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
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
|
#include "common.h"
#include <sched.h>
char pidfile[FILENAME_MAX + 1] = "";
void sig_handler_exit(int signo)
{
if(signo) {
error_log_limit_unlimited();
error("Received signal %d. Exiting...", signo);
netdata_exit = 1;
}
}
void sig_handler_logrotate(int signo)
{
if(signo) {
error_log_limit_unlimited();
info("Received signal %d to re-open the log files", signo);
reopen_all_log_files();
error_log_limit_reset();
}
}
void sig_handler_save(int signo)
{
if(signo) {
error_log_limit_unlimited();
info("Received signal %d to save the database...", signo);
rrdset_save_all();
error_log_limit_reset();
}
}
void sig_handler_reload_health(int signo)
{
if(signo) {
error_log_limit_unlimited();
info("Received signal %d to reload health configuration...", signo);
health_reload();
error_log_limit_reset();
}
}
static void chown_open_file(int fd, uid_t uid, gid_t gid) {
if(fd == -1) return;
struct stat buf;
if(fstat(fd, &buf) == -1) {
error("Cannot fstat() fd %d", fd);
return;
}
if((buf.st_uid != uid || buf.st_gid != gid) && S_ISREG(buf.st_mode)) {
if(fchown(fd, uid, gid) == -1)
error("Cannot fchown() fd %d.", fd);
}
}
int become_user(const char *username, int pid_fd)
{
struct passwd *pw = getpwnam(username);
if(!pw) {
error("User %s is not present.", username);
return -1;
}
uid_t uid = pw->pw_uid;
gid_t gid = pw->pw_gid;
int ngroups = (int)sysconf(_SC_NGROUPS_MAX);
gid_t *supplementary_groups = NULL;
if(ngroups) {
supplementary_groups = mallocz(sizeof(gid_t) * ngroups);
if(getgrouplist(username, gid, supplementary_groups, &ngroups) == -1) {
error("Cannot get supplementary groups of user '%s'.", username);
freez(supplementary_groups);
supplementary_groups = NULL;
ngroups = 0;
}
}
chown_open_file(STDOUT_FILENO, uid, gid);
chown_open_file(STDERR_FILENO, uid, gid);
chown_open_file(stdaccess_fd, uid, gid);
chown_open_file(pid_fd, uid, gid);
if(supplementary_groups && ngroups) {
if(setgroups(ngroups, supplementary_groups) == -1)
error("Cannot set supplementary groups for user '%s'", username);
freez(supplementary_groups);
supplementary_groups = NULL;
ngroups = 0;
}
if(setresgid(gid, gid, gid) != 0) {
error("Cannot switch to user's %s group (gid: %u).", username, gid);
return -1;
}
if(setresuid(uid, uid, uid) != 0) {
error("Cannot switch to user %s (uid: %u).", username, uid);
return -1;
}
if(setgid(gid) != 0) {
error("Cannot switch to user's %s group (gid: %u).", username, gid);
return -1;
}
if(setegid(gid) != 0) {
error("Cannot effectively switch to user's %s group (gid: %u).", username, gid);
return -1;
}
if(setuid(uid) != 0) {
error("Cannot switch to user %s (uid: %u).", username, uid);
return -1;
}
if(seteuid(uid) != 0) {
error("Cannot effectively switch to user %s (uid: %u).", username, uid);
return -1;
}
return(0);
}
void oom_score_adj(int score) {
int done = 0;
int fd = open("/proc/self/oom_score_adj", O_WRONLY);
if(fd != -1) {
char buf[10 + 1];
ssize_t len = snprintfz(buf, 10, "%d", score);
if(write(fd, buf, len) == len) done = 1;
close(fd);
}
if(!done)
error("Cannot adjust my Out-Of-Memory score to %d.", score);
else
info("Adjusted my Out-Of-Memory score to %d.", score);
}
int sched_setscheduler_idle(void) {
#ifdef SCHED_IDLE
const struct sched_param param = {
.sched_priority = 0
};
int i = sched_setscheduler(0, SCHED_IDLE, ¶m);
if(i != 0)
error("Cannot adjust my scheduling priority to IDLE.");
else
info("Adjusted my scheduling priority to IDLE.");
return i;
#else
return -1;
#endif
}
int become_daemon(int dont_fork, const char *user)
{
if(!dont_fork) {
int i = fork();
if(i == -1) {
perror("cannot fork");
exit(1);
}
if(i != 0) {
exit(0); // the parent
}
// become session leader
if (setsid() < 0) {
perror("Cannot become session leader.");
exit(2);
}
// fork() again
i = fork();
if(i == -1) {
perror("cannot fork");
exit(1);
}
if(i != 0) {
exit(0); // the parent
}
}
// generate our pid file
int pidfd = -1;
if(pidfile[0]) {
pidfd = open(pidfile, O_WRONLY | O_CREAT, 0644);
if(pidfd >= 0) {
if(ftruncate(pidfd, 0) != 0)
error("Cannot truncate pidfile '%s'.", pidfile);
char b[100];
sprintf(b, "%d\n", getpid());
ssize_t i = write(pidfd, b, strlen(b));
if(i <= 0)
error("Cannot write pidfile '%s'.", pidfile);
}
else error("Failed to open pidfile '%s'.", pidfile);
}
// Set new file permissions
umask(0002);
// adjust my Out-Of-Memory score
oom_score_adj(1000);
// never become a problem
if(sched_setscheduler_idle() != 0) {
if(nice(19) == -1) error("Cannot lower my CPU priority.");
else info("Set my nice value to 19.");
}
if(user && *user) {
if(become_user(user, pidfd) != 0) {
error("Cannot become user '%s'. Continuing as we are.", user);
}
else info("Successfully became user '%s'.", user);
}
if(pidfd != -1) {
close(pidfd);
pidfd = -1;
}
return(0);
}
|
