[PATCH] Recognize NT_VERSION notes.

Mark Wielaard mark@klomp.org
Sun Nov 11 23:08:00 GMT 2018


NT_VERSION notes are emitted by the gas .version directive.
They have an empty description and (ab)use the owner name to store the
version data string.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 libebl/ChangeLog            |  9 +++++++++
 libebl/eblobjnote.c         | 10 +++++++++-
 libebl/eblobjnotetypename.c |  8 +++++++-
 libebl/libebl.h             |  4 ++--
 src/ChangeLog               |  7 +++++++
 src/elflint.c               | 27 +++++++++++++++++++++------
 src/readelf.c               |  1 +
 tests/ChangeLog             |  5 +++++
 tests/run-readelf-n.sh      | 19 ++++++++++++++++++-
 9 files changed, 79 insertions(+), 11 deletions(-)

diff --git a/libebl/ChangeLog b/libebl/ChangeLog
index 120c84c06..076596f09 100644
--- a/libebl/ChangeLog
+++ b/libebl/ChangeLog
@@ -1,3 +1,12 @@
+2018-11-11  Mark Wielaard  <mark@klomp.org>
+
+	* eblobjnote.c (ebl_object_note): Recognize NT_VERSION with zero
+	descriptor. Add explicit "GNU" name check.
+	* eblobjnotetypename.c (ebl_object_note_type_name): Add extra
+	argument descsz. Recognize NT_VERSION using descsz. With "GNU"
+	name it is  NT_GNU_ABI_TAG.
+	* libebl.h (ebl_object_note_type_name): Add extra argument descsz.
+
 2018-10-18  Mark Wielaard  <mark@klomp.org>
 
 	* eblobjnote.c (ebl_object_note): Handle NT_GNU_PROPERTY_TYPE_0.
diff --git a/libebl/eblobjnote.c b/libebl/eblobjnote.c
index 57e9f52f4..8fda7d992 100644
--- a/libebl/eblobjnote.c
+++ b/libebl/eblobjnote.c
@@ -135,6 +135,14 @@ ebl_object_note (Ebl *ebl, const char *name, uint32_t type,
 	  return;
 	}
 
+      /* NT_VERSION doesn't have any info.  All data is in the name.  */
+      if (descsz == 0 && type == NT_VERSION)
+	return;
+
+      /* Everything else should have the "GNU" owner name.  */
+      if (strcmp ("GNU", name) != 0)
+	return;
+
       switch (type)
 	{
 	case NT_GNU_BUILD_ID:
@@ -337,7 +345,7 @@ ebl_object_note (Ebl *ebl, const char *name, uint32_t type,
 	  break;
 
 	case NT_GNU_ABI_TAG:
-	  if (strcmp (name, "GNU") == 0 && descsz >= 8 && descsz % 4 == 0)
+	  if (descsz >= 8 && descsz % 4 == 0)
 	    {
 	      Elf_Data in =
 		{
diff --git a/libebl/eblobjnotetypename.c b/libebl/eblobjnotetypename.c
index af23caea8..8cdd78199 100644
--- a/libebl/eblobjnotetypename.c
+++ b/libebl/eblobjnotetypename.c
@@ -39,6 +39,7 @@
 
 const char *
 ebl_object_note_type_name (Ebl *ebl, const char *name, uint32_t type,
+			   GElf_Word descsz,
 			   char *buf, size_t len)
 {
   const char *res = ebl->object_note_type_name (name, type, buf, len);
@@ -80,14 +81,19 @@ ebl_object_note_type_name (Ebl *ebl, const char *name, uint32_t type,
 
       if (strcmp (name, "GNU") != 0)
 	{
+	  /* NT_VERSION is special, all data is in the name.  */
+	  if (descsz == 0 && type == NT_VERSION)
+	    return "VERSION";
+
 	  snprintf (buf, len, "%s: %" PRIu32, gettext ("<unknown>"), type);
 	  return buf;
 	}
 
+      /* And finally all the "GNU" note types.  */
       static const char *knowntypes[] =
 	{
 #define KNOWNSTYPE(name) [NT_##name] = #name
-	  KNOWNSTYPE (VERSION),
+	  KNOWNSTYPE (GNU_ABI_TAG),
 	  KNOWNSTYPE (GNU_HWCAP),
 	  KNOWNSTYPE (GNU_BUILD_ID),
 	  KNOWNSTYPE (GNU_GOLD_VERSION),
diff --git a/libebl/libebl.h b/libebl/libebl.h
index a34fe48dd..583065475 100644
--- a/libebl/libebl.h
+++ b/libebl/libebl.h
@@ -175,8 +175,8 @@ extern const char *ebl_core_note_type_name (Ebl *ebl, uint32_t type, char *buf,
 
 /* Return name of the note section type for an object file.  */
 extern const char *ebl_object_note_type_name (Ebl *ebl, const char *name,
-					      uint32_t type, char *buf,
-					      size_t len);
+					      uint32_t type, GElf_Word descsz,
+					      char *buf, size_t len);
 
 /* Print information about object note if available.  */
 extern void ebl_object_note (Ebl *ebl, const char *name, uint32_t type,
diff --git a/src/ChangeLog b/src/ChangeLog
index fc6d414ff..9f26b259a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2018-11-11  Mark Wielaard  <mark@klomp.org>
+
+	* readelf.c (handle_notes_data): Pass n_descsz to
+	ebl_object_note_type_name.
+	* elflint.c (check_note_data): Recognize NT_VERSION, add owner
+	name to unknown note error.
+
 2018-11-10  Mark Wielaard  <mark@klomp.org>
 
 	* elflint.c (check_program_header): Allow PT_GNU_EH_FRAME segment
diff --git a/src/elflint.c b/src/elflint.c
index 658f2ae2c..bddb8dd8e 100644
--- a/src/elflint.c
+++ b/src/elflint.c
@@ -1,5 +1,5 @@
 /* Pedantic checking of ELF files compliance with gABI/psABI spec.
-   Copyright (C) 2001-2015, 2017 Red Hat, Inc.
+   Copyright (C) 2001-2015, 2017, 2018 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <drepper@redhat.com>, 2001.
 
