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
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
|
/*
* SPDX-FileCopyrightText: 1991 - 1994, Julianne Frances Haugh
* SPDX-FileCopyrightText: 1996 - 2000, Marek Michałkiewicz
* SPDX-FileCopyrightText: 2000 - 2006, Tomasz Kłoczko
* SPDX-FileCopyrightText: 2007 - 2009, Nicolas François
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <config.h>
#ident "$Id: $"
#include <assert.h>
#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
#include <unistd.h>
#include "defines.h"
#include "prototypes.h"
#ifdef ENABLE_SUBIDS
#include "subordinateio.h"
#endif /* ENABLE_SUBIDS */
#include "shadowlog.h"
#include "string/sprintf.h"
#ifdef __linux__
static int check_status (const char *name, const char *sname, uid_t uid);
static int user_busy_processes (const char *name, uid_t uid);
#else /* !__linux__ */
static int user_busy_utmp (const char *name);
#endif /* !__linux__ */
/*
* user_busy - check if a user is currently running processes
*/
int user_busy (const char *name, uid_t uid)
{
/* There are no standard ways to get the list of processes.
* An option could be to run an external tool (ps).
*/
#ifdef __linux__
/* On Linux, directly parse /proc */
return user_busy_processes (name, uid);
#else /* !__linux__ */
/* If we cannot rely on /proc, check if there is a record in utmp
* indicating that the user is still logged in */
return user_busy_utmp (name);
#endif /* !__linux__ */
}
#ifndef __linux__
static int
user_busy_utmp(const char *name)
{
struct utmpx *utent;
setutxent();
while ((utent = getutxent()) != NULL)
{
if (utent->ut_type != USER_PROCESS) {
continue;
}
if (strncmp (utent->ut_user, name, sizeof utent->ut_user) != 0) {
continue;
}
if (kill (utent->ut_pid, 0) != 0) {
continue;
}
fprintf (log_get_logfd(),
_("%s: user %s is currently logged in\n"),
log_get_progname(), name);
return 1;
}
return 0;
}
#endif /* !__linux__ */
#ifdef __linux__
#ifdef ENABLE_SUBIDS
#define in_parentuid_range(uid) ((uid) >= parentuid && (uid) < parentuid + range)
static int different_namespace (const char *sname)
{
/* 41: /proc/xxxxxxxxxx/task/xxxxxxxxxx/ns/user + \0 */
char path[41];
char buf[512], buf2[512];
ssize_t llen1, llen2;
SNPRINTF(path, "/proc/%s/ns/user", sname);
if ((llen1 = readlink (path, buf, sizeof(buf))) == -1)
return 0;
if ((llen2 = readlink ("/proc/self/ns/user", buf2, sizeof(buf2))) == -1)
return 0;
if (llen1 == llen2 && memcmp (buf, buf2, llen1) == 0)
return 0; /* same namespace */
return 1;
}
#endif /* ENABLE_SUBIDS */
static int check_status (const char *name, const char *sname, uid_t uid)
{
/* 40: /proc/xxxxxxxxxx/task/xxxxxxxxxx/status + \0 */
char status[40];
char line[1024];
FILE *sfile;
SNPRINTF(status, "/proc/%s/status", sname);
sfile = fopen (status, "r");
if (NULL == sfile) {
return 0;
}
while (fgets (line, sizeof (line), sfile) == line) {
if (strncmp (line, "Uid:\t", 5) == 0) {
unsigned long ruid, euid, suid;
assert (uid == (unsigned long) uid);
(void) fclose (sfile);
if (sscanf (line,
"Uid:\t%lu\t%lu\t%lu\n",
&ruid, &euid, &suid) == 3) {
if ( (ruid == (unsigned long) uid)
|| (euid == (unsigned long) uid)
|| (suid == (unsigned long) uid) ) {
return 1;
}
#ifdef ENABLE_SUBIDS
if ( different_namespace (sname)
&& ( have_sub_uids(name, ruid, 1)
|| have_sub_uids(name, euid, 1)
|| have_sub_uids(name, suid, 1))
) {
return 1;
}
#endif /* ENABLE_SUBIDS */
} else {
/* Ignore errors. This is just a best effort. */
}
return 0;
}
}
(void) fclose (sfile);
return 0;
}
static int user_busy_processes (const char *name, uid_t uid)
{
DIR *proc;
DIR *task_dir;
char *tmp_d_name;
/* 22: /proc/xxxxxxxxxx/task + \0 */
char task_path[22];
char root_path[22];
pid_t pid;
struct stat sbroot;
struct stat sbroot_process;
struct dirent *ent;
#ifdef ENABLE_SUBIDS
sub_uid_open (O_RDONLY);
#endif /* ENABLE_SUBIDS */
proc = opendir ("/proc");
if (proc == NULL) {
perror ("opendir /proc");
#ifdef ENABLE_SUBIDS
sub_uid_close();
#endif
return 0;
}
if (stat ("/", &sbroot) != 0) {
perror ("stat (\"/\")");
(void) closedir (proc);
#ifdef ENABLE_SUBIDS
sub_uid_close();
#endif
return 0;
}
while ((ent = readdir (proc)) != NULL) {
tmp_d_name = ent->d_name;
/*
* Ingo Molnar's patch introducing NPTL for 2.4 hides
* threads in the /proc directory by prepending a period.
* This patch is applied by default in some RedHat
* kernels.
*/
if ( (strcmp (tmp_d_name, ".") == 0)
|| (strcmp (tmp_d_name, "..") == 0)) {
continue;
}
if (*tmp_d_name == '.') {
tmp_d_name++;
}
/* Check if this is a valid PID */
if (get_pid(tmp_d_name, &pid) == -1) {
continue;
}
/* Check if the process is in our chroot */
SNPRINTF(root_path, "/proc/%lu/root", (unsigned long) pid);
if (stat (root_path, &sbroot_process) != 0) {
continue;
}
if ( (sbroot.st_dev != sbroot_process.st_dev)
|| (sbroot.st_ino != sbroot_process.st_ino)) {
continue;
}
if (check_status (name, tmp_d_name, uid) != 0) {
(void) closedir (proc);
#ifdef ENABLE_SUBIDS
sub_uid_close();
#endif
fprintf (log_get_logfd(),
_("%s: user %s is currently used by process %d\n"),
log_get_progname(), name, pid);
return 1;
}
SNPRINTF(task_path, "/proc/%lu/task", (unsigned long) pid);
task_dir = opendir (task_path);
if (task_dir != NULL) {
while ((ent = readdir (task_dir)) != NULL) {
pid_t tid;
if (get_pid(ent->d_name, &tid) == -1) {
continue;
}
if (tid == pid) {
continue;
}
if (check_status (name, task_path+6, uid) != 0) {
(void) closedir (proc);
(void) closedir (task_dir);
#ifdef ENABLE_SUBIDS
sub_uid_close();
#endif
fprintf (log_get_logfd(),
_("%s: user %s is currently used by process %d\n"),
log_get_progname(), name, pid);
return 1;
}
}
(void) closedir (task_dir);
} else {
/* Ignore errors. This is just a best effort */
}
}
(void) closedir (proc);
#ifdef ENABLE_SUBIDS
sub_uid_close();
#endif /* ENABLE_SUBIDS */
return 0;
}
#endif /* __linux__ */
|
