commit 72e30c2e0cb49a9a300667fdd5ff09082f717950

Author: Mark Wielaard <mark@klomp.org>

Date:   Mon Nov 12 23:34:24 2018 +0100

    Handle GNU Build Attribute ELF Notes.

    GNU Build Attribute ELF Notes are generated by the GCC annobin plugin

    and described at https://fedoraproject.org/wiki/Toolchain/Watermark

    Unfortunately the constants aren't yet described in the standard glibc

    elf.h so they have been added to the elfutils specific elf-knowledge.h.

    The notes abuse the name owner field to encode some data not in the

    description. This makes it a bit hard to parse. We have to match the

    note owner name prefix (to "GA") to be sure the type is valid. We also

    cannot rely on the owner name being a valid C string since the attribute

    name and value can contain zero (terminators). So pass around namesz

    to the ebl note parsing functions.

    eu-elflint will recognize and eu-readelf -n will now show the notes:

    Note section [27] '.gnu.build.attributes' of 56080 bytes at offset 0x114564:

      Owner          Data size  Type

      GA                    16  GNU Build Attribute OPEN

        Address Range: 0x2f30f - 0x2f30f

        VERSION: "3p8"

      GA                     0  GNU Build Attribute OPEN

        TOOL: "gcc 8.2.1 20180801"

      GA                     0  GNU Build Attribute OPEN

        "GOW": 45

      GA                     0  GNU Build Attribute OPEN

        STACK_PROT: 0

      GA                     0  GNU Build Attribute OPEN

        "stack_clash": TRUE

      GA                     0  GNU Build Attribute OPEN

        "cf_protection": 0

      GA                     0  GNU Build Attribute OPEN

        "GLIBCXX_ASSERTIONS": TRUE

      GA                     0  GNU Build Attribute OPEN

        "FORTIFY": 0

      GA                     0  GNU Build Attribute OPEN

        PIC: 3

      GA                     0  GNU Build Attribute OPEN

        SHORT_ENUM: FALSE

      GA                     0  GNU Build Attribute OPEN

        ABI: c001100000012

      GA                     0  GNU Build Attribute OPEN

        "stack_realign": FALSE

    A new test was added to run-readelf -n for the existing annobin file.

    Signed-off-by: Mark Wielaard <mark@klomp.org>

diff --git a/libebl/eblobjnote.c b/libebl/eblobjnote.c

index 8fda7d9..58ac86d 100644

--- a/libebl/eblobjnote.c

+++ b/libebl/eblobjnote.c

@@ -37,11 +37,14 @@

 #include <string.h>

 #include <libeblP.h>

+#include "common.h"

 #include "libelfP.h"

+#include "libdwP.h"

+#include "memory-access.h"

 void

-ebl_object_note (Ebl *ebl, const char *name, uint32_t type,

+ebl_object_note (Ebl *ebl, uint32_t namesz, const char *name, uint32_t type,

 		 uint32_t descsz, const char *desc)

 {

   if (! ebl->object_note (name, type, descsz, desc))

@@ -135,6 +138,152 @@ ebl_object_note (Ebl *ebl, const char *name, uint32_t type,

 	  return;

 	}

+      if (strncmp (name, ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX,

+		   strlen (ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX)) == 0

+	  && (type == NT_GNU_BUILD_ATTRIBUTE_OPEN

+	      || type == NT_GNU_BUILD_ATTRIBUTE_FUNC))

+	{

+	  /* There might or might not be a pair of addresses in the desc.  */

+	  if (descsz > 0)

+	    {

+	      printf ("    Address Range: ");

+

+	      union

+	      {

+		Elf64_Addr a64[2];

+		Elf32_Addr a32[2];

+	      } addrs;

+

+	      size_t addr_size = gelf_fsize (ebl->elf, ELF_T_ADDR,

+					     2, EV_CURRENT);

+	      if (descsz != addr_size)

+		printf ("<unknown data>\n");

+	      else

+		{

+		  Elf_Data src =

+		    {

+		     .d_type = ELF_T_ADDR, .d_version = EV_CURRENT,

+		     .d_buf = (void *) desc, .d_size = descsz

+		    };

+

+		  Elf_Data dst =

+		    {

+		     .d_type = ELF_T_ADDR, .d_version = EV_CURRENT,

+		     .d_buf = &addrs, .d_size = descsz

+		    };

+

+		  if (gelf_xlatetom (ebl->elf, &dst, &src,

+				     elf_getident (ebl->elf,

+						   NULL)[EI_DATA]) == NULL)

+		    printf ("%s\n", elf_errmsg (-1));

+		  else

+		    {

+		      if (addr_size == 4)

+			printf ("%#" PRIx32 " - %#" PRIx32 "\n",

+				addrs.a32[0], addrs.a32[1]);

+		      else

+			printf ("%#" PRIx64 " - %#" PRIx64 "\n",

+				addrs.a64[0], addrs.a64[1]);

+		    }

+		}

+	    }

+

+	  /* Most data actually is inside the name.

