elf: Move vDSO setup to rtld (BZ#24967)

This patch moves the vDSO setup from libc to loader code, just after
the vDSO link_map setup.  For static case the initialization
is moved to _dl_non_dynamic_init instead.

Instead of using the mangled pointer, the vDSO data is set as
attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for
static).  It is read-only even with partial relro.

It fixes BZ#24967 now that the vDSO pointer is setup earlier than
malloc interposition is called.

Also, vDSO calls should not be a problem for static dlopen as
indicated by BZ#20802.  The vDSO pointer would be zero-initialized
and the syscall will be issued instead.

Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu,
powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and
sparcv9-linux-gnu.  I also run some tests on mips.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

31 files changed, 257 insertions, 289 deletions

diff --git a/csu/init-first.c b/csu/init-first.c
index 669b779b70..1cd8a75098 100644
--- a/csu/init-first.c
+++ b/csu/init-first.c
@@ -74,10 +74,6 @@ _init (int argc, char **argv, char **envp)
   _dl_non_dynamic_init ();
 #endif
 
-#ifdef VDSO_SETUP
-  VDSO_SETUP ();
-#endif
-
   __init_misc (argc, argv, envp);
 
   /* Initialize ctype data.  */
diff --git a/elf/dl-support.c b/elf/dl-support.c
index 508a5c1196..ad791ab6ab 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -34,6 +34,8 @@
 #include <unsecvars.h>
 #include <hp-timing.h>
 #include <stackinfo.h>
+#include <dl-vdso.h>
+#include <dl-vdso-setup.h>
 
 extern char *__progname;
 char **_dl_argv = &__progname;	/* This is checked for some error messages.  */
@@ -201,6 +203,8 @@ struct link_map *_dl_sysinfo_map;
 # include "get-dynamic-info.h"
 #endif
 #include "setup-vdso.h"
+/* Define the vDSO function pointers.  */
+#include <dl-vdso-setup.c>
 
 /* During the program run we must not modify the global data of
    loaded shared object simultanously in two threads.  Therefore we
@@ -315,6 +319,9 @@ _dl_non_dynamic_init (void)
      so they can influence _dl_init_paths.  */
   setup_vdso (NULL, NULL);
 
+  /* With vDSO setup we can initialize the function pointers.  */
+  setup_vdso_pointers ();
+
   /* Initialize the data structures for the search paths for shared
      objects.  */
   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
diff --git a/elf/rtld.c b/elf/rtld.c
index 817fb86eac..553cfbd1b7 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -39,6 +39,8 @@
 #include <dl-osinfo.h>
 #include <dl-procinfo.h>
 #include <dl-prop.h>
+#include <dl-vdso.h>
+#include <dl-vdso-setup.h>
 #include <tls.h>
 #include <stap-probe.h>
 #include <stackinfo.h>
@@ -833,7 +835,7 @@ security_init (void)
   _dl_random = NULL;
 }
 
-#include "setup-vdso.h"
+#include <setup-vdso.h>
 
 /* The library search path.  */
 static const char *library_path attribute_relro;
@@ -1538,6 +1540,9 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
      so they can influence _dl_init_paths.  */
   setup_vdso (main_map, &first_preload);
 
+  /* With vDSO setup we can initialize the function pointers.  */
+  setup_vdso_pointers ();
+
 #ifdef DL_SYSDEP_OSCHECK
   DL_SYSDEP_OSCHECK (_dl_fatal_printf);
 #endif
diff --git a/malloc/tst-interpose-aux.c b/malloc/tst-interpose-aux.c
index 52696e92d3..a0ab2e5903 100644
--- a/malloc/tst-interpose-aux.c
+++ b/malloc/tst-interpose-aux.c
@@ -28,6 +28,7 @@
 #include <sys/mman.h>
 #include <sys/uio.h>
 #include <unistd.h>
+#include <time.h>
 
 #if INTERPOSE_THREADS
 #include <pthread.h>
@@ -96,6 +97,7 @@ struct __attribute__ ((aligned (__alignof__ (max_align_t)))) allocation_header
 {
   size_t allocation_index;
   size_t allocation_size;
+  struct timespec ts;
 };
 
