[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/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_RDONLY(inode))
			return -EROFS;
		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 permission(inode, mask, NULL);
}

int
vfs_setxattr(struct dentry *dentry, char *name, 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, 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, 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, char __user *name, 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(char __user *path, char __user *name, void __user *value,
	     size_t size, int flags)
{
	struct nameidata nd;
	int error;

	error = user_path_walk(path, &nd);
	if (error)
		return error;
	error = setxattr(nd.path.dentry, name, value, size, flags);
	path_put(&nd.path);
	return error;
}

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

	error = user_path_walk_link(path, &nd);
	if (error)
		return error;
	error = setxattr(nd.path.dentry, name, value, size, flags);
	path_put(&nd.path);
	return error;
}

asmlinkage long
sys_fsetxattr(int fd, char __user *name, 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 = setxattr(dentry, name, value, size, flags);
	fput(f);
	return error;
}

/*
 * Extended attribute GET operations
 */
static ssize_t
getxattr(struct dentry *d, 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(char __user *path, char __user *name, void __user *value,
	     size_t size)
{
	struct nameidata nd;
	ssize_t error;

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

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

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

asmlinkage ssize_t
sys_fgetxattr(int fd, 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(char __user *path, char __user *list, size_t size)
{
	struct nameidata nd;
	ssize_t error;

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

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

	error = user_path_walk_link(path, &nd);
	if (error)
		return error;
	error = listxattr(nd.path.dentry, list, size);
	path_put(&nd.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, 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(char __user *path, char __user *name)
{
	struct nameidata nd;
	int error;

	error = user_path_walk(path, &nd);
	if (error)
		return error;
	error = removexattr(nd.path.dentry, name);
	path_put(&nd.path);
	return error;
}

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

	error = user_path_walk_link(path, &nd);
	if (error)
		return error;
	error = removexattr(nd.path.dentry, name);
	path_put(&nd.path);
	return error;
}

