X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?p=xscreensaver;a=blobdiff_plain;f=driver%2Fpasswd-pam.c;h=a4b132123f7c8ce63078961b80617466efef6a54;hp=0d14e262313ea8471661d85632d71f78860c110e;hb=07faf451b99879183ed7e909e43a0e065be1ee7f;hpb=278c59e14c53fd412b734e699bd4f314f766f804 diff --git a/driver/passwd-pam.c b/driver/passwd-pam.c index 0d14e262..a4b13212 100644 --- a/driver/passwd-pam.c +++ b/driver/passwd-pam.c @@ -1,7 +1,7 @@ /* passwd-pam.c --- verifying typed passwords with PAM * (Pluggable Authentication Modules.) * written by Bill Nottingham (and jwz) for - * xscreensaver, Copyright (c) 1993-1998 Jamie Zawinski + * xscreensaver, Copyright (c) 1993-2003 Jamie Zawinski * * Permission to use, copy, modify, distribute, and sell this software and its * documentation for any purpose is hereby granted without fee, provided that @@ -52,9 +52,13 @@ extern char *blurb(void); #include #include #include +#include +#include #include +extern sigset_t block_sigchld (void); +extern void unblock_sigchld (void); /* blargh */ #undef Bool @@ -67,6 +71,13 @@ extern char *blurb(void); #undef countof #define countof(x) (sizeof((x))/sizeof(*(x))) +/* Some time between Red Hat 4.2 and 7.0, the words were transposed + in the various PAM_x_CRED macro names. Yay! + */ +#ifndef PAM_REFRESH_CRED +# define PAM_REFRESH_CRED PAM_CRED_REFRESH +#endif + static int pam_conversation (int nmsgs, const struct pam_message **msg, struct pam_response **resp, @@ -78,6 +89,8 @@ struct pam_closure { Bool verbose_p; }; +Bool pam_passwd_valid_p (const char *typed_passwd, Bool verbose_p); +Bool pam_priv_init (int argc, char **argv, Bool verbose_p); #ifdef HAVE_PAM_FAIL_DELAY /* We handle delays ourself.*/ @@ -150,6 +163,9 @@ struct pam_closure { /* On SunOS 5.6, the `pam_conv.appdata_ptr' slot seems to be ignored, and the `closure' argument to pc.conv always comes in as random garbage. So we get around this by using a global variable instead. Shoot me! + + (I've been told this is bug 4092227, and is fixed in Solaris 7.) + (I've also been told that it's fixed in Solaris 2.6 by patch 106257-05.) */ static void *suns_pam_implementation_blows = 0; @@ -167,6 +183,8 @@ pam_passwd_valid_p (const char *typed_passwd, Bool verbose_p) struct pam_conv pc; struct pam_closure c; char *user = 0; + sigset_t set; + struct timespec timeout; struct passwd *p = getpwuid (getuid ()); if (!p) return False; @@ -200,38 +218,101 @@ pam_passwd_valid_p (const char *typed_passwd, Bool verbose_p) far as PAM is concerned...) */ { - const char *tty = ":0.0"; - status = pam_set_item (pamh, PAM_TTY, strdup(tty)); + char *tty = strdup (":0.0"); + status = pam_set_item (pamh, PAM_TTY, tty); if (verbose_p) fprintf (stderr, "%s: pam_set_item (p, PAM_TTY, \"%s\") ==> %d (%s)\n", blurb(), tty, status, PAM_STRERROR(pamh, status)); + free (tty); } /* Try to authenticate as the current user. + We must turn off our SIGCHLD handler for the duration of the call to + pam_authenticate(), because in some cases, the underlying PAM code + will do this: + + 1: fork a setuid subprocess to do some dirty work; + 2: read a response from that subprocess; + 3: waitpid(pid, ...) on that subprocess. + + If we (the ignorant parent process) have a SIGCHLD handler, then there's + a race condition between steps 2 and 3: if the subprocess exits before + waitpid() was called, then our SIGCHLD handler fires, and gets notified + of the subprocess death; then PAM's call to waitpid() fails, because the + process has already been reaped. + + I consider this a bug in PAM, since the caller should be able to have + whatever signal handlers it wants -- the PAM documentation doesn't say + "oh by the way, if you use PAM, you can't use SIGCHLD." */ + PAM_NO_DELAY(pamh); + + timeout.tv_sec = 0; + timeout.tv_nsec = 1; + set = block_sigchld(); status = pam_authenticate (pamh, 0); + sigtimedwait (&set, NULL, &timeout); + unblock_sigchld(); + if (verbose_p) fprintf (stderr, "%s: pam_authenticate (...) ==> %d (%s)\n", blurb(), status, PAM_STRERROR(pamh, status)); if (status == PAM_SUCCESS) /* Win! */ - goto DONE; + { + int status2; + /* We don't actually care if the account modules fail or succeed, + * but we need to run them anyway because certain pam modules + * depend on side effects of the account modules getting run. + */ + status2 = pam_acct_mgmt (pamh, 0); + + if (verbose_p) + fprintf (stderr, "%s: pam_acct_mgmt (...) ==> %d (%s)\n", + blurb(), status2, PAM_STRERROR(pamh, status2)); + + /* Each time we successfully authenticate, refresh credentials, + for Kerberos/AFS/DCE/etc. If this fails, just ignore that + failure and blunder along; it shouldn't matter. + + Note: this used to be PAM_REFRESH_CRED instead of + PAM_REINITIALIZE_CRED, but Jason Heiss + says that the Linux PAM library ignores that one, and only refreshes + credentials when using PAM_REINITIALIZE_CRED. + */ + status2 = pam_setcred (pamh, PAM_REINITIALIZE_CRED); + if (verbose_p) + fprintf (stderr, "%s: pam_setcred (...) ==> %d (%s)\n", + blurb(), status2, PAM_STRERROR(pamh, status2)); + goto DONE; + } + +#ifdef ALLOW_ROOT_PASSWD /* If that didn't work, set the user to root, and try to authenticate again. */ - c.user = "root"; - status = pam_set_item (pamh, PAM_USER, strdup(c.user)); + if (user) free (user); + user = strdup ("root"); + c.user = user; + status = pam_set_item (pamh, PAM_USER, c.user); if (verbose_p) fprintf (stderr, "%s: pam_set_item(p, PAM_USER, \"%s\") ==> %d (%s)\n", blurb(), c.user, status, PAM_STRERROR(pamh, status)); if (status != PAM_SUCCESS) goto DONE; PAM_NO_DELAY(pamh); + + set = block_sigchld(); status = pam_authenticate (pamh, 0); + sigtimedwait(&set, NULL, &timeout); + unblock_sigchld(); + if (verbose_p) fprintf (stderr, "%s: pam_authenticate (...) ==> %d (%s)\n", blurb(), status, PAM_STRERROR(pamh, status)); +#endif /* ALLOW_ROOT_PASSWD */ + DONE: if (user) free (user); if (pamh) @@ -263,7 +344,11 @@ pam_priv_init (int argc, char **argv, Bool verbose_p) const char file2[] = "/etc/pam.conf"; struct stat st; - if (stat (dir, &st) == 0 && st.st_mode & S_IFDIR) +# ifndef S_ISDIR +# define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR) +# endif + + if (stat (dir, &st) == 0 && S_ISDIR(st.st_mode)) { if (stat (file, &st) != 0) fprintf (stderr,