Add sepdebugcrcfix to fixup old style gnu_debuglink CRC checksum.

Some old tools might still use the .gnu_debuglink section to find
separate debuginfo files instead of build-id style lookups. When
dwz has compresses the .debug files the original CRC in the main
ELF file will no longer match. Make sure to run sepdebugcrcfix
after dwz to recalculate the CRC.

The original fix was created by Jan Kratochvil based on code
from GNU binutils BFD. https://bugzilla.redhat.com/show_bug.cgi?id=971119
I added a testcase to make sure the CRCs were all correctly
updated after dwz has run to compress a debuginfo package.
And a change (plus testcase) to make sure implicit suid binaries
didn't accidentially got their suid flag bit.

Signed-off-by: Mark Wielaard <mjw@redhat.com>

5 files changed, 514 insertions, 0 deletions

diff --git a/Makefile.am b/Makefile.am
index 157e79d39..08d8c8e3b 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -170,6 +170,10 @@ rpmlibexec_PROGRAMS +=	elfdeps
 elfdeps_SOURCES =	tools/elfdeps.c
 elfdeps_LDADD =		rpmio/librpmio.la
 elfdeps_LDADD +=	@WITH_LIBELF_LIB@ @WITH_POPT_LIB@
+
+rpmlibexec_PROGRAMS +=	sepdebugcrcfix
+sepdebugcrcfix_SOURCES = tools/sepdebugcrcfix.c
+sepdebugcrcfix_LDADD =	@WITH_LIBELF_LIB@
 endif
 endif
 
diff --git a/scripts/find-debuginfo.sh b/scripts/find-debuginfo.sh
index f02b6dc4c..f1abb6c38 100644
--- a/scripts/find-debuginfo.sh
+++ b/scripts/find-debuginfo.sh
@@ -117,10 +117,12 @@ done
 LISTFILE="$BUILDDIR/$out"
 SOURCEFILE="$BUILDDIR/debugsources.list"
 LINKSFILE="$BUILDDIR/debuglinks.list"
+ELFBINSFILE="$BUILDDIR/elfbins.list"
 
 > "$SOURCEFILE"
 > "$LISTFILE"
 > "$LINKSFILE"
+> "$ELFBINSFILE"
 
 debugdir="${RPM_BUILD_ROOT}/usr/lib/debug"
 
@@ -321,6 +323,8 @@ while read nlinks inum f; do
   # strip -g implies we have full symtab, don't add mini symtab in that case.
   $strip_g || ($include_minidebug && add_minidebug "${debugfn}" "$f")
 
+  echo "./${f#$RPM_BUILD_ROOT}" >> "$ELFBINSFILE"
+
   if [ -n "$id" ]; then
     make_id_link "$id" "$dn/$(basename $f)"
     make_id_link "$id" "/usr/lib/debug$dn/$bn" .debug
@@ -355,6 +359,11 @@ if $run_dwz && type dwz >/dev/null 2>&1 \
       [ -n "$id" ] \
 	&& make_id_link "$id" "/usr/lib/debug/.dwz/${dwz_multifile_name}" .debug
     fi
+
+    # dwz invalidates .gnu_debuglink CRC32 in the main files.
+    cat "$ELFBINSFILE" |
+    (cd "$RPM_BUILD_ROOT"; \
+     xargs -d '\n' ${lib_rpm_dir}/sepdebugcrcfix usr/lib/debug)
   fi
 fi
 
diff --git a/tests/data/SPECS/hello2-suid.spec b/tests/data/SPECS/hello2-suid.spec
new file mode 100644
index 000000000..32bdce1f9
--- /dev/null
+++ b/tests/data/SPECS/hello2-suid.spec
@@ -0,0 +1,67 @@
+Summary: hello2 -- double hello, world rpm
+Name: hello2
+Version: 1.0
+Release: 1
+Group: Utilities
+License: GPL
+Distribution: RPM test suite.
+Vendor: Red Hat Software
+Packager: Red Hat Software <bugs@redhat.com>
+URL: http://www.redhat.com
+Source0: hello-1.0.tar.gz
+Patch0: hello-1.0-modernize.patch
+Excludearch: lsi
+Excludeos: cpm
+Provides: hi
+Conflicts: goodbye
+Obsoletes: howdy
+Prefix: /usr
+
+%description
+Simple rpm demonstration.
+
+%prep
+%setup -q -n hello-1.0
+%patch0 -p1 -b .modernize
+
+%build
+make CFLAGS="-g -O1"
+mv hello hello2
+make CFLAGS="-g -O2 -D_FORTIFY_SOURCE=2"
+
+%install
+rm -rf $RPM_BUILD_ROOT
+mkdir -p $RPM_BUILD_ROOT/usr/local/bin
+# Note explicit install hello as suid
+install -m 4755 hello $RPM_BUILD_ROOT/usr/local/bin
+install -m 755 hello2 $RPM_BUILD_ROOT/usr/local/bin
+
+%clean
+rm -rf $RPM_BUILD_ROOT
+
+%pre
+
+%post
+
+%preun
+
+%postun
+
+%files
+# Note we don't set any attrs. We expect the suid flag to have been picked up.
+/usr/local/bin/hello
+/usr/local/bin/hello2
+%defattr(-,root,root)
+%doc	FAQ
+#%readme README
+#%license COPYING
+
+%changelog
+* Tue Jun 14 2016 Mark Wielaard <mjw@redhat.com>
+- Make hello (implicit) suid
+
+* Wed May 18 2016 Mark Wielaard <mjw@redhat.com>
+- Add hello2 for dwz testing support.
+
+* Tue Oct 20 1998 Jeff Johnson <jbj@redhat.com>
+- create.
diff --git a/tests/rpmbuild.at b/tests/rpmbuild.at
index 2fea1b621..1dd57e924 100644
--- a/tests/rpmbuild.at
+++ b/tests/rpmbuild.at
@@ -459,3 +459,76 @@ test "$canonmultiref" = "$canonmultifile" || exit 1
 [],
 [ignore])
 AT_CLEANUP
+
+# ------------------------------
+# Check that old style gnu_debuglink CRC checksums are correct even after
+# using dwz to compress the debuginfo files.
+AT_SETUP([rpmbuild debuginfo dwz gnu_debuglink crc])
+AT_KEYWORDS([build] [debuginfo])
+AT_CHECK([
+rm -rf ${TOPDIR}
+AS_MKDIR_P(${TOPDIR}/SOURCES)
+
+# Build a package that
+cp "${abs_srcdir}"/data/SOURCES/hello-1.0.tar.gz "${abs_srcdir}"/data/SOURCES/hello-1.0-modernize.patch ${TOPDIR}/SOURCES
+
+run rpmbuild --quiet \
+  --macros=${abs_top_builddir}/macros:${abs_top_builddir}/tests/testing/usr/local/lib/rpm/platform/%{_target_cpu}-%{_target_os}/macros:${top_srcdir}/macros.debug \
+  --rcfile=${abs_top_builddir}/rpmrc \
+  -ba "${abs_srcdir}"/data/SPECS/hello2.spec
+
+# Unpack the main and debuginfo rpms so we can check binaries and .debug files.
+rpm2cpio ${abs_builddir}/testing/build/RPMS/*/hello2-debuginfo-1.0-1.*.rpm \
+  | cpio -diu
+rpm2cpio ${abs_builddir}/testing/build/RPMS/*/hello2-1.0-1.*.rpm \
+  | cpio -diu
+
+# Check that dwz has ran and a multi file has been produced
+test -f ./usr/lib/debug/.dwz/hello2-1.0-1.* || exit 1
+
+# Run sepdbugcrcfix on the binaries, both should have correct CRC already.
+${abs_top_builddir}/sepdebugcrcfix ./usr/lib/debug \
+  ./usr/local/bin/hello ./usr/local/bin/hello2 | grep CRC32 | cut -f2 -d:
+],
+[0],
+[ Updated 0 CRC32s, 2 CRC32s did match.
+],
+[ignore])
+AT_CLEANUP
+
+# ------------------------------
+# Check that an implicit suid binary get included with the suid bit set.
+# We explicitly build with all debug.macros to test those helpers.
+AT_SETUP([rpmbuild implicit suid binary])
+AT_KEYWORDS([build] [debuginfo] [dwz] [suid])
+AT_CHECK([
+rm -rf ${TOPDIR}
+AS_MKDIR_P(${TOPDIR}/SOURCES)
+
+# Build a package that has some debuginfo
+cp "${abs_srcdir}"/data/SOURCES/hello-1.0.tar.gz "${abs_srcdir}"/data/SOURCES/hello-1.0-modernize.patch ${TOPDIR}/SOURCES
+
+run rpmbuild --quiet \
+  --rcfile=${abs_top_builddir}/rpmrc \
+  --macros=${abs_top_builddir}/macros:${abs_top_builddir}/tests/testing/usr/local/lib/rpm/platform/%{_target_cpu}-%{_target_os}/macros:${top_srcdir}/macros.debug \
+  -ba "${abs_srcdir}"/data/SPECS/hello2-suid.spec
+
+# Unpack rpm so we can check the included binaries.
+rpm2cpio ${abs_builddir}/testing/build/RPMS/*/hello2-1.0-1.*.rpm \
+  | cpio -diu --quiet
+
+# List all binaries with suid bit set (should be one, hello).
+echo "suid:"
+find usr -executable -type f -perm /4000
+# List all binaries without suid bit set (should also be one, hello2).
+echo "no-suid:"
+find usr -executable -type f \! -perm /4000
+],
+[0],
+[suid:
+usr/local/bin/hello
+no-suid:
+usr/local/bin/hello2
+],
+[ignore])
+AT_CLEANUP
diff --git a/tools/sepdebugcrcfix.c b/tools/sepdebugcrcfix.c
new file mode 100644
index 000000000..cd7fa02a0
--- /dev/null
+++ b/tools/sepdebugcrcfix.c
@@ -0,0 +1,361 @@
+/* Copyright (C) 2013 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Version 2013-06-24.  */
+
+#define _GNU_SOURCE
+#include <string.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <endian.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <error.h>
+#include <libelf.h>
+#include <gelf.h>
+#include <bfd.h>
+
+#define _(x) x
+#define static_assert(expr) \
+  extern int never_defined_just_used_for_checking[(expr) ? 1 : -1]
+#ifndef min
+# define min(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+static_assert (sizeof (unsigned long) >= sizeof (uint32_t));
+
+typedef int bool;
+static const bool false = 0, true = 1;
+
+/* This is bfd_calc_gnu_debuglink_crc32 from bfd/opncls.c.  */
+static unsigned long
+    calc_gnu_debuglink_crc32 (unsigned long crc,
+			      const unsigned char *buf,
+			      bfd_size_type len)
+{
+  static const unsigned long crc32_table[256] =
+    {
+      0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
+      0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
+      0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
+      0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
+      0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
+      0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+      0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
+      0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
+      0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
+      0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
+      0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
+      0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+      0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
+      0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
+      0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
+      0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
+      0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
+      0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+      0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
+      0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
+      0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
+      0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
+      0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
+      0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+      0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
+      0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
+      0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
+      0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
+      0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
+      0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+      0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
+      0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
+      0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
+      0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
+      0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
+      0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+      0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
+      0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
+      0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
+      0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
+      0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
+      0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+      0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
+      0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
+      0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
+      0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
+      0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
+      0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+      0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
+      0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
+      0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
+      0x2d02ef8d
+    };
+  const unsigned char *end;
+
+  crc = ~crc & 0xffffffff;
+  for (end = buf + len; buf < end; ++ buf)
+    crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);
+  return ~crc & 0xffffffff;
+}
+
+static size_t updated_count, matched_count, failed_count;
+
+static const char *usr_lib_debug;
+
+static bool
+crc32 (const char *fname, const char *base_fname, uint32_t *crcp)
+{
+  char *reldir = strdup (base_fname);
+  if (reldir == NULL)
+    error (1, 0, _("out of memory"));
+  char *s = reldir + strlen (reldir);
+  while (s > reldir && s[-1] != '/')
+    *--s = '\0';
+  char *debugname;
+  if (asprintf (&debugname, "%s/%s/%s", usr_lib_debug, reldir, fname) <= 0)
+    error (1, 0, _("out of memory"));
+  free (reldir);
+  int fd = open (debugname, O_RDONLY);
+  if (fd == -1)
+    {
+      error (0, errno, _("cannot open \"%s\""), debugname);
+      return false;
+    }
+  off64_t size = lseek64 (fd, 0, SEEK_END);
+  if (size == -1)
+    {
+      error (0, errno, _("cannot get size of \"%s\""), debugname);
+      return false;
+    }
+  off_t offset = 0;
+  uint32_t crc = 0;
+  void *buf = NULL;
+  while (offset < size)
+    {
+      const size_t maplen = min (0x10000, size - offset);
+      void *map = NULL;
+      if (buf == NULL)
+	{
+	  map = mmap (NULL, maplen, PROT_READ, MAP_PRIVATE | MAP_POPULATE,
+		      fd, offset);
+	  if (map == MAP_FAILED)
+	    {
+	      error (0, errno, _("cannot map 0x%llx bytes at offset 0x%llx "
+				 "of file \"%s\""),
+		     (unsigned long long) maplen, (unsigned long long) offset,
+		     debugname);
+	      map = NULL;
+	    }
+	}
+      if (map == NULL)
+	{
+	  if (buf == NULL)
+	    {
+	      buf = malloc (maplen);
+	      if (buf == NULL)
+		error (1, 0, _("out of memory"));
+	    }
+	  ssize_t got = pread (fd, buf, maplen, offset);
+	  if (got != maplen)
+	    {
+	      error (0, errno, _("cannot read 0x%llx bytes at offset 0x%llx "
+				 "of file \"%s\""),
+		     (unsigned long long) maplen, (unsigned long long) offset,
+		     debugname);
+	      free (buf);
+	      free (debugname);
+	      return false;
+	    }
+	}
+      crc = calc_gnu_debuglink_crc32 (crc, map ?: buf, maplen);
+      if (map && munmap (map, maplen) != 0)
+	error (1, errno, _("cannot unmap 0x%llx bytes at offset 0x%llx "
+			   "of file \"%s\""),
+	       (unsigned long long) maplen, (unsigned long long) offset,
+	       debugname);
+      offset += maplen;
+    }
+  free (buf);
+  if (close (fd) != 0)
+    {
+      error (0, errno, _("cannot close \"%s\""), debugname);
+      free (debugname);
+      return false;
+    }
+  free (debugname);
+  *crcp = crc;
+  return true;
+}
+
+static bool
+process (Elf *elf, int fd, const char *fname)
+{
+  GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem);
+  if (ehdr == NULL)
+    {
+      error (0, 0, _("cannot get ELF header of \"%s\""), fname);
+      return false;
+    }
+  if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB
+      && ehdr->e_ident[EI_DATA] != ELFDATA2MSB)
+    {
+      error (0, 0, _("invalid ELF endianity of \"%s\""), fname);
+      return false;
+    }
+  Elf_Scn *scn = NULL;
+  const char scnname[] = ".gnu_debuglink";
+  while ((scn = elf_nextscn (elf, scn)) != NULL)
+    {
+      GElf_Shdr shdr_mem, *shdr = gelf_getshdr (scn, &shdr_mem);
+      if (shdr == NULL)
+	{
+	  error (0, 0, _("cannot get section # %zu in \"%s\""),
+		 elf_ndxscn (scn), fname);
+	  continue;
+	}
+      const char *sname = elf_strptr (elf, ehdr->e_shstrndx, shdr->sh_name);
+      if (sname == NULL)
+	{
+	  error (0, 0, _("cannot get name of section # %zu in \"%s\""),
+		 elf_ndxscn (scn), fname);
+	  continue;
+	}
+      if (strcmp (sname, scnname) != 0)
+	continue;
+      Elf_Data *data = elf_getdata (scn, NULL);
+      if (data == NULL)
+	{
+	  error (0, 0, _("cannot get data of section \"%s\" # %zu in \"%s\""),
+		 scnname, elf_ndxscn (scn), fname);
+	  continue;
+	}
+      if ((data->d_size & 3) != 0)
+	{
+	  error (0, 0, _("invalid size of section \"%s\" # %zu in \"%s\""),
+		 scnname, elf_ndxscn (scn), fname);
+	  continue;
+	}
+      const uint8_t *zerop = memchr (data->d_buf, '\0', data->d_size);
+      const uint8_t *crcp = (zerop == NULL
+			     ? NULL
+			     : (const uint8_t *) ((uintptr_t) (zerop + 1 + 3)
+						  & -4));
+      if (crcp + 4 != (uint8_t *) data->d_buf + data->d_size)
+	{
+	  error (0, 0, _("invalid format of section \"%s\" # %zu in \"%s\""),
+		 scnname, elf_ndxscn (scn), fname);
+	  continue;
+	}
+      uint32_t had_crc_targetendian = *(const uint32_t *) crcp;
+      uint32_t had_crc = (ehdr->e_ident[EI_DATA] == ELFDATA2LSB
+			  ? le32toh (had_crc_targetendian)
+			  : be32toh (had_crc_targetendian));
+      uint32_t crc;
+      if (! crc32 (data->d_buf, fname, &crc))
+	return false;
+      if (crc == had_crc)
+	{
+	  matched_count++;
+	  return true;
+	}
+      updated_count++;
+      off64_t seekto = (shdr->sh_offset + data->d_off
+			+ (crcp - (const uint8_t *) data->d_buf));
+      uint32_t crc_targetendian = (ehdr->e_ident[EI_DATA] == ELFDATA2LSB
+				   ? htole32 (crc) : htobe32 (crc));
+      ssize_t wrote = pwrite (fd, &crc_targetendian, sizeof (crc_targetendian),
+			      seekto);
+      if (wrote != sizeof (crc_targetendian))
+	{
+	  error (0, 0, _("cannot write new CRC to 0x%llx "
+			 "inside section \"%s\" # %zu in \"%s\""),
+		 (unsigned long long) seekto, scnname, elf_ndxscn (scn), fname);
+	  return false;
+	}
+      return true;
+    }
+  error (0, 0, _("cannot find section \"%s\" in \"%s\""), scnname, fname);
+  return false;
+}
+
+int
+main (int argc, char **argv)
+{
+  if (argc < 2)
+    error (1, 0, _("usr/lib/debug [<relative filenames>...]"));
+  usr_lib_debug = argv[1];
+  if (elf_version (EV_CURRENT) == EV_NONE)
+    error (1, 0, _("error initializing libelf: %s"), elf_errmsg (-1));
+  for (int argi = 2; argi < argc; argi++)
+    {
+      const char *fname = argv[argi];
+      struct stat stat_buf;
+      if (stat(fname, &stat_buf) < 0)
+	{
+	  error (0, errno, _("cannot stat input \"%s\""), fname);
+	  failed_count++;
+	  continue;
+	}
+
+      /* Make sure we can read and write */
+      chmod (fname, stat_buf.st_mode | S_IRUSR | S_IWUSR);
+
+      bool failed = false;
+      int fd = open64 (fname, O_RDWR);
+      if (fd == -1)
+	{
+	  error (0, errno, _("cannot open \"%s\""), fname);
+	  failed = true;
+	}
+      else
+	{
+	  Elf *elf = elf_begin (fd, ELF_C_READ_MMAP, NULL);
+	  if (elf == NULL)
+	    {
+	      error (0, 0, _("cannot open \"%s\" as ELF: %s"), fname,
+		     elf_errmsg (-1));
+	      failed = true;
+	    }
+	  else
+	    {
+	      if (! process (elf, fd, fname))
+		failed = true;
+	      if (elf_end (elf) != 0)
+		{
+		  error (0, 0, _("cannot close \"%s\" as ELF: %s"), fname,
+			 elf_errmsg (-1));
+		  failed = true;
+		}
+	    }
+	  if (close (fd) != 0)
+	    {
+	      error (0, errno, _("cannot close \"%s\""), fname);
+	      failed = true;
+	    }
+	}
+
+      /* Restore old access rights. Including any suid bits reset. */
+      chmod (fname, stat_buf.st_mode);
+
+      if (failed)
+	failed_count++;
+    }
+  printf ("%s: Updated %zu CRC32s, %zu CRC32s did match.\n", argv[0],
+	  updated_count, matched_count);
+  if (failed_count)
+    printf ("%s: Failed for %zu files.\n", argv[0], failed_count);
+  return failed_count == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+}