@@ -4332,7 +4332,17 @@ section [%2d] '%s': unknown core file note type %" PRIu32
 	  case NT_GNU_BUILD_ID:
 	  case NT_GNU_GOLD_VERSION:
 	  case NT_GNU_PROPERTY_TYPE_0:
-	    break;
+	    if (nhdr.n_namesz == sizeof ELF_NOTE_GNU
+		&& strcmp (data->d_buf + name_offset, ELF_NOTE_GNU) == 0)
+	      break;
+	    else
+	      {
+		/* NT_VERSION is 1, same as NT_GNU_ABI_TAG.  It has no
+		   descriptor and (ab)uses the name as version string.  */
+		if (nhdr.n_descsz == 0 && nhdr.n_type == NT_VERSION)
+		  break;
+	      }
+	      goto unknown_note;
 
 	  case 0:
 	    /* Linux vDSOs use a type 0 note for the kernel version word.  */
@@ -4341,16 +4351,21 @@ section [%2d] '%s': unknown core file note type %" PRIu32
 	      break;
 	    FALLTHROUGH;
 	  default:
+	    {
+	    unknown_note:
 	    if (shndx == 0)
 	      ERROR (gettext ("\
-phdr[%d]: unknown object file note type %" PRIu32 " at offset %zu\n"),
-		     phndx, (uint32_t) nhdr.n_type, offset);
+phdr[%d]: unknown object file note type %" PRIu32 " with owner name '%s' at offset %zu\n"),
+		     phndx, (uint32_t) nhdr.n_type,
+		     (char *) data->d_buf + name_offset, offset);
 	    else
 	      ERROR (gettext ("\
 section [%2d] '%s': unknown object file note type %" PRIu32
-			      " at offset %zu\n"),
+			      " with owner name '%s' at offset %zu\n"),
 		     shndx, section_name (ebl, shndx),
-		     (uint32_t) nhdr.n_type, offset);
+		     (uint32_t) nhdr.n_type,
+		     (char *) data->d_buf + name_offset, offset);
+	    }
 	  }
     }
 
diff --git a/src/readelf.c b/src/readelf.c
index c6c3fb323..659e34fb5 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -12201,6 +12201,7 @@ handle_notes_data (Ebl *ebl, const GElf_Ehdr *ehdr,
 	      ? ebl_core_note_type_name (ebl, nhdr.n_type,
 					 buf, sizeof (buf))
 	      : ebl_object_note_type_name (ebl, name, nhdr.n_type,
+					   nhdr.n_descsz,
 					   buf2, sizeof (buf2)));
 
       /* Filter out invalid entries.  */
diff --git a/tests/ChangeLog b/tests/ChangeLog
index 92dfb95d7..d92b8e3ac 100644
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,3 +1,8 @@
+2018-11-11  Mark Wielaard  <mark@klomp.org>
+
+	* run-readelf-n.sh: Fix NT_GNU_ABI_TAG type. Add testfile11 test
+	for NT_VERSION.
+
 2018-11-04  Mark Wielaard  <mark@klomp.org>
 
 	* testfile-bpf-reloc.expect.bz2: Update with new expected jump
diff --git a/tests/run-readelf-n.sh b/tests/run-readelf-n.sh
index 3ae7cf02f..7e2a845e6 100755
--- a/tests/run-readelf-n.sh
+++ b/tests/run-readelf-n.sh
@@ -48,8 +48,25 @@ Note segment of 32 bytes at offset 0x300:
 
 Note segment of 68 bytes at offset 0x320:
   Owner          Data size  Type
-  GNU                   16  VERSION
+  GNU                   16  GNU_ABI_TAG
     OS: Linux, ABI: 3.2.0
   GNU                   20  GNU_BUILD_ID
     Build ID: 83cb2229fabd2065d1361f5b46424cd75270f94b
 EOF
+
+# NT_VERSION note type clashes with "GNU" owner type NT_GNU_ABI_TAG.
+# Uses owner name (with zero desc) for version string.
+testfiles testfile11
+testrun_compare ${abs_top_builddir}/src/readelf -n testfile11 << EOF
+
+Note section [ 2] '.note.ABI-tag' of 32 bytes at offset 0x128:
+  Owner          Data size  Type
+  GNU                   16  GNU_ABI_TAG
+    OS: Linux, ABI: 2.2.5
+
+Note section [35] '.note' of 60 bytes at offset 0x13364:
+  Owner          Data size  Type
+  01.01                  0  VERSION
+  01.01                  0  VERSION
+  01.01                  0  VERSION
+EOF
-- 
2.19.1



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