOMEM;
	337	}
	338
5be196e5	339	error = vfs_getxattr(d, kname, kvalue, size);
f549d6c1 SS	340	if (error > 0) {
	341	if (size && copy_to_user(value, kvalue, error))
	342	error = -EFAULT;
	343	} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
	344	/* The file system tried to returned a value bigger
	345	than XATTR_SIZE_MAX bytes. Not possible. */
	346	error = -E2BIG;
1da177e4	347	}
f99d49ad	348	kfree(kvalue);
1da177e4 LT	349	return error;
	350	}
	351
	352	asmlinkage ssize_t
2d8f3038	353	sys_getxattr(const char __user pathname, const char __user name,
8f0cfa52	354	void __user *value, size_t size)
1da177e4	355	{
2d8f3038	356	struct path path;
1da177e4 LT	357	ssize_t error;
1da177e4 LT	358
2d8f3038	359	error = user_path(pathname, &path);
1da177e4 LT	360	if (error)
1da177e4 LT	361	return error;
2d8f3038 AV	362	error = getxattr(path.dentry, name, value, size);
2d8f3038 AV	363	path_put(&path);
1da177e4 LT	364	return error;
	365	}
	366
	367	asmlinkage ssize_t
2d8f3038	368	sys_lgetxattr(const char __user pathname, const char __user name, void __user *value,
1da177e4 LT	369	size_t size)
1da177e4 LT	370	{
2d8f3038	371	struct path path;
1da177e4 LT	372	ssize_t error;
1da177e4 LT	373
2d8f3038	374	error = user_lpath(pathname, &path);
1da177e4 LT	375	if (error)
1da177e4 LT	376	return error;
2d8f3038 AV	377	error = getxattr(path.dentry, name, value, size);
2d8f3038 AV	378	path_put(&path);
1da177e4 LT	379	return error;
	380	}
	381
	382	asmlinkage ssize_t
8f0cfa52	383	sys_fgetxattr(int fd, const char __user name, void __user value, size_t size)
1da177e4 LT	384	{
	385	struct file *f;
	386	ssize_t error = -EBADF;
	387
	388	f = fget(fd);
	389	if (!f)
	390	return error;
5a190ae6	391	audit_inode(NULL, f->f_path.dentry);
0f7fc9e4	392	error = getxattr(f->f_path.dentry, name, value, size);
1da177e4 LT	393	fput(f);
	394	return error;
	395	}
	396
	397	/*
	398	* Extended attribute LIST operations
	399	*/
	400	static ssize_t
	401	listxattr(struct dentry d, char __user list, size_t size)
	402	{
	403	ssize_t error;
	404	char *klist = NULL;
	405
	406	if (size) {
	407	if (size > XATTR_LIST_MAX)
	408	size = XATTR_LIST_MAX;
	409	klist = kmalloc(size, GFP_KERNEL);
	410	if (!klist)
	411	return -ENOMEM;
	412	}
	413
659564c8	414	error = vfs_listxattr(d, klist, size);
f549d6c1 SS	415	if (error > 0) {
	416	if (size && copy_to_user(list, klist, error))
	417	error = -EFAULT;
	418	} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
	419	/* The file system tried to returned a list bigger
	420	than XATTR_LIST_MAX bytes. Not possible. */
	421	error = -E2BIG;
1da177e4	422	}
f99d49ad	423	kfree(klist);
1da177e4 LT	424	return error;
	425	}
	426
	427	asmlinkage ssize_t
2d8f3038	428	sys_listxattr(const char __user pathname, char __user list, size_t size)
1da177e4	429	{
2d8f3038	430	struct path path;
1da177e4 LT	431	ssize_t error;
1da177e4 LT	432
2d8f3038	433	error = user_path(pathname, &path);
1da177e4 LT	434	if (error)
1da177e4 LT	435	return error;
2d8f3038 AV	436	error = listxattr(path.dentry, list, size);
2d8f3038 AV	437	path_put(&path);
1da177e4 LT	438	return error;
	439	}
	440
	441	asmlinkage ssize_t
2d8f3038	442	sys_llistxattr(const char __user pathname, char __user list, size_t size)
1da177e4	443	{
2d8f3038	444	struct path path;
1da177e4 LT	445	ssize_t error;