asmlinkage long
sys_fremovexattr(int fd, 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 = removexattr(dentry, name);
	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>
	13	#include <linux/xattr.h>
	14	#include <linux/namei.h>
	15	#include <linux/security.h>
	16	#include <linux/syscalls.h>
	17	#include <linux/module.h>
0eeca283	18	#include <linux/fsnotify.h>
73241ccc	19	#include <linux/audit.h>
1da177e4 LT	20	#include <asm/uaccess.h>
1da177e4 LT	21
5be196e5	22
e0ad7b07	23	/*
	24	* Check permissions for extended attribute access. This is a bit complicated
	25	* because different namespaces have very different rules.
	26	*/
	27	static int
	28	xattr_permission(struct inode inode, const char name, int mask)
	29	{
	30	/*
	31	* We can never set or remove an extended attribute on a read-only
	32	* filesystem or on an immutable / append-only inode.
	33	*/
	34	if (mask & MAY_WRITE) {
	35	if (IS_RDONLY(inode))
	36	return -EROFS;
	37	if (IS_IMMUTABLE(inode) \|\| IS_APPEND(inode))
	38	return -EPERM;
	39	}
	40
	41	/*
	42	* No restriction for security.* and system.* from the VFS. Decision
	43	* on these is left to the underlying filesystem / security module.
	44	*/
	45	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) \|\|
	46	!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
	47	return 0;
	48
	49	/*
f1f2d871	50	* The trusted.* namespace can only be accessed by a privileged user.
e0ad7b07	51	*/
	52	if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
	53	return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);
	54
f1f2d871 AG	55	/* In user.* namespace, only regular files and directories can have
	56	* extended attributes. For sticky directories, only the owner and
	57	* privileged user can write attributes.
	58	*/
e0ad7b07	59	if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
f1f2d871 AG	60	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
	61	return -EPERM;
	62	if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
3bd858ab	63	(mask & MAY_WRITE) && !is_owner_or_cap(inode))
e0ad7b07	64	return -EPERM;
	65	}
	66
	67	return permission(inode, mask, NULL);
	68	}
	69
5be196e5 CH	70	int
	71	vfs_setxattr(struct dentry dentry, char name, void *value,
	72	size_t size, int flags)
	73	{
	74	struct inode *inode = dentry->d_inode;
	75	int error;
	76
e0ad7b07	77	error = xattr_permission(inode, name, MAY_WRITE);
	78	if (error)
	79	return error;
	80
5be196e5 CH	81	mutex_lock(&inode->i_mutex);
	82	error = security_inode_setxattr(dentry, name, value, size, flags);
	83	if (error)
	84	goto out;
	85	error = -EOPNOTSUPP;
	86	if (inode->i_op->setxattr) {
	87	error = inode->i_op->setxattr(dentry, name, value, size, flags);
	88	if (!error) {
	89	fsnotify_xattr(dentry);
	90	security_inode_post_setxattr(dentry, name, value,
	91	size, flags);
	92	}
	93	} else if (!strncmp(name, XATTR_SECURITY_PREFIX,
e0ad7b07	94	XATTR_SECURITY_PREFIX_LEN)) {
e0ad7b07	95	const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
5be196e5 CH	96	error = security_inode_setsecurity(inode, suffix, value,
	97	size, flags);
	98	if (!error)
	99	fsnotify_xattr(dentry);
	100	}
	101	out:
	102	mutex_unlock(&inode->i_mutex);
	103	return error;
	104	}
	105	EXPORT_SYMBOL_GPL(vfs_setxattr);
	106
42492594 DQ	107	ssize_t
	108	xattr_getsecurity(struct inode inode, const char name, void *value,
	109	size_t size)
	110	{
	111	void *buffer = NULL;
	112	ssize_t len;
	113
	114	if (!value \|\| !size) {
	115	len = security_inode_getsecurity(inode, name, &buffer, false);
	116	goto out_noalloc;
	117	}
	118
