acl.c

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/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/xattr.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <linux/gfs2_ondisk.h>

#include "gfs2.h"
#include "incore.h"
#include "acl.h"
#include "xattr.h"
#include "glock.h"
#include "inode.h"
#include "meta_io.h"
#include "trans.h"
#include "util.h"

static const char *gfs2_acl_name(int type)
{
    switch (type) {
    case ACL_TYPE_ACCESS:
        return GFS2_POSIX_ACL_ACCESS;
    case ACL_TYPE_DEFAULT:
        return GFS2_POSIX_ACL_DEFAULT;
    }
    return NULL;
}

struct posix_acl *gfs2_get_acl(struct inode *inode, int type)
{
    struct gfs2_inode *ip = GFS2_I(inode);
    struct posix_acl *acl;
    const char *name;
    char *data;
    int len;

    if (!ip->i_eattr)
        return NULL;

    acl = get_cached_acl(&ip->i_inode, type);
    if (acl != ACL_NOT_CACHED)
        return acl;

    name = gfs2_acl_name(type);
    if (name == NULL)
        return ERR_PTR(-EINVAL);

    len = gfs2_xattr_acl_get(ip, name, &data);
    if (len < 0)
        return ERR_PTR(len);
    if (len == 0)
        return NULL;

    acl = posix_acl_from_xattr(&init_user_ns, data, len);
    kfree(data);
    return acl;
}

static int gfs2_set_mode(struct inode *inode, umode_t mode)
{
    int error = 0;

    if (mode != inode->i_mode) {
        inode->i_mode = mode;
        mark_inode_dirty(inode);
    }

    return error;
}

static int gfs2_acl_set(struct inode *inode, int type, struct posix_acl *acl)
{
    int error;
    int len;
    char *data;
    const char *name = gfs2_acl_name(type);

    BUG_ON(name == NULL);
    len = posix_acl_to_xattr(&init_user_ns, acl, NULL, 0);
    if (len == 0)
        return 0;
    data = kmalloc(len, GFP_NOFS);
    if (data == NULL)
        return -ENOMEM;
    error = posix_acl_to_xattr(&init_user_ns, acl, data, len);
    if (error < 0)
        goto out;
    error = __gfs2_xattr_set(inode, name, data, len, 0, GFS2_EATYPE_SYS);
    if (!error)
        set_cached_acl(inode, type, acl);
out:
    kfree(data);
    return error;
}

int gfs2_acl_create(struct gfs2_inode *dip, struct inode *inode)
{
    struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
    struct posix_acl *acl;
    umode_t mode = inode->i_mode;
    int error = 0;

    if (!sdp->sd_args.ar_posix_acl)
        return 0;
    if (S_ISLNK(inode->i_mode))
        return 0;

    acl = gfs2_get_acl(&dip->i_inode, ACL_TYPE_DEFAULT);
    if (IS_ERR(acl))
        return PTR_ERR(acl);
    if (!acl) {
        mode &= ~current_umask();
        return gfs2_set_mode(inode, mode);
    }

    if (S_ISDIR(inode->i_mode)) {
        error = gfs2_acl_set(inode, ACL_TYPE_DEFAULT, acl);
        if (error)
            goto out;
    }

    error = posix_acl_create(&acl, GFP_NOFS, &mode);
    if (error < 0)
        return error;

    if (error == 0)
        goto munge;

    error = gfs2_acl_set(inode, ACL_TYPE_ACCESS, acl);
    if (error)
        goto out;
munge:
    error = gfs2_set_mode(inode, mode);
out:
    posix_acl_release(acl);
    return error;
}

int gfs2_acl_chmod(struct gfs2_inode *ip, struct iattr *attr)
{
    struct inode *inode = &ip->i_inode;
    struct posix_acl *acl;
    char *data;
    unsigned int len;
    int error;

    acl = gfs2_get_acl(&ip->i_inode, ACL_TYPE_ACCESS);
    if (IS_ERR(acl))
        return PTR_ERR(acl);
    if (!acl)
        return gfs2_setattr_simple(inode, attr);

