/*

File: fs/xattr.c

Extended attribute handling.

Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>

Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>

Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>

*/

#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/evm.h>

#include <linux/syscalls.h>

#include <linux/export.h>

#include <linux/fsnotify.h>

#include <linux/audit.h>

#include <linux/vmalloc.h>

#include <linux/posix_acl_xattr.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 privileged users.

*/

if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {

if (!capable(CAP_SYS_ADMIN))

return (mask & MAY_WRITE) ? -EPERM : -ENODATA;

return 0;

}

/*

* In the user.* namespace, only regular files and directories can have

* extended attributes. For sticky directories, only the owner and

* privileged users 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 (mask & MAY_WRITE) ? -EPERM : -ENODATA;

if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&

(mask & MAY_WRITE) && !inode_owner_or_capable(inode))

return -EPERM;

}

return inode_permission(inode, mask);

}

/**

* __vfs_setxattr_noperm - perform setxattr operation without performing

* permission checks.

*

* @dentry - object to perform setxattr on

* @name - xattr name to set

* @value - value to set @name to

* @size - size of @value

* @flags - flags to pass into filesystem operations

*

* returns the result of the internal setxattr or setsecurity operations.

*

* This function requires the caller to lock the inode's i_mutex before it

* is executed. It also assumes that the caller will make the appropriate

* permission checks.

*/

int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,

const void *value, size_t size, int flags)

{

struct inode *inode = dentry->d_inode;

int error = -EOPNOTSUPP;

int issec = !strncmp(name, XATTR_SECURITY_PREFIX,

XATTR_SECURITY_PREFIX_LEN);

if (issec)

inode->i_flags &= ~S_NOSEC;

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 (issec) {

const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;

error = security_inode_setsecurity(inode, suffix, value,

size, flags);

if (!error)

fsnotify_xattr(dentry);

}

return error;

}

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 = __vfs_setxattr_noperm(dentry, name, value, size, flags);

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);

/*

* vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr

*

* Allocate memory, if not already allocated, or re-allocate correct size,

* before retrieving the extended attribute.

*

* Returns the result of alloc, if failed, or the getxattr operation.

*/

ssize_t

vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,

size_t xattr_size, gfp_t flags)

{

struct inode *inode = dentry->d_inode;

char *value = *xattr_value;

int error;

error = xattr_permission(inode, name, MAY_READ);

if (error)

return error;

if (!inode->i_op->getxattr)

return -EOPNOTSUPP;

error = inode->i_op->getxattr(dentry, name, NULL, 0);

if (error < 0)

return error;

if (!value || (error > xattr_size)) {

value = krealloc(*xattr_value, error + 1, flags);

if (!value)

return -ENOMEM;

memset(value, 0, error + 1);

}

error = inode->i_op->getxattr(dentry, name, value, error);

*xattr_value = value;

return error;

}

/* Compare an extended attribute value with the given value */

int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,

const char *value, size_t size, gfp_t flags)

{

char *xattr_value = NULL;

int rc;

rc = vfs_getxattr_alloc(dentry, xattr_name, &xattr_value, 0, flags);

if (rc < 0)

return rc;

if ((rc != size) || (memcmp(xattr_value, value, rc) != 0))

rc = -EINVAL;

else

rc = 0;

kfree(xattr_value);

return rc;

}

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;

mutex_lock(&inode->i_mutex);

error = security_inode_removexattr(dentry, name);

if (error) {

mutex_unlock(&inode->i_mutex);

return error;

}

error = inode->i_op->removexattr(dentry, name);

mutex_unlock(&inode->i_mutex);

if (!error) {

fsnotify_xattr(dentry);

evm_inode_post_removexattr(dentry, name);

}

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;

void *vvalue = NULL; /* If non-NULL, we used vmalloc() */

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 | __GFP_NOWARN);

if (!kvalue) {

vvalue = vmalloc(size);

if (!vvalue)

return -ENOMEM;

kvalue = vvalue;

}

if (copy_from_user(kvalue, value, size)) {

error = -EFAULT;

goto out;

}

if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||

(strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))

posix_acl_fix_xattr_from_user(kvalue, size);

}

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

out:

if (vvalue)

vfree(vvalue);

else

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;

unsigned int lookup_flags = LOOKUP_FOLLOW;

retry:

error = user_path_at(AT_FDCWD, pathname, lookup_flags, &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);

if (retry_estale(error, lookup_flags)) {

lookup_flags |= LOOKUP_REVAL;

goto retry;

}

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;

unsigned int lookup_flags = 0;

retry:

error = user_path_at(AT_FDCWD, pathname, lookup_flags, &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);

if (retry_estale(error, lookup_flags)) {

lookup_flags |= LOOKUP_REVAL;

goto retry;

