acl.c

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/*
 * Copyright IBM Corporation, 2010
 * Author Aneesh Kumar K.V <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/posix_acl_xattr.h>
#include "xattr.h"
#include "acl.h"
#include "v9fs.h"
#include "v9fs_vfs.h"

static struct posix_acl *__v9fs_get_acl(struct p9_fid *fid, char *name)
{
    ssize_t size;
    void *value = NULL;
    struct posix_acl *acl = NULL;

    size = v9fs_fid_xattr_get(fid, name, NULL, 0);
    if (size > 0) {
        value = kzalloc(size, GFP_NOFS);
        if (!value)
            return ERR_PTR(-ENOMEM);
        size = v9fs_fid_xattr_get(fid, name, value, size);
        if (size > 0) {
            acl = posix_acl_from_xattr(&init_user_ns, value, size);
            if (IS_ERR(acl))
                goto err_out;
        }
    } else if (size == -ENODATA || size == 0 ||
           size == -ENOSYS || size == -EOPNOTSUPP) {
        acl = NULL;
    } else
        acl = ERR_PTR(-EIO);

err_out:
    kfree(value);
    return acl;
}

int v9fs_get_acl(struct inode *inode, struct p9_fid *fid)
{
    int retval = 0;
    struct posix_acl *pacl, *dacl;
    struct v9fs_session_info *v9ses;

    v9ses = v9fs_inode2v9ses(inode);
    if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
            ((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
        set_cached_acl(inode, ACL_TYPE_DEFAULT, NULL);
        set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
        return 0;
    }
    /* get the default/access acl values and cache them */
    dacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_DEFAULT);
    pacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_ACCESS);

    if (!IS_ERR(dacl) && !IS_ERR(pacl)) {
        set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
        set_cached_acl(inode, ACL_TYPE_ACCESS, pacl);
    } else
        retval = -EIO;

    if (!IS_ERR(dacl))
        posix_acl_release(dacl);

    if (!IS_ERR(pacl))
        posix_acl_release(pacl);

    return retval;
}

static struct posix_acl *v9fs_get_cached_acl(struct inode *inode, int type)
{
    struct posix_acl *acl;
    /*
     * 9p Always cache the acl value when
     * instantiating the inode (v9fs_inode_from_fid)
     */
    acl = get_cached_acl(inode, type);
    BUG_ON(acl == ACL_NOT_CACHED);
    return acl;
}

struct posix_acl *v9fs_iop_get_acl(struct inode *inode, int type)
{
    struct v9fs_session_info *v9ses;

    v9ses = v9fs_inode2v9ses(inode);
    if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
            ((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
        /*
         * On access = client  and acl = on mode get the acl
         * values from the server
         */
        return NULL;
    }
    return v9fs_get_cached_acl(inode, type);

}

static int v9fs_set_acl(struct dentry *dentry, int type, struct posix_acl *acl)
{
    int retval;
    char *name;
    size_t size;
    void *buffer;
    struct inode *inode = dentry->d_inode;

    set_cached_acl(inode, type, acl);

    if (!acl)
        return 0;

    /* Set a setxattr request to server */
    size = posix_acl_xattr_size(acl->a_count);
    buffer = kmalloc(size, GFP_KERNEL);
    if (!buffer)
        return -ENOMEM;
    retval = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
    if (retval < 0)
        goto err_free_out;
    switch (type) {
    case ACL_TYPE_ACCESS:
        name = POSIX_ACL_XATTR_ACCESS;
        break;
    case ACL_TYPE_DEFAULT:
        name = POSIX_ACL_XATTR_DEFAULT;
        break;
    default:
        BUG();
    }
    retval = v9fs_xattr_set(dentry, name, buffer, size, 0);
err_free_out:
    kfree(buffer);
    return retval;
}

int v9fs_acl_chmod(struct dentry *dentry)
{
    int retval = 0;
    struct posix_acl *acl;
    struct inode *inode = dentry->d_inode;

    if (S_ISLNK(inode->i_mode))
        return -EOPNOTSUPP;
    acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
    if (acl) {
        retval = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
        if (retval)
            return retval;
        retval = v9fs_set_acl(dentry, ACL_TYPE_ACCESS, acl);
        posix_acl_release(acl);
    }
    return retval;
}

int v9fs_set_create_acl(struct dentry *dentry,
            struct posix_acl **dpacl, struct posix_acl **pacl)
{
    if (dentry) {
        v9fs_set_acl(dentry, ACL_TYPE_DEFAULT, *dpacl);
        v9fs_set_acl(dentry, ACL_TYPE_ACCESS, *pacl);
    }
    posix_acl_release(*dpacl);
    posix_acl_release(*pacl);
    *dpacl = *pacl = NULL;
    return 0;
}

int v9fs_acl_mode(struct inode *dir, umode_t *modep,
          struct posix_acl **dpacl, struct posix_acl **pacl)
{
    int retval = 0;
    umode_t mode = *modep;
    struct posix_acl *acl = NULL;

    if (!S_ISLNK(mode)) {
        acl = v9fs_get_cached_acl(dir, ACL_TYPE_DEFAULT);
        if (IS_ERR(acl))
            return PTR_ERR(acl);
        if (!acl)
            mode &= ~current_umask();
    }
    if (acl) {
        if (S_ISDIR(mode))
            *dpacl = posix_acl_dup(acl);
        retval = posix_acl_create(&acl, GFP_NOFS, &mode);
        if (retval < 0)
            return retval;
        if (retval > 0)
            *pacl = acl;
        else
            posix_acl_release(acl);
    }
    *modep  = mode;
    return 0;
}

