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path: root/modules/pam_securetty/pam_securetty.c
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Diffstat (limited to 'modules/pam_securetty/pam_securetty.c')
-rw-r--r--modules/pam_securetty/pam_securetty.c290
1 files changed, 290 insertions, 0 deletions
diff --git a/modules/pam_securetty/pam_securetty.c b/modules/pam_securetty/pam_securetty.c
new file mode 100644
index 0000000..4e97ef5
--- /dev/null
+++ b/modules/pam_securetty/pam_securetty.c
@@ -0,0 +1,290 @@
+/* pam_securetty module */
+
+#define SECURETTY_FILE "/etc/securetty"
+#define TTY_PREFIX "/dev/"
+#define CMDLINE_FILE "/proc/cmdline"
+#define CONSOLEACTIVE_FILE "/sys/class/tty/console/active"
+
+/*
+ * by Elliot Lee <sopwith@redhat.com>, Red Hat Software.
+ * July 25, 1996.
+ * This code shamelessly ripped from the pam_rootok module.
+ * Slight modifications AGM. 1996/12/3
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <syslog.h>
+#include <stdarg.h>
+#include <pwd.h>
+#include <string.h>
+#include <ctype.h>
+#include <limits.h>
+
+/*
+ * here, we make a definition for the externally accessible function
+ * in this file (this definition is required for static a module
+ * but strongly encouraged generally) it is used to instruct the
+ * modules include file to define the function prototypes.
+ */
+
+#define PAM_SM_AUTH
+#define PAM_SM_ACCOUNT
+
+#include <security/pam_modules.h>
+#include <security/pam_modutil.h>
+#include <security/pam_ext.h>
+
+#define PAM_DEBUG_ARG 0x0001
+#define PAM_NOCONSOLE_ARG 0x0002
+
+static int
+_pam_parse (const pam_handle_t *pamh, int argc, const char **argv)
+{
+ int ctrl=0;
+
+ /* step through arguments */
+ for (ctrl=0; argc-- > 0; ++argv) {
+
+ /* generic options */
+
+ if (!strcmp(*argv,"debug"))
+ ctrl |= PAM_DEBUG_ARG;
+ else if (!strcmp(*argv, "noconsole"))
+ ctrl |= PAM_NOCONSOLE_ARG;
+ else {
+ pam_syslog(pamh, LOG_ERR, "unknown option: %s", *argv);
+ }
+ }
+
+ return ctrl;
+}
+
+static int
+securetty_perform_check (pam_handle_t *pamh, int ctrl,
+ const char *function_name)
+{
+ int retval = PAM_AUTH_ERR;
+ const char *username;
+ const char *uttyname;
+ const void *void_uttyname;
+ char ttyfileline[256];
+ char ptname[256];
+ struct stat ttyfileinfo;
+ struct passwd *user_pwd;
+ FILE *ttyfile;
+
+ /* log a trail for debugging */
+ if (ctrl & PAM_DEBUG_ARG) {
+ pam_syslog(pamh, LOG_DEBUG, "pam_securetty called via %s function",
+ function_name);
+ }
+
+ retval = pam_get_user(pamh, &username, NULL);
+ if (retval != PAM_SUCCESS || username == NULL) {
+ pam_syslog(pamh, LOG_WARNING, "cannot determine username");
+ return (retval == PAM_CONV_AGAIN ? PAM_INCOMPLETE:PAM_SERVICE_ERR);
+ }
+
+ user_pwd = pam_modutil_getpwnam(pamh, username);
+ if (user_pwd != NULL && user_pwd->pw_uid != 0) {
+ /* If the user is not root, securetty's does not apply to them */
+ return PAM_SUCCESS;
+ }
+ /* The user is now either root or an invalid / mistyped username */
+
+ retval = pam_get_item(pamh, PAM_TTY, &void_uttyname);
+ uttyname = void_uttyname;
+ if (retval != PAM_SUCCESS || uttyname == NULL) {
+ pam_syslog (pamh, LOG_WARNING, "cannot determine user's tty");
+ return PAM_SERVICE_ERR;
+ }
+
+ /* The PAM_TTY item may be prefixed with "/dev/" - skip that */
+ if (strncmp(TTY_PREFIX, uttyname, sizeof(TTY_PREFIX)-1) == 0) {
+ uttyname += sizeof(TTY_PREFIX)-1;
+ }
+
+ if (stat(SECURETTY_FILE, &ttyfileinfo)) {
+ pam_syslog(pamh, LOG_NOTICE, "Couldn't open %s: %m", SECURETTY_FILE);
+ return PAM_SUCCESS; /* for compatibility with old securetty handling,
+ this needs to succeed. But we still log the
+ error. */
+ }
+
+ if ((ttyfileinfo.st_mode & S_IWOTH) || !S_ISREG(ttyfileinfo.st_mode)) {