}

return error;

}

SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,

const void __user *,value, size_t, size, int, flags)

{

struct fd f = fdget(fd);

struct dentry *dentry;

int error = -EBADF;

if (!f.file)

return error;

dentry = f.file->f_path.dentry;

audit_inode(NULL, dentry, 0);

error = mnt_want_write_file(f.file);

if (!error) {

error = setxattr(dentry, name, value, size, flags);

mnt_drop_write_file(f.file);

}

fdput(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;

void *vvalue = 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 | __GFP_NOWARN);

if (!kvalue) {

vvalue = vmalloc(size);

if (!vvalue)

return -ENOMEM;

kvalue = vvalue;

}

}

error = vfs_getxattr(d, kname, kvalue, size);

if (error > 0) {

if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||

(strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))

posix_acl_fix_xattr_to_user(kvalue, size);

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;

}

if (vvalue)

vfree(vvalue);

else

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;

unsigned int lookup_flags = LOOKUP_FOLLOW;

retry:

error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);

if (error)

return error;

error = getxattr(path.dentry, name, value, size);

path_put(&path);

if (retry_estale(error, lookup_flags)) {

lookup_flags |= LOOKUP_REVAL;

goto retry;

}

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;

unsigned int lookup_flags = 0;

retry:

error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);

if (error)

return error;

error = getxattr(path.dentry, name, value, size);

path_put(&path);

if (retry_estale(error, lookup_flags)) {

lookup_flags |= LOOKUP_REVAL;

goto retry;

}

return error;

}

SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,

void __user *, value, size_t, size)

{

struct fd f = fdget(fd);

ssize_t error = -EBADF;

if (!f.file)

return error;

audit_inode(NULL, f.file->f_path.dentry, 0);

error = getxattr(f.file->f_path.dentry, name, value, size);

fdput(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;

char *vlist = NULL; /* If non-NULL, we used vmalloc() */

if (size) {

if (size > XATTR_LIST_MAX)

size = XATTR_LIST_MAX;

klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL);

if (!klist) {

vlist = vmalloc(size);

if (!vlist)

return -ENOMEM;

klist = vlist;

}

}

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;

}

if (vlist)

vfree(vlist);

else

kfree(klist);

return error;

}

SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,

size_t, size)

{

struct path path;

ssize_t error;

unsigned int lookup_flags = LOOKUP_FOLLOW;

retry:

error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);

if (error)

return error;

error = listxattr(path.dentry, list, size);

path_put(&path);

if (retry_estale(error, lookup_flags)) {

lookup_flags |= LOOKUP_REVAL;

goto retry;

}

return error;

}

SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,

size_t, size)

{

struct path path;

ssize_t error;

unsigned int lookup_flags = 0;

retry:

error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);

if (error)

return error;

error = listxattr(path.dentry, list, size);

path_put(&path);

if (retry_estale(error, lookup_flags)) {

lookup_flags |= LOOKUP_REVAL;

goto retry;

}

return error;

}

SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)

{

struct fd f = fdget(fd);

ssize_t error = -EBADF;

if (!f.file)

return error;

audit_inode(NULL, f.file->f_path.dentry, 0);

error = listxattr(f.file->f_path.dentry, list, size);

fdput(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;

unsigned int lookup_flags = LOOKUP_FOLLOW;

retry:

error = user_path_at(AT_FDCWD, pathname, lookup_flags, &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);

if (retry_estale(error, lookup_flags)) {

lookup_flags |= LOOKUP_REVAL;

goto retry;

}

return error;

}

SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,

const char __user *, name)

{

struct path path;

int error;

unsigned int lookup_flags = 0;

retry:

error = user_path_at(AT_FDCWD, pathname, lookup_flags, &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);

if (retry_estale(error, lookup_flags)) {

lookup_flags |= LOOKUP_REVAL;

goto retry;

}

return error;

}

SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)

{

struct fd f = fdget(fd);

struct dentry *dentry;

int error = -EBADF;

if (!f.file)

return error;

dentry = f.file->f_path.dentry;

audit_inode(NULL, dentry, 0);

error = mnt_want_write_file(f.file);

if (!error) {

error = removexattr(dentry, name);

mnt_drop_write_file(f.file);

}

fdput(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 const struct xattr_handler *

xattr_resolve_name(const struct xattr_handler **handlers, const char **name)

{

const 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)

{

const struct xattr_handler *handler;

handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);

if (!handler)

return -EOPNOTSUPP;

return handler->get(dentry, name, buffer, size, handler->flags);

}

/*

* 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)

{

const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;

unsigned int size = 0;

if (!buffer) {

for_each_xattr_handler(handlers, handler) {

size += handler->list(dentry, NULL, 0, NULL, 0,

handler->flags);

