- dtucker@cvs.openbsd.org 2007/03/19 12:16:42

     [ssh-agent.c]
     Remove the signal handler that checks if the agent's parent process
     has gone away, instead check when the select loop returns.  Record when
     the next key will expire when scanning for expired keys.  Set the select
     timeout to whichever of these two things happens next.  With djm@, with &
     ok deraadt@ markus@

1 files changed, 41 insertions, 25 deletions

diff --git a/ssh-agent.c b/ssh-agent.c
index a3a867c33..c3d5e5a75 100644
--- a/ssh-agent.c
+++ b/ssh-agent.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-agent.c,v 1.154 2007/02/28 00:55:30 dtucker Exp $ */
+/* $OpenBSD: ssh-agent.c,v 1.155 2007/03/19 12:16:42 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -120,6 +120,7 @@ int max_fd = 0;
 
 /* pid of shell == parent of agent */
 pid_t parent_pid = -1;
+u_int parent_alive_interval = 0;
 
 /* pathname and directory for AUTH_SOCKET */
 char socket_name[MAXPATHLEN];
@@ -421,10 +422,11 @@ process_remove_all_identities(SocketEntry *e, int version)
         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 }
 
-static void
+/* removes expired keys and returns number of seconds until the next expiry */
+static u_int
 reaper(void)
 {
-        u_int now = time(NULL);
+        u_int deadline = 0, now = time(NULL);
         Identity *id, *nxt;
         int version;
         Idtab *tab;
@@ -433,14 +435,22 @@ reaper(void)
                 tab = idtab_lookup(version);
                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
                         nxt = TAILQ_NEXT(id, next);
-                        if (id->death != 0 && now >= id->death) {
+                        if (id->death == 0)
+                                continue;
+                        if (now >= id->death) {
                                 debug("expiring key '%s'", id->comment);
                                 TAILQ_REMOVE(&tab->idlist, id, next);
                                 free_identity(id);
                                 tab->nentries--;
-                        }
+                        } else
+                                deadline = (deadline == 0) ? id->death :
+                                    MIN(deadline, id->death);
                 }
         }
+        if (deadline == 0 || deadline <= now)
+                return 0;
+        else
+                return (deadline - now);
 }
 
 static void
@@ -826,10 +836,12 @@ new_socket(sock_type type, int fd)
 }
 
 static int
-prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
+prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
+    struct timeval **tvpp)
 {
-        u_int i, sz;
+        u_int i, sz, deadline;
         int n = 0;
+        static struct timeval tv;
 
         for (i = 0; i < sockets_alloc; i++) {
                 switch (sockets[i].type) {
@@ -873,6 +885,17 @@ prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
                         break;
                 }
         }
+        deadline = reaper();
+        if (parent_alive_interval != 0)
+                deadline = (deadline == 0) ? parent_alive_interval :
+                    MIN(deadline, parent_alive_interval);
+        if (deadline == 0) {
+                *tvpp = NULL;
+        } else {
+                tv.tv_sec = deadline;
+                tv.tv_usec = 0;
+                *tvpp = &tv;
+        }
         return (1);
 }
 
@@ -980,19 +1003,14 @@ cleanup_handler(int sig)
         _exit(2);
 }
 
-/*ARGSUSED*/
 static void
-check_parent_exists(int sig)
+check_parent_exists(void)
 {
-        int save_errno = errno;
-
         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
                 /* printf("Parent has died - Authentication agent exiting.\n"); */
-                cleanup_handler(sig); /* safe */
+                cleanup_socket();
+                _exit(2);
         }
-        mysignal(SIGALRM, check_parent_exists);
-        alarm(10);
-        errno = save_errno;
 }
 
 static void
@@ -1027,7 +1045,7 @@ main(int ac, char **av)
         extern char *optarg;
         pid_t pid;
         char pidstrbuf[1 + 3 * sizeof pid];
-        struct timeval tv;
+        struct timeval *tvp = NULL;
 
         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
         sanitise_stdfd();
@@ -1228,10 +1246,8 @@ main(int ac, char **av)
 
 skip:
         new_socket(AUTH_SOCKET, sock);
-        if (ac > 0) {
-                mysignal(SIGALRM, check_parent_exists);
-                alarm(10);
-        }
+        if (ac > 0)
+                parent_alive_interval = 10;
         idtab_init();
         if (!d_flag)
                 signal(SIGINT, SIG_IGN);
@@ -1241,12 +1257,12 @@ skip:
         nalloc = 0;
 
         while (1) {
-                tv.tv_sec = 10;
-                tv.tv_usec = 0;
-                prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
-                result = select(max_fd + 1, readsetp, writesetp, NULL, &tv);
+                prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
+                result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
                 saved_errno = errno;
-                reaper();       /* remove expired keys */
+                if (parent_alive_interval != 0)
+                        check_parent_exists();
+                (void) reaper();        /* remove expired keys */
                 if (result < 0) {
                         if (saved_errno == EINTR)
                                 continue;