[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->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 = memdup_user(value, size);
		if (IS_ERR(kvalue))
			return PTR_ERR(kvalue);
	}

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

SYSCALL_DEFINE5(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;
}

SYSCALL_DEFINE5(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;
}

SYSCALL_DEFINE5(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_file(f);
	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;
}

SYSCALL_DEFINE4(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;
}

SYSCALL_DEFINE4(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;
}

SYSCALL_DEFINE4(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;
}

SYSCALL_DEFINE3(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;
}

SYSCALL_DEFINE3(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;
}

SYSCALL_DEFINE3(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);
}

SYSCALL_DEFINE2(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;
}

SYSCALL_DEFINE2(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;
}

SYSCALL_DEFINE2(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_file(f);
	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;
acfa4380	178	if (d->d_inode->i_op->listxattr) {
659564c8 BN	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;
3939fcde LZ	240	kvalue = memdup_user(value, size);
	241	if (IS_ERR(kvalue))
	242	return PTR_ERR(kvalue);
1da177e4 LT	243	}
1da177e4 LT	244
5be196e5	245	error = vfs_setxattr(d, kname, kvalue, size, flags);
f99d49ad	246	kfree(kvalue);
1da177e4 LT	247	return error;
	248	}
	249
64fd1de3 HC	250	SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
	251	const char __user , name, const void __user , value,
	252	size_t, size, int, flags)
1da177e4	253	{
2d8f3038	254	struct path path;
1da177e4 LT	255	int error;
1da177e4 LT	256
2d8f3038	257	error = user_path(pathname, &path);
1da177e4 LT	258	if (error)
1da177e4 LT	259	return error;
2d8f3038	260	error = mnt_want_write(path.mnt);
18f335af	261	if (!error) {
2d8f3038 AV	262	error = setxattr(path.dentry, name, value, size, flags);
2d8f3038 AV	263	mnt_drop_write(path.mnt);
18f335af	264	}
2d8f3038	265	path_put(&path);
1da177e4 LT	266	return error;
	267	}
	268
64fd1de3 HC	269	SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
	270	const char __user , name, const void __user , value,
	271	size_t, size, int, flags)
1da177e4	272	{
2d8f3038	273	struct path path;
1da177e4 LT	274	int error;
1da177e4 LT	275
2d8f3038	276	error = user_lpath(pathname, &path);
1da177e4 LT	277	if (error)
1da177e4 LT	278	return error;
2d8f3038	279	error = mnt_want_write(path.mnt);
18f335af	280	if (!error) {
2d8f3038 AV	281	error = setxattr(path.dentry, name, value, size, flags);
2d8f3038 AV	282	mnt_drop_write(path.mnt);
18f335af	283	}
2d8f3038	284	path_put(&path);
1da177e4 LT	285	return error;
	286	}
	287
64fd1de3 HC	288	SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
64fd1de3 HC	289	const void __user *,value, size_t, size, int, flags)
1da177e4 LT	290	{
1da177e4 LT	291	struct file *f;
73241ccc	292	struct dentry *dentry;
1da177e4 LT	293	int error = -EBADF;
	294
	295	f = fget(fd);
	296	if (!f)
	297	return error;
0f7fc9e4	298	dentry = f->f_path.dentry;
5a190ae6	299	audit_inode(NULL, dentry);
96029c4e	300	error = mnt_want_write_file(f);
18f335af DH	301	if (!error) {
	302	error = setxattr(dentry, name, value, size, flags);
	303	mnt_drop_write(f->f_path.mnt);