    error = posix_acl_chmod(&acl, GFP_NOFS, attr->ia_mode);
    if (error)
        return error;

    len = posix_acl_to_xattr(&init_user_ns, acl, NULL, 0);
    data = kmalloc(len, GFP_NOFS);
    error = -ENOMEM;
    if (data == NULL)
        goto out;
    posix_acl_to_xattr(&init_user_ns, acl, data, len);
    error = gfs2_xattr_acl_chmod(ip, attr, data);
    kfree(data);
    set_cached_acl(&ip->i_inode, ACL_TYPE_ACCESS, acl);

out:
    posix_acl_release(acl);
    return error;
}

static int gfs2_acl_type(const char *name)
{
    if (strcmp(name, GFS2_POSIX_ACL_ACCESS) == 0)
        return ACL_TYPE_ACCESS;
    if (strcmp(name, GFS2_POSIX_ACL_DEFAULT) == 0)
        return ACL_TYPE_DEFAULT;
    return -EINVAL;
}

static int gfs2_xattr_system_get(struct dentry *dentry, const char *name,
                 void *buffer, size_t size, int xtype)
{
    struct inode *inode = dentry->d_inode;
    struct gfs2_sbd *sdp = GFS2_SB(inode);
    struct posix_acl *acl;
    int type;
    int error;

    if (!sdp->sd_args.ar_posix_acl)
        return -EOPNOTSUPP;

    type = gfs2_acl_type(name);
    if (type < 0)
        return type;

    acl = gfs2_get_acl(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 gfs2_xattr_system_set(struct dentry *dentry, const char *name,
                 const void *value, size_t size, int flags,
                 int xtype)
{
    struct inode *inode = dentry->d_inode;
    struct gfs2_sbd *sdp = GFS2_SB(inode);
    struct posix_acl *acl = NULL;
    int error = 0, type;

    if (!sdp->sd_args.ar_posix_acl)
        return -EOPNOTSUPP;

    type = gfs2_acl_type(name);
    if (type < 0)
        return type;
    if (flags & XATTR_CREATE)
        return -EINVAL;
    if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
        return value ? -EACCES : 0;
    if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
        return -EPERM;
    if (S_ISLNK(inode->i_mode))
        return -EOPNOTSUPP;

    if (!value)
        goto set_acl;

    acl = posix_acl_from_xattr(&init_user_ns, value, size);
    if (!acl) {
        /*
         * acl_set_file(3) may request that we set default ACLs with
         * zero length -- defend (gracefully) against that here.
         */
        goto out;
    }
    if (IS_ERR(acl)) {
        error = PTR_ERR(acl);
        goto out;
    }

    error = posix_acl_valid(acl);
    if (error)
        goto out_release;

    error = -EINVAL;
    if (acl->a_count > GFS2_ACL_MAX_ENTRIES)
        goto out_release;

    if (type == ACL_TYPE_ACCESS) {
        umode_t mode = inode->i_mode;
        error = posix_acl_equiv_mode(acl, &mode);

        if (error <= 0) {
            posix_acl_release(acl);
            acl = NULL;

            if (error < 0)
                return error;
        }

        error = gfs2_set_mode(inode, mode);
        if (error)
            goto out_release;
    }

set_acl:
    error = __gfs2_xattr_set(inode, name, value, size, 0, GFS2_EATYPE_SYS);
    if (!error) {
        if (acl)
            set_cached_acl(inode, type, acl);
        else
            forget_cached_acl(inode, type);
    }
out_release:
    posix_acl_release(acl);
out:
    return error;
}

const struct xattr_handler gfs2_xattr_system_handler = {
    .prefix = XATTR_SYSTEM_PREFIX,
    .flags  = GFS2_EATYPE_SYS,
    .get    = gfs2_xattr_system_get,
    .set    = gfs2_xattr_system_set,
};