267 lines
6.2 KiB
C
267 lines
6.2 KiB
C
/*
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* SPDX-FileCopyrightText: 1991 - 1994, Julianne Frances Haugh
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* SPDX-FileCopyrightText: 1996 - 2000, Marek Michałkiewicz
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* SPDX-FileCopyrightText: 2000 - 2006, Tomasz Kłoczko
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* SPDX-FileCopyrightText: 2007 - 2009, Nicolas François
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <config.h>
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#ident "$Id: $"
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#include <assert.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include <dirent.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "defines.h"
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#include "prototypes.h"
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#ifdef ENABLE_SUBIDS
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#include "subordinateio.h"
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#endif /* ENABLE_SUBIDS */
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#include "shadowlog.h"
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#ifdef __linux__
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static int check_status (const char *name, const char *sname, uid_t uid);
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static int user_busy_processes (const char *name, uid_t uid);
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#else /* !__linux__ */
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static int user_busy_utmp (const char *name);
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#endif /* !__linux__ */
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/*
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* user_busy - check if a user is currently running processes
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*/
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int user_busy (const char *name, uid_t uid)
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{
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/* There are no standard ways to get the list of processes.
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* An option could be to run an external tool (ps).
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*/
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#ifdef __linux__
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/* On Linux, directly parse /proc */
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return user_busy_processes (name, uid);
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#else /* !__linux__ */
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/* If we cannot rely on /proc, check is there is a record in utmp
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* indicating that the user is still logged in */
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return user_busy_utmp (name);
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#endif /* !__linux__ */
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}
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#ifndef __linux__
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static int user_busy_utmp (const char *name)
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{
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struct utmp *utent;
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setutent ();
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while ((utent = getutent ()) != NULL)
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{
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if (utent->ut_type != USER_PROCESS) {
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continue;
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}
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if (strncmp (utent->ut_user, name, sizeof utent->ut_user) != 0) {
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continue;
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}
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if (kill (utent->ut_pid, 0) != 0) {
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continue;
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}
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fprintf (log_get_logfd(),
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_("%s: user %s is currently logged in\n"),
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log_get_progname(), name);
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return 1;
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}
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return 0;
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}
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#endif /* !__linux__ */
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#ifdef __linux__
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#ifdef ENABLE_SUBIDS
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#define in_parentuid_range(uid) ((uid) >= parentuid && (uid) < parentuid + range)
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static int different_namespace (const char *sname)
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{
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/* 41: /proc/xxxxxxxxxx/task/xxxxxxxxxx/ns/user + \0 */
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char path[41];
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char buf[512], buf2[512];
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ssize_t llen1, llen2;
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snprintf (path, 41, "/proc/%s/ns/user", sname);
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if ((llen1 = readlink (path, buf, sizeof(buf))) == -1)
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return 0;
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if ((llen2 = readlink ("/proc/self/ns/user", buf2, sizeof(buf2))) == -1)
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return 0;
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if (llen1 == llen2 && memcmp (buf, buf2, llen1) == 0)
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return 0; /* same namespace */
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return 1;
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}
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#endif /* ENABLE_SUBIDS */
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static int check_status (const char *name, const char *sname, uid_t uid)
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{
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/* 40: /proc/xxxxxxxxxx/task/xxxxxxxxxx/status + \0 */
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char status[40];
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char line[1024];
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FILE *sfile;
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snprintf (status, 40, "/proc/%s/status", sname);
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sfile = fopen (status, "r");
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if (NULL == sfile) {
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return 0;
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}
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while (fgets (line, sizeof (line), sfile) == line) {
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if (strncmp (line, "Uid:\t", 5) == 0) {
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unsigned long ruid, euid, suid;
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assert (uid == (unsigned long) uid);
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(void) fclose (sfile);
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if (sscanf (line,
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"Uid:\t%lu\t%lu\t%lu\n",
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&ruid, &euid, &suid) == 3) {
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if ( (ruid == (unsigned long) uid)
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|| (euid == (unsigned long) uid)
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|| (suid == (unsigned long) uid) ) {
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return 1;
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}
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#ifdef ENABLE_SUBIDS
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if ( different_namespace (sname)
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&& ( have_sub_uids(name, ruid, 1)
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|| have_sub_uids(name, euid, 1)
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|| have_sub_uids(name, suid, 1))