}

} else {

char *buf = buffer;

for_each_xattr_handler(handlers, handler) {

size = handler->list(dentry, buf, buffer_size,

NULL, 0, handler->flags);

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)

{

const struct xattr_handler *handler;

if (size == 0)

value = ""; /* empty EA, do not remove */

handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);

if (!handler)

return -EOPNOTSUPP;

return handler->set(dentry, name, value, size, flags, handler->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)

{

const struct xattr_handler *handler;

handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);

if (!handler)

return -EOPNOTSUPP;

return handler->set(dentry, name, NULL, 0,

XATTR_REPLACE, handler->flags);

}

EXPORT_SYMBOL(generic_getxattr);

EXPORT_SYMBOL(generic_listxattr);

EXPORT_SYMBOL(generic_setxattr);

EXPORT_SYMBOL(generic_removexattr);

/*

* Allocate new xattr and copy in the value; but leave the name to callers.

*/

struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)

{

struct simple_xattr *new_xattr;

size_t len;

/* wrap around? */

len = sizeof(*new_xattr) + size;

if (len <= sizeof(*new_xattr))

return NULL;

new_xattr = kmalloc(len, GFP_KERNEL);

if (!new_xattr)

return NULL;

new_xattr->size = size;

memcpy(new_xattr->value, value, size);

return new_xattr;

}

/*

* xattr GET operation for in-memory/pseudo filesystems

*/

int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,

void *buffer, size_t size)

{

struct simple_xattr *xattr;

int ret = -ENODATA;

spin_lock(&xattrs->lock);

list_for_each_entry(xattr, &xattrs->head, list) {

if (strcmp(name, xattr->name))

continue;

ret = xattr->size;

if (buffer) {

if (size < xattr->size)

ret = -ERANGE;

else

memcpy(buffer, xattr->value, xattr->size);

}

break;

}

spin_unlock(&xattrs->lock);

return ret;

}

static int __simple_xattr_set(struct simple_xattrs *xattrs, const char *name,

const void *value, size_t size, int flags)

{

struct simple_xattr *xattr;

struct simple_xattr *new_xattr = NULL;

int err = 0;

/* value == NULL means remove */

if (value) {

new_xattr = simple_xattr_alloc(value, size);

if (!new_xattr)

return -ENOMEM;

new_xattr->name = kstrdup(name, GFP_KERNEL);

if (!new_xattr->name) {

kfree(new_xattr);

return -ENOMEM;

}

}

spin_lock(&xattrs->lock);

list_for_each_entry(xattr, &xattrs->head, list) {

if (!strcmp(name, xattr->name)) {

if (flags & XATTR_CREATE) {

xattr = new_xattr;

err = -EEXIST;

} else if (new_xattr) {

list_replace(&xattr->list, &new_xattr->list);

} else {

list_del(&xattr->list);

}

goto out;

}

}

if (flags & XATTR_REPLACE) {

xattr = new_xattr;

err = -ENODATA;

} else {

list_add(&new_xattr->list, &xattrs->head);

xattr = NULL;

}

out:

spin_unlock(&xattrs->lock);

if (xattr) {

kfree(xattr->name);

kfree(xattr);

}

return err;

}

/**

* simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems

* @xattrs: target simple_xattr list

* @name: name of the new extended attribute

* @value: value of the new xattr. If %NULL, will remove the attribute

* @size: size of the new xattr

* @flags: %XATTR_{CREATE|REPLACE}

*

* %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails

* with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist;

* otherwise, fails with -ENODATA.

*

* Returns 0 on success, -errno on failure.

*/

int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,

const void *value, size_t size, int flags)

{

if (size == 0)

value = ""; /* empty EA, do not remove */

return __simple_xattr_set(xattrs, name, value, size, flags);

}

/*

* xattr REMOVE operation for in-memory/pseudo filesystems

*/

int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)

{

return __simple_xattr_set(xattrs, name, NULL, 0, XATTR_REPLACE);

}

static bool xattr_is_trusted(const char *name)

{

return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);

}

/*

* xattr LIST operation for in-memory/pseudo filesystems

*/

ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,

size_t size)

{

bool trusted = capable(CAP_SYS_ADMIN);

struct simple_xattr *xattr;

size_t used = 0;

spin_lock(&xattrs->lock);

list_for_each_entry(xattr, &xattrs->head, list) {

size_t len;

/* skip "trusted." attributes for unprivileged callers */

if (!trusted && xattr_is_trusted(xattr->name))

continue;

len = strlen(xattr->name) + 1;

used += len;

if (buffer) {

if (size < used) {

used = -ERANGE;

break;

}

memcpy(buffer, xattr->name, len);

buffer += len;

}

}

spin_unlock(&xattrs->lock);