svn commit: r328909 - head/sys/kern

[John Baldwin]

Author: jhb
Date: Mon Feb  5 23:27:42 2018
New Revision: 328909
URL: https://svnweb.freebsd.org/changeset/base/328909

Log:
  Always give ELF brands a chance to veto a match.
  
  If a brand provides a header_supported hook, check it when trying to
  find a brand based on a matching interpreter as well as in the final
  loop for the fallback brand. Previously a brand might reject a binary
  via a header_supported hook in one of the earlier loops, but still be
  chosen by one of these later loops.
  
  Reviewed by:	kib
  Obtained from:	CheriBSD
  MFC after:	2 weeks
  Sponsored by:	DARPA / AFRL
  Differential Revision:	https://reviews.freebsd.org/D13945

Modified:
  head/sys/kern/imgact_elf.c

Modified: head/sys/kern/imgact_elf.c
==============================================================================
--- head/sys/kern/imgact_elf.c	Mon Feb  5 23:14:20 2018	(r328908)
+++ head/sys/kern/imgact_elf.c	Mon Feb  5 23:27:42 2018	(r328909)
@@ -321,7 +321,7 @@ __elfN(get_brandinfo)(struct image_params *imgp, const
 		    strcmp((const char *)&hdr->e_ident[OLD_EI_BRAND],
 		    bi->compat_3_brand) == 0))) {
 			/* Looks good, but give brand a chance to veto */
-			if (!bi->header_supported ||
+			if (bi->header_supported == NULL ||
 			    bi->header_supported(imgp)) {
 				/*
 				 * Again, prefer strictly matching
@@ -369,7 +369,8 @@ __elfN(get_brandinfo)(struct image_params *imgp, const
 			    /* ELF image p_filesz includes terminating zero */
 			    strlen(bi->interp_path) + 1 == interp_name_len &&
 			    strncmp(interp, bi->interp_path, interp_name_len)
-			    == 0)
+			    == 0 && (bi->header_supported == NULL ||
+			    bi->header_supported(imgp)))
 				return (bi);
 		}
 	}
@@ -381,7 +382,9 @@ __elfN(get_brandinfo)(struct image_params *imgp, const
 		    (interp != NULL && (bi->flags & BI_BRAND_ONLY_STATIC) != 0))
 			continue;
 		if (hdr->e_machine == bi->machine &&
-		    __elfN(fallback_brand) == bi->brand)
+		    __elfN(fallback_brand) == bi->brand &&
+		    (bi->header_supported == NULL ||
+		    bi->header_supported(imgp)))
 			return (bi);
 	}
 	return (NULL);