summaryrefslogtreecommitdiff
path: root/source4/libcli/security/access_check.c
blob: 0ffca1ade893a2e7d7af6ef9944945aa56e9767a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
/*
   Unix SMB/CIFS implementation.

   security access checking routines

   Copyright (C) Andrew Tridgell 2004

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"
#include "librpc/gen_ndr/ndr_security.h"


/*
  check if a sid is in the supplied token
*/
static BOOL sid_active_in_token(const struct dom_sid *sid, 
				const struct security_token *token)
{
	int i;
	for (i=0;i<token->num_sids;i++) {
		if (dom_sid_equal(sid, token->sids[i])) {
			return True;
		}
	}
	return False;
}


/*
  perform a SEC_FLAG_MAXIMUM_ALLOWED access check
*/
static uint32_t access_check_max_allowed(const struct security_descriptor *sd, 
					 const struct security_token *token)
{
	uint32_t denied = 0, granted = 0;
	unsigned i;
	
	if (sid_active_in_token(sd->owner_sid, token)) {
		granted |= SEC_STD_WRITE_DAC | SEC_STD_READ_CONTROL | SEC_STD_DELETE;
	} else if (sec_privilege_check(token, SEC_PRIV_RESTORE)) {
		granted |= SEC_STD_DELETE;
	}

	for (i = 0;i<sd->dacl->num_aces; i++) {
		struct security_ace *ace = &sd->dacl->aces[i];

		if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
			continue;
		}

		if (!sid_active_in_token(&ace->trustee, token)) {
			continue;
		}

		switch (ace->type) {
		case SEC_ACE_TYPE_ACCESS_ALLOWED:
			granted |= ace->access_mask;
			break;
		case SEC_ACE_TYPE_ACCESS_DENIED:
		case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
			denied |= ace->access_mask;
			break;
		default:	/* Other ACE types not handled/supported */
			break;
		}
	}

	return granted & ~denied;
}

/*
  the main entry point for access checking. 
*/
NTSTATUS sec_access_check(const struct security_descriptor *sd, 
			  const struct security_token *token,
			  uint32_t access_desired,
			  uint32_t *access_granted)
{
	int i;
	uint32_t bits_remaining;

	*access_granted = access_desired;
	bits_remaining = access_desired;

	/* handle the maximum allowed flag */
	if (access_desired & SEC_FLAG_MAXIMUM_ALLOWED) {
		access_desired |= access_check_max_allowed(sd, token);
		access_desired &= ~SEC_FLAG_MAXIMUM_ALLOWED;
		*access_granted = access_desired;
		bits_remaining = access_desired & ~SEC_STD_DELETE;
	}

	if (access_desired & SEC_FLAG_SYSTEM_SECURITY) {
		if (sec_privilege_check(token, SEC_PRIV_SECURITY)) {
			bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
		} else {
			return NT_STATUS_ACCESS_DENIED;
		}
	}

	/* dacl not present allows access */
	if (!(sd->type & SEC_DESC_DACL_PRESENT)) {
		*access_granted = access_desired;
		return NT_STATUS_OK;
	}

	/* empty dacl denies access */
	if (sd->dacl == NULL || sd->dacl->num_aces == 0) {
		return NT_STATUS_ACCESS_DENIED;
	}

	/* the owner always gets SEC_STD_WRITE_DAC, SEC_STD_READ_CONTROL and SEC_STD_DELETE */
	if ((bits_remaining & (SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE)) &&
	    sid_active_in_token(sd->owner_sid, token)) {
		bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE);
	}
	if ((bits_remaining & SEC_STD_DELETE) &&
	    sec_privilege_check(token, SEC_PRIV_RESTORE)) {
		bits_remaining &= ~SEC_STD_DELETE;
	}

	/* check each ace in turn. */
	for (i=0; bits_remaining && i < sd->dacl->num_aces; i++) {
		struct security_ace *ace = &sd->dacl->aces[i];

		if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
			continue;
		}

		if (!sid_active_in_token(&ace->trustee, token)) {
			continue;
		}

		switch (ace->type) {
		case SEC_ACE_TYPE_ACCESS_ALLOWED:
			bits_remaining &= ~ace->access_mask;
			break;
		case SEC_ACE_TYPE_ACCESS_DENIED:
		case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
			if (bits_remaining & ace->access_mask) {
				return NT_STATUS_ACCESS_DENIED;
			}
			break;
		default:	/* Other ACE types not handled/supported */
			break;
		}
	}

	if (bits_remaining != 0) {
		return NT_STATUS_ACCESS_DENIED;
	}

	return NT_STATUS_OK;
}