	119	len = security_inode_getsecurity(inode, name, &buffer, true);
	120	if (len < 0)
	121	return len;
	122	if (size < len) {
	123	len = -ERANGE;
	124	goto out;
	125	}
	126	memcpy(value, buffer, len);
	127	out:
	128	security_release_secctx(buffer, len);
	129	out_noalloc:
	130	return len;
	131	}
	132	EXPORT_SYMBOL_GPL(xattr_getsecurity);
	133
5be196e5 CH	134	ssize_t
	135	vfs_getxattr(struct dentry dentry, char name, void *value, size_t size)
	136	{
	137	struct inode *inode = dentry->d_inode;
	138	int error;
	139
e0ad7b07	140	error = xattr_permission(inode, name, MAY_READ);
	141	if (error)
	142	return error;
	143
5be196e5 CH	144	error = security_inode_getxattr(dentry, name);
	145	if (error)
	146	return error;
	147
5be196e5	148	if (!strncmp(name, XATTR_SECURITY_PREFIX,
e0ad7b07	149	XATTR_SECURITY_PREFIX_LEN)) {
e0ad7b07	150	const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
42492594	151	int ret = xattr_getsecurity(inode, suffix, value, size);
5be196e5 CH	152	/*
	153	* Only overwrite the return value if a security module
	154	* is actually active.
	155	*/
4bea5805 DQ	156	if (ret == -EOPNOTSUPP)
	157	goto nolsm;
	158	return ret;
5be196e5	159	}
4bea5805 DQ	160	nolsm:
	161	if (inode->i_op->getxattr)
	162	error = inode->i_op->getxattr(dentry, name, value, size);
	163	else
	164	error = -EOPNOTSUPP;
5be196e5 CH	165
	166	return error;
	167	}
	168	EXPORT_SYMBOL_GPL(vfs_getxattr);
	169
659564c8 BN	170	ssize_t
	171	vfs_listxattr(struct dentry d, char list, size_t size)
	172	{
	173	ssize_t error;
	174
	175	error = security_inode_listxattr(d);
	176	if (error)
	177	return error;
	178	error = -EOPNOTSUPP;
	179	if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
	180	error = d->d_inode->i_op->listxattr(d, list, size);
	181	} else {
	182	error = security_inode_listsecurity(d->d_inode, list, size);
	183	if (size && error > size)
	184	error = -ERANGE;
	185	}
	186	return error;
	187	}
	188	EXPORT_SYMBOL_GPL(vfs_listxattr);
	189
5be196e5 CH	190	int
	191	vfs_removexattr(struct dentry dentry, char name)
	192	{
	193	struct inode *inode = dentry->d_inode;
	194	int error;
	195
	196	if (!inode->i_op->removexattr)
	197	return -EOPNOTSUPP;
	198
e0ad7b07	199	error = xattr_permission(inode, name, MAY_WRITE);
	200	if (error)
	201	return error;
	202
5be196e5 CH	203	error = security_inode_removexattr(dentry, name);
	204	if (error)
	205	return error;
	206
	207	mutex_lock(&inode->i_mutex);
	208	error = inode->i_op->removexattr(dentry, name);
	209	mutex_unlock(&inode->i_mutex);
	210
	211	if (!error)
	212	fsnotify_xattr(dentry);
	213	return error;
	214	}
	215	EXPORT_SYMBOL_GPL(vfs_removexattr);
	216
	217
1da177e4 LT	218	/*
	219	* Extended attribute SET operations
	220	*/
	221	static long
	222	setxattr(struct dentry d, char __user name, void __user *value,
	223	size_t size, int flags)
	224	{
	225	int error;
	226	void *kvalue = NULL;
	227	char kname[XATTR_NAME_MAX + 1];
	228
	229	if (flags & ~(XATTR_CREATE\|XATTR_REPLACE))
	230	return -EINVAL;
	231
	232	error = strncpy_from_user(kname, name, sizeof(kname));
	233	if (error == 0 \|\| error == sizeof(kname))
	234	error = -ERANGE;
	235	if (error < 0)
	236	return error;
	237
	238	if (size) {
	239	if (size > XATTR_SIZE_MAX)
	240	return -E2BIG;
	241	kvalue = kmalloc(size, GFP_KERNEL);
	242	if (!kvalue)
	243	return -ENOMEM;
	244	if (copy_from_user(kvalue, value, size)) {
	245	kfree(kvalue);
	246	return -EFAULT;
	247	}
	248	}
	249
5be196e5	250	error = vfs_setxattr(d, kname, kvalue, size, flags);
f99d49ad	251	kfree(kvalue);
1da177e4 LT	252	return error;