+	     https://fedoraproject.org/wiki/Toolchain/Watermark  */

+

+	  /* We need at least 2 chars of data to describe the

+	     attribute and value encodings.  */

+	  const char *data = (name

+			      + strlen (ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX));

+	  if (namesz < 2)

+	    {

+	      printf ("<insufficient data>\n");

+	      return;

+	    }

+

+	  printf ("    ");

+

+	  /* In most cases the value comes right after the encoding bytes.  */

+	  const char *value = &data[2];

+	  switch (data[1])

+	    {

+	    case GNU_BUILD_ATTRIBUTE_VERSION:

+	      printf ("VERSION: ");

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_STACK_PROT:

+	      printf ("STACK_PROT: ");

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_RELRO:

+	      printf ("RELRO: ");

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_STACK_SIZE:

+	      printf ("STACK_SIZE: ");

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_TOOL:

+	      printf ("TOOL: ");

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_ABI:

+	      printf ("ABI: ");

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_PIC:

+	      printf ("PIC: ");

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_SHORT_ENUM:

+	      printf ("SHORT_ENUM: ");

+	      break;

+	    case 32 ... 126:

+	      printf ("\"%s\": ", &data[1]);

+	      value += strlen (&data[1]) + 1;

+	      break;

+	    default:

+	      printf ("<unknown>: ");

+	      break;

+	    }

+

+	  switch (data[0])

+	    {

+	    case GNU_BUILD_ATTRIBUTE_TYPE_NUMERIC:

+	      {

+		/* Any numbers are always in (unsigned) little endian.  */

+		static const Dwarf dbg

+		  = { .other_byte_order = MY_ELFDATA != ELFDATA2LSB };

+		size_t bytes = namesz - (value - name);

+		uint64_t val;

+		if (bytes == 1)

+		  val = *(unsigned char *) value;

+		else if (bytes == 2)

+		  val = read_2ubyte_unaligned (&dbg, value);

+		else if (bytes == 4)

+		  val = read_4ubyte_unaligned (&dbg, value);

+		else if (bytes == 8)

+		  val = read_8ubyte_unaligned (&dbg, value);

+		else

+		  goto unknown;

+		printf ("%" PRIx64, val);

+	      }

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_TYPE_STRING:

+	      printf ("\"%s\"", value);

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_TYPE_BOOL_TRUE:

+	      printf ("TRUE");

+	      break;

+	    case GNU_BUILD_ATTRIBUTE_TYPE_BOOL_FALSE:

+	      printf ("FALSE");

+	      break;

+	    default:

+	      {

+	      unknown:

+		printf ("<unknown>");

+	      }

+	      break;

+	    }

+

+	  printf ("\n");

+

+	  return;

+	}

+

       /* NT_VERSION doesn't have any info.  All data is in the name.  */

       if (descsz == 0 && type == NT_VERSION)

 	return;

diff --git a/libebl/eblobjnotetypename.c b/libebl/eblobjnotetypename.c

index 8cdd781..29a5391 100644

--- a/libebl/eblobjnotetypename.c

+++ b/libebl/eblobjnotetypename.c

@@ -1,5 +1,5 @@

 /* Return note type name.

-   Copyright (C) 2002, 2007, 2009, 2011, 2016 Red Hat, Inc.

+   Copyright (C) 2002, 2007, 2009, 2011, 2016, 2018 Red Hat, Inc.

    This file is part of elfutils.

    Written by Ulrich Drepper <drepper@redhat.com>, 2002.

@@ -79,6 +79,29 @@ ebl_object_note_type_name (Ebl *ebl, const char *name, uint32_t type,

 	    }

 	}

+      if (strncmp (name, ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX,

+		   strlen (ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX)) == 0)

+	{

+	  /* GNU Build Attribute notes (ab)use the owner name to store

+	     most of their data.  Don't decode everything here.  Just

+	     the type.*/

+	  char *t = buf;

+	  const char *gba = "GNU Build Attribute";

+	  int w = snprintf (t, len, "%s ", gba);

+	  t += w;

+	  len -= w;

+	  if (type == NT_GNU_BUILD_ATTRIBUTE_OPEN)

+	    w = snprintf (t, len, "OPEN");

+	  else if (type == NT_GNU_BUILD_ATTRIBUTE_FUNC)

+	    w = snprintf (t, len, "FUNC");

+	  else

+	    w = snprintf (t, len, "%x", type);

+	  t += w;

+	  len -= w;

+

+	  return buf;

+	}

+

       if (strcmp (name, "GNU") != 0)

 	{

 	  /* NT_VERSION is special, all data is in the name.  */

diff --git a/libebl/libebl.h b/libebl/libebl.h

index 5830654..ca9b9fe 100644

--- a/libebl/libebl.h

+++ b/libebl/libebl.h

@@ -179,8 +179,8 @@ extern const char *ebl_object_note_type_name (Ebl *ebl, const char *name,

 					      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,

-			     uint32_t descsz, const char *desc);

+extern void ebl_object_note (Ebl *ebl, uint32_t namesz, const char *name,

+			     uint32_t type, uint32_t descsz, const char *desc);

 /* Check whether an attribute in a .gnu_attributes section is recognized.

