svn commit: r295277 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Thu Feb  4 20:55:49 2016
New Revision: 295277
URL: https://svnweb.freebsd.org/changeset/base/295277

Log:
  When matching brand to the ELF binary by notes, try to find a brand
  with interpreter name exactly matching one wanted by the binary.  If
  no such brand exists, return first brand which accepted the binary by
  note.
  
  The change fixes a regression after r292749, where e.g. our two ia32
  compat brands, ia32_brand_info and ia32_brand_oinfo, only differ by
  the interpeter path and binary matches to a brand by linkage order.
  Then old binaries which require /usr/libexec/ld-elf.so.1 but matched
  against ia32_brand_info with interp_path /libexec/ld-elf.so.1, were
  considered requiring non-standard interpreter name, and magic to force
  ld-elf32.so.1 did not happen.
  
  Note that it might make sense to apply the same selection of brands
  for other matching criteria, SCO EI_OSABI and 3.x string.
  
  Reported and tested by:	dwmalone
  Sponsored by:	The FreeBSD Foundation
  MFC after:	3 days

Modified:
  head/sys/kern/imgact_elf.c

Modified: head/sys/kern/imgact_elf.c
==============================================================================
--- head/sys/kern/imgact_elf.c	Thu Feb  4 19:53:54 2016	(r295276)
+++ head/sys/kern/imgact_elf.c	Thu Feb  4 20:55:49 2016	(r295277)
@@ -258,7 +258,7 @@ __elfN(get_brandinfo)(struct image_param
     int interp_name_len, int32_t *osrel)
 {
 	const Elf_Ehdr *hdr = (const Elf_Ehdr *)imgp->image_header;
-	Elf_Brandinfo *bi;
+	Elf_Brandinfo *bi, *bi_m;
 	boolean_t ret;
 	int i;
 
@@ -270,6 +270,7 @@ __elfN(get_brandinfo)(struct image_param
 	 */
 
 	/* Look for an ".note.ABI-tag" ELF section */
+	bi_m = NULL;
 	for (i = 0; i < MAX_BRANDS; i++) {
 		bi = elf_brand_list[i];
 		if (bi == NULL)
@@ -280,10 +281,28 @@ __elfN(get_brandinfo)(struct image_param
 			/* Give brand a chance to veto check_note's guess */
 			if (ret && bi->header_supported)
 				ret = bi->header_supported(imgp);
+			/*
+			 * If note checker claimed the binary, but the
+			 * interpreter path in the image does not
+			 * match default one for the brand, try to
+			 * search for other brands with the same
+			 * interpreter.  Either there is better brand
+			 * with the right interpreter, or, failing
+			 * this, we return first brand which accepted
+			 * our note and, optionally, header.
+			 */
+			if (ret && bi_m == NULL && (strlen(bi->interp_path) +
+			    1 != interp_name_len || strncmp(interp,
+			    bi->interp_path, interp_name_len) != 0)) {
+				bi_m = bi;
+				ret = 0;
+			}
 			if (ret)
 				return (bi);
 		}
 	}
+	if (bi_m != NULL)
+		return (bi_m);
 
 	/* If the executable has a brand, search for it in the brand list. */
 	for (i = 0; i < MAX_BRANDS; i++) {