 /* Array of known allocations, to track invalid frees.  */
@@ -166,6 +168,9 @@ malloc_internal (size_t size)
       .allocation_index = index,
       .allocation_size = allocation_size
     };
+  /* BZ#24967: Check if calling a symbol which may use the vDSO does not fail.
+     The CLOCK_REALTIME should be supported on all systems.  */
+  clock_gettime (CLOCK_REALTIME, &allocations[index]->ts);
   return allocations[index] + 1;
 }
 
diff --git a/sysdeps/generic/dl-vdso-setup.c b/sysdeps/generic/dl-vdso-setup.c
new file mode 100644
index 0000000000..6e25b021ab
--- /dev/null
+++ b/sysdeps/generic/dl-vdso-setup.c
@@ -0,0 +1 @@
+/* Empty.  */
diff --git a/sysdeps/generic/dl-vdso-setup.h b/sysdeps/generic/dl-vdso-setup.h
new file mode 100644
index 0000000000..5ef7531fac
--- /dev/null
+++ b/sysdeps/generic/dl-vdso-setup.h
@@ -0,0 +1,28 @@
+/* ELF symbol initialization functions for VDSO objects.
+   Copyright (C) 2020 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_VDSO_INIT_H
+#define _DL_VDSO_INIT_H
+
+/* Initialize the VDSO functions pointers.  */
+static inline void __attribute__ ((always_inline))
+setup_vdso_pointers (void)
+{
+}
+
+#endif
diff --git a/sysdeps/generic/dl-vdso.h b/sysdeps/generic/dl-vdso.h
new file mode 100644
index 0000000000..70379a82a1
--- /dev/null
+++ b/sysdeps/generic/dl-vdso.h
@@ -0,0 +1,30 @@
+/* ELF symbol resolve functions for VDSO objects.
+   Copyright (C) 2020 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_VDSO_H
+#define _DL_VDSO_H	1
+
+/* Function for resolving symbols in the VDSO link map.  Return the
+   address of the vdso symbol NAME. */
+static inline void *
+dl_vdso_vsym (const char *name)
+{
+  return NULL;
+}
+
+#endif
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 0a5d3473f5..497938ffa2 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -608,6 +608,12 @@ struct rtld_global_ro
   /* At startup time we set up the normal DSO data structure for it,
      and this points to it.  */
   EXTERN struct link_map *_dl_sysinfo_map;
+
+# define PROCINFO_DECL
+# ifndef PROCINFO_CLASS
+#  define PROCINFO_CLASS EXTERN
+# endif
+# include <dl-vdso-setup.c>
 #endif
 
   /* Mask for more hardware capabilities that are available on some
diff --git a/sysdeps/powerpc/powerpc32/backtrace.c b/sysdeps/powerpc/powerpc32/backtrace.c
index 4a35588671..7c2d4726f8 100644
--- a/sysdeps/powerpc/powerpc32/backtrace.c
+++ b/sysdeps/powerpc/powerpc32/backtrace.c
@@ -51,14 +51,14 @@ struct signal_frame_32 {
   /* We don't care about the rest, since IP value is at 'mctx' field.  */
 };
 
-static inline int
+static inline bool
 is_sigtramp_address (void *nip)
 {
 #ifdef HAVE_SIGTRAMP_RT32
-  if (nip == VDSO_SYMBOL (sigtramp32))
-    return 1;
+  if (nip == GLRO (dl_vdso_sigtramp_32))
+    return true;
 #endif
-  return 0;
+  return false;
 }
 
 struct rt_signal_frame_32 {
@@ -68,14 +68,14 @@ struct rt_signal_frame_32 {
   /* We don't care about the rest, since IP value is at 'uc' field.  */
 };
 
-static inline int
+static inline bool
 is_sigtramp_address_rt (void * nip)
 {
 #ifdef HAVE_SIGTRAMP_32
-  if (nip == VDSO_SYMBOL (sigtramp_rt32))
-    return 1;
+  if (nip == GLRO (dl_vdso_sigtramp_rt32))
+    return true;
 #endif
-  return 0;
+  return false;
 }
 
 int
diff --git a/sysdeps/powerpc/powerpc64/backtrace.c b/sysdeps/powerpc/powerpc64/backtrace.c
index ee8ba21f27..65c260ab76 100644
--- a/sysdeps/powerpc/powerpc64/backtrace.c
+++ b/sysdeps/powerpc/powerpc64/backtrace.c
@@ -54,14 +54,14 @@ struct signal_frame_64 {
   /* We don't care about the rest, since the IP value is at 'uc' field.  */
 };
 
