commit d1b9bee29a1c4e0b80db53f228e22550c3604894

Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>

Date:   Mon Jul 19 18:42:26 2021 -0300

    elf: Issue audit la_objopen for vDSO

    The vDSO is is listed in the link_map chain, but is never the subject of

    an la_objopen call.  A new internal flag __RTLD_VDSO is added that

    acts as __RTLD_OPENEXEC to allocate the required 'struct auditstate'

    extra space for the 'struct link_map'.

    The return value from the callback is currently ignored, since there

    is no PLT call involved by glibc when using the vDSO, neither the vDSO

    are exported directly.

    Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.

    Reviewed-by: Florian Weimer <fweimer@redhat.com>

    (cherry picked from commit f0e23d34a7bdf6b90fba954ee741419171ac41b2)

    Resolved conflicts:

            elf/Makefile

diff --git a/elf/Makefile b/elf/Makefile

index 29f545d2272bf6e2..465442bf59fa9794 100644

--- a/elf/Makefile

+++ b/elf/Makefile

@@ -366,6 +366,7 @@ tests += \

   tst-audit17 \

   tst-audit18 \

   tst-audit19b \

+  tst-audit22 \

   tst-auditmany \

   tst-auxobj \

   tst-auxobj-dlopen \

@@ -649,6 +650,7 @@ modules-names = \

   tst-auditmod18 \

   tst-auditmod19a \

   tst-auditmod19b \

+  tst-auditmod22 \

   tst-auxvalmod \

   tst-big-note-lib \

   tst-deep1mod1 \

@@ -2035,6 +2037,9 @@ $(objpfx)tst-audit19b.out: $(objpfx)tst-auditmod19b.so

 $(objpfx)tst-audit19b: $(objpfx)tst-audit19bmod.so

 tst-audit19b-ARGS = -- $(host-test-program-cmd)

+$(objpfx)tst-audit22.out: $(objpfx)tst-auditmod22.so

+tst-audit22-ARGS = -- $(host-test-program-cmd)

+

 # tst-sonamemove links against an older implementation of the library.

 LDFLAGS-tst-sonamemove-linkmod1.so = \

   -Wl,--version-script=tst-sonamemove-linkmod1.map \

diff --git a/elf/dl-object.c b/elf/dl-object.c

index 1875599eb274dc35..dee49a32d4fdf07d 100644

--- a/elf/dl-object.c

+++ b/elf/dl-object.c

@@ -59,16 +59,19 @@ _dl_new_object (char *realname, const char *libname, int type,

 {

 #ifdef SHARED

   unsigned int naudit;

-  if (__glibc_unlikely ((mode & __RTLD_OPENEXEC) != 0))

+  if (__glibc_unlikely ((mode & (__RTLD_OPENEXEC | __RTLD_VDSO)) != 0))

     {

-      assert (type == lt_executable);

-      assert (nsid == LM_ID_BASE);

+      if (mode & __RTLD_OPENEXEC)

+	{

+	  assert (type == lt_executable);

+	  assert (nsid == LM_ID_BASE);

-      /* Ignore the specified libname for the main executable.  It is

-	 only known with an explicit loader invocation.  */

-      libname = "";

+	  /* Ignore the specified libname for the main executable.  It is

+	     only known with an explicit loader invocation.  */

+	  libname = "";

+	}

-      /* We create the map for the executable before we know whether

+      /* We create the map for the executable and vDSO before we know whether

 	 we have auditing libraries and if yes, how many.  Assume the

 	 worst.  */

       naudit = DL_NNS;

diff --git a/elf/rtld.c b/elf/rtld.c

index f632a767d7a269ef..b089e5cf4740443e 100644

--- a/elf/rtld.c

+++ b/elf/rtld.c

@@ -1922,6 +1922,12 @@ dl_main (const ElfW(Phdr) *phdr,

       assert (i == npreloads);

     }

+#ifdef NEED_DL_SYSINFO_DSO

+  /* Now that the audit modules are opened, call la_objopen for the vDSO.  */

+  if (GLRO(dl_sysinfo_map) != NULL)

+    _dl_audit_objopen (GLRO(dl_sysinfo_map), LM_ID_BASE);

+#endif

+

   /* Load all the libraries specified by DT_NEEDED entries.  If LD_PRELOAD

      specified some libraries to load, these are inserted before the actual

      dependencies in the executable's searchlist for symbol resolution.  */

diff --git a/elf/setup-vdso.h b/elf/setup-vdso.h

index 3f20578046de76ed..2b013d974a377a83 100644

--- a/elf/setup-vdso.h

+++ b/elf/setup-vdso.h

@@ -30,7 +30,7 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),

      We just want our data structures to describe it as if we had just

      mapped and relocated it normally.  */

   struct link_map *l = _dl_new_object ((char *) "", "", lt_library, NULL,

-				       0, LM_ID_BASE);

+				       __RTLD_VDSO, LM_ID_BASE);

   if (__glibc_likely (l != NULL))

     {

       l->l_phdr = ((const void *) GLRO(dl_sysinfo_dso)

diff --git a/elf/tst-audit22.c b/elf/tst-audit22.c

new file mode 100644

index 0000000000000000..18fd22a760ddc3d8

--- /dev/null

+++ b/elf/tst-audit22.c

@@ -0,0 +1,124 @@

+/* Check DTAUDIT and vDSO interaction.

