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author | Steve Langasek <vorlon@debian.org> | 2014-01-16 00:38:42 +0000 |
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committer | Steve Langasek <vorlon@debian.org> | 2014-01-16 00:38:42 +0000 |
commit | 60fe4501b4194949d3117a937abdfa90d3f138e9 (patch) | |
tree | 212a6a00baa11e9d0ca7bc27b12420d1dce6f07c /modules/pam_securetty/pam_securetty.c | |
download | pam-60fe4501b4194949d3117a937abdfa90d3f138e9.tar.gz pam-60fe4501b4194949d3117a937abdfa90d3f138e9.tar.bz2 pam-60fe4501b4194949d3117a937abdfa90d3f138e9.zip |
Import pam_1.1.8.orig.tar.gz
[dgit import orig pam_1.1.8.orig.tar.gz]
Diffstat (limited to 'modules/pam_securetty/pam_securetty.c')
-rw-r--r-- | modules/pam_securetty/pam_securetty.c | 290 |
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 00000000..5f2d1bec --- /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 */ |