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) {
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return 1;
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}
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#endif /* ENABLE_SUBIDS */
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} else {
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/* Ignore errors. This is just a best effort. */
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}
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return 0;
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}
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}
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(void) fclose (sfile);
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return 0;
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}
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static int user_busy_processes (const char *name, uid_t uid)
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{
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DIR *proc;
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struct dirent *ent;
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char *tmp_d_name;
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pid_t pid;
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DIR *task_dir;
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/* 22: /proc/xxxxxxxxxx/task + \0 */
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char task_path[22];
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char root_path[22];
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struct stat sbroot;
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struct stat sbroot_process;
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#ifdef ENABLE_SUBIDS
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sub_uid_open (O_RDONLY);
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#endif /* ENABLE_SUBIDS */
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proc = opendir ("/proc");
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if (proc == NULL) {
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perror ("opendir /proc");
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#ifdef ENABLE_SUBIDS
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sub_uid_close();
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#endif
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return 0;
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}
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if (stat ("/", &sbroot) != 0) {
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perror ("stat (\"/\")");
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(void) closedir (proc);
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#ifdef ENABLE_SUBIDS
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sub_uid_close();
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#endif
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return 0;
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}
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while ((ent = readdir (proc)) != NULL) {
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tmp_d_name = ent->d_name;
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/*
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* Ingo Molnar's patch introducing NPTL for 2.4 hides
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* threads in the /proc directory by prepending a period.
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* This patch is applied by default in some RedHat
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* kernels.
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*/
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if ( (strcmp (tmp_d_name, ".") == 0)
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|| (strcmp (tmp_d_name, "..") == 0)) {
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continue;
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}
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if (*tmp_d_name == '.') {
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tmp_d_name++;
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}
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/* Check if this is a valid PID */
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if (get_pid (tmp_d_name, &pid) == 0) {
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continue;
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}
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/* Check if the process is in our chroot */
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snprintf (root_path, 22, "/proc/%lu/root", (unsigned long) pid);
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root_path[21] = '\0';
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if (stat (root_path, &sbroot_process) != 0) {
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continue;
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}
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if ( (sbroot.st_dev != sbroot_process.st_dev)
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|| (sbroot.st_ino != sbroot_process.st_ino)) {
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continue;
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}
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if (check_status (name, tmp_d_name, uid) != 0) {
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(void) closedir (proc);
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#ifdef ENABLE_SUBIDS
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sub_uid_close();
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#endif
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fprintf (log_get_logfd(),
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_("%s: user %s is currently used by process %d\n"),
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log_get_progname(), name, pid);
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return 1;
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}
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snprintf (task_path, 22, "/proc/%lu/task", (unsigned long) pid);
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task_path[21] = '\0';
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task_dir = opendir (task_path);
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if (task_dir != NULL) {
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while ((ent = readdir (task_dir)) != NULL) {
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pid_t tid;
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if (get_pid (ent->d_name, &tid) == 0) {
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continue;
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}
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if (tid == pid) {
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continue;
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}
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if (check_status (name, task_path+6, uid) != 0) {
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(void) closedir (proc);
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(void) closedir (task_dir);
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#ifdef ENABLE_SUBIDS
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sub_uid_close();
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#endif
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fprintf (log_get_logfd(),
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_("%s: user %s is currently used by process %d\n"),
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log_get_progname(), name, pid);
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return 1;
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}
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}
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(void) closedir (task_dir);
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} else {
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/* Ignore errors. This is just a best effort */
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}
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}
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(void) closedir (proc);
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#ifdef ENABLE_SUBIDS
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sub_uid_close();
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#endif /* ENABLE_SUBIDS */
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return 0;
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}
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#endif /* __linux__ */
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