static int v9fs_remote_get_acl(struct dentry *dentry, const char *name,
                   void *buffer, size_t size, int type)
{
    char *full_name;

    switch (type) {
    case ACL_TYPE_ACCESS:
        full_name =  POSIX_ACL_XATTR_ACCESS;
        break;
    case ACL_TYPE_DEFAULT:
        full_name = POSIX_ACL_XATTR_DEFAULT;
        break;
    default:
        BUG();
    }
    return v9fs_xattr_get(dentry, full_name, buffer, size);
}

static int v9fs_xattr_get_acl(struct dentry *dentry, const char *name,
                  void *buffer, size_t size, int type)
{
    struct v9fs_session_info *v9ses;
    struct posix_acl *acl;
    int error;

    if (strcmp(name, "") != 0)
        return -EINVAL;

    v9ses = v9fs_dentry2v9ses(dentry);
    /*
     * We allow set/get/list of acl when access=client is not specified
     */
    if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
        return v9fs_remote_get_acl(dentry, name, buffer, size, type);

    acl = v9fs_get_cached_acl(dentry->d_inode, type);
    if (IS_ERR(acl))
        return PTR_ERR(acl);
    if (acl == NULL)
        return -ENODATA;
    error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
    posix_acl_release(acl);

    return error;
}

static int v9fs_remote_set_acl(struct dentry *dentry, const char *name,
                  const void *value, size_t size,
                  int flags, int type)
{
    char *full_name;

    switch (type) {
    case ACL_TYPE_ACCESS:
        full_name =  POSIX_ACL_XATTR_ACCESS;
        break;
    case ACL_TYPE_DEFAULT:
        full_name = POSIX_ACL_XATTR_DEFAULT;
        break;
    default:
        BUG();
    }
    return v9fs_xattr_set(dentry, full_name, value, size, flags);
}


static int v9fs_xattr_set_acl(struct dentry *dentry, const char *name,
                  const void *value, size_t size,
                  int flags, int type)
{
    int retval;
    struct posix_acl *acl;
    struct v9fs_session_info *v9ses;
    struct inode *inode = dentry->d_inode;

    if (strcmp(name, "") != 0)
        return -EINVAL;

    v9ses = v9fs_dentry2v9ses(dentry);
    /*
     * set the attribute on the remote. Without even looking at the
     * xattr value. We leave it to the server to validate
     */
    if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
        return v9fs_remote_set_acl(dentry, name,
                       value, size, flags, type);

    if (S_ISLNK(inode->i_mode))
        return -EOPNOTSUPP;
    if (!inode_owner_or_capable(inode))
        return -EPERM;
    if (value) {
        /* update the cached acl value */
        acl = posix_acl_from_xattr(&init_user_ns, value, size);
        if (IS_ERR(acl))
            return PTR_ERR(acl);
        else if (acl) {
            retval = posix_acl_valid(acl);
            if (retval)
                goto err_out;
        }
    } else
        acl = NULL;

    switch (type) {
    case ACL_TYPE_ACCESS:
        name = POSIX_ACL_XATTR_ACCESS;
        if (acl) {
            umode_t mode = inode->i_mode;
            retval = posix_acl_equiv_mode(acl, &mode);
            if (retval < 0)
                goto err_out;
            else {
                struct iattr iattr;
                if (retval == 0) {
                    /*
                     * ACL can be represented
                     * by the mode bits. So don't
                     * update ACL.
                     */
                    acl = NULL;
                    value = NULL;
                    size = 0;
                }
                /* Updte the mode bits */
                iattr.ia_mode = ((mode & S_IALLUGO) |
                         (inode->i_mode & ~S_IALLUGO));
                iattr.ia_valid = ATTR_MODE;
                /* FIXME should we update ctime ?
                 * What is the following setxattr update the
                 * mode ?
                 */
                v9fs_vfs_setattr_dotl(dentry, &iattr);
            }
        }
        break;
    case ACL_TYPE_DEFAULT:
        name = POSIX_ACL_XATTR_DEFAULT;
        if (!S_ISDIR(inode->i_mode)) {
            retval = acl ? -EINVAL : 0;
            goto err_out;
        }
        break;
    default:
        BUG();
    }
    retval = v9fs_xattr_set(dentry, name, value, size, flags);
    if (!retval)
        set_cached_acl(inode, type, acl);
err_out:
    posix_acl_release(acl);
    return retval;
}

const struct xattr_handler v9fs_xattr_acl_access_handler = {
    .prefix = POSIX_ACL_XATTR_ACCESS,
    .flags  = ACL_TYPE_ACCESS,
    .get    = v9fs_xattr_get_acl,
    .set    = v9fs_xattr_set_acl,
};

const struct xattr_handler v9fs_xattr_acl_default_handler = {
    .prefix = POSIX_ACL_XATTR_DEFAULT,
    .flags  = ACL_TYPE_DEFAULT,
    .get    = v9fs_xattr_get_acl,
    .set    = v9fs_xattr_set_acl,
};