    Fills in *TAG_NAME with the name for this tag.

diff --git a/libelf/elf-knowledge.h b/libelf/elf-knowledge.h

index 64f5887..9d3be0f 100644

--- a/libelf/elf-knowledge.h

+++ b/libelf/elf-knowledge.h

@@ -77,4 +77,25 @@

    || ((Ehdr)->e_machine == EM_S390					      \

        && (Ehdr)->e_ident[EI_CLASS] == ELFCLASS64) ? 8 : 4)

+/* GNU Annobin notes are not fully standardized and abuses the owner name.  */

+

+#define ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX "GA"

+

+#define NT_GNU_BUILD_ATTRIBUTE_OPEN 0x100

+#define NT_GNU_BUILD_ATTRIBUTE_FUNC 0x101

+

+#define GNU_BUILD_ATTRIBUTE_TYPE_NUMERIC	'*'

+#define GNU_BUILD_ATTRIBUTE_TYPE_STRING		'$'

+#define GNU_BUILD_ATTRIBUTE_TYPE_BOOL_TRUE	'+'

+#define GNU_BUILD_ATTRIBUTE_TYPE_BOOL_FALSE	'!'

+

+#define GNU_BUILD_ATTRIBUTE_VERSION	1

+#define GNU_BUILD_ATTRIBUTE_STACK_PROT	2

+#define GNU_BUILD_ATTRIBUTE_RELRO	3

+#define GNU_BUILD_ATTRIBUTE_STACK_SIZE	4

+#define GNU_BUILD_ATTRIBUTE_TOOL	5

+#define GNU_BUILD_ATTRIBUTE_ABI		6

+#define GNU_BUILD_ATTRIBUTE_PIC		7

+#define GNU_BUILD_ATTRIBUTE_SHORT_ENUM	8

+

 #endif	/* elf-knowledge.h */

diff --git a/src/elflint.c b/src/elflint.c

index dff74ee..184ca12 100644

--- a/src/elflint.c

+++ b/src/elflint.c

@@ -4344,6 +4344,19 @@ section [%2d] '%s': unknown core file note type %" PRIu32

 	      }

 	      goto unknown_note;

+	  case NT_GNU_BUILD_ATTRIBUTE_OPEN:

+	  case NT_GNU_BUILD_ATTRIBUTE_FUNC:

+	    /* GNU Build Attributes store most data in the owner

+	       name, which must start with the

+	       ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX "GA".  */

+	    if (nhdr.n_namesz >= sizeof ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX

+		&& strncmp (data->d_buf + name_offset,

+			    ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX,

+			    strlen (ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX)) == 0)

+	      break;

+	    else

+	      goto unknown_note;

+

 	  case 0:

 	    /* Linux vDSOs use a type 0 note for the kernel version word.  */

 	    if (nhdr.n_namesz == sizeof "Linux"

diff --git a/src/readelf.c b/src/readelf.c

index 659e34f..3a73710 100644

--- a/src/readelf.c

+++ b/src/readelf.c

@@ -12193,10 +12193,21 @@ handle_notes_data (Ebl *ebl, const GElf_Ehdr *ehdr,

       const char *name = nhdr.n_namesz == 0 ? "" : data->d_buf + name_offset;

       const char *desc = data->d_buf + desc_offset;

+      /* GNU Build Attributes are weird, they store most of their data

+	 into the owner name field.  Extract just the owner name

+	 prefix here, then use the rest later as data.  */

+      bool is_gnu_build_attr

+	= strncmp (name, ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX,

+		   strlen (ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX)) == 0;

+      const char *print_name = (is_gnu_build_attr

+				? ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX : name);

+      size_t print_namesz = (is_gnu_build_attr

+			     ? strlen (print_name) : nhdr.n_namesz);

+

       char buf[100];

       char buf2[100];

       printf (gettext ("  %-13.*s  %9" PRId32 "  %s\n"),

-	      (int) nhdr.n_namesz, name, nhdr.n_descsz,

+	      (int) print_namesz, print_name, nhdr.n_descsz,

 	      ehdr->e_type == ET_CORE

 	      ? ebl_core_note_type_name (ebl, nhdr.n_type,

 					 buf, sizeof (buf))

@@ -12237,7 +12248,8 @@ handle_notes_data (Ebl *ebl, const GElf_Ehdr *ehdr,

 		handle_core_note (ebl, &nhdr, name, desc);

 	    }

 	  else

-	    ebl_object_note (ebl, name, nhdr.n_type, nhdr.n_descsz, desc);

+	    ebl_object_note (ebl, nhdr.n_namesz, name, nhdr.n_type,

+			     nhdr.n_descsz, desc);

 	}

     }