-static inline int
+static inline bool
 is_sigtramp_address (void *nip)
 {
 #ifdef HAVE_SIGTRAMP_RT64
-  if (nip == VDSO_SYMBOL (sigtramp_rt64))
-    return 1;
+  if (nip == GLRO (dl_vdso_sigtramp_rt64))
+    return true;
 #endif
-  return 0;
+  return false;
 }
 
 int
diff --git a/sysdeps/unix/sysv/linux/aarch64/Makefile b/sysdeps/unix/sysv/linux/aarch64/Makefile
index 57bbfeaac6..4bcae85bca 100644
--- a/sysdeps/unix/sysv/linux/aarch64/Makefile
+++ b/sysdeps/unix/sysv/linux/aarch64/Makefile
@@ -5,7 +5,6 @@ shared-only-routines += libc-__read_tp
 endif
 
 ifeq ($(subdir),elf)
-sysdep_routines	     += dl-vdso
 sysdep-rtld-routines += __read_tp
 ifeq ($(build-shared),yes)
 # This is needed for DSO loading from static binaries.
diff --git a/sysdeps/unix/sysv/linux/arm/Makefile b/sysdeps/unix/sysv/linux/arm/Makefile
index d7a2f6a8a7..abdf01f00c 100644
--- a/sysdeps/unix/sysv/linux/arm/Makefile
+++ b/sysdeps/unix/sysv/linux/arm/Makefile
@@ -1,5 +1,4 @@
 ifeq ($(subdir),elf)
-sysdep_routines += dl-vdso
 sysdep-rtld-routines += aeabi_read_tp libc-do-syscall
 endif
 
diff --git a/sysdeps/unix/sysv/linux/dl-vdso-setup.c b/sysdeps/unix/sysv/linux/dl-vdso-setup.c
new file mode 100644
index 0000000000..352fcae529
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dl-vdso-setup.c
@@ -0,0 +1,81 @@
+/* Data for vDSO support.  Linux version.
+   Copyright (C) 2020 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/>.  */
+
+/* This file is included in three different modes for both static (libc.a)
+   and shared (rtld) modes:
+
+   1. PROCINFO_DECL is defined, meaning we are only interested in
+      declarations.  For static it requires use the extern keywork along with
+      the attribute_relro while for shared it will be embedded in the
+      rtld_global_ro.
+
+   2. PROCINFO_DECL and SHARED are not defined.  Nothing to do, the default
+      zero initializion is suffice.
+
+   3. PROCINFO_DECL is not defined while SHARED is.  Similar to 2., the zero
+      initialization of rtld_global_ro is suffice.  */
+
+#ifndef PROCINFO_CLASS
+# define PROCINFO_CLASS
+#endif
+
+#ifndef SHARED
+# define RELRO attribute_relro
+#else
+# define RELRO
+#endif
+
+#if defined PROCINFO_DECL || !defined SHARED
+# ifdef HAVE_CLOCK_GETTIME_VSYSCALL
+PROCINFO_CLASS int (*_dl_vdso_clock_gettime) (clockid_t,
+					      struct timespec *) RELRO;
+#endif
+# ifdef HAVE_GETTIMEOFDAY_VSYSCALL
+PROCINFO_CLASS int (*_dl_vdso_gettimeofday) (struct timeval *, void *) RELRO;
+#endif
+# ifdef HAVE_TIME_VSYSCALL
+PROCINFO_CLASS time_t (*_dl_vdso_time) (time_t *) RELRO;
+# endif
+# ifdef HAVE_GETCPU_VSYSCALL
+PROCINFO_CLASS int (*_dl_vdso_getcpu) (unsigned *, unsigned *, void *) RELRO;
+# endif
+# ifdef HAVE_CLOCK_GETRES_VSYSCALL
+PROCINFO_CLASS int (*_dl_vdso_clock_getres) (clockid_t,
+					     struct timespec *) RELRO;
+# endif
+
+/* PowerPC specific ones.  */
+# ifdef HAVE_GET_TBFREQ
+PROCINFO_CLASS uint64_t (*_dl_vdso_get_tbfreq)(void) RELRO;
+# endif
+/* The sigtramp are used on powerpc backtrace without using
+   INLINE_VSