svn commit: r289324 - head/libexec/rtld-elf

[Konstantin Belousov]

Author: kib
Date: Wed Oct 14 18:29:21 2015
New Revision: 289324
URL: https://svnweb.freebsd.org/changeset/base/289324

Log:
  Allow PT_NOTES segments to be located anywhere in the executable
  image.
  
  The dynamic linker still requires that program headers of the
  executable or dso are mapped by a PT_LOAD segment.
  
  Reviewed by:	emaste, jhb
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks
  Differential revision:	https://reviews.freebsd.org/D3871

Modified:
  head/libexec/rtld-elf/map_object.c

Modified: head/libexec/rtld-elf/map_object.c
==============================================================================
--- head/libexec/rtld-elf/map_object.c	Wed Oct 14 18:29:00 2015	(r289323)
+++ head/libexec/rtld-elf/map_object.c	Wed Oct 14 18:29:21 2015	(r289324)
@@ -88,6 +88,8 @@ map_object(int fd, const char *path, con
     size_t relro_size;
     Elf_Addr note_start;
     Elf_Addr note_end;
+    char *note_map;
+    size_t note_map_len;
 
     hdr = get_elf_header(fd, path);
     if (hdr == NULL)
@@ -108,6 +110,7 @@ map_object(int fd, const char *path, con
     relro_size = 0;
     note_start = 0;
     note_end = 0;
+    note_map = NULL;
     segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
     stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
     while (phdr < phlimit) {
@@ -150,9 +153,20 @@ map_object(int fd, const char *path, con
 
 	case PT_NOTE:
 	    if (phdr->p_offset > PAGE_SIZE ||
-	      phdr->p_offset + phdr->p_filesz > PAGE_SIZE)
-		break;
-	    note_start = (Elf_Addr)(char *)hdr + phdr->p_offset;
+	      phdr->p_offset + phdr->p_filesz > PAGE_SIZE) {
+		note_map_len = round_page(phdr->p_offset +
+		  phdr->p_filesz) - trunc_page(phdr->p_offset);
+		note_map = mmap(NULL, note_map_len, PROT_READ,
+		  MAP_PRIVATE, fd, trunc_page(phdr->p_offset));
+		if (note_map == MAP_FAILED) {
+		    _rtld_error("%s: error mapping PT_NOTE (%d)", path, errno);
+		    goto error;
+		}
+		note_start = (Elf_Addr)(note_map + phdr->p_offset -
+		  trunc_page(phdr->p_offset));
+	    } else {
+		note_start = (Elf_Addr)(char *)hdr + phdr->p_offset;
+	    }
 	    note_end = note_start + phdr->p_filesz;
 	    break;
 	}
@@ -295,12 +309,16 @@ map_object(int fd, const char *path, con
     obj->relro_size = round_page(relro_size);
     if (note_start < note_end)
 	digest_notes(obj, note_start, note_end);
+    if (note_map != NULL)
+	munmap(note_map, note_map_len);
     munmap(hdr, PAGE_SIZE);
     return (obj);
 
 error1:
     munmap(mapbase, mapsize);
 error:
+    if (note_map != NULL && note_map != MAP_FAILED)
+	munmap(note_map, note_map_len);
     munmap(hdr, PAGE_SIZE);
     return (NULL);
 }