diff options
Diffstat (limited to 'modules/pam_securetty/pam_securetty.c')
| -rw-r--r-- | modules/pam_securetty/pam_securetty.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/modules/pam_securetty/pam_securetty.c b/modules/pam_securetty/pam_securetty.c new file mode 100644 index 00000000..9e6121e8 --- /dev/null +++ b/modules/pam_securetty/pam_securetty.c @@ -0,0 +1,191 @@ +/* pam_securetty module */ + +#define SECURETTY_FILE "/etc/securetty" +#define TTY_PREFIX "/dev/" + +/* + * 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 + */ + +#define _GNU_SOURCE + +#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> + +#define PAM_SM_AUTH + +/* + * 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 + +#include <security/pam_modules.h> + +/* some syslogging */ + +static void _pam_log(int err, const char *format, ...) +{ + va_list args; + + va_start(args, format); + openlog("PAM-securetty", LOG_CONS|LOG_PID, LOG_AUTH); + vsyslog(err, format, args); + va_end(args); + closelog(); +} + +/* argument parsing */ + +#define PAM_DEBUG_ARG 0x0001 + +static int _pam_parse(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 { + _pam_log(LOG_ERR,"pam_parse: unknown option; %s",*argv); + } + } + + return ctrl; +} + +/* --- authentication management functions (only) --- */ + +PAM_EXTERN +int pam_sm_authenticate(pam_handle_t *pamh,int flags,int argc + ,const char **argv) +{ + int retval = PAM_AUTH_ERR; + const char *username; + char *uttyname; + char ttyfileline[256]; + struct stat ttyfileinfo; + struct passwd *user_pwd; + FILE *ttyfile; + int ctrl; + + /* parse the arguments */ + ctrl = _pam_parse(argc, argv); + + retval = pam_get_user(pamh, &username, NULL); + if (retval != PAM_SUCCESS || username == NULL) { + if (ctrl & PAM_DEBUG_ARG) { + _pam_log(LOG_WARNING, "cannot determine username"); + } + return (retval == PAM_CONV_AGAIN + ? PAM_INCOMPLETE:PAM_SERVICE_ERR); + } + + retval = pam_get_item(pamh, PAM_TTY, (const void **)&uttyname); + if (retval != PAM_SUCCESS || uttyname == NULL) { + if (ctrl & PAM_DEBUG_ARG) { + _pam_log(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; + + user_pwd = getpwnam(username); + if (user_pwd == NULL) { + return PAM_IGNORE; + } else if (user_pwd->pw_uid != 0) { /* If the user is not root, + securetty's does not apply + to them */ + return PAM_SUCCESS; + } + + if (stat(SECURETTY_FILE, &ttyfileinfo)) { + _pam_log(LOG_NOTICE, "Couldn't open " 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_log(LOG_ERR, SECURETTY_FILE + " is either world writable or not a normal file"); + return PAM_AUTH_ERR; + } + + ttyfile = fopen(SECURETTY_FILE,"r"); + if(ttyfile == NULL) { /* Check that we opened it successfully */ + _pam_log(LOG_ERR, + "Error opening " SECURETTY_FILE); + return PAM_SERVICE_ERR; + } + /* There should be no more errors from here on */ + retval=PAM_AUTH_ERR; + /* This loop assumes that PAM_SUCCESS == 0 + and PAM_AUTH_ERR != 0 */ + while((fgets(ttyfileline,sizeof(ttyfileline)-1, ttyfile) != NULL) + && retval) { + if(ttyfileline[strlen(ttyfileline) - 1] == '\n') + ttyfileline[strlen(ttyfileline) - 1] = '\0'; + retval = strcmp(ttyfileline,uttyname); + } + fclose(ttyfile); + if(retval) { + if (ctrl & PAM_DEBUG_ARG) + _pam_log(LOG_WARNING, "access denied: tty '%s' is not secure !", + uttyname); + retval = PAM_AUTH_ERR; + } + if ((retval == PAM_SUCCESS) && (ctrl & PAM_DEBUG_ARG)) + _pam_log(LOG_DEBUG, "access allowed for '%s' on '%s'", + username, uttyname); + return retval; +} + +PAM_EXTERN +int pam_sm_setcred(pam_handle_t *pamh,int flags,int argc + ,const char **argv) +{ + return PAM_SUCCESS; +} + + +#ifdef PAM_STATIC + +/* static module data */ + +struct pam_module _pam_securetty_modstruct = { + "pam_securetty", + pam_sm_authenticate, + pam_sm_setcred, + NULL, + NULL, + NULL, + NULL, +}; + +#endif + +/* end of module definition */ |