FreeBSD-5.3/lib/libc/posix1e/acl_support.c
/*-
* Copyright (c) 1999, 2000, 2001 Robert N. M. Watson
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Support functionality for the POSIX.1e ACL interface
* These calls are intended only to be called within the library.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/lib/libc/posix1e/acl_support.c,v 1.13 2003/11/03 21:00:16 rwatson Exp $");
#include <sys/types.h>
#include "namespace.h"
#include <sys/acl.h>
#include "un-namespace.h"
#include <errno.h>
#include <grp.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include "acl_support.h"
#define ACL_STRING_PERM_WRITE 'w'
#define ACL_STRING_PERM_READ 'r'
#define ACL_STRING_PERM_EXEC 'x'
#define ACL_STRING_PERM_NONE '-'
/*
* _posix1e_acl_entry_compare -- compare two acl_entry structures to
* determine the order they should appear in. Used by _posix1e_acl_sort to
* sort ACL entries into the kernel-desired order -- i.e., the order useful
* for evaluation and O(n) validity checking. Beter to have an O(nlogn) sort
* in userland and an O(n) in kernel than to have both in kernel.
*/
typedef int (*compare)(const void *, const void *);
static int
_posix1e_acl_entry_compare(struct acl_entry *a, struct acl_entry *b)
{
/*
* First, sort between tags -- conveniently defined in the correct
* order for verification.
*/
if (a->ae_tag < b->ae_tag)
return (-1);
if (a->ae_tag > b->ae_tag)
return (1);
/*
* Next compare uids/gids on appropriate types.
*/
if (a->ae_tag == ACL_USER || a->ae_tag == ACL_GROUP) {
if (a->ae_id < b->ae_id)
return (-1);
if (a->ae_id > b->ae_id)
return (1);
/* shouldn't be equal, fall through to the invalid case */
}
/*
* Don't know how to sort multiple entries of the rest--either it's
* a bad entry, or there shouldn't be more than one. Ignore and the
* validity checker can get it later.
*/
return (0);
}
/*
* _posix1e_acl_sort -- sort ACL entries in POSIX.1e-formatted ACLs
* Give the opportunity to fail, although we don't currently have a way
* to fail.
*/
int
_posix1e_acl_sort(acl_t acl)
{
struct acl *acl_int;
acl_int = &acl->ats_acl;
qsort(&acl_int->acl_entry[0], acl_int->acl_cnt,
sizeof(struct acl_entry), (compare) _posix1e_acl_entry_compare);
return (0);
}
/*
* acl_posix1e -- in what situations should we acl_sort before submission?
* We apply posix1e ACL semantics for any ACL of type ACL_TYPE_ACCESS or
* ACL_TYPE_DEFAULT
*/
int
_posix1e_acl(acl_t acl, acl_type_t type)
{
return ((type == ACL_TYPE_ACCESS) || (type == ACL_TYPE_DEFAULT));
}
/*
* _posix1e_acl_check -- given an ACL, check its validity. This is mirrored
* from code in sys/kern/kern_acl.c, and if changes are made in one, they
* should be made in the other also. This copy of acl_check is made
* available * in userland for the benefit of processes wanting to check ACLs
* for validity before submitting them to the kernel, or for performing
* in userland file system checking. Needless to say, the kernel makes
* the real checks on calls to get/setacl.
*
* See the comments in kernel for explanation -- just briefly, it assumes
* an already sorted ACL, and checks based on that assumption. The
* POSIX.1e interface, acl_valid(), will perform the sort before calling
* this. Returns 0 on success, EINVAL on failure.
*/
int
_posix1e_acl_check(acl_t acl)
{
struct acl *acl_int;
struct acl_entry *entry; /* current entry */
uid_t obj_uid=-1, obj_gid=-1, highest_uid=0, highest_gid=0;
int stage = ACL_USER_OBJ;
int i = 0;
int count_user_obj=0, count_user=0, count_group_obj=0,
count_group=0, count_mask=0, count_other=0;
acl_int = &acl->ats_acl;
/* printf("_posix1e_acl_check: checking acl with %d entries\n",
acl->acl_cnt); */
while (i < acl_int->acl_cnt) {
entry = &acl_int->acl_entry[i];
if ((entry->ae_perm | ACL_PERM_BITS) != ACL_PERM_BITS)
return (EINVAL);
switch(entry->ae_tag) {
case ACL_USER_OBJ:
/* printf("_posix1e_acl_check: %d: ACL_USER_OBJ\n",
i); */
if (stage > ACL_USER_OBJ)
return (EINVAL);
stage = ACL_USER;
count_user_obj++;
obj_uid = entry->ae_id;
break;
case ACL_USER:
/* printf("_posix1e_acl_check: %d: ACL_USER\n", i); */
if (stage > ACL_USER)
return (EINVAL);
stage = ACL_USER;
if (entry->ae_id == obj_uid)
return (EINVAL);
if (count_user && (entry->ae_id <= highest_uid))
return (EINVAL);
highest_uid = entry->ae_id;
count_user++;
break;
case ACL_GROUP_OBJ:
/* printf("_posix1e_acl_check: %d: ACL_GROUP_OBJ\n",
i); */
if (stage > ACL_GROUP_OBJ)
return (EINVAL);
stage = ACL_GROUP;
count_group_obj++;
obj_gid = entry->ae_id;
break;
case ACL_GROUP:
/* printf("_posix1e_acl_check: %d: ACL_GROUP\n", i); */
if (stage > ACL_GROUP)
return (EINVAL);
stage = ACL_GROUP;
if (entry->ae_id == obj_gid)
return (EINVAL);
if (count_group && (entry->ae_id <= highest_gid))
return (EINVAL);
highest_gid = entry->ae_id;
count_group++;
break;
case ACL_MASK:
/* printf("_posix1e_acl_check: %d: ACL_MASK\n", i); */
if (stage > ACL_MASK)
return (EINVAL);
stage = ACL_MASK;
count_mask++;
break;
case ACL_OTHER:
/* printf("_posix1e_acl_check: %d: ACL_OTHER\n", i); */
if (stage > ACL_OTHER)
return (EINVAL);
stage = ACL_OTHER;
count_other++;
break;
default:
/* printf("_posix1e_acl_check: %d: INVALID\n", i); */
return (EINVAL);
}
i++;
}
if (count_user_obj != 1)
return (EINVAL);
if (count_group_obj != 1)
return (EINVAL);
if (count_mask != 0 && count_mask != 1)
return (EINVAL);
if (count_other != 1)
return (EINVAL);
return (0);
}
/*
* Given a uid/gid, return a username/groupname for the text form of an ACL.
