root/fs/xattr.c

/*
  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>
 */
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/file.h>
#include <linux/xattr.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <asm/uaccess.h>

/*
 * 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 = -EOPNOTSUPP;
        if (d->d_inode->i_op && d->d_inode->i_op->setxattr) {
                down(&d->d_inode->i_sem);
                error = security_inode_setxattr(d, kname, kvalue, size, flags);
                if (error)
                        goto out;
                error = d->d_inode->i_op->setxattr(d, kname, kvalue, size, flags);
                if (!error)
                        security_inode_post_setxattr(d, kname, kvalue, size, flags);
out:
                up(&d->d_inode->i_sem);
        }
        if (kvalue)
                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.dentry, name, value, size, flags);
        path_release(&nd);
        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.dentry, name, value, size, flags);
        path_release(&nd);
        return error;
}

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

        f = fget(fd);
        if (!f)
                return error;
        error = setxattr(f->f_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 = kmalloc(size, GFP_KERNEL);
                if (!kvalue)
                        return -ENOMEM;
        }

        error = -EOPNOTSUPP;
        if (d->d_inode->i_op && d->d_inode->i_op->getxattr) {
                error = security_inode_getxattr(d, kname);
                if (error)
                        goto out;
                error = d->d_inode->i_op->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;
                }
        }
out:
        if (kvalue)
                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.dentry, name, value, size);
        path_release(&nd);
        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.dentry, name, value, size);
        path_release(&nd);
        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;
        error = getxattr(f->f_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 = -EOPNOTSUPP;
        if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
                error = security_inode_listxattr(d);
                if (error)
                        goto out;
                error = d->d_inode->i_op->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;
                }
        }
out:
        if (klist)
                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.dentry, list, size);
        path_release(&nd);
        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.dentry, list, size);
        path_release(&nd);
        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;
        error = listxattr(f->f_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;

        error = -EOPNOTSUPP;
        if (d->d_inode->i_op && d->d_inode->i_op->removexattr) {
                error = security_inode_removexattr(d, kname);
                if (error)
                        goto out;
                down(&d->d_inode->i_sem);
                error = d->d_inode->i_op->removexattr(d, kname);
                up(&d->d_inode->i_sem);
        }
out:
        return error;
}

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.dentry, name);
        path_release(&nd);
        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.dentry, name);
        path_release(&nd);
        return error;
}

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

        f = fget(fd);
        if (!f)
                return error;
        error = removexattr(f->f_dentry, name);
        fput(f);
        return error;
}