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linux/fs/gfs2/acl.c
Satyam Sharma 3bd858ab1c Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check 
Introduce is_owner_or_cap() macro in fs.h, and convert over relevant
users to it. This is done because we want to avoid bugs in the future
where we check for only effective fsuid of the current task against a
file's owning uid, without simultaneously checking for CAP_FOWNER as
well, thus violating its semantics.
[ XFS uses special macros and structures, and in general looked ...
untouchable, so we leave it alone -- but it has been looked over. ]

The (current->fsuid != inode->i_uid) check in generic_permission() and
exec_permission_lite() is left alone, because those operations are
covered by CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH. Similarly operations
falling under the purview of CAP_CHOWN and CAP_LEASE are also left alone.

Signed-off-by: Satyam Sharma <ssatyam@cse.iitk.ac.in>
Cc: Al Viro <viro@ftp.linux.org.uk>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 12:00:03 -07:00

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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/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <linux/gfs2_ondisk.h>
#include <linux/lm_interface.h>
#include "gfs2.h"
#include "incore.h"
#include "acl.h"
#include "eaops.h"
#include "eattr.h"
#include "glock.h"
#include "inode.h"
#include "meta_io.h"
#include "trans.h"
#include "util.h"
#define ACL_ACCESS 1
#define ACL_DEFAULT 0
int gfs2_acl_validate_set(struct gfs2_inode *ip, int access,
struct gfs2_ea_request *er,
int *remove, mode_t *mode)
{
struct posix_acl *acl;
int error;
error = gfs2_acl_validate_remove(ip, access);
if (error)
return error;
if (!er->er_data)
return -EINVAL;
acl = posix_acl_from_xattr(er->er_data, er->er_data_len);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (!acl) {
*remove = 1;
return 0;
}
error = posix_acl_valid(acl);
if (error)
goto out;
if (access) {
error = posix_acl_equiv_mode(acl, mode);
if (!error)
*remove = 1;
else if (error > 0)
error = 0;
}
out:
posix_acl_release(acl);
return error;
}
int gfs2_acl_validate_remove(struct gfs2_inode *ip, int access)
{
if (!GFS2_SB(&ip->i_inode)->sd_args.ar_posix_acl)
return -EOPNOTSUPP;
if (!is_owner_or_cap(&ip->i_inode))
return -EPERM;
if (S_ISLNK(ip->i_inode.i_mode))
return -EOPNOTSUPP;
if (!access && !S_ISDIR(ip->i_inode.i_mode))
return -EACCES;
return 0;
}
static int acl_get(struct gfs2_inode *ip, int access, struct posix_acl **acl,
struct gfs2_ea_location *el, char **data, unsigned int *len)
{
struct gfs2_ea_request er;
struct gfs2_ea_location el_this;
int error;
if (!ip->i_di.di_eattr)
return 0;
memset(&er, 0, sizeof(struct gfs2_ea_request));
if (access) {
er.er_name = GFS2_POSIX_ACL_ACCESS;
er.er_name_len = GFS2_POSIX_ACL_ACCESS_LEN;
} else {
er.er_name = GFS2_POSIX_ACL_DEFAULT;
er.er_name_len = GFS2_POSIX_ACL_DEFAULT_LEN;
}
er.er_type = GFS2_EATYPE_SYS;
if (!el)
el = &el_this;
error = gfs2_ea_find(ip, &er, el);
if (error)
return error;
if (!el->el_ea)
return 0;
if (!GFS2_EA_DATA_LEN(el->el_ea))
goto out;
er.er_data_len = GFS2_EA_DATA_LEN(el->el_ea);
er.er_data = kmalloc(er.er_data_len, GFP_KERNEL);
error = -ENOMEM;
if (!er.er_data)
goto out;
error = gfs2_ea_get_copy(ip, el, er.er_data);
if (error)
goto out_kfree;
