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
|
/*
Spawns dirmngr with UID and GID with a specific UID and GID.
The path for dirmngr is specified by the compiled-in definition
DIRMNGR_USER, normally passed as a compiler argument:
`-D DIRMNGR_USER=DEFINITION'
The UID and GID are the uid and gid for user DIRMNGR_USER.
DIRMNGR_USER is normally defined through a compiler argument
also.
*/
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <pwd.h>
#include <syslog.h>
#define MAX_ARGS 40
#ifndef TRUE
#define TRUE 1
#endif /* TRUE */
#ifndef FALSE
#define FALSE 0
#endif /* FALSE */
void error_sys(char *str)
{
/* Output error message to syslog */
char msg[1024];
snprintf(msg, sizeof(msg), "runDirmngr : %s : %s", str, strerror(errno));
syslog(LOG_ALERT, msg);
}
int obtainUIDandGID(const char *name, uid_t *pw_uid, gid_t *pw_gid)
{
/* Obtain UID and GID from passwd entry identified by name */
struct passwd *pw_entry;
char msg[100];
if ((pw_entry = getpwnam(name)) == NULL)
{
snprintf(msg, sizeof(msg), "failed to get password entry for %s", name);
error_sys(msg);
return FALSE;
}
else
{
*pw_uid = pw_entry->pw_uid;
*pw_gid = pw_entry->pw_gid;
return TRUE;
}
}
int main (int argc, char **argv )
{
pid_t pid;
uid_t UID;
gid_t GID;
pid_t pidwait;
int waitstat;
/* Sanity check */
if (argc > MAX_ARGS)
{
error_sys("arg buffer too small");
exit(-1);
}
/*
if (getpid() != 0)
{
error_sys("must be called by root");
exit(-1);
}
*/
/* fork child that will become dirmngr */
if ((pid = fork()) < 0)
error_sys("fork error");
else
{
if (pid == 0)
{
/* We're the child */
char *args[MAX_ARGS];
unsigned int i;
if (!obtainUIDandGID(DIRMNGR_USER, &UID, &GID))
exit(-1);
/* Drop privileges immediately */
if (setgid(GID) < 0)
{
/* It is VERY important to check return
value and not continue if setgid fails
*/
error_sys ("setgid failed");
exit (-1);
}
if (setuid(UID) < 0)
{
/* It is VERY important to check return
value and not continue if setuid fails
*/
error_sys ("setuid failed");
exit (-1);
}
/* Build calling argv */
args[0] = DIRMNGR_PATH;
for (i=1;i<argc;i++)
{
args[i] = argv[i];
}
args[i++] = NULL;
/* Finally transform self into dirmngr */
if (execvp(DIRMNGR_PATH, args) < 0)
error_sys("execve error");
else
; /* avoid if-then ambiguity */
}
else
{
/* We're the parent
Wait for child to terminate
*/
pidwait = waitpid(pid, &waitstat, 0);
switch (pidwait) {
case 0: exit(0);
case -1:
perror(strerror(errno));
exit(-1);
default:
if (WIFEXITED(waitstat)) {
exit(WEXITSTATUS(waitstat));
}
else
{
exit(-1);
}
}
}
}
}
|
