d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

6762 POSIX write should imply DELETE_CHILD on directories - and

Browse Source 
some additional considerations

Reviewed by: Gordon Ross <gwr@nexenta.com>
Reviewed by: Yuri Pankov <yuri.pankov@nexenta.com>
Author: Kevin Crowe <kevin.crowe@nexenta.com>

openzfs/openzfs@d316fffc9c
This commit is contained in:
Alexander Motin 2016-05-11 12:58:12 +00:00
parent 8dae715e56
commit bc74124f24
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/vendor-sys/illumos/dist/; revision=299442
3 changed files with 208 additions and 112 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
common/acl/acl_common.c
View File

@ -20,7 +20,7 @@
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
* Copyright 2014 Nexenta Systems, Inc. All rights reserved.
*/
#include <sys/types.h>
@ -1575,7 +1575,8 @@ acl_trivial_access_masks(mode_t mode, boolean_t isdir, trivial_acl_t *masks)
uint32_t write_mask = ACE_WRITE_DATA|ACE_APPEND_DATA;
uint32_t execute_mask = ACE_EXECUTE;
(void) isdir; /* will need this later */
if (isdir)
write_mask |= ACE_DELETE_CHILD;
masks->deny1 = 0;
if (!(mode & S_IRUSR) && (mode & (S_IRGRP|S_IROTH)))
@ -1719,10 +1720,17 @@ ace_trivial_common(void *acep, int aclcnt,
return (1);
/*
* Delete permissions are never set by default
* Delete permission is never set by default
*/
if (mask & (ACE_DELETE|ACE_DELETE_CHILD))
if (mask & ACE_DELETE)
return (1);
/*
* Child delete permission should be accompanied by write
*/
if ((mask & ACE_DELETE_CHILD) && !(mask & ACE_WRITE_DATA))
return (1);
/*
* only allow owner@ to have
* write_acl/write_owner/write_attributes/write_xattr/

