Change how the mailer is waited for. Instead of having a SIGCHLD

handler, use the double fork trick to orphan the child that opens
the pipe to sendmail.  Fixes a problem running su on some Linux distros.

diff --git a/logging.c b/logging.c
index d8b676cf1b7c713e4906c7c260ab48fb07c47382..4b29aa591e11b517446b8311c7b65d811623d7c9 100644 (file)
--- a/logging.c
+++ b/logging.c
@@ -425,8 +425,8 @@ send_mail(line)
 {
     FILE *mail;
     char *p;
-    int pfd[2];
-    pid_t pid;
+    int pfd[2], status;
+    pid_t pid, rv;
     sigaction_t sa, saved_sa_pipe;
 #ifndef NO_ROOT_MAILER
     static char *root_envp[] = {
@@ -443,19 +443,58 @@ send_mail(line)
     if (!def_mailerpath || !def_mailto)
        return;
 
+    /* Fork a child so we can be asyncronous. */
+    switch (pid = fork()) {
+       case -1:
+           /* Error. */
+           error(1, "cannot fork");
+           break;
+       case 0:
+           /* Child continues below. */
+           break;
+       default:
+           /* Parent waits and returns. */
+           do {
+#ifdef sudo_waitpid
+               rv = sudo_waitpid(pid, &status, 0);
+#else
+               rv = wait(&status);
+#endif
+           } while (rv == -1 && errno == EINTR);
+           return;
+    }
+
+    /* Fork again and orphan the grandchild so parent can continue. */
+    switch (pid = fork()) {
+       case -1:
+           /* Error. */
+           warning("cannot fork");
+           _exit(1);
+           break;
+       case 0:
+           /* Grandchild continues below. */
+           break;
+       default:
+           /* Orphan grandchild. */
+           _exit(0);
+    }
+
     /* Ignore SIGPIPE in case mailer exits prematurely (or is missing). */
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = 0;
     sa.sa_handler = SIG_IGN;
     (void) sigaction(SIGPIPE, &sa, &saved_sa_pipe);
 
-    if (pipe(pfd) == -1)
-       error(1, "cannot open pipe");
+    if (pipe(pfd) == -1) {
+       warning("cannot open pipe");
+       _exit(1);
+    }
 
     switch (pid = fork()) {
        case -1:
            /* Error. */
-           error(1, "cannot fork");
+           warning("cannot fork");
+           _exit(1);
            break;
        case 0:
            {
@@ -463,7 +502,7 @@ send_mail(line)
                char *mpath, *mflags;
                int i;
 
-               /* Child, set stdin to output side of the pipe */
+               /* Great-grandchild, set stdin to output side of the pipe */
                if (pfd[0] != STDIN_FILENO) {
                    (void) dup2(pfd[0], STDIN_FILENO);
                    (void) close(pfd[0]);
@@ -533,7 +572,13 @@ send_mail(line)
     (void) fprintf(mail, "\n\n%s : %s : %s : %s\n\n", user_host,
        get_timestr(), user_name, line);
     fclose(mail);
-
+    do {
+#ifdef sudo_waitpid
+        rv = sudo_waitpid(pid, &status, 0);
+#else
+        rv = wait(&status);
+#endif
+    } while (rv == -1 && errno == EINTR);
     (void) sigaction(SIGPIPE, &saved_sa_pipe, NULL);
 }
 
@@ -551,26 +596,6 @@ should_mail(status)
        (def_mail_no_perms && !ISSET(status, VALIDATE_OK)));
 }
 
-/*
- * SIGCHLD sig handler--wait for children as they die.
- */
-RETSIGTYPE
-reapchild(sig)
-    int sig;
-{
-    int status, serrno = errno;
-#ifdef sudo_waitpid
-    pid_t pid;
-
-    do {
-       pid = sudo_waitpid(-1, &status, WNOHANG);
-    } while (pid != 0 && (pid != -1 || errno == EINTR));
-#else
-    (void) wait(&status);
-#endif
-    errno = serrno;
-}
-
 /*
  * Return an ascii string with the current date + time
  * Uses strftime() if available, else falls back to ctime().

