2 files changed, 70 insertions, 21 deletions

diff --git a/configure.ac b/configure.ac
index 1c35b090b..8c6c4637c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -679,6 +679,9 @@ main() { if (NSVersionOfRunTimeLibrary("System") >= (60 << 16))
         AC_CHECK_LIB([sandbox], [sandbox_apply], [
             SSHDLIBS="$SSHDLIBS -lsandbox"
         ])
+        # proc_pidinfo()-based closefrom() replacement.
+        AC_CHECK_HEADERS([libproc.h])
+        AC_CHECK_FUNCS([proc_pidinfo])
         ;;
 *-*-dragonfly*)
         SSHDLIBS="$SSHDLIBS -lcrypt"
diff --git a/openbsd-compat/bsd-closefrom.c b/openbsd-compat/bsd-closefrom.c
index b56476a2d..8b9a56278 100644
--- a/openbsd-compat/bsd-closefrom.c
+++ b/openbsd-compat/bsd-closefrom.c
@@ -46,6 +46,9 @@
 #  include <ndir.h>
 # endif
 #endif
+#if defined(HAVE_LIBPROC_H)
+# include <libproc.h>
+#endif
 
 #ifndef OPEN_MAX
 # define OPEN_MAX       256
@@ -55,21 +58,73 @@
 __unused static const char rcsid[] = "$Sudo: closefrom.c,v 1.11 2006/08/17 15:26:54 millert Exp $";
 #endif /* lint */
 
+#ifndef HAVE_FCNTL_CLOSEM
 /*
  * Close all file descriptors greater than or equal to lowfd.
  */
+static void
+closefrom_fallback(int lowfd)
+{
+        long fd, maxfd;
+
+        /*
+         * Fall back on sysconf() or getdtablesize().  We avoid checking
+         * resource limits since it is possible to open a file descriptor
+         * and then drop the rlimit such that it is below the open fd.
+         */
+#ifdef HAVE_SYSCONF
+        maxfd = sysconf(_SC_OPEN_MAX);
+#else
+        maxfd = getdtablesize();
+#endif /* HAVE_SYSCONF */
+        if (maxfd < 0)
+                maxfd = OPEN_MAX;
+
+        for (fd = lowfd; fd < maxfd; fd++)
+                (void) close((int) fd);
+}
+#endif /* HAVE_FCNTL_CLOSEM */
+
 #ifdef HAVE_FCNTL_CLOSEM
 void
 closefrom(int lowfd)
 {
     (void) fcntl(lowfd, F_CLOSEM, 0);
 }
-#else
+#elif defined(HAVE_LIBPROC_H) && defined(HAVE_PROC_PIDINFO)
 void
 closefrom(int lowfd)
 {
-    long fd, maxfd;
-#if defined(HAVE_DIRFD) && defined(HAVE_PROC_PID)
+        int i, r, sz;
+        pid_t pid = getpid();
+        struct proc_fdinfo *fdinfo_buf = NULL;
+
+        sz = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, NULL, 0);
+        if (sz == 0)
+                return; /* no fds, really? */
+        else if (sz == -1)
+                goto fallback;
+        if ((fdinfo_buf = malloc(sz)) == NULL)
+                goto fallback;
+        r = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, fdinfo_buf, sz);
+        if (r < 0 || r >= sz)
+                goto fallback;
+        for (i = 0; i < sz / (int)PROC_PIDLISTFD_SIZE; i++) {
+                if (fdinfo_buf[i].proc_fd >= lowfd)
+                        close(fdinfo_buf[i].proc_fd);
+        }
+        free(fdinfo_buf);
+        return;
+ fallback:
+        free(fdinfo_buf);
+        closefrom_fallback(lowfd);
+        return;
+}
+#elif defined(HAVE_DIRFD) && defined(HAVE_PROC_PID)
+void
+closefrom(int lowfd)
+{
+    long fd;
     char fdpath[PATH_MAX], *endp;
     struct dirent *dent;
     DIR *dirp;
@@ -85,25 +140,16 @@ closefrom(int lowfd)
                 (void) close((int) fd);
         }
         (void) closedir(dirp);
-    } else
-#endif
-    {
-        /*
-         * Fall back on sysconf() or getdtablesize().  We avoid checking
-         * resource limits since it is possible to open a file descriptor
-         * and then drop the rlimit such that it is below the open fd.
-         */
-#ifdef HAVE_SYSCONF
-        maxfd = sysconf(_SC_OPEN_MAX);
-#else
-        maxfd = getdtablesize();
-#endif /* HAVE_SYSCONF */
-        if (maxfd < 0)
-            maxfd = OPEN_MAX;
-
-        for (fd = lowfd; fd < maxfd; fd++)
-            (void) close((int) fd);
+        return;
     }
+    /* /proc/$$/fd strategy failed, fall back to brute force closure */
+    closefrom_fallback(lowfd);
+}
+#else
+void
+closefrom(int lowfd)
+{
+        closefrom_fallback(lowfd);
 }
 #endif /* !HAVE_FCNTL_CLOSEM */
 #endif /* HAVE_CLOSEFROM */