	304	}
1da177e4 LT	305	fput(f);
	306	return error;
	307	}
	308
	309	/*
	310	* Extended attribute GET operations
	311	*/
	312	static ssize_t
8f0cfa52 DH	313	getxattr(struct dentry d, const char __user name, void __user *value,
8f0cfa52 DH	314	size_t size)
1da177e4 LT	315	{
	316	ssize_t error;
	317	void *kvalue = NULL;
	318	char kname[XATTR_NAME_MAX + 1];
	319
	320	error = strncpy_from_user(kname, name, sizeof(kname));
	321	if (error == 0 \|\| error == sizeof(kname))
	322	error = -ERANGE;
	323	if (error < 0)
	324	return error;
	325
	326	if (size) {
	327	if (size > XATTR_SIZE_MAX)
	328	size = XATTR_SIZE_MAX;
d381d8a9	329	kvalue = kzalloc(size, GFP_KERNEL);
1da177e4 LT	330	if (!kvalue)
	331	return -ENOMEM;
	332	}
	333
5be196e5	334	error = vfs_getxattr(d, kname, kvalue, size);
f549d6c1 SS	335	if (error > 0) {
	336	if (size && copy_to_user(value, kvalue, error))
	337	error = -EFAULT;
	338	} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
	339	/* The file system tried to returned a value bigger
	340	than XATTR_SIZE_MAX bytes. Not possible. */
	341	error = -E2BIG;
1da177e4	342	}
f99d49ad	343	kfree(kvalue);
1da177e4 LT	344	return error;
	345	}
	346
64fd1de3 HC	347	SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
64fd1de3 HC	348	const char __user , name, void __user , value, size_t, size)
1da177e4	349	{
2d8f3038	350	struct path path;
1da177e4 LT	351	ssize_t error;
1da177e4 LT	352
2d8f3038	353	error = user_path(pathname, &path);
1da177e4 LT	354	if (error)
1da177e4 LT	355	return error;
2d8f3038 AV	356	error = getxattr(path.dentry, name, value, size);
2d8f3038 AV	357	path_put(&path);
1da177e4 LT	358	return error;
	359	}
	360
64fd1de3 HC	361	SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
64fd1de3 HC	362	const char __user , name, void __user , value, size_t, size)
1da177e4	363	{
2d8f3038	364	struct path path;
1da177e4 LT	365	ssize_t error;
1da177e4 LT	366
2d8f3038	367	error = user_lpath(pathname, &path);
1da177e4 LT	368	if (error)
1da177e4 LT	369	return error;
2d8f3038 AV	370	error = getxattr(path.dentry, name, value, size);
2d8f3038 AV	371	path_put(&path);
1da177e4 LT	372	return error;
	373	}
	374
64fd1de3 HC	375	SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
64fd1de3 HC	376	void __user *, value, size_t, size)
1da177e4 LT	377	{
	378	struct file *f;
	379	ssize_t error = -EBADF;
	380
	381	f = fget(fd);
	382	if (!f)
	383	return error;
5a190ae6	384	audit_inode(NULL, f->f_path.dentry);
0f7fc9e4	385	error = getxattr(f->f_path.dentry, name, value, size);
1da177e4 LT	386	fput(f);
	387	return error;
	388	}
	389
	390	/*
	391	* Extended attribute LIST operations
	392	*/
	393	static ssize_t
	394	listxattr(struct dentry d, char __user list, size_t size)
	395	{
	396	ssize_t error;
	397	char *klist = NULL;
	398
	399	if (size) {
	400	if (size > XATTR_LIST_MAX)
	401	size = XATTR_LIST_MAX;
	402	klist = kmalloc(size, GFP_KERNEL);
	403	if (!klist)
	404	return -ENOMEM;
	405	}
	406
659564c8	407	error = vfs_listxattr(d, klist, size);
f549d6c1 SS	408	if (error > 0) {
	409	if (size && copy_to_user(list, klist, error))
	410	error = -EFAULT;
	411	} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
	412	/* The file system tried to returned a list bigger
	413	than XATTR_LIST_MAX bytes. Not possible. */
	414	error = -E2BIG;
1da177e4	415	}
f99d49ad	416	kfree(klist);
1da177e4 LT	417	return error;
	418	}
	419
64fd1de3 HC	420	SYSCALL_DEFINE3(listxattr, const char __user , pathname, char __user , list,
64fd1de3 HC	421	size_t, size)
