/*
* 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"
#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 an user if 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 is 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)
{
#ifdef USE_UTMPX
struct utmpx *utent;
setutxent ();
while ((utent = getutxent ()) != NULL)
#else /* !USE_UTMPX */
struct utmp *utent;
setutent ();
while ((utent = getutent ()) != NULL)
#endif /* !USE_UTMPX */
{
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, 41, "/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, 40, "/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;
struct dirent *ent;
char *tmp_d_name;
pid_t pid;
DIR *task_dir;
/* 22: /proc/xxxxxxxxxx/task + \0 */
char task_path[22];
char root_path[22];
struct stat sbroot;
struct stat sbroot_process;
#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) == 0) {
continue;
}
/* Check if the process is in our chroot */
snprintf (root_path, 22, "/proc/%lu/root", (unsigned long) pid);
root_path[21] = '\0';
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, 22, "/proc/%lu/task", (unsigned long) pid);
task_path[21] = '\0';
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) == 0) {
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__ */