1da177e4 LT	446
2d8f3038	447	error = user_lpath(pathname, &path);
1da177e4 LT	448	if (error)
1da177e4 LT	449	return error;
2d8f3038 AV	450	error = listxattr(path.dentry, list, size);
2d8f3038 AV	451	path_put(&path);
1da177e4 LT	452	return error;
	453	}
	454
	455	asmlinkage ssize_t
	456	sys_flistxattr(int fd, char __user *list, size_t size)
	457	{
	458	struct file *f;
	459	ssize_t error = -EBADF;
	460
	461	f = fget(fd);
	462	if (!f)
	463	return error;
5a190ae6	464	audit_inode(NULL, f->f_path.dentry);
0f7fc9e4	465	error = listxattr(f->f_path.dentry, list, size);
1da177e4 LT	466	fput(f);
	467	return error;
	468	}
	469
	470	/*
	471	* Extended attribute REMOVE operations
	472	*/
	473	static long
8f0cfa52	474	removexattr(struct dentry d, const char __user name)
1da177e4 LT	475	{
	476	int error;
	477	char kname[XATTR_NAME_MAX + 1];
	478
	479	error = strncpy_from_user(kname, name, sizeof(kname));
	480	if (error == 0 \|\| error == sizeof(kname))
	481	error = -ERANGE;
	482	if (error < 0)
	483	return error;
	484
5be196e5	485	return vfs_removexattr(d, kname);
1da177e4 LT	486	}
	487
	488	asmlinkage long
2d8f3038	489	sys_removexattr(const char __user pathname, const char __user name)
1da177e4	490	{
2d8f3038	491	struct path path;
1da177e4 LT	492	int error;
1da177e4 LT	493
2d8f3038	494	error = user_path(pathname, &path);
1da177e4 LT	495	if (error)
1da177e4 LT	496	return error;
2d8f3038	497	error = mnt_want_write(path.mnt);
18f335af	498	if (!error) {
2d8f3038 AV	499	error = removexattr(path.dentry, name);
2d8f3038 AV	500	mnt_drop_write(path.mnt);
18f335af	501	}
2d8f3038	502	path_put(&path);
1da177e4 LT	503	return error;
	504	}
	505
	506	asmlinkage long
2d8f3038	507	sys_lremovexattr(const char __user pathname, const char __user name)
1da177e4	508	{
2d8f3038	509	struct path path;
1da177e4 LT	510	int error;
1da177e4 LT	511
2d8f3038	512	error = user_lpath(pathname, &path);
1da177e4 LT	513	if (error)
1da177e4 LT	514	return error;
2d8f3038	515	error = mnt_want_write(path.mnt);
18f335af	516	if (!error) {
2d8f3038 AV	517	error = removexattr(path.dentry, name);
2d8f3038 AV	518	mnt_drop_write(path.mnt);
18f335af	519	}
2d8f3038	520	path_put(&path);
1da177e4 LT	521	return error;
	522	}
	523
	524	asmlinkage long
8f0cfa52	525	sys_fremovexattr(int fd, const char __user *name)
1da177e4 LT	526	{
1da177e4 LT	527	struct file *f;
73241ccc	528	struct dentry *dentry;
1da177e4 LT	529	int error = -EBADF;
	530
	531	f = fget(fd);
	532	if (!f)
	533	return error;
0f7fc9e4	534	dentry = f->f_path.dentry;
5a190ae6	535	audit_inode(NULL, dentry);
18f335af DH	536	error = mnt_want_write(f->f_path.mnt);
	537	if (!error) {
	538	error = removexattr(dentry, name);
	539	mnt_drop_write(f->f_path.mnt);
	540	}
1da177e4 LT	541	fput(f);
	542	return error;
	543	}
	544
	545
	546	static const char *
	547	strcmp_prefix(const char a, const char a_prefix)
	548	{
	549	while (a_prefix && a == *a_prefix) {
	550	a++;
	551	a_prefix++;
	552	}
	553	return *a_prefix ? NULL : a;
	554	}
	555
	556	/*
	557	* In order to implement different sets of xattr operations for each xattr
	558	* prefix with the generic xattr API, a filesystem should create a
	559	* null-terminated array of struct xattr_handler (one for each prefix) and
	560	* hang a pointer to it off of the s_xattr field of the superblock.