if (acl) {
*acl = posix_acl_from_xattr(er.er_data, er.er_data_len);
if (IS_ERR(*acl))
error = PTR_ERR(*acl);
}
out_kfree:
if (error || !data)
kfree(er.er_data);
else {
*data = er.er_data;
*len = er.er_data_len;
}
out:
if (error || el == &el_this)
brelse(el->el_bh);
return error;
}
/**
* gfs2_check_acl - Check an ACL to see if we're allowed to do something
* @inode: the file we want to do something to
* @mask: what we want to do
*
* Returns: errno
*/
int gfs2_check_acl(struct inode *inode, int mask)
{
struct posix_acl *acl = NULL;
int error;
error = acl_get(GFS2_I(inode), ACL_ACCESS, &acl, NULL, NULL, NULL);
if (error)
return error;
if (acl) {
error = posix_acl_permission(inode, acl, mask);
posix_acl_release(acl);
return error;
}
return -EAGAIN;
}
static int munge_mode(struct gfs2_inode *ip, mode_t mode)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
struct buffer_head *dibh;
int error;
error = gfs2_trans_begin(sdp, RES_DINODE, 0);
if (error)
return error;
error = gfs2_meta_inode_buffer(ip, &dibh);
if (!error) {
gfs2_assert_withdraw(sdp,
(ip->i_inode.i_mode & S_IFMT) == (mode & S_IFMT));
ip->i_inode.i_mode = mode;
gfs2_trans_add_bh(ip->i_gl, dibh, 1);
gfs2_dinode_out(ip, dibh->b_data);
brelse(dibh);
}
gfs2_trans_end(sdp);
return 0;
}
int gfs2_acl_create(struct gfs2_inode *dip, struct gfs2_inode *ip)
{
struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
struct posix_acl *acl = NULL, *clone;
struct gfs2_ea_request er;
mode_t mode = ip->i_inode.i_mode;
int error;
if (!sdp->sd_args.ar_posix_acl)
return 0;
if (S_ISLNK(ip->i_inode.i_mode))
return 0;
memset(&er, 0, sizeof(struct gfs2_ea_request));
er.er_type = GFS2_EATYPE_SYS;
error = acl_get(dip, ACL_DEFAULT, &acl, NULL,
&er.er_data, &er.er_data_len);
if (error)
return error;
if (!acl) {
mode &= ~current->fs->umask;
if (mode != ip->i_inode.i_mode)
error = munge_mode(ip, mode);
return error;
}
clone = posix_acl_clone(acl, GFP_KERNEL);
error = -ENOMEM;
if (!clone)
goto out;
posix_acl_release(acl);
acl = clone;
if (S_ISDIR(ip->i_inode.i_mode)) {
er.er_name = GFS2_POSIX_ACL_DEFAULT;
er.er_name_len = GFS2_POSIX_ACL_DEFAULT_LEN;
error = gfs2_system_eaops.eo_set(ip, &er);
if (error)
goto out;
}
error = posix_acl_create_masq(acl, &mode);
if (error < 0)
goto out;
if (error > 0) {
er.er_name = GFS2_POSIX_ACL_ACCESS;
er.er_name_len = GFS2_POSIX_ACL_ACCESS_LEN;
posix_acl_to_xattr(acl, er.er_data, er.er_data_len);
er.er_mode = mode;
er.er_flags = GFS2_ERF_MODE;
error = gfs2_system_eaops.eo_set(ip, &er);
if (error)
goto out;
} else
munge_mode(ip, mode);
out:
posix_acl_release(acl);
kfree(er.er_data);
return error;
}
int gfs2_acl_chmod(struct gfs2_inode *ip, struct iattr *attr)
{
struct posix_acl *acl = NULL, *clone;
struct gfs2_ea_location el;
char *data;
unsigned int len;
int error;
error = acl_get(ip, ACL_ACCESS, &acl, &el, &data, &len);
if (error)
return error;
if (!acl)
return gfs2_setattr_simple(ip, attr);
clone = posix_acl_clone(acl, GFP_KERNEL);
error = -ENOMEM;
if (!clone)
goto out;
posix_acl_release(acl);
acl = clone;
error = posix_acl_chmod_masq(acl, attr->ia_mode);
if (!error) {
posix_acl_to_xattr(acl, data, len);
error = gfs2_ea_acl_chmod(ip, &el, attr, data);
}
out:
posix_acl_release(acl);
brelse(el.el_bh);
kfree(data);
return error;
}
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