	253	}
	254
	255	asmlinkage long
	256	sys_setxattr(char __user path, char __user name, void __user *value,
	257	size_t size, int flags)
	258	{
	259	struct nameidata nd;
	260	int error;
	261
	262	error = user_path_walk(path, &nd);
	263	if (error)
	264	return error;
4ac91378	265	error = setxattr(nd.path.dentry, name, value, size, flags);
1d957f9b	266	path_put(&nd.path);
1da177e4 LT	267	return error;
	268	}
	269
	270	asmlinkage long
	271	sys_lsetxattr(char __user path, char __user name, void __user *value,
	272	size_t size, int flags)
	273	{
	274	struct nameidata nd;
	275	int error;
	276
	277	error = user_path_walk_link(path, &nd);
	278	if (error)
	279	return error;
4ac91378	280	error = setxattr(nd.path.dentry, name, value, size, flags);
1d957f9b	281	path_put(&nd.path);
1da177e4 LT	282	return error;
	283	}
	284
	285	asmlinkage long
	286	sys_fsetxattr(int fd, char __user name, void __user value,
	287	size_t size, int flags)
	288	{
	289	struct file *f;
73241ccc	290	struct dentry *dentry;
1da177e4 LT	291	int error = -EBADF;
	292
	293	f = fget(fd);
	294	if (!f)
	295	return error;
0f7fc9e4	296	dentry = f->f_path.dentry;
5a190ae6	297	audit_inode(NULL, dentry);
73241ccc	298	error = setxattr(dentry, name, value, size, flags);
1da177e4 LT	299	fput(f);
	300	return error;
	301	}
	302
	303	/*
	304	* Extended attribute GET operations
	305	*/
	306	static ssize_t
	307	getxattr(struct dentry d, char __user name, void __user *value, size_t size)
	308	{
	309	ssize_t error;
	310	void *kvalue = NULL;
	311	char kname[XATTR_NAME_MAX + 1];
	312
	313	error = strncpy_from_user(kname, name, sizeof(kname));
	314	if (error == 0 \|\| error == sizeof(kname))
	315	error = -ERANGE;
	316	if (error < 0)
	317	return error;
	318
	319	if (size) {
	320	if (size > XATTR_SIZE_MAX)
	321	size = XATTR_SIZE_MAX;
d381d8a9	322	kvalue = kzalloc(size, GFP_KERNEL);
1da177e4 LT	323	if (!kvalue)
	324	return -ENOMEM;
	325	}
	326
5be196e5	327	error = vfs_getxattr(d, kname, kvalue, size);
f549d6c1 SS	328	if (error > 0) {
	329	if (size && copy_to_user(value, kvalue, error))
	330	error = -EFAULT;
	331	} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
	332	/* The file system tried to returned a value bigger
	333	than XATTR_SIZE_MAX bytes. Not possible. */
	334	error = -E2BIG;
1da177e4	335	}
f99d49ad	336	kfree(kvalue);
1da177e4 LT	337	return error;
	338	}
	339
	340	asmlinkage ssize_t
	341	sys_getxattr(char __user path, char __user name, void __user *value,
	342	size_t size)
	343	{
	344	struct nameidata nd;
	345	ssize_t error;
	346
	347	error = user_path_walk(path, &nd);
	348	if (error)
	349	return error;
4ac91378	350	error = getxattr(nd.path.dentry, name, value, size);
1d957f9b	351	path_put(&nd.path);
1da177e4 LT	352	return error;
	353	}
	354
	355	asmlinkage ssize_t
	356	sys_lgetxattr(char __user path, char __user name, void __user *value,
	357	size_t size)
	358	{
	359	struct nameidata nd;
	360	ssize_t error;
	361
	362	error = user_path_walk_link(path, &nd);
	363	if (error)
	364	return error;
4ac91378	365	error = getxattr(nd.path.dentry, name, value, size);
1d957f9b	366	path_put(&nd.path);
1da177e4 LT	367	return error;
	368	}
	369
	370	asmlinkage ssize_t
	371	sys_fgetxattr(int fd, char __user name, void __user value, size_t size)
	372	{
	373	struct file *f;
	374	ssize_t error = -EBADF;
	375
	376	f = fget(fd);
	377	if (!f)
	378	return error;
5a190ae6	379	audit_inode(NULL, f->f_path.dentry);
0f7fc9e4	380	error = getxattr(f->f_path.dentry, name, value, size);
1da177e4 LT	381	fput(f);
	382	return error;
	383	}
	384