	561	*
	562	* The generic_fooxattr() functions will use this list to dispatch xattr
	563	* operations to the correct xattr_handler.
	564	*/
	565	#define for_each_xattr_handler(handlers, handler) \
	566	for ((handler) = *(handlers)++; \
	567	(handler) != NULL; \
	568	(handler) = *(handlers)++)
	569
	570	/*
	571	* Find the xattr_handler with the matching prefix.
	572	*/
	573	static struct xattr_handler *
	574	xattr_resolve_name(struct xattr_handler handlers, const char name)
	575	{
	576	struct xattr_handler *handler;
	577
	578	if (!*name)
	579	return NULL;
	580
	581	for_each_xattr_handler(handlers, handler) {
	582	const char n = strcmp_prefix(name, handler->prefix);
	583	if (n) {
	584	*name = n;
	585	break;
	586	}
	587	}
	588	return handler;
	589	}
	590
	591	/*
	592	* Find the handler for the prefix and dispatch its get() operation.
	593	*/
	594	ssize_t
	595	generic_getxattr(struct dentry dentry, const char name, void *buffer, size_t size)
	596	{
	597	struct xattr_handler *handler;
	598	struct inode *inode = dentry->d_inode;
	599
	600	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
	601	if (!handler)
	602	return -EOPNOTSUPP;
	603	return handler->get(inode, name, buffer, size);
	604	}
605
606	/*
607	* Combine the results of the list() operation from every xattr_handler in the
608	* list.
609	*/
610	ssize_t
611	generic_listxattr(struct dentry dentry, char buffer, size_t buffer_size)
612	{
613	struct inode *inode = dentry->d_inode;
614	struct xattr_handler handler, *handlers = inode->i_sb->s_xattr;
615	unsigned int size = 0;
616
617	if (!buffer) {
618	for_each_xattr_handler(handlers, handler)
619	size += handler->list(inode, NULL, 0, NULL, 0);
620	} else {
621	char *buf = buffer;
622
623	for_each_xattr_handler(handlers, handler) {
624	size = handler->list(inode, buf, buffer_size, NULL, 0);
625	if (size > buffer_size)
626	return -ERANGE;
627	buf += size;
628	buffer_size -= size;
629	}
630	size = buf - buffer;
631	}
632	return size;
633	}
634
635	/*
636	* Find the handler for the prefix and dispatch its set() operation.
637	*/
638	int
639	generic_setxattr(struct dentry dentry, const char name, const void *value, size_t size, int flags)
640	{
641	struct xattr_handler *handler;
642	struct inode *inode = dentry->d_inode;
643
644	if (size == 0)
645	value = ""; /* empty EA, do not remove */
646	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
647	if (!handler)
648	return -EOPNOTSUPP;
649	return handler->set(inode, name, value, size, flags);
650	}
651
652	/*
653	* Find the handler for the prefix and dispatch its set() operation to remove
654	* any associated extended attribute.
655	*/
656	int
657	generic_removexattr(struct dentry dentry, const char name)
658	{
659	struct xattr_handler *handler;
660	struct inode *inode = dentry->d_inode;
661
662	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
663	if (!handler)
664	return -EOPNOTSUPP;
665	return handler->set(inode, name, NULL, 0, XATTR_REPLACE);
666	}
667
668	EXPORT_SYMBOL(generic_getxattr);
669	EXPORT_SYMBOL(generic_listxattr);
670	EXPORT_SYMBOL(generic_setxattr);
671	EXPORT_SYMBOL(generic_removexattr);