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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
/*-------------------------------------------------------------------------
*
* restricted_token.c
* helper routine to ensure restricted token on Windows
*
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/common/restricted_token.c
*
*-------------------------------------------------------------------------
*/
#ifndef FRONTEND
#error "This file is not expected to be compiled for backend code"
#endif
#include "postgres_fe.h"
#include "common/logging.h"
#include "common/restricted_token.h"
#ifdef WIN32
/* internal vars */
char *restrict_env;
typedef BOOL (WINAPI * __CreateRestrictedToken) (HANDLE, DWORD, DWORD, PSID_AND_ATTRIBUTES, DWORD, PLUID_AND_ATTRIBUTES, DWORD, PSID_AND_ATTRIBUTES, PHANDLE);
/* Windows API define missing from some versions of MingW headers */
#ifndef DISABLE_MAX_PRIVILEGE
#define DISABLE_MAX_PRIVILEGE 0x1
#endif
/*
* Create a restricted token and execute the specified process with it.
*
* Returns restricted token on success and 0 on failure.
*
* On any system not containing the required functions, do nothing
* but still report an error.
*/
HANDLE
CreateRestrictedProcess(char *cmd, PROCESS_INFORMATION *processInfo)
{
BOOL b;
STARTUPINFO si;
HANDLE origToken;
HANDLE restrictedToken;
SID_IDENTIFIER_AUTHORITY NtAuthority = {SECURITY_NT_AUTHORITY};
SID_AND_ATTRIBUTES dropSids[2];
__CreateRestrictedToken _CreateRestrictedToken;
HANDLE Advapi32Handle;
ZeroMemory(&si, sizeof(si));
si.cb = sizeof(si);
Advapi32Handle = LoadLibrary("ADVAPI32.DLL");
if (Advapi32Handle == NULL)
{
pg_log_error("could not load library \"%s\": error code %lu",
"ADVAPI32.DLL", GetLastError());
return 0;
}
_CreateRestrictedToken = (__CreateRestrictedToken) (pg_funcptr_t) GetProcAddress(Advapi32Handle, "CreateRestrictedToken");
if (_CreateRestrictedToken == NULL)
{
pg_log_error("cannot create restricted tokens on this platform: error code %lu",
GetLastError());
FreeLibrary(Advapi32Handle);
return 0;
}
/* Open the current token to use as a base for the restricted one */
if (!OpenProcessToken(GetCurrentProcess(), TOKEN_ALL_ACCESS, &origToken))
{
pg_log_error("could not open process token: error code %lu",
GetLastError());
FreeLibrary(Advapi32Handle);
return 0;
}
/* Allocate list of SIDs to remove */
ZeroMemory(&dropSids, sizeof(dropSids));
if (!AllocateAndInitializeSid(&NtAuthority, 2,
SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS, 0, 0, 0, 0, 0,
0, &dropSids[0].Sid) ||
!AllocateAndInitializeSid(&NtAuthority, 2,
SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_POWER_USERS, 0, 0, 0, 0, 0,
0, &dropSids[1].Sid))
{
pg_log_error("could not allocate SIDs: error code %lu",
GetLastError());
CloseHandle(origToken);
FreeLibrary(Advapi32Handle);
return 0;
}
b = _CreateRestrictedToken(origToken,
DISABLE_MAX_PRIVILEGE,
sizeof(dropSids) / sizeof(dropSids[0]),
dropSids,
0, NULL,
0, NULL,
&restrictedToken);
FreeSid(dropSids[1].Sid);
FreeSid(dropSids[0].Sid);
CloseHandle(origToken);
FreeLibrary(Advapi32Handle);
if (!b)
{
pg_log_error("could not create restricted token: error code %lu", GetLastError());
return 0;
}
#ifndef __CYGWIN__
AddUserToTokenDacl(restrictedToken);
#endif
if (!CreateProcessAsUser(restrictedToken,
NULL,
cmd,
NULL,
NULL,
TRUE,
CREATE_SUSPENDED,
NULL,
NULL,
&si,
processInfo))
{
pg_log_error("could not start process for command \"%s\": error code %lu", cmd, GetLastError());
return 0;
}
ResumeThread(processInfo->hThread);
return restrictedToken;
}
#endif
/*
* On Windows make sure that we are running with a restricted token,
* On other platforms do nothing.
*/
void
get_restricted_token(void)
{
#ifdef WIN32
HANDLE restrictedToken;
/*
* Before we execute another program, make sure that we are running with a
* restricted token. If not, re-execute ourselves with one.
*/
if ((restrict_env = getenv("PG_RESTRICT_EXEC")) == NULL
|| strcmp(restrict_env, "1") != 0)
{
PROCESS_INFORMATION pi;
char *cmdline;
ZeroMemory(&pi, sizeof(pi));
cmdline = pg_strdup(GetCommandLine());
setenv("PG_RESTRICT_EXEC", "1", 1);
if ((restrictedToken = CreateRestrictedProcess(cmdline, &pi)) == 0)
{
pg_log_error("could not re-execute with restricted token: error code %lu", GetLastError());
}
else
{
/*
* Successfully re-executed. Now wait for child process to capture
* the exit code.
*/
DWORD x;
CloseHandle(restrictedToken);
CloseHandle(pi.hThread);
WaitForSingleObject(pi.hProcess, INFINITE);
if (!GetExitCodeProcess(pi.hProcess, &x))
{
pg_log_error("could not get exit code from subprocess: error code %lu", GetLastError());
exit(1);
}
exit(x);
}
pg_free(cmdline);
}
#endif
}
|