	385	/*
	386	* Extended attribute LIST operations
	387	*/
	388	static ssize_t
	389	listxattr(struct dentry d, char __user list, size_t size)
	390	{
	391	ssize_t error;
	392	char *klist = NULL;
	393
	394	if (size) {
	395	if (size > XATTR_LIST_MAX)
	396	size = XATTR_LIST_MAX;
	397	klist = kmalloc(size, GFP_KERNEL);
	398	if (!klist)
	399	return -ENOMEM;
	400	}
	401
659564c8	402	error = vfs_listxattr(d, klist, size);
f549d6c1 SS	403	if (error > 0) {
	404	if (size && copy_to_user(list, klist, error))
	405	error = -EFAULT;
	406	} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
	407	/* The file system tried to returned a list bigger
	408	than XATTR_LIST_MAX bytes. Not possible. */
	409	error = -E2BIG;
1da177e4	410	}
f99d49ad	411	kfree(klist);
1da177e4 LT	412	return error;
	413	}
	414
	415	asmlinkage ssize_t
	416	sys_listxattr(char __user path, char __user list, size_t size)
	417	{
	418	struct nameidata nd;
	419	ssize_t error;
	420
	421	error = user_path_walk(path, &nd);
	422	if (error)
	423	return error;
4ac91378	424	error = listxattr(nd.path.dentry, list, size);
1d957f9b	425	path_put(&nd.path);
1da177e4 LT	426	return error;
	427	}
	428
	429	asmlinkage ssize_t
	430	sys_llistxattr(char __user path, char __user list, size_t size)
	431	{
	432	struct nameidata nd;
	433	ssize_t error;
	434
	435	error = user_path_walk_link(path, &nd);
	436	if (error)
	437	return error;
4ac91378	438	error = listxattr(nd.path.dentry, list, size);
1d957f9b	439	path_put(&nd.path);
1da177e4 LT	440	return error;
	441	}
	442
	443	asmlinkage ssize_t
	444	sys_flistxattr(int fd, char __user *list, size_t size)
	445	{
	446	struct file *f;
	447	ssize_t error = -EBADF;
	448
	449	f = fget(fd);
	450	if (!f)
	451	return error;
5a190ae6	452	audit_inode(NULL, f->f_path.dentry);
0f7fc9e4	453	error = listxattr(f->f_path.dentry, list, size);
1da177e4 LT	454	fput(f);
	455	return error;
	456	}
	457
	458	/*
	459	* Extended attribute REMOVE operations
	460	*/
	461	static long
	462	removexattr(struct dentry d, char __user name)
	463	{
	464	int error;
	465	char kname[XATTR_NAME_MAX + 1];
	466
	467	error = strncpy_from_user(kname, name, sizeof(kname));
	468	if (error == 0 \|\| error == sizeof(kname))
	469	error = -ERANGE;
	470	if (error < 0)
	471	return error;
	472
5be196e5	473	return vfs_removexattr(d, kname);
1da177e4 LT	474	}
	475
	476	asmlinkage long
	477	sys_removexattr(char __user path, char __user name)
	478	{
	479	struct nameidata nd;
	480	int error;
	481
	482	error = user_path_walk(path, &nd);
	483	if (error)
	484	return error;
4ac91378	485	error = removexattr(nd.path.dentry, name);
1d957f9b	486	path_put(&nd.path);
1da177e4 LT	487	return error;
	488	}
	489
	490	asmlinkage long
	491	sys_lremovexattr(char __user path, char __user name)
	492	{
	493	struct nameidata nd;
	494	int error;
	495
	496	error = user_path_walk_link(path, &nd);
	497	if (error)
	498	return error;
4ac91378	499	error = removexattr(nd.path.dentry, name);
1d957f9b	500	path_put(&nd.path);
1da177e4 LT	501	return error;
	502	}
	503
	504	asmlinkage long
	505	sys_fremovexattr(int fd, char __user *name)
	506	{
	507	struct file *f;
73241ccc	508	struct dentry *dentry;
1da177e4 LT	509	int error = -EBADF;
	510
	511	f = fget(fd);
	512	if (!f)
	513	return error;
0f7fc9e4	514	dentry = f->f_path.dentry;
5a190ae6	515	audit_inode(NULL, dentry);
73241ccc	516	error = removexattr(dentry, name);
1da177e4 LT	517	fput(f);
	518	return error;
	519	}
	520
	521
	522	static const char *
	523	strcmp_prefix(const char a, const char a_prefix)
	524	{