239
uts/common/fs/zfs/zfs_acl.c
View File

@ -20,8 +20,8 @@
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2013 by Delphix. All rights reserved.
* Copyright 2014 Nexenta Systems, Inc. All rights reserved.
*/
#include <sys/types.h>
@ -2080,7 +2080,7 @@ zfs_zaccess_dataset_check(znode_t *zp, uint32_t v4_mode)
* placed into the working_mode, giving the caller a mask of denied
* accesses. Returns:
* 0 if all AoI granted
* EACCESS if the denied mask is non-zero
* EACCES if the denied mask is non-zero
* other error if abnormal failure (e.g., IO error)
*
* A secondary usage of the function is to determine if any of the
@ -2517,46 +2517,30 @@ zfs_zaccess_unix(znode_t *zp, mode_t mode, cred_t *cr)
return (zfs_zaccess(zp, v4_mode, 0, B_FALSE, cr));
}
static int
zfs_delete_final_check(znode_t *zp, znode_t *dzp,
mode_t available_perms, cred_t *cr)
{
int error;
uid_t downer;
downer = zfs_fuid_map_id(dzp->z_zfsvfs, dzp->z_uid, cr, ZFS_OWNER);
error = secpolicy_vnode_access2(cr, ZTOV(dzp),
downer, available_perms, VWRITE|VEXEC);
if (error == 0)
error = zfs_sticky_remove_access(dzp, zp, cr);
return (error);
}
/* See zfs_zaccess_delete() */
int zfs_write_implies_delete_child = 1;
/*
* Determine whether Access should be granted/deny, without
* consulting least priv subsystem.
* Determine whether delete access should be granted.
*
* The following chart is the recommended NFSv4 enforcement for
* ability to delete an object.
*
* -------------------------------------------------------
* | Parent Dir | Target Object Permissions |
* | Parent Dir | Target Object Permissions |
* | permissions | |
* -------------------------------------------------------
* | | ACL Allows | ACL Denies| Delete |
* | | Delete | Delete | unspecified|
* -------------------------------------------------------
* | ACL Allows | Permit | Permit | Permit |
* | DELETE_CHILD | |
* | ACL Allows | Permit | Permit * | Permit |
* | DELETE_CHILD | | | |
* -------------------------------------------------------
* | ACL Denies | Permit | Deny | Deny |
* | ACL Denies | Permit * | Deny | Deny |
* | DELETE_CHILD | | | |
* -------------------------------------------------------
* | ACL specifies | | | |
* | only allow | Permit | Permit | Permit |
* | only allow | Permit | Permit * | Permit |
* | write and | | | |
* | execute | | | |
* -------------------------------------------------------
@ -2566,91 +2550,174 @@ zfs_delete_final_check(znode_t *zp, znode_t *dzp,
* -------------------------------------------------------
* ^
* |
* No search privilege, can't even look up file?
* Re. execute permission on the directory: if that's missing,
* the vnode lookup of the target will fail before we get here.
*
* Re [*] in the table above: We are intentionally disregarding the
* NFSv4 committee recommendation for these three cells of the matrix
* because that recommendation conflicts with the behavior expected
* by Windows clients for ACL evaluation. See acl.h for notes on
* which ACE_... flags should be checked for which operations.
* Specifically, the NFSv4 committee recommendation is in conflict
* with the Windows interpretation of DENY ACEs, where DENY ACEs
* should take precedence ahead of ALLOW ACEs.
*
* This implementation takes a conservative approach by checking for
* DENY ACEs on both the target object and it's container; checking
* the ACE_DELETE on the target object, and ACE_DELETE_CHILD on the
* container. If a DENY ACE is found for either of those, delete
* access is denied. (Note that DENY ACEs are very rare.)
*
* Note that after these changes, entire the second row and the
* entire middle column of the table above change to Deny.
* Accordingly, the logic here is somewhat simplified.
*
* First check for DENY ACEs that apply.
* If either target or container has a deny, EACCES.
*
* Delete access can then be summarized as follows:
* 1: The object to be deleted grants ACE_DELETE, or
* 2: The containing directory grants ACE_DELETE_CHILD.
* In a Windows system, that would be the end of the story.
* In this system, (2) has some complications...
* 2a: "sticky" bit on a directory adds restrictions, and
* 2b: existing ACEs from previous versions of ZFS may
* not carry ACE_DELETE_CHILD where they should, so we
* also allow delete when ACE_WRITE_DATA is granted.
*
* Note: 2b is technically a work-around for a prior bug,
* which hopefully can go away some day. For those who
* no longer need the work around, and for testing, this
* work-around is made conditional via the tunable:
* zfs_write_implies_delete_child
*/
int
zfs_zaccess_delete(znode_t *dzp, znode_t *zp, cred_t *cr)
{
uint32_t wanted_dirperms;
uint32_t dzp_working_mode = 0;
uint32_t zp_working_mode = 0;
int dzp_error, zp_error;
mode_t available_perms;
boolean_t dzpcheck_privs = B_TRUE;
boolean_t zpcheck_privs = B_TRUE;
/*
* We want specific DELETE permissions to
* take precedence over WRITE/EXECUTE. We don't
* want an ACL such as this to mess us up.
* user:joe:write_data:deny,user:joe:delete:allow
*
* However, deny permissions may ultimately be overridden
* by secpolicy_vnode_access().
*
* We will ask for all of the necessary permissions and then