+ /* If the file is world writable or is not a
+ normal file, return error */
+ pam_syslog(pamh, LOG_ERR,
+ "%s is either world writable or not a normal file",
+ SECURETTY_FILE);
+ return PAM_AUTH_ERR;
+ }
+
+ ttyfile = fopen(SECURETTY_FILE,"r");
+ if (ttyfile == NULL) { /* Check that we opened it successfully */
+ pam_syslog(pamh, LOG_ERR, "Error opening %s: %m", SECURETTY_FILE);
+ return PAM_SERVICE_ERR;
+ }
+
+ if (isdigit(uttyname[0])) {
+ snprintf(ptname, sizeof(ptname), "pts/%s", uttyname);
+ } else {
+ ptname[0] = '\0';
+ }
+
+ retval = 1;
+
+ while ((fgets(ttyfileline, sizeof(ttyfileline)-1, ttyfile) != NULL)
+ && retval) {
+ if (ttyfileline[strlen(ttyfileline) - 1] == '\n')
+ ttyfileline[strlen(ttyfileline) - 1] = '\0';
+
+ retval = ( strcmp(ttyfileline, uttyname)
+ && (!ptname[0] || strcmp(ptname, uttyname)) );
+ }
+ fclose(ttyfile);
+
+ if (retval && !(ctrl & PAM_NOCONSOLE_ARG)) {
+ FILE *cmdlinefile;
+
+ /* Allow access from the kernel console, if enabled */
+ cmdlinefile = fopen(CMDLINE_FILE, "r");
+
+ if (cmdlinefile != NULL) {
+ char line[LINE_MAX], *p;
+
+ line[0] = 0;
+ fgets(line, sizeof(line), cmdlinefile);
+ fclose(cmdlinefile);
+
+ for (p = line; p; p = strstr(p+1, "console=")) {
+ char *e;
+
+ /* Test whether this is a beginning of a word? */
+ if (p > line && p[-1] != ' ')
+ continue;
+
+ /* Is this our console? */
+ if (strncmp(p + 8, uttyname, strlen(uttyname)))
+ continue;
+
+ /* Is there any garbage after the TTY name? */
+ e = p + 8 + strlen(uttyname);
+ if (*e == ',' || *e == ' ' || *e == '\n' || *e == 0) {
+ retval = 0;
+ break;
+ }
+ }
+ }
+ }
+ if (retval && !(ctrl & PAM_NOCONSOLE_ARG)) {
+ FILE *consoleactivefile;
+
+ /* Allow access from the active console */
+ consoleactivefile = fopen(CONSOLEACTIVE_FILE, "r");
+
+ if (consoleactivefile != NULL) {
+ char line[LINE_MAX], *p, *n;
+
+ line[0] = 0;
+ p = fgets(line, sizeof(line), consoleactivefile);
+ fclose(consoleactivefile);
+
+ if (p) {
+ /* remove the newline character at end */
+ if (line[strlen(line)-1] == '\n')
+ line[strlen(line)-1] = 0;
+
+ for (n = p; n != NULL; p = n+1) {
+ if ((n = strchr(p, ' ')) != NULL)
+ *n = '\0';
+
+ if (strcmp(p, uttyname) == 0) {
+ retval = 0;
+ break;
+ }
+ }
+ }
+ }
+ }
+
+ if (retval) {
+ pam_syslog(pamh, LOG_WARNING, "access denied: tty '%s' is not secure !",
+ uttyname);
+
+ retval = PAM_AUTH_ERR;
+ if (user_pwd == NULL) {
+ retval = PAM_USER_UNKNOWN;
+ }
+ } else {
+ if (ctrl & PAM_DEBUG_ARG) {
+ pam_syslog(pamh, LOG_DEBUG, "access allowed for '%s' on '%s'",
+ username, uttyname);
+ }
+ retval = PAM_SUCCESS;
+
+ }
+
+ return retval;
+}
+
+/* --- authentication management functions --- */
+
+PAM_EXTERN
+int pam_sm_authenticate(pam_handle_t *pamh, int flags UNUSED, int argc,
+ const char **argv)
+{
+ int ctrl;
+
+ /* parse the arguments */
+ ctrl = _pam_parse (pamh, argc, argv);
+
+ return securetty_perform_check(pamh, ctrl, __FUNCTION__);
+}
+
+PAM_EXTERN int
+pam_sm_setcred (pam_handle_t *pamh UNUSED, int flags UNUSED,
+ int argc UNUSED, const char **argv UNUSED)
+{
+ return PAM_SUCCESS;
+}
+
+/* --- account management functions --- */
+
+PAM_EXTERN int
+pam_sm_acct_mgmt (pam_handle_t *pamh, int flags UNUSED,
+ int argc, const char **argv)
+{
+ int ctrl;
+
+ /* parse the arguments */
+ ctrl = _pam_parse (pamh, argc, argv);
+
+ /* take the easy route */
+ return securetty_perform_check(pamh, ctrl, __FUNCTION__);
+}
+
+
+#ifdef PAM_STATIC
+
+/* static module data */
+
+struct pam_module _pam_securetty_modstruct = {
+ "pam_securetty",
+ pam_sm_authenticate,
+ pam_sm_setcred,
+ pam_sm_acct_mgmt,
+ NULL,
+ NULL,
+ NULL,
+};
+
+#endif /* PAM_STATIC */
+
+/* end of module definition */
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