diff mbox series

[v2] elf: Add elf checks for main executable

Message ID 20211214123110.1857119-1-adhemerval.zanella@linaro.org
State New
Headers show
Series [v2] elf: Add elf checks for main executable | expand

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit success Build for i686

Commit Message

Adhemerval Zanella Dec. 14, 2021, 12:31 p.m. UTC
The ELF header integrity check is only done on open_verify(), i.e,
for objects explicitly loaded.  For main executable (issued with
execve() for the binary) only kernel checks are done, which does
not check EI_ABIVERSION.

To enable it, the loader needs to find where the ELF header is placed
at program start, however Linux auxiliary vectors only provides
the program header table (AT_EHDR).  To avoid require upstream
kernel support, the ELF header is implicitly obtained from the PT_LOAD
values by checking for a segment with offset 0 and memory size
different than 0 (For Linux it is start the ELF file issued by
execve()).

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
---
v2: Fix header value for main executable and add a abort on tests
    if the subprocess can be executed.

---
 elf/Makefile                           |   8 +-
 elf/dl-check-err.h                     |  14 ++
 elf/dl-check.c                         | 151 +++++++++++++++++
 elf/dl-check.h                         |  45 +++++
 elf/dl-load.c                          | 114 ++-----------
 elf/rtld.c                             |   8 +
 elf/tst-elf-check.c                    | 220 +++++++++++++++++++++++++
 sysdeps/generic/dl-elf-check.h         |  28 ++++
 sysdeps/unix/sysv/linux/dl-elf-check.h |  32 ++++
 9 files changed, 518 insertions(+), 102 deletions(-)
 create mode 100644 elf/dl-check-err.h
 create mode 100644 elf/dl-check.c
 create mode 100644 elf/dl-check.h
 create mode 100644 elf/tst-elf-check.c
 create mode 100644 sysdeps/generic/dl-elf-check.h
 create mode 100644 sysdeps/unix/sysv/linux/dl-elf-check.h
diff mbox series

Patch

diff --git a/elf/Makefile b/elf/Makefile
index fe42caeb0e..5f71530f25 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -36,7 +36,8 @@  dl-routines	= $(addprefix dl-,load lookup object reloc deps \
 				  exception sort-maps lookup-direct \
 				  call-libc-early-init write \
 				  thread_gscope_wait tls_init_tp \
-				  debug-symbols minimal-malloc)
+				  debug-symbols minimal-malloc \
+				  check)
 ifeq (yes,$(use-ldconfig))
 dl-routines += dl-cache
 endif
@@ -239,7 +240,8 @@  tests-internal += loadtest unload unload2 circleload1 \
 	 tst-ptrguard1 tst-stackguard1 \
 	 tst-create_format1 tst-tls-surplus tst-dl-hwcaps_split
 tests-container += tst-pldd tst-dlopen-tlsmodid-container \
-  tst-dlopen-self-container tst-preload-pthread-libc
+  tst-dlopen-self-container tst-preload-pthread-libc \
+  tst-elf-check
 test-srcs = tst-pathopt
 ifeq (yes,$(have-fpie))
 tests-pie += tst-align3
@@ -498,6 +500,8 @@  tests-special += $(objpfx)order-cmp.out $(objpfx)tst-array1-cmp.out \
 		 $(objpfx)tst-unused-dep-cmp.out
 endif
 