* look at the working modes from the directory and target object
* to determine what was found.
*/
boolean_t dzpcheck_privs;
boolean_t zpcheck_privs;
if (zp->z_pflags & (ZFS_IMMUTABLE | ZFS_NOUNLINK))
return (SET_ERROR(EPERM));
/*
* First row
* If the directory permissions allow the delete, we are done.
*/
if ((dzp_error = zfs_zaccess_common(dzp, ACE_DELETE_CHILD,
&dzp_working_mode, &dzpcheck_privs, B_FALSE, cr)) == 0)
return (0);
/*
* If target object has delete permission then we are done
*/
if ((zp_error = zfs_zaccess_common(zp, ACE_DELETE, &zp_working_mode,
&zpcheck_privs, B_FALSE, cr)) == 0)
return (0);
ASSERT(dzp_error && zp_error);
if (!dzpcheck_privs)
return (dzp_error);
if (!zpcheck_privs)
return (zp_error);
/*
* Second row
* Case 1:
* If target object grants ACE_DELETE then we are done. This is
* indicated by a return value of 0. For this case we don't worry
* about the sticky bit because sticky only applies to the parent
* directory and this is the child access result.
*
* If directory returns EACCES then delete_child was denied
* due to deny delete_child. In this case send the request through
* secpolicy_vnode_remove(). We don't use zfs_delete_final_check()
* since that *could* allow the delete based on write/execute permission
* and we want delete permissions to override write/execute.
* If we encounter a DENY ACE here, we're also done (EACCES).
* Note that if we hit a DENY ACE here (on the target) it should
* take precedence over a DENY ACE on the container, so that when
* we have more complete auditing support we will be able to
* report an access failure against the specific target.
* (This is part of why we're checking the target first.)
*/
if (dzp_error == EACCES)
zp_error = zfs_zaccess_common(zp, ACE_DELETE, &zp_working_mode,
&zpcheck_privs, B_FALSE, cr);
if (zp_error == EACCES) {
/* We hit a DENY ACE. */
if (!zpcheck_privs)
return (SET_ERROR(zp_error));
return (secpolicy_vnode_remove(cr));
/*
* Third Row
* only need to see if we have write/execute on directory.
*/
}
if (zp_error == 0)
return (0);
dzp_error = zfs_zaccess_common(dzp, ACE_EXECUTE|ACE_WRITE_DATA,
/*
* Case 2:
* If the containing directory grants ACE_DELETE_CHILD,
* or we're in backward compatibility mode and the
* containing directory has ACE_WRITE_DATA, allow.
* Case 2b is handled with wanted_dirperms.
*/
wanted_dirperms = ACE_DELETE_CHILD;
if (zfs_write_implies_delete_child)
wanted_dirperms |= ACE_WRITE_DATA;
dzp_error = zfs_zaccess_common(dzp, wanted_dirperms,
&dzp_working_mode, &dzpcheck_privs, B_FALSE, cr);
if (dzp_error != 0 && !dzpcheck_privs)
return (dzp_error);
if (dzp_error == EACCES) {
/* We hit a DENY ACE. */
if (!dzpcheck_privs)
return (SET_ERROR(dzp_error));
return (secpolicy_vnode_remove(cr));
}
/*
* Fourth row
* Cases 2a, 2b (continued)
*
* Note: dzp_working_mode now contains any permissions
* that were NOT granted. Therefore, if any of the
* wanted_dirperms WERE granted, we will have:
* dzp_working_mode != wanted_dirperms
* We're really asking if ANY of those permissions
* were granted, and if so, grant delete access.
*/
if (dzp_working_mode != wanted_dirperms)
dzp_error = 0;
available_perms = (dzp_working_mode & ACE_WRITE_DATA) ? 0 : VWRITE;
available_perms |= (dzp_working_mode & ACE_EXECUTE) ? 0 : VEXEC;
/*
* dzp_error is 0 if the container granted us permissions to "modify".
* If we do not have permission via one or more ACEs, our current
* privileges may still permit us to modify the container.
*
* dzpcheck_privs is false when i.e. the FS is read-only.
* Otherwise, do privilege checks for the container.
*/
if (dzp_error != 0 && dzpcheck_privs) {
uid_t owner;
return (zfs_delete_final_check(zp, dzp, available_perms, cr));
/*
* The secpolicy call needs the requested access and
* the current access mode of the container, but it
* only knows about Unix-style modes (VEXEC, VWRITE),
* so this must condense the fine-grained ACE bits into
* Unix modes.
*
* The VEXEC flag is easy, because we know that has
* always been checked before we get here (during the
* lookup of the target vnode). The container has not
* granted us permissions to "modify", so we do not set
* the VWRITE flag in the current access mode.
*/
owner = zfs_fuid_map_id(dzp->z_zfsvfs, dzp->z_uid, cr,
ZFS_OWNER);
dzp_error = secpolicy_vnode_access2(cr, ZTOV(dzp),
owner, VEXEC, VWRITE|VEXEC);
}
if (dzp_error != 0) {
/*
* Note: We may have dzp_error = -1 here (from
* zfs_zacess_common). Don't return that.
*/
return (SET_ERROR(EACCES));
}
/*
* At this point, we know that the directory permissions allow
* us to modify, but we still need to check for the additional
* restrictions that apply when the "sticky bit" is set.
*
* Yes, zfs_sticky_remove_access() also checks this bit, but
* checking it here and skipping the call below is nice when
* you're watching all of this with dtrace.
*/
if ((dzp->z_mode & S_ISVTX) == 0)
return (0);
/*
* zfs_sticky_remove_access will succeed if:
* 1. The sticky bit is absent.
* 2. We pass the sticky bit restrictions.
* 3. We have privileges that always allow file removal.
*/
return (zfs_sticky_remove_access(dzp, zp, cr));
}
int