+   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 <errno.h>

+#include <getopt.h>

+#include <limits.h>

+#include <inttypes.h>

+#include <string.h>

+#include <stdlib.h>

+#include <support/capture_subprocess.h>

+#include <support/check.h>

+#include <support/xstdio.h>

+#include <support/support.h>

+#include <sys/auxv.h>

+

+static int restart;

+#define CMDLINE_OPTIONS \

+  { "restart", no_argument, &restart, 1 },

+

+static uintptr_t vdso_addr;

+

+static int

+handle_restart (void)

+{

+  fprintf (stderr, "vdso: %p\n", (void*) vdso_addr);

+  return 0;

+}

+

+static uintptr_t

+parse_address (const char *str)

+{

+  void *r;

+  TEST_COMPARE (sscanf (str, "%p\n", &r), 1);

+  return (uintptr_t) r;

+}

+

+static inline bool

+startswith (const char *str, const char *pre)

+{

+  size_t lenpre = strlen (pre);

+  size_t lenstr = strlen (str);

+  return lenstr >= lenpre && memcmp (pre, str, lenpre) == 0;

+}

+

+static int

+do_test (int argc, char *argv[])

+{

+  vdso_addr = getauxval (AT_SYSINFO_EHDR);

+  if (vdso_addr == 0)

+    FAIL_UNSUPPORTED ("getauxval (AT_SYSINFO_EHDR) returned 0");

+

+  /* We must have either:

+     - One our fource parameters left if called initially:

+       + path to ld.so         optional

+       + "--library-path"      optional

+       + the library path      optional

+       + the application name  */

+  if (restart)

+    return handle_restart ();

+

+  char *spargv[9];

+  int i = 0;

+  for (; i < argc - 1; i++)

+    spargv[i] = argv[i + 1];

+  spargv[i++] = (char *) "--direct";

+  spargv[i++] = (char *) "--restart";

+  spargv[i] = NULL;

+

+  setenv ("LD_AUDIT", "tst-auditmod22.so", 0);

+  struct support_capture_subprocess result

+    = support_capture_subprogram (spargv[0], spargv);

+  support_capture_subprocess_check (&result, "tst-audit22", 0, sc_allow_stderr);

+

+  /* The respawned process should always print the vDSO address (otherwise it

+     will fails as unsupported).  However, on some architectures the audit

+     module might see the vDSO with l_addr being 0, meaning a fixed mapping

+     (linux-gate.so).  In this case we don't check its value against

+     AT_SYSINFO_EHDR one.  */

+  uintptr_t vdso_process = 0;

+  bool vdso_audit_found = false;

+  uintptr_t vdso_audit = 0;

+

+  FILE *out = fmemopen (result.err.buffer, result.err.length, "r");

+  TEST_VERIFY (out != NULL);

+  char *buffer = NULL;

+  size_t buffer_length = 0;

+  while (xgetline (&buffer, &buffer_length, out))

+    {

+      if (startswith (buffer, "vdso: "))

+	vdso_process = parse_address (buffer + strlen ("vdso: "));

+      else if (startswith (buffer, "vdso found: "))

+	{

+	  vdso_audit = parse_address (buffer + strlen ("vdso found: "));

+          vdso_audit_found = true;

+	}

+    }

+

+  TEST_COMPARE (vdso_audit_found, true);

+  if (vdso_audit != 0)

+    TEST_COMPARE (vdso_process, vdso_audit);

+

+  free (buffer);

+  xfclose (out);

+

+  return 0;

+}

+

+#define TEST_FUNCTION_ARGV do_test

+#include <support/test-driver.c>

diff --git a/elf/tst-auditmod22.c b/elf/tst-auditmod22.c

new file mode 100644

index 0000000000000000..8e05ce8cbb215dd5

--- /dev/null

+++ b/elf/tst-auditmod22.c

@@ -0,0 +1,51 @@

+/* Check DTAUDIT and vDSO interaction.

+   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 <link.h>

+#include <inttypes.h>

+#include <stdbool.h>

+#include <string.h>

+#include <stdio.h>

+#include <sys/auxv.h>

+

+static inline bool

+startswith (const char *str, const char *pre)

+{

+  size_t lenpre = strlen (pre);

+  size_t lenstr = strlen (str);

+  return lenstr < lenpre ? false : memcmp (pre, str, lenpre) == 0;

+}

+

+unsigned int

+la_version (unsigned int version)

+{

+  return LAV_CURRENT;

+}

+

+unsigned int

+la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie)

+{

+  /* The linux-gate.so is placed at a fixed address, thus l_addr being 0,

+     and it might be the value reported as the AT_SYSINFO_EHDR.  */

+  if (map->l_addr == 0 && startswith (map->l_name, "linux-gate.so"))

+    fprintf (stderr, "vdso found: %p\n", NULL);

+  else if (map->l_addr == getauxval (AT_SYSINFO_EHDR))

+    fprintf (stderr, "vdso found: %p\n", (void*) map->l_addr);

+

+  return 0;

+}

diff --git a/include/dlfcn.h b/include/dlfcn.h

index a4c283728f94deb4..e73294b0af587913 100644

--- a/include/dlfcn.h

+++ b/include/dlfcn.h

@@ -12,6 +12,8 @@

 #define __RTLD_AUDIT	0x08000000

 #define __RTLD_SECURE	0x04000000 /* Apply additional security checks.  */

 #define __RTLD_NOIFUNC	0x02000000 /* Suppress calling ifunc functions.  */

+#define __RTLD_VDSO	0x01000000 /* Tell _dl_new_object the object is

+				      system-loaded.  */

 #define __LM_ID_CALLER	-2