1da177e4	422	{
2d8f3038	423	struct path path;
1da177e4 LT	424	ssize_t error;
1da177e4 LT	425
2d8f3038	426	error = user_path(pathname, &path);
1da177e4 LT	427	if (error)
1da177e4 LT	428	return error;
2d8f3038 AV	429	error = listxattr(path.dentry, list, size);
2d8f3038 AV	430	path_put(&path);
1da177e4 LT	431	return error;
	432	}
	433
64fd1de3 HC	434	SYSCALL_DEFINE3(llistxattr, const char __user , pathname, char __user , list,
64fd1de3 HC	435	size_t, size)
1da177e4	436	{
2d8f3038	437	struct path path;
1da177e4 LT	438	ssize_t error;
1da177e4 LT	439
2d8f3038	440	error = user_lpath(pathname, &path);
1da177e4 LT	441	if (error)
1da177e4 LT	442	return error;
2d8f3038 AV	443	error = listxattr(path.dentry, list, size);
2d8f3038 AV	444	path_put(&path);
1da177e4 LT	445	return error;
	446	}
	447
64fd1de3	448	SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
1da177e4 LT	449	{
	450	struct file *f;
	451	ssize_t error = -EBADF;
	452
	453	f = fget(fd);
	454	if (!f)
	455	return error;
5a190ae6	456	audit_inode(NULL, f->f_path.dentry);
0f7fc9e4	457	error = listxattr(f->f_path.dentry, list, size);
1da177e4 LT	458	fput(f);
	459	return error;
	460	}
	461
	462	/*
	463	* Extended attribute REMOVE operations
	464	*/
	465	static long
8f0cfa52	466	removexattr(struct dentry d, const char __user name)
1da177e4 LT	467	{
	468	int error;
	469	char kname[XATTR_NAME_MAX + 1];
	470
	471	error = strncpy_from_user(kname, name, sizeof(kname));
	472	if (error == 0 \|\| error == sizeof(kname))
	473	error = -ERANGE;
	474	if (error < 0)
	475	return error;
	476
5be196e5	477	return vfs_removexattr(d, kname);
1da177e4 LT	478	}
1da177e4 LT	479
64fd1de3 HC	480	SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
64fd1de3 HC	481	const char __user *, name)
1da177e4	482	{
2d8f3038	483	struct path path;
1da177e4 LT	484	int error;
1da177e4 LT	485
2d8f3038	486	error = user_path(pathname, &path);
1da177e4 LT	487	if (error)
1da177e4 LT	488	return error;
2d8f3038	489	error = mnt_want_write(path.mnt);
18f335af	490	if (!error) {
2d8f3038 AV	491	error = removexattr(path.dentry, name);
2d8f3038 AV	492	mnt_drop_write(path.mnt);
18f335af	493	}
2d8f3038	494	path_put(&path);
1da177e4 LT	495	return error;
	496	}
	497
6a6160a7 HC	498	SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
6a6160a7 HC	499	const char __user *, name)
1da177e4	500	{
2d8f3038	501	struct path path;
1da177e4 LT	502	int error;
1da177e4 LT	503
2d8f3038	504	error = user_lpath(pathname, &path);
1da177e4 LT	505	if (error)
1da177e4 LT	506	return error;
2d8f3038	507	error = mnt_want_write(path.mnt);
18f335af	508	if (!error) {
2d8f3038 AV	509	error = removexattr(path.dentry, name);
2d8f3038 AV	510	mnt_drop_write(path.mnt);
18f335af	511	}
2d8f3038	512	path_put(&path);
1da177e4 LT	513	return error;
	514	}
	515
6a6160a7	516	SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
1da177e4 LT	517	{
1da177e4 LT	518	struct file *f;
73241ccc	519	struct dentry *dentry;
1da177e4 LT	520	int error = -EBADF;
	521
	522	f = fget(fd);
	523	if (!f)
	524	return error;
0f7fc9e4	525	dentry = f->f_path.dentry;
5a190ae6	526	audit_inode(NULL, dentry);
96029c4e	527	error = mnt_want_write_file(f);
18f335af DH	528	if (!error) {
	529	error = removexattr(dentry, name);
	530	mnt_drop_write(f->f_path.mnt);
	531	}
1da177e4 LT	532	fput(f);
	533	return error;
	534	}
	535
	536
	537	static const char *
	538	strcmp_prefix(const char a, const char a_prefix)
	539	{
	540	while (a_prefix && a == *a_prefix) {
	541	a++;
	542	a_prefix++;