65
uts/common/sys/acl.h
View File

@ -23,6 +23,8 @@
*
* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*
* Copyright 2014 Nexenta Systems, Inc. All rights reserved.
*/
#ifndef _SYS_ACL_H
@ -76,37 +78,55 @@ typedef struct acl_info acl_t;
/*
* The following are defined for ace_t.
*
* Note, these are intentionally the same as the Windows
* "File Access Rights Constants" you can find on MSDN.
* (See also: "Standard Access Rights" on MSDN).
*
* The equivalent Windows names for these are just like
* those show below, with FILE_ in place of ACE_, except
* as noted below. Also note that Windows uses a special
* privilege: BYPASS_TRAVERSE_CHECKING, normally granted
* to everyone, that causes the absence of ACE_TRAVERSE
* to be ignored.
*/
#define ACE_READ_DATA 0x00000001
#define ACE_LIST_DIRECTORY 0x00000001
#define ACE_WRITE_DATA 0x00000002
#define ACE_ADD_FILE 0x00000002
#define ACE_APPEND_DATA 0x00000004
#define ACE_ADD_SUBDIRECTORY 0x00000004
#define ACE_READ_NAMED_ATTRS 0x00000008
#define ACE_WRITE_NAMED_ATTRS 0x00000010
#define ACE_EXECUTE 0x00000020
#define ACE_DELETE_CHILD 0x00000040
#define ACE_READ_ATTRIBUTES 0x00000080
#define ACE_WRITE_ATTRIBUTES 0x00000100
#define ACE_DELETE 0x00010000
#define ACE_READ_ACL 0x00020000
#define ACE_WRITE_ACL 0x00040000
#define ACE_WRITE_OWNER 0x00080000
#define ACE_SYNCHRONIZE 0x00100000
#define ACE_READ_DATA 0x00000001 /* file: read data */
#define ACE_LIST_DIRECTORY 0x00000001 /* dir: list files */
#define ACE_WRITE_DATA 0x00000002 /* file: write data */
#define ACE_ADD_FILE 0x00000002 /* dir: create file */
#define ACE_APPEND_DATA 0x00000004 /* file: append data */
#define ACE_ADD_SUBDIRECTORY 0x00000004 /* dir: create subdir */
#define ACE_READ_NAMED_ATTRS 0x00000008 /* FILE_READ_EA */
#define ACE_WRITE_NAMED_ATTRS 0x00000010 /* FILE_WRITE_EA */
#define ACE_EXECUTE 0x00000020 /* file: execute */
#define ACE_TRAVERSE 0x00000020 /* dir: lookup name */
#define ACE_DELETE_CHILD 0x00000040 /* dir: unlink child */
#define ACE_READ_ATTRIBUTES 0x00000080 /* (all) stat, etc. */
#define ACE_WRITE_ATTRIBUTES 0x00000100 /* (all) utimes, etc. */
#define ACE_DELETE 0x00010000 /* (all) unlink self */
#define ACE_READ_ACL 0x00020000 /* (all) getsecattr */
#define ACE_WRITE_ACL 0x00040000 /* (all) setsecattr */
#define ACE_WRITE_OWNER 0x00080000 /* (all) chown */
#define ACE_SYNCHRONIZE 0x00100000 /* (all) see MSDN */
#define ACE_FILE_INHERIT_ACE 0x0001
#define ACE_DIRECTORY_INHERIT_ACE 0x0002
#define ACE_NO_PROPAGATE_INHERIT_ACE 0x0004
#define ACE_INHERIT_ONLY_ACE 0x0008
/*
* Some of the following are the same as Windows uses. (but NOT ALL!)
* See the "ACE_HEADER" structure description on MSDN for details.
* Comments show relations to the MSDN names.
*/
#define ACE_FILE_INHERIT_ACE 0x0001 /* = OBJECT_INHERIT_ACE */
#define ACE_DIRECTORY_INHERIT_ACE 0x0002 /* = CONTAINER_INHERIT_ACE */
#define ACE_NO_PROPAGATE_INHERIT_ACE 0x0004 /* = NO_PROPAGATE_INHERIT_ACE */
#define ACE_INHERIT_ONLY_ACE 0x0008 /* = INHERIT_ONLY_ACE */
#define ACE_SUCCESSFUL_ACCESS_ACE_FLAG 0x0010
#define ACE_FAILED_ACCESS_ACE_FLAG 0x0020
#define ACE_IDENTIFIER_GROUP 0x0040
#define ACE_INHERITED_ACE 0x0080
#define ACE_INHERITED_ACE 0x0080 /* INHERITED_ACE, 0x10 on NT */
#define ACE_OWNER 0x1000
#define ACE_GROUP 0x2000
#define ACE_EVERYONE 0x4000
/* These four are the same as Windows, but with an ACE_ prefix added. */
#define ACE_ACCESS_ALLOWED_ACE_TYPE 0x0000
#define ACE_ACCESS_DENIED_ACE_TYPE 0x0001
#define ACE_SYSTEM_AUDIT_ACE_TYPE 0x0002
@ -122,6 +142,7 @@ typedef struct acl_info acl_t;
/*
* These are only applicable in a CIFS context.
* Here again, same as Windows, but with an ACE_ prefix added.
*/
#define ACE_ACCESS_ALLOWED_COMPOUND_ACE_TYPE 0x04
#define ACE_ACCESS_ALLOWED_OBJECT_ACE_TYPE 0x05