PATCH (Re: [musl] be able to break inheritance of LD_LIBRARY_PATH)

[u-igbb@aetey.se]

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On Fri, Mar 28, 2014 at 02:00:36PM +0000, u-igbb@aetey.se wrote:
> By the way, when you say this - LD_PRELOAD should be actually usable
> in a non-inheritable way too. It brings otherwise the same problems
> as LD_LIBRARY_PATH. It could deserve its own loader argument I guess,
> like --preload.
> 
> > (there ar no "different versions of the loader" in musl)
> 
> Yes this is why I thought that a LD_LIBRARY_PATH removal would
> be enough. Of course it is much better to do this properly, by
> extending the behaviour of the loader when it is being used standalone.
> 
> This would cost just a few bytes I guess. I will look into proposing a patch.

Attaching the patch. It seems to work, under some primitive testing.
Could this or similar be considered for applying upstream?

Regards,
Rune

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--- src/ldso/dynlink.c.ori	2014-03-28 10:37:34.821317811 +0100
+++ src/ldso/dynlink.c	2014-03-28 16:45:26.435994022 +0100
@@ -1041,12 +1041,34 @@
 		size_t l = strlen(ldname);
 		if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
 		*argv++ = (void *)-1;
-		if (argv[0] && !strcmp(argv[0], "--")) *argv++ = (void *)-1;
+		while (argv[0] && argv[0][0] == '-') {
+			if (argv[0][1] == '-' && argv[0][2] == 0) { /* "--" */
+				*argv++ = (void *)-1;
+				break;
+			}
+			/* care about someone making the dynamic loader
+			 * itself (!) setuid? (s)he has possibly good
+			 * reasons, who am I to interfere -- thus
+			 * no setuid checking here -- rl */
+			if (!strcmp(argv[0], "--library-path")) {
+				*argv++ = (void *)-1;
+				env_path = argv[0]; /* even if NULL */
+			} else if (!strcmp(argv[0], "--preload")) {
+				*argv++ = (void *)-1;
+				env_preload = argv[0]; /* even if NULL */
+			} else
+				/* any -<something-else> stops parsing */
+				break;
+			if (!argv[0])
+				/* missing argument? */
+				break;
+			*argv++ = (void *)-1;
+		}
 		if (!argv[0]) {
 			dprintf(2, "musl libc\n"
 				"Version %s\n"
 				"Dynamic Program Loader\n"
-				"Usage: %s [--] pathname%s\n",
+				"Usage: %s [--library-path path] [--preload path] [--] pathname%s\n",
 				__libc_get_version(), ldname,
 				ldd_mode ? "" : " [args]");
 			_exit(1);