diff --git a/sudo.c b/sudo.c
index a4ed546138b44a2f82932eb5b0b18a69db549847..abf9c37acbf137249abdabd365e52abdd62517d3 100644 (file)
--- a/sudo.c
+++ b/sudo.c
@@ -153,7 +153,7 @@ login_cap_t *lc;
 #ifdef HAVE_BSD_AUTH_H
 char *login_style;
 #endif /* HAVE_BSD_AUTH_H */
-sigaction_t saved_sa_int, saved_sa_quit, saved_sa_tstp, saved_sa_chld;
+sigaction_t saved_sa_int, saved_sa_quit, saved_sa_tstp;
 static char *runas_user;
 static char *runas_group;
 static struct sudo_nss_list *snl;
@@ -208,8 +208,6 @@ main(argc, argv, envp)
     (void) sigaction(SIGINT, &sa, &saved_sa_int);
     (void) sigaction(SIGQUIT, &sa, &saved_sa_quit);
     (void) sigaction(SIGTSTP, &sa, &saved_sa_tstp);
-    sa.sa_handler = reapchild;
-    (void) sigaction(SIGCHLD, &sa, &saved_sa_chld);
 
     /*
      * Turn off core dumps and make sure fds 0-2 are open.
@@ -492,7 +490,6 @@ main(argc, argv, envp)
        (void) sigaction(SIGINT, &saved_sa_int, NULL);
        (void) sigaction(SIGQUIT, &saved_sa_quit, NULL);
        (void) sigaction(SIGTSTP, &saved_sa_tstp, NULL);
-       (void) sigaction(SIGCHLD, &saved_sa_chld, NULL);
 
        /* Close the password and group files and free up memory. */
        sudo_endpwent();

diff --git a/sudo_edit.c b/sudo_edit.c
index ca67716152fba33e7d5435936dad625d61501463..8548d7a50525f858e2559eef4a3fc8cf724952a7 100644 (file)
--- a/sudo_edit.c
+++ b/sudo_edit.c
@@ -59,7 +59,7 @@
 __unused static const char rcsid[] = "$Sudo$";
 #endif /* lint */
 
-extern sigaction_t saved_sa_int, saved_sa_quit, saved_sa_tstp, saved_sa_chld;
+extern sigaction_t saved_sa_int, saved_sa_quit, saved_sa_tstp;
 extern char **environ;
 
 /*
@@ -226,11 +226,10 @@ int sudo_edit(argc, argv, envp)
        nargv[ac++] = tf[i++].tfile;
     nargv[ac] = NULL;
 
-    /* We wait for our own children and can be suspended. */
+    /* Allow the editor to be suspended. */
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = SA_RESTART;
     sa.sa_handler = SIG_DFL;
-    (void) sigaction(SIGCHLD, &sa, NULL);
     (void) sigaction(SIGTSTP, &saved_sa_tstp, NULL);
 
     /*
@@ -246,7 +245,6 @@ int sudo_edit(argc, argv, envp)
        /* child */
        (void) sigaction(SIGINT, &saved_sa_int, NULL);
        (void) sigaction(SIGQUIT, &saved_sa_quit, NULL);
-       (void) sigaction(SIGCHLD, &saved_sa_chld, NULL);
        set_perms(PERM_FULL_USER);
        closefrom(def_closefrom + 1);
        execvp(nargv[0], nargv);

diff --git a/visudo.c b/visudo.c
index dc6d11ffb668ef764f68848cb1adc2ad99b0bb23..433614ef6e66d4ef7d1fbe5b6059c4e5c613922c 100644 (file)
--- a/visudo.c
+++ b/visudo.c
@@ -651,19 +651,13 @@ run_command(path, argv)
     char **argv;
 {
     int status;
-    pid_t pid;
-    sigset_t set, oset;
-
-    (void) sigemptyset(&set);
-    (void) sigaddset(&set, SIGCHLD);
-    (void) sigprocmask(SIG_BLOCK, &set, &oset);
+    pid_t pid, rv;
 
     switch (pid = fork()) {
        case -1:
            error(1, "unable to run %s", path);
            break;      /* NOTREACHED */
        case 0:
-           (void) sigprocmask(SIG_SETMASK, &oset, NULL);
            sudo_endpwent();
            sudo_endgrent();
            closefrom(STDERR_FILENO + 1);
@@ -673,15 +667,15 @@ run_command(path, argv)
            break;      /* NOTREACHED */
     }
 
+    do {
 #ifdef sudo_waitpid
-    pid = sudo_waitpid(pid, &status, 0);
+       rv = sudo_waitpid(pid, &status, 0);
 #else
-    pid = wait(&status);
+       rv = wait(&status);
 #endif
+    } while (rv == -1 && errno == EINTR);
 
-    (void) sigprocmask(SIG_SETMASK, &oset, NULL);
-
-    if (pid == -1 || !WIFEXITED(status))
+    if (rv == -1 || !WIFEXITED(status))
        return(-1);
     return(WEXITSTATUS(status));
 }