diff options
Diffstat (limited to 'modules/pam_securetty/pam_securetty.c')
| -rw-r--r-- | modules/pam_securetty/pam_securetty.c | 286 |
1 files changed, 286 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..47a5cd9 --- /dev/null +++ b/modules/pam_securetty/pam_securetty.c @@ -0,0 +1,286 @@ +/* + * pam_securetty module + * + * 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> +#include <errno.h> + +#include <security/pam_modules.h> +#include <security/pam_modutil.h> +#include <security/pam_ext.h> +#include "pam_inline.h" + +#define PAM_DEBUG_ARG 0x0001 +#define PAM_NOCONSOLE_ARG 0x0002 + +#define SECURETTY_FILE "/etc/securetty" +#ifdef VENDORDIR +#define SECURETTY2_FILE VENDORDIR"/securetty" +#endif +#define TTY_PREFIX "/dev/" +#define CMDLINE_FILE "/proc/cmdline" +#define CONSOLEACTIVE_FILE "/sys/class/tty/console/active" + +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 *securettyfile; + const char *username; + const char *uttyname; + const char *str; + 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) { + pam_syslog(pamh, LOG_NOTICE, "cannot determine user name: %s", + pam_strerror(pamh, retval)); + return (retval == PAM_CONV_AGAIN ? PAM_INCOMPLETE : retval); + } + + 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_ERR, "cannot determine user's tty"); + return PAM_SERVICE_ERR; + } + + /* The PAM_TTY item may be prefixed with "/dev/" - skip that */ + if ((str = pam_str_skip_prefix(uttyname, TTY_PREFIX)) != NULL) + uttyname = str; + + if (stat(SECURETTY_FILE, &ttyfileinfo)) { +#ifdef VENDORDIR + if (errno == ENOENT) { + if (stat(SECURETTY2_FILE, &ttyfileinfo)) { + if (ctrl & PAM_DEBUG_ARG) + pam_syslog(pamh, LOG_DEBUG, + "Couldn't open %s: %m", SECURETTY2_FILE); + return PAM_SUCCESS; /* for compatibility with old securetty handling, + this needs to succeed. But we still log the + error. */ + } + securettyfile = SECURETTY2_FILE; + } else { +#endif + if (ctrl & PAM_DEBUG_ARG) + pam_syslog(pamh, LOG_DEBUG, "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. */ +#ifdef VENDORDIR + } +#endif + } else { + securettyfile = SECURETTY_FILE; + } + + 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", + securettyfile); + return PAM_AUTH_ERR; + } + + ttyfile = fopen(securettyfile,"r"); + if (ttyfile == NULL) { /* Check that we opened it successfully */ + pam_syslog(pamh, LOG_ERR, "Error opening %s: %m", securettyfile); + 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; + + p = fgets(line, sizeof(line), cmdlinefile); + fclose(cmdlinefile); + + for (; p; p = strstr(p+1, "console=")) { + const char *e; + + /* Test whether this is a beginning of a word? */ + if (p > line && p[-1] != ' ') + continue; + + /* Is this our console? */ + if ((e = pam_str_skip_prefix_len(p + 8, uttyname, strlen(uttyname))) == NULL) + continue; + + /* Is there any garbage after the TTY name? */ + 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_NOTICE, "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 --- */ + +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__); +} + +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 --- */ + +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__); +} + +/* end of module definition */ |