Attachment 3307 Details for Bug 3049 – attempt #2

[patch] attempt #2

bv3049.diff (text/plain), 4.19 KB, created by Damien Miller on 2019-08-02 16:42:23 AEST

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Creator: Damien Miller

Created: 2019-08-02 16:42:23 AEST

Size: 4.19 KB

patch

obsolete

>commit b0ac8fbc0edea1cf2dfc78df55095757f65ca243
>Author: Damien Miller <djm@mindrot.org>
>Date:   Fri Aug 2 10:56:36 2019 +1000
>
>    add proc_fdinfo strategy for closefrom()
>    
>    based on patch from likan_999.student@sina.com in bz#3049
>    
>    refactor out fallback brute-force closefrom() implementation and
>    share it between /proc/pid/fd and proc_fdinfo strategies.
>    
>    ok dtucker@
>
>diff --git a/configure.ac b/configure.ac
>index 1c35b090..8c6c4637 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 b56476a2..12d159ac 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 +58,88 @@
> __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, need, got = 0;
>+	pid_t pid = getpid();
>+	struct proc_fdinfo *fdinfo_buf = NULL;
>+
>+	/*
>+	 * Obtain map of open fds.
>+	 *
>+	 * Be prepared to retry in case the table size changes between the
>+	 * size query and the actual attempt to fetch it.
>+	 */
>+	for (i = 0; i < 2; i++) {
>+		/* Obtain size */
>+		need = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, NULL, 0);
>+		if (need == 0)
>+			return; /* no fds, really? */
>+		else if (need == -1)
>+			break;
>+		if ((fdinfo_buf = malloc(need)) == NULL)
>+			break;
>+		got = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, fdinfo_buf, need);
>+		if (got >= 0 && got <= need)
>+			break; /* success */
>+		free(fdinfo_buf);
>+		fdinfo_buf = NULL;
>+		if (got == -1)
>+			break;
>+		/* fd table size increased; retry */
>+	}
>+	/* If unable to obtain the fd map, then fall back to brute force */
>+	if (fdinfo_buf == NULL) {
>+		closefrom_fallback(lowfd);
>+		return
>+	}
>+	/* Close fds from map */
>+	for (i = 0; i < got / PROC_PIDLISTFD_SIZE; i++) {
>+		if (fdinfo_buf[i].proc_fd >= lowfd)
>+			close(fdinfo_buf[i].proc_fd);
>+	}
>+	free(fdinfo_buf);
>+}
>+#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 +155,16 @@ 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 */

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