* Note that we truncate user and group names, rather than error out, as
* this is consistent with other tools manipulating user and group names.
* XXX NOT THREAD SAFE, RELIES ON GETPWUID, GETGRGID
* XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE
* MAY HAVE SIDE-EFFECTS
*/
int
_posix1e_acl_id_to_name(acl_tag_t tag, uid_t id, ssize_t buf_len, char *buf)
{
struct group *g;
struct passwd *p;
int i;
switch(tag) {
case ACL_USER:
p = getpwuid(id);
if (!p)
i = snprintf(buf, buf_len, "%d", id);
else
i = snprintf(buf, buf_len, "%s", p->pw_name);
if (i < 0) {
errno = ENOMEM;
return (-1);
}
return (0);
case ACL_GROUP:
g = getgrgid(id);
if (g == NULL)
i = snprintf(buf, buf_len, "%d", id);
else
i = snprintf(buf, buf_len, "%s", g->gr_name);
if (i < 0) {
errno = ENOMEM;
return (-1);
}
return (0);
default:
return (EINVAL);
}
}
/*
* Given a username/groupname from a text form of an ACL, return the uid/gid
* XXX NOT THREAD SAFE, RELIES ON GETPWNAM, GETGRNAM
* XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE
* MAY HAVE SIDE-EFFECTS
*
* XXX currently doesn't deal correctly with a numeric uid being passed
* instead of a username. What is correct behavior here? Check chown.
*/
int
_posix1e_acl_name_to_id(acl_tag_t tag, char *name, uid_t *id)
{
struct group *g;
struct passwd *p;
unsigned long l;
char *endp;
switch(tag) {
case ACL_USER:
p = getpwnam(name);
if (p == NULL) {
l = strtoul(name, &endp, 0);
if (*endp != '\0' || l != (unsigned long)(uid_t)l) {
errno = EINVAL;
return (-1);
}
*id = (uid_t)l;
return (0);
}
*id = p->pw_uid;
return (0);
case ACL_GROUP:
g = getgrnam(name);
if (g == NULL) {
l = strtoul(name, &endp, 0);
if (*endp != '\0' || l != (unsigned long)(gid_t)l) {
errno = EINVAL;
return (-1);
}
*id = (gid_t)l;
return (0);
}
*id = g->gr_gid;
return (0);
default:
return (EINVAL);
}
}
/*
* Given a right-shifted permission (i.e., direct ACL_PERM_* mask), fill
* in a string describing the permissions.
*/
int
_posix1e_acl_perm_to_string(acl_perm_t perm, ssize_t buf_len, char *buf)
{
if (buf_len < _POSIX1E_ACL_STRING_PERM_MAXSIZE + 1) {
errno = ENOMEM;
return (-1);
}
if ((perm | ACL_PERM_BITS) != ACL_PERM_BITS) {
errno = EINVAL;
return (-1);
}
buf[3] = 0; /* null terminate */
if (perm & ACL_READ)
buf[0] = ACL_STRING_PERM_READ;
else
buf[0] = ACL_STRING_PERM_NONE;
if (perm & ACL_WRITE)
buf[1] = ACL_STRING_PERM_WRITE;
else
buf[1] = ACL_STRING_PERM_NONE;
if (perm & ACL_EXECUTE)
buf[2] = ACL_STRING_PERM_EXEC;
else
buf[2] = ACL_STRING_PERM_NONE;
return (0);
}
/*
* given a string, return a permission describing it
*/
int
_posix1e_acl_string_to_perm(char *string, acl_perm_t *perm)
{
acl_perm_t myperm = ACL_PERM_NONE;
char *ch;
ch = string;
while (*ch) {
switch(*ch) {
case ACL_STRING_PERM_READ:
myperm |= ACL_READ;
break;
case ACL_STRING_PERM_WRITE:
myperm |= ACL_WRITE;
break;
case ACL_STRING_PERM_EXEC:
myperm |= ACL_EXECUTE;
break;
case ACL_STRING_PERM_NONE:
break;
default:
return (EINVAL);
}
ch++;
}
*perm = myperm;
return (0);
}
/*
* Add an ACL entry without doing much checking, et al
*/
int
_posix1e_acl_add_entry(acl_t acl, acl_tag_t tag, uid_t id, acl_perm_t perm)
{
struct acl *acl_int;
struct acl_entry *e;
acl_int = &acl->ats_acl;
if (acl_int->acl_cnt >= ACL_MAX_ENTRIES) {
errno = ENOMEM;
return (-1);
}
e = &(acl_int->acl_entry[acl_int->acl_cnt]);
e->ae_perm = perm;
e->ae_tag = tag;
e->ae_id = id;
acl_int->acl_cnt++;
return (0);
}