TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * restricted_token.c
4 : * helper routine to ensure restricted token on Windows
5 : *
6 : *
7 : * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
8 : * Portions Copyright (c) 1994, Regents of the University of California
9 : *
10 : *
11 : * IDENTIFICATION
12 : * src/common/restricted_token.c
13 : *
14 : *-------------------------------------------------------------------------
15 : */
16 :
17 : #ifndef FRONTEND
18 : #error "This file is not expected to be compiled for backend code"
19 : #endif
20 :
21 : #include "postgres_fe.h"
22 :
23 : #include "common/logging.h"
24 : #include "common/restricted_token.h"
25 :
26 : #ifdef WIN32
27 :
28 : /* internal vars */
29 : char *restrict_env;
30 :
31 : /* Windows API define missing from some versions of MingW headers */
32 : #ifndef DISABLE_MAX_PRIVILEGE
33 : #define DISABLE_MAX_PRIVILEGE 0x1
34 : #endif
35 :
36 : /*
37 : * Create a restricted token and execute the specified process with it.
38 : *
39 : * Returns restricted token on success and 0 on failure.
40 : *
41 : * On any system not containing the required functions, do nothing
42 : * but still report an error.
43 : */
44 : HANDLE
45 : CreateRestrictedProcess(char *cmd, PROCESS_INFORMATION *processInfo)
46 : {
47 : BOOL b;
48 : STARTUPINFO si;
49 : HANDLE origToken;
50 : HANDLE restrictedToken;
51 : SID_IDENTIFIER_AUTHORITY NtAuthority = {SECURITY_NT_AUTHORITY};
52 : SID_AND_ATTRIBUTES dropSids[2];
53 :
54 : ZeroMemory(&si, sizeof(si));
55 : si.cb = sizeof(si);
56 :
57 : /* Open the current token to use as a base for the restricted one */
58 : if (!OpenProcessToken(GetCurrentProcess(), TOKEN_ALL_ACCESS, &origToken))
59 : {
60 : pg_log_error("could not open process token: error code %lu",
61 : GetLastError());
62 : return 0;
63 : }
64 :
65 : /* Allocate list of SIDs to remove */
66 : ZeroMemory(&dropSids, sizeof(dropSids));
67 : if (!AllocateAndInitializeSid(&NtAuthority, 2,
68 : SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS, 0, 0, 0, 0, 0,
69 : 0, &dropSids[0].Sid) ||
70 : !AllocateAndInitializeSid(&NtAuthority, 2,
71 : SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_POWER_USERS, 0, 0, 0, 0, 0,
72 : 0, &dropSids[1].Sid))
73 : {
74 : pg_log_error("could not allocate SIDs: error code %lu",
75 : GetLastError());
76 : CloseHandle(origToken);
77 : return 0;
78 : }
79 :
80 : b = CreateRestrictedToken(origToken,
81 : DISABLE_MAX_PRIVILEGE,
82 : sizeof(dropSids) / sizeof(dropSids[0]),
83 : dropSids,
84 : 0, NULL,
85 : 0, NULL,
86 : &restrictedToken);
87 :
88 : FreeSid(dropSids[1].Sid);
89 : FreeSid(dropSids[0].Sid);
90 : CloseHandle(origToken);
91 :
92 : if (!b)
93 : {
94 : pg_log_error("could not create restricted token: error code %lu", GetLastError());
95 : return 0;
96 : }
97 :
98 : #ifndef __CYGWIN__
99 : AddUserToTokenDacl(restrictedToken);
100 : #endif
101 :
102 : if (!CreateProcessAsUser(restrictedToken,
103 : NULL,
104 ECB : cmd,
105 : NULL,
106 : NULL,
107 : TRUE,
108 : CREATE_SUSPENDED,
109 : NULL,
110 : NULL,
111 : &si,
112 : processInfo))
113 :
114 : {
115 : pg_log_error("could not start process for command \"%s\": error code %lu", cmd, GetLastError());
116 : return 0;
117 : }
118 :
119 : ResumeThread(processInfo->hThread);
120 : return restrictedToken;
121 : }
122 : #endif
123 :
124 : /*
125 : * On Windows make sure that we are running with a restricted token,
126 : * On other platforms do nothing.
127 : */
128 : void
129 GIC 650 : get_restricted_token(void)
130 : {
131 : #ifdef WIN32
132 : HANDLE restrictedToken;
133 :
134 : /*
135 : * Before we execute another program, make sure that we are running with a
136 : * restricted token. If not, re-execute ourselves with one.
137 : */
138 :
139 : if ((restrict_env = getenv("PG_RESTRICT_EXEC")) == NULL
140 : || strcmp(restrict_env, "1") != 0)
141 : {
142 : PROCESS_INFORMATION pi;
143 : char *cmdline;
144 :
145 : ZeroMemory(&pi, sizeof(pi));
146 :
147 : cmdline = pg_strdup(GetCommandLine());
148 :
149 ECB : setenv("PG_RESTRICT_EXEC", "1", 1);
150 :
151 : if ((restrictedToken = CreateRestrictedProcess(cmdline, &pi)) == 0)
152 : {
153 : pg_log_error("could not re-execute with restricted token: error code %lu", GetLastError());
154 : }
155 : else
156 : {
157 : /*
158 : * Successfully re-executed. Now wait for child process to capture
159 : * the exit code.
160 : */
161 : DWORD x;
162 :
163 : CloseHandle(restrictedToken);
164 : CloseHandle(pi.hThread);
165 : WaitForSingleObject(pi.hProcess, INFINITE);
166 :
167 : if (!GetExitCodeProcess(pi.hProcess, &x))
168 : pg_fatal("could not get exit code from subprocess: error code %lu", GetLastError());
169 : exit(x);
170 : }
171 : pg_free(cmdline);
172 : }
173 : #endif
174 GIC 650 : }
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