+tst-elf-check-ARGS = -- $(host-test-program-cmd)
+
 ifndef avoid-generated
 # DSO sorting tests:
 # The dso-ordering-test.py script generates testcase source files in $(objpfx),
diff --git a/elf/dl-check-err.h b/elf/dl-check-err.h
new file mode 100644
index 0000000000..6ca5246eb8
--- /dev/null
+++ b/elf/dl-check-err.h
@@ -0,0 +1,14 @@ 
+_S(DL_ELFHDR_OK, "")
+_S(DL_ELFHDR_ERR_ELFMAG,     N_("invalid ELF header"))
+_S(DL_ELFHDR_ERR_CLASS32,    N_("wrong ELF class: ELFCLASS32"))
+_S(DL_ELFHDR_ERR_CLASS64,    N_("wrong ELF class: ELFCLASS64"))
+_S(DL_ELFHDR_ERR_BENDIAN,    N_("ELF file data encoding not big-endian"))
+_S(DL_ELFHDR_ERR_LENDIAN,    N_("ELF file data encoding not little-endian"))
+_S(DL_ELFHDR_ERR_EIVERSION,  N_("ELF file version ident does not match current one"))
+_S(DL_ELFHDR_ERR_OSABI,      N_("ELF file OS ABI invalid"))
+_S(DL_ELFHDR_ERR_ABIVERSION, N_("ELF file ABI version invalid"))
+_S(DL_ELFHDR_ERR_PAD,        N_("nonzero padding in e_ident"))
+_S(DL_ELFHDR_ERR_VERSION,    N_("ELF file version does not match current one"))
+_S(DL_ELFHDR_ERR_TYPE,       N_("only ET_DYN and ET_EXEC can be loaded"))
+_S(DL_ELFHDR_ERR_PHENTSIZE,  N_("ELF file's phentsize not the expected size"))
+_S(DL_ELFHDR_ERR_INTERNAL,   N_("internal error"))
diff --git a/elf/dl-check.c b/elf/dl-check.c
new file mode 100644
index 0000000000..ef1720df2a
--- /dev/null
+++ b/elf/dl-check.c
@@ -0,0 +1,151 @@ 
+/* ELF header consistency and ABI checks.
+   Copyright (C) 1995-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <dl-check.h>
+#include <endian.h>
+#include <ldsodefs.h>
+#include <libintl.h>
+
+int
+_dl_elfhdr_check (const ElfW(Ehdr) *ehdr)
+{
+#define ELF32_CLASS ELFCLASS32
+#define ELF64_CLASS ELFCLASS64
+#if BYTE_ORDER == BIG_ENDIAN
+# define byteorder ELFDATA2MSB
+#elif BYTE_ORDER == LITTLE_ENDIAN
+# define byteorder ELFDATA2LSB
+#else
+# error "Unknown BYTE_ORDER " BYTE_ORDER
+# define byteorder ELFDATANONE
+#endif
+  MORE_ELF_HEADER_DATA;
+  static const unsigned char expected[EI_NIDENT] =
+  {
+    [EI_MAG0] = ELFMAG0,
+    [EI_MAG1] = ELFMAG1,
+    [EI_MAG2] = ELFMAG2,
+    [EI_MAG3] = ELFMAG3,
+    [EI_CLASS] = ELFW(CLASS),
+    [EI_DATA] = byteorder,
+    [EI_VERSION] = EV_CURRENT,
+    [EI_OSABI] = ELFOSABI_SYSV,
+    [EI_ABIVERSION] = 0
+  };
+
+  /* See whether the ELF header is what we expect.  */
+  if (__glibc_unlikely (! VALID_ELF_HEADER (ehdr->e_ident, expected,
+					    EI_ABIVERSION)
+			|| !VALID_ELF_ABIVERSION (ehdr->e_ident[EI_OSABI],
+						  ehdr->e_ident[EI_ABIVERSION])
+			|| memcmp (&ehdr->e_ident[EI_PAD],
+				   &expected[EI_PAD],
+				   EI_NIDENT - EI_PAD) != 0))
+    {
+      /* Something is wrong.  */
+      const Elf32_Word *magp = (const void *) ehdr->e_ident;
+      if (*magp !=
+#if BYTE_ORDER == LITTLE_ENDIAN
+	  ((ELFMAG0 << (EI_MAG0 * 8))
+	   | (ELFMAG1 << (EI_MAG1 * 8))
+	   | (ELFMAG2 << (EI_MAG2 * 8))
+	   | (ELFMAG3 << (EI_MAG3 * 8)))
+#else
+	  ((ELFMAG0 << (EI_MAG3 * 8))
+	   | (ELFMAG1 << (EI_MAG2 * 8))
+	   | (ELFMAG2 << (EI_MAG1 * 8))
+	   | (ELFMAG3 << (EI_MAG0 * 8)))
+#endif
+	  )
+	return DL_ELFHDR_ERR_ELFMAG;
+      else if (ehdr->e_ident[EI_CLASS] != ELFW(CLASS))
+	return ELFW(CLASS) == ELFCLASS32
+	       ? DL_ELFHDR_ERR_CLASS64
+	       : DL_ELFHDR_ERR_CLASS32;
+      else if (ehdr->e_ident[EI_DATA] != byteorder)
+	{
+	  if (BYTE_ORDER == BIG_ENDIAN)
+	    return DL_ELFHDR_ERR_BENDIAN;
+	  else
+	    return DL_ELFHDR_ERR_LENDIAN;
+	}
+      else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT)
+	return DL_ELFHDR_ERR_EIVERSION;
+      /* XXX We should be able so set system specific versions which are
+	 allowed here.  */
+      else if (!VALID_ELF_OSABI (ehdr->e_ident[EI_OSABI]))
+	return DL_ELFHDR_ERR_OSABI;
+      else if (!VALID_ELF_ABIVERSION (ehdr->e_ident[EI_OSABI],
+				      ehdr->e_ident[EI_ABIVERSION]))
+	return DL_ELFHDR_ERR_ABIVERSION;
+      else if (memcmp (&ehdr->e_ident[EI_PAD], &expected[EI_PAD],
+		       EI_NIDENT - EI_PAD) != 0)
+	return DL_ELFHDR_ERR_PAD;
+      else
+	return DL_ELFHDR_ERR_INTERNAL;
+    }
+
+  if (__glibc_unlikely (ehdr->e_version != EV_CURRENT))
+    return DL_ELFHDR_ERR_VERSION;
+  else if (__glibc_unlikely (ehdr->e_type != ET_DYN
+			     && ehdr->e_type != ET_EXEC))
+    return DL_ELFHDR_ERR_TYPE;
+  else if (__glibc_unlikely (ehdr->e_phentsize != sizeof (ElfW(Phdr))))
+    return DL_ELFHDR_ERR_PHENTSIZE;
+
+  return DL_ELFHDR_OK;
+}
+
+static const union elfhdr_errstr_t
+{
+  struct
+  {
+#define _S(n, s) char str##n[sizeof (s)];
+#include "dl-check-err.h"
+#undef _S
+  };
+  char str[0];
+} elfhdr_errstr =
+{
+  {
+#define _S(n, s) s,
+#include "dl-check-err.h"
+#undef _S
+  }
+};
+
+static const unsigned short elfhder_erridx[] =
+{
+#define _S(n, s) [n] = offsetof(union elfhdr_errstr_t, str##n),
+#include "dl-check-err.h"
+#undef _S
+};
+
+const char *
+_dl_elfhdr_errstr (int err)
+{
+#if 0
+  if (err >= 0 && err < array_length (elfhdr_errstr))
+    return elfhdr_errstr[err];
+  return NULL;
+#endif
+  if (err < 0 || err >= array_length (elfhder_erridx))
+    err = 0;
+  return elfhdr_errstr.str + elfhder_erridx[err];
+}
diff --git a/elf/dl-check.h b/elf/dl-check.h
new file mode 100644
index 0000000000..5104a353ed
--- /dev/null
+++ b/elf/dl-check.h
@@ -0,0 +1,45 @@ 
+/* ELF header consistency and ABI checks.
+   Copyright (C) 1995-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_OPENCHECK_H
+#define _DL_OPENCHECK_H
+
+#include <link.h>
+
+enum
+ {
+   DL_ELFHDR_OK,
+   DL_ELFHDR_ERR_ELFMAG,     /* Invalid ELFMAGX value.  */
+   DL_ELFHDR_ERR_CLASS32,    /* Mismatched EI_CLASS.  */
+   DL_ELFHDR_ERR_CLASS64,    /* Mismatched EI_CLASS.  */
+   DL_ELFHDR_ERR_BENDIAN,    /* Mismatched EI_DATA (not big-endian).  */
+   DL_ELFHDR_ERR_LENDIAN,    /* Mismatched EI_DATA (not little-endian).  */
+   DL_ELFHDR_ERR_EIVERSION,  /* Invalid EI_VERSION.  */
+   DL_ELFHDR_ERR_OSABI,      /* Invalid EI_OSABI.  */
+   DL_ELFHDR_ERR_ABIVERSION, /* Invalid ABI vrsion.  */
+   DL_ELFHDR_ERR_PAD,        /* Invalid EI_PAD value.  */
+   DL_ELFHDR_ERR_VERSION,    /* Invalid e_version.  */
+   DL_ELFHDR_ERR_TYPE,       /* Invalid e_type.  */
+   DL_ELFHDR_ERR_PHENTSIZE,  /* Invalid e_phentsize.  */
+   DL_ELFHDR_ERR_INTERNAL    /* Internal error.  */
+ };
+
+int _dl_elfhdr_check (const ElfW(Ehdr) *ehdr) attribute_hidden;
+const char *_dl_elfhdr_errstr (int err) attribute_hidden;
+
+#endif
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 721593135e..22c1d16cd3 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -74,19 +74,9 @@  struct filebuf
 #include <dl-machine-reject-phdr.h>
 #include <dl-sysdep-open.h>
 #include <dl-prop.h>
+#include <dl-check.h>
 #include <not-cancel.h>
 
-#include <endian.h>
-#if BYTE_ORDER == BIG_ENDIAN
-# define byteorder ELFDATA2MSB
-#elif BYTE_ORDER == LITTLE_ENDIAN
-# define byteorder ELFDATA2LSB
-#else
-# error "Unknown BYTE_ORDER " BYTE_ORDER
-# define byteorder ELFDATANONE
-#endif
-
-#define STRING(x) __STRING (x)
 
 
 int __stack_prot attribute_hidden attribute_relro
@@ -1600,25 +1590,6 @@  open_verify (const char *name, int fd,
   /* This is the expected ELF header.  */
 #define ELF32_CLASS ELFCLASS32
 #define ELF64_CLASS ELFCLASS64
-#ifndef VALID_ELF_HEADER
-# define VALID_ELF_HEADER(hdr,exp,size)	(memcmp (hdr, exp, size) == 0)
-# define VALID_ELF_OSABI(osabi)		(osabi == ELFOSABI_SYSV)
-# define VALID_ELF_ABIVERSION(osabi,ver) (ver == 0)
-#elif defined MORE_ELF_HEADER_DATA
-  MORE_ELF_HEADER_DATA;
-#endif
-  static const unsigned char expected[EI_NIDENT] =
-  {
-    [EI_MAG0] = ELFMAG0,
-    [EI_MAG1] = ELFMAG1,
-    [EI_MAG2] = ELFMAG2,
-    [EI_MAG3] = ELFMAG3,
-    [EI_CLASS] = ELFW(CLASS),
-    [EI_DATA] = byteorder,
-    [EI_VERSION] = EV_CURRENT,
-    [EI_OSABI] = ELFOSABI_SYSV,
-    [EI_ABIVERSION] = 0
-  };
   static const struct
   {
     ElfW(Word) vendorlen;
@@ -1711,83 +1682,26 @@  open_verify (const char *name, int fd,
 	}
 
       /* See whether the ELF header is what we expect.  */
-      if (__glibc_unlikely (! VALID_ELF_HEADER (ehdr->e_ident, expected,
-						EI_ABIVERSION)
-			    || !VALID_ELF_ABIVERSION (ehdr->e_ident[EI_OSABI],
-						      ehdr->e_ident[EI_ABIVERSION])
-			    || memcmp (&ehdr->e_ident[EI_PAD],
-				       &expected[EI_PAD],
-				       EI_NIDENT - EI_PAD) != 0))
+      int err = _dl_elfhdr_check (ehdr);
+      switch (err)
 	{
-	  /* Something is wrong.  */
-	  const Elf32_Word *magp = (const void *) ehdr->e_ident;
-	  if (*magp !=
-#if BYTE_ORDER == LITTLE_ENDIAN
-	      ((ELFMAG0 << (EI_MAG0 * 8))
-	       | (ELFMAG1 << (EI_MAG1 * 8))
-	       | (ELFMAG2 << (EI_MAG2 * 8))
-	       | (ELFMAG3 << (EI_MAG3 * 8)))
-#else
-	      ((ELFMAG0 << (EI_MAG3 * 8))
-	       | (ELFMAG1 << (EI_MAG2 * 8))
-	       | (ELFMAG2 << (EI_MAG1 * 8))
-	       | (ELFMAG3 << (EI_MAG0 * 8)))
-#endif
-	      )
-	    errstring = N_("invalid ELF header");
-	  else if (ehdr->e_ident[EI_CLASS] != ELFW(CLASS))
-	    {
-	      /* This is not a fatal error.  On architectures where
-		 32-bit and 64-bit binaries can be run this might
-		 happen.  */
-	      *found_other_class = true;
-	      goto close_and_out;
-	    }
-	  else if (ehdr->e_ident[EI_DATA] != byteorder)
-	    {
-	      if (BYTE_ORDER == BIG_ENDIAN)
-		errstring = N_("ELF file data encoding not big-endian");
-	      else
-		errstring = N_("ELF file data encoding not little-endian");
-	    }
-	  else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT)
-	    errstring
-	      = N_("ELF file version ident does not match current one");
-	  /* XXX We should be able so set system specific versions which are
-	     allowed here.  */
-	  else if (!VALID_ELF_OSABI (ehdr->e_ident[EI_OSABI]))
-	    errstring = N_("ELF file OS ABI invalid");
-	  else if (!VALID_ELF_ABIVERSION (ehdr->e_ident[EI_OSABI],
-					  ehdr->e_ident[EI_ABIVERSION]))
-	    errstring = N_("ELF file ABI version invalid");
-	  else if (memcmp (&ehdr->e_ident[EI_PAD], &expected[EI_PAD],
-			   EI_NIDENT - EI_PAD) != 0)
-	    errstring = N_("nonzero padding in e_ident");
-	  else
-	    /* Otherwise we don't know what went wrong.  */
-	    errstring = N_("internal error");
+	case DL_ELFHDR_OK:
+	  break;
 
-	  goto lose;
-	}
+	case DL_ELFHDR_ERR_CLASS32:
+	case DL_ELFHDR_ERR_CLASS64:
+	  /* This is not a fatal error.  On architectures where 32-bit and
+	     64-bit binaries can be run this might happen.  */
+	  *found_other_class = true;
+	  goto close_and_out;
 
-      if (__glibc_unlikely (ehdr->e_version != EV_CURRENT))
-	{
-	  errstring = N_("ELF file version does not match current one");
+	default:
+	  errstring = _dl_elfhdr_errstr (err);
 	  goto lose;
 	}
+
       if (! __glibc_likely (elf_machine_matches_host (ehdr)))
 	goto close_and_out;
-      else if (__glibc_unlikely (ehdr->e_type != ET_DYN
-				 && ehdr->e_type != ET_EXEC))
-	{
-	  errstring = N_("only ET_DYN and ET_EXEC can be loaded");
-	  goto lose;
-	}
-      else if (__glibc_unlikely (ehdr->e_phentsize != sizeof (ElfW(Phdr))))
-	{
-	  errstring = N_("ELF file's phentsize not the expected size");
-	  goto lose;
-	}
 
       maplength = ehdr->e_phnum * sizeof (ElfW(Phdr));
       if (ehdr->e_phoff + maplength <= (size_t) fbp->len)
diff --git a/elf/rtld.c b/elf/rtld.c
index 4b09e84b0d..761d19617a 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -51,6 +51,7 @@ 
 #include <dl-tunables.h>
 #include <get-dynamic-info.h>
 #include <dl-execve.h>
+#include <dl-elf-check.h>
 
 #include <assert.h>
 
@@ -1152,6 +1153,7 @@  dl_main (const ElfW(Phdr) *phdr,
 	 ElfW(Addr) *user_entry,
 	 ElfW(auxv_t) *auxv)
 {
+  const ElfW(Ehdr) *ehdr = NULL;
   const ElfW(Phdr) *ph;
   struct link_map *main_map;
   size_t file_size;
@@ -1558,6 +1560,9 @@  dl_main (const ElfW(Phdr) *phdr,
 	  if (main_map->l_map_start > mapstart)
 	    main_map->l_map_start = mapstart;
 
+	  if (ph->p_offset == 0 && ph->p_memsz > 0)
+	    ehdr = (void *) mapstart;
+
 	  /* Also where it ends.  */
 	  allocend = main_map->l_addr + ph->p_vaddr + ph->p_memsz;
 	  if (main_map->l_map_end < allocend)
@@ -1611,6 +1616,9 @@  dl_main (const ElfW(Phdr) *phdr,
 	break;
       }
 
+  if (ehdr != NULL)
+    _dl_check_ehdr (ehdr);
+
   /* Adjust the address of the TLS initialization image in case
      the executable is actually an ET_DYN object.  */
   if (main_map->l_tls_initimage != NULL)
diff --git a/elf/tst-elf-check.c b/elf/tst-elf-check.c
new file mode 100644
index 0000000000..5d1c56f1ef
--- /dev/null
+++ b/elf/tst-elf-check.c
@@ -0,0 +1,220 @@ 
+/* Check ELF header error paths.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <elf.h>
+#include <getopt.h>
+#include <link.h>
+#include <libc-abis.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/xunistd.h>
+#include <support/temp_file.h>
+
+static char *spargv[6];
+static char *tmpbin;
+
+static int restart;
+#define CMDLINE_OPTIONS \
+    { "restart", no_argument, &restart, 1 },
+
+static void
+copy_binary (const char *binary_path)
+{
+  int fdin = xopen (binary_path, O_RDONLY | O_LARGEFILE, 0);
+  struct stat64 st;
+  xfstat (fdin, &st);
+  int fdout = create_temp_file ("tst-elf-check-", &tmpbin);
+  xfchmod (fdout, S_IXUSR | S_IRUSR | S_IWUSR);
+  TEST_VERIFY_EXIT (fdout >= 0);
+  xcopy_file_range (fdin, NULL, fdout, NULL, st.st_size, 0);
+  xclose (fdin);
+  xclose (fdout);
+}
+
+static void
+run_test_expect_failure (void (*modify)(ElfW(Ehdr) *), const char *errmsg)
+{
+  int fd = xopen (tmpbin, O_RDWR | O_LARGEFILE, 0);
+  ElfW(Ehdr) orig_hdr;
+  if (read (fd, &orig_hdr, sizeof (orig_hdr)) != sizeof (orig_hdr))
+    FAIL_EXIT1 ("read (%s): %m\n", tmpbin);
+  ElfW(Ehdr) hdr = orig_hdr;
+  modify (&hdr);
+  if (lseek (fd, 0, SEEK_SET) != 0)
+    FAIL_EXIT1 ("lseek: %m");
+  xwrite (fd, &hdr, sizeof (hdr));
+  xclose (fd);
+
+  struct support_capture_subprocess proc =
+      support_capture_subprogram (spargv[0], spargv);
+  support_capture_subprocess_check (&proc, "tst-elf-check", 127,
+				    sc_allow_stderr);
+  TEST_VERIFY (strstr (proc.err.buffer, errmsg) != NULL);
+  support_capture_subprocess_free (&proc);
+
+  /* Restore previous header.  */
+  fd = xopen (tmpbin, O_RDWR | O_LARGEFILE, 0);
+  xwrite (fd, &orig_hdr, sizeof (orig_hdr));
+  xclose (fd);
+}
+
+static void
+modify_mag (ElfW(Ehdr) *ehdr)
+{
+  ehdr->e_ident[EI_MAG0] = EI_MAG3;
+  ehdr->e_ident[EI_MAG1] = EI_MAG2;
+  ehdr->e_ident[EI_MAG2] = EI_MAG1;
+  ehdr->e_ident[EI_MAG3] = EI_MAG0;
+}
+
+static void
+modify_class (ElfW(Ehdr) *ehdr)
+{
+  ehdr->e_ident[EI_CLASS] = ELFCLASSNONE;
+}
+
+static void
+modify_endian (ElfW(Ehdr) *ehdr)
+{
+  ehdr->e_ident[EI_DATA] = ELFDATANONE;
+}
+
+static void
+modify_eiversion (ElfW(Ehdr) *ehdr)
+{
+  ehdr->e_ident[EI_VERSION] = EV_CURRENT + 1;
+}
+
+static void
+modify_osabi (ElfW(Ehdr) *ehdr)
+{
+  ehdr->e_ident[EI_OSABI] = ELFOSABI_STANDALONE;
+}
+
+static void
+modify_abiversion (ElfW(Ehdr) *ehdr)
+{
+  ehdr->e_ident[EI_ABIVERSION] = LIBC_ABI_MAX;
+}
+
+static void
+modify_pad (ElfW(Ehdr) *ehdr)
+{
+  memset (&ehdr->e_ident[EI_PAD], 0xff, EI_NIDENT - EI_PAD);
+}
+
+static void
+modify_version (ElfW(Ehdr) *ehdr)
+{
+  ehdr->e_version = EV_NONE;
+}
+
+static void
+modify_type (ElfW(Ehdr) *ehdr)
+{
+  ehdr->e_type = ET_NONE;
+}
+
+static void
+modify_phentsize (ElfW(Ehdr) *ehdr)
+{
+  ehdr->e_phentsize = sizeof (ElfW(Phdr)) + 1;
+}
+
+static void
