[src/trunk]: src/libexec/ld.aout_so Document LD_PRELOAD, fixing PR lib/9663, ...

[kleink <kleink%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/f09a38001f6a
branches:  trunk
changeset: 484066:f09a38001f6a
user:      kleink <kleink%NetBSD.org@localhost>
date:      Fri Mar 24 20:10:28 2000 +0000

description:
Document LD_PRELOAD, fixing PR lib/9663, and note that (and why) neither
this nor LD_LIBRARY_PATH are honored when executing set[ug]id.

diffstat:

 libexec/ld.aout_so/rtld.1 |  19 +++++++++++++++++--
 1 files changed, 17 insertions(+), 2 deletions(-)

diffs (44 lines):

diff -r 6d836ce2f2b7 -r f09a38001f6a libexec/ld.aout_so/rtld.1
--- a/libexec/ld.aout_so/rtld.1 Fri Mar 24 19:07:12 2000 +0000
+++ b/libexec/ld.aout_so/rtld.1 Fri Mar 24 20:10:28 2000 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: rtld.1,v 1.9 1999/11/18 19:07:48 kristerw Exp $
+.\"    $NetBSD: rtld.1,v 1.10 2000/03/24 20:10:28 kleink Exp $
 .\"
 .\" Copyright (c) 1998 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -34,7 +34,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd June 27, 1995
+.Dd March 24, 2000
 .Dt RTLD 1
 .Os
 .Sh NAME
@@ -144,6 +144,12 @@
 .It Ev LD_LIBRARY_PATH
 A colon separated list of directories, overriding the default search path
 for shared libraries.
+.It Ev LD_PRELOAD
+A colon separated list of shared object filenames to be loaded
+.Em after
+the main program but
+.Em before
+its shared object dependencies.
 .It Ev LD_WARN_NON_PURE_CODE
 When set, issue a warning whenever a link-editing operation requires
 modification of the text segment of some loaded object. This is usually
@@ -219,3 +225,12 @@
 .Xr ldconfig 8
 .Sh HISTORY
 The shared library model employed first appeared in SunOS 4.0.
+.Pp
+.Sh SECURITY CONSIDERATIONS
+The environment variables
+.Ev LD_LIBRARY_PATH
+and
+.Ev LD_PRELOAD
+are not honored when executing in a set-user-ID or set-group-ID environment.
+This action is taken to prevent malicious substitution of shared object
+dependencies or interposition of symbols.