	543	}
	544	return *a_prefix ? NULL : a;
	545	}
	546
	547	/*
	548	* In order to implement different sets of xattr operations for each xattr
	549	* prefix with the generic xattr API, a filesystem should create a
	550	* null-terminated array of struct xattr_handler (one for each prefix) and
	551	* hang a pointer to it off of the s_xattr field of the superblock.
	552	*
	553	* The generic_fooxattr() functions will use this list to dispatch xattr
	554	* operations to the correct xattr_handler.
	555	*/
	556	#define for_each_xattr_handler(handlers, handler) \
	557	for ((handler) = *(handlers)++; \
	558	(handler) != NULL; \
	559	(handler) = *(handlers)++)
	560
	561	/*
	562	* Find the xattr_handler with the matching prefix.
	563	*/
	564	static struct xattr_handler *
	565	xattr_resolve_name(struct xattr_handler handlers, const char name)
	566	{
	567	struct xattr_handler *handler;
	568
	569	if (!*name)
	570	return NULL;
	571
	572	for_each_xattr_handler(handlers, handler) {
	573	const char n = strcmp_prefix(name, handler->prefix);
	574	if (n) {
	575	*name = n;
	576	break;
	577	}
	578	}
	579	return handler;
	580	}
	581
	582	/*
	583	* Find the handler for the prefix and dispatch its get() operation.
	584	*/
	585	ssize_t
	586	generic_getxattr(struct dentry dentry, const char name, void *buffer, size_t size)
	587	{
	588	struct xattr_handler *handler;
	589	struct inode *inode = dentry->d_inode;
	590
	591	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
	592	if (!handler)
	593	return -EOPNOTSUPP;
	594	return handler->get(inode, name, buffer, size);
	595	}
596
597	/*
598	* Combine the results of the list() operation from every xattr_handler in the
599	* list.
600	*/
601	ssize_t
602	generic_listxattr(struct dentry dentry, char buffer, size_t buffer_size)
603	{
604	struct inode *inode = dentry->d_inode;
605	struct xattr_handler handler, *handlers = inode->i_sb->s_xattr;
606	unsigned int size = 0;
607
608	if (!buffer) {
609	for_each_xattr_handler(handlers, handler)
610	size += handler->list(inode, NULL, 0, NULL, 0);
611	} else {
612	char *buf = buffer;
613
614	for_each_xattr_handler(handlers, handler) {
615	size = handler->list(inode, buf, buffer_size, NULL, 0);
616	if (size > buffer_size)
617	return -ERANGE;
618	buf += size;
619	buffer_size -= size;
620	}
621	size = buf - buffer;
622	}
623	return size;
624	}
625
626	/*
627	* Find the handler for the prefix and dispatch its set() operation.
628	*/
629	int
630	generic_setxattr(struct dentry dentry, const char name, const void *value, size_t size, int flags)
631	{
632	struct xattr_handler *handler;
633	struct inode *inode = dentry->d_inode;
634
635	if (size == 0)
636	value = ""; /* empty EA, do not remove */
637	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
638	if (!handler)
639	return -EOPNOTSUPP;
640	return handler->set(inode, name, value, size, flags);
641	}
642
643	/*
644	* Find the handler for the prefix and dispatch its set() operation to remove
645	* any associated extended attribute.
646	*/
647	int
648	generic_removexattr(struct dentry dentry, const char name)
649	{
650	struct xattr_handler *handler;
651	struct inode *inode = dentry->d_inode;
652
653	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
654	if (!handler)
655	return -EOPNOTSUPP;
656	return handler->set(inode, name, NULL, 0, XATTR_REPLACE);
657	}
658
659	EXPORT_SYMBOL(generic_getxattr);
660	EXPORT_SYMBOL(generic_listxattr);
661	EXPORT_SYMBOL(generic_setxattr);
662	EXPORT_SYMBOL(generic_removexattr);