	525	while (a_prefix && a == *a_prefix) {
	526	a++;
	527	a_prefix++;
	528	}
	529	return *a_prefix ? NULL : a;
	530	}
	531
	532	/*
	533	* In order to implement different sets of xattr operations for each xattr
	534	* prefix with the generic xattr API, a filesystem should create a
	535	* null-terminated array of struct xattr_handler (one for each prefix) and
	536	* hang a pointer to it off of the s_xattr field of the superblock.
	537	*
	538	* The generic_fooxattr() functions will use this list to dispatch xattr
	539	* operations to the correct xattr_handler.
	540	*/
	541	#define for_each_xattr_handler(handlers, handler) \
	542	for ((handler) = *(handlers)++; \
	543	(handler) != NULL; \
	544	(handler) = *(handlers)++)
	545
	546	/*
	547	* Find the xattr_handler with the matching prefix.
	548	*/
	549	static struct xattr_handler *
	550	xattr_resolve_name(struct xattr_handler handlers, const char name)
	551	{
	552	struct xattr_handler *handler;
	553
	554	if (!*name)
	555	return NULL;
	556
	557	for_each_xattr_handler(handlers, handler) {
	558	const char n = strcmp_prefix(name, handler->prefix);
	559	if (n) {
	560	*name = n;
	561	break;
	562	}
	563	}
	564	return handler;
	565	}
	566
	567	/*
	568	* Find the handler for the prefix and dispatch its get() operation.
	569	*/
	570	ssize_t
	571	generic_getxattr(struct dentry dentry, const char name, void *buffer, size_t size)
	572	{
	573	struct xattr_handler *handler;
	574	struct inode *inode = dentry->d_inode;
	575
	576	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
	577	if (!handler)
	578	return -EOPNOTSUPP;
	579	return handler->get(inode, name, buffer, size);
	580	}
581
582	/*
583	* Combine the results of the list() operation from every xattr_handler in the
584	* list.
585	*/
586	ssize_t
587	generic_listxattr(struct dentry dentry, char buffer, size_t buffer_size)
588	{
589	struct inode *inode = dentry->d_inode;
590	struct xattr_handler handler, *handlers = inode->i_sb->s_xattr;
591	unsigned int size = 0;
592
593	if (!buffer) {
594	for_each_xattr_handler(handlers, handler)
595	size += handler->list(inode, NULL, 0, NULL, 0);
596	} else {
597	char *buf = buffer;
598
599	for_each_xattr_handler(handlers, handler) {
600	size = handler->list(inode, buf, buffer_size, NULL, 0);
601	if (size > buffer_size)
602	return -ERANGE;
603	buf += size;
604	buffer_size -= size;
605	}
606	size = buf - buffer;
607	}
608	return size;
609	}
610
611	/*
612	* Find the handler for the prefix and dispatch its set() operation.
613	*/
614	int
615	generic_setxattr(struct dentry dentry, const char name, const void *value, size_t size, int flags)
616	{
617	struct xattr_handler *handler;
618	struct inode *inode = dentry->d_inode;
619
620	if (size == 0)
621	value = ""; /* empty EA, do not remove */
622	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
623	if (!handler)
624	return -EOPNOTSUPP;
625	return handler->set(inode, name, value, size, flags);
626	}
627
628	/*
629	* Find the handler for the prefix and dispatch its set() operation to remove
630	* any associated extended attribute.
631	*/
632	int
633	generic_removexattr(struct dentry dentry, const char name)
634	{
635	struct xattr_handler *handler;
636	struct inode *inode = dentry->d_inode;
637
638	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
639	if (!handler)
640	return -EOPNOTSUPP;
641	return handler->set(inode, name, NULL, 0, XATTR_REPLACE);
642	}
643
644	EXPORT_SYMBOL(generic_getxattr);
645	EXPORT_SYMBOL(generic_listxattr);
646	EXPORT_SYMBOL(generic_setxattr);
647	EXPORT_SYMBOL(generic_removexattr);