+do_test_kernel (void)
+{
+  run_test_expect_failure (modify_mag,
+			   "invalid ELF header");
+  run_test_expect_failure (modify_type,
+			   "only ET_DYN and ET_EXEC can be loaded");
+  run_test_expect_failure (modify_phentsize,
+			   "ELF file's phentsize not the expected size");
+  run_test_expect_failure (modify_class,
+			   "wrong ELF class");
+}
+
+static void
+do_test_common (void)
+{
+  run_test_expect_failure (modify_endian,
+			   "ELF file data encoding not");
+  run_test_expect_failure (modify_eiversion,
+			   "ELF file version ident does not match current one");
+  run_test_expect_failure (modify_pad,
+			   "nonzero padding in e_ident");
+  run_test_expect_failure (modify_osabi,
+			   "ELF file OS ABI invalid");
+  run_test_expect_failure (modify_abiversion,
+			   "ELF file ABI version invalid");
+  run_test_expect_failure (modify_version,
+			   "ELF file version does not match current one");
+}
+
+static int
+do_test (int argc, char *argv[])
+{
+  /* We must have one or four parameters:
+     + argv[0]:   the application name
+     + argv[1]:   path for ld.so        optional
+     + argv[2]:   "--library-path"      optional
+     + argv[3]:   the library path      optional
+     + argv[4/1]: the application name  */
+
+  if (!restart)
+    copy_binary (argv[0]);
+  else
+    abort ();
+
+  bool hardpath = argc == 2;
+
+  int i;
+  for (i = 0; i < argc - 2; i++)
+    spargv[i] = argv[i+1];
+  spargv[i++] = tmpbin;
+  spargv[i++] = (char *) "--direct";
+  spargv[i++] = (char *) "--restart";
+  spargv[i] = NULL;
+
+  /* Some fields are checked by the kernel results in a execve failure, so skip
+     them for --enable-hardcoded-path-in-tests.  */
+  if (!hardpath)
+    do_test_kernel ();
+  do_test_common ();
+
+  /* Also run the tests without issuing the loader.  */
+  if (hardpath)
+    return 0;
+
+  spargv[0] = tmpbin;
+  spargv[1] = (char *) "--direct";
+  spargv[2] = (char *) "--restart";
+  spargv[3] = NULL;
+
+  do_test_common ();
+
+  return 0;
+}
+
+#define TEST_FUNCTION_ARGV do_test
+#include <support/test-driver.c>
diff --git a/sysdeps/generic/dl-elf-check.h b/sysdeps/generic/dl-elf-check.h
new file mode 100644
index 0000000000..48eb82e9e7
--- /dev/null
+++ b/sysdeps/generic/dl-elf-check.h
@@ -0,0 +1,28 @@ 
+/* ELF header consistency and ABI checks.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_ELF_CHECK_H
+#define _DL_ELF_CHECK_H
+
+/* Called from the loader just after the program headers are processed.  */
+static inline void
+_dl_check_ehdr (const ElfW(Ehdr) *ehdr)
+{
+}
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/dl-elf-check.h b/sysdeps/unix/sysv/linux/dl-elf-check.h
new file mode 100644
index 0000000000..9e4925c090
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dl-elf-check.h
@@ -0,0 +1,32 @@ 
+/* ELF header consistency and ABI checks.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_ELF_CHECK_H
+#define _DL_ELF_CHECK_H
+
+#include <dl-check.h>
+
+static inline void
+_dl_check_ehdr (const ElfW(Ehdr) *ehdr)
+{
+  int err = _dl_elfhdr_check (ehdr);
+  if (err != DL_ELFHDR_OK)
+    _dl_fatal_printf ("program loading error: %s\n", _dl_elfhdr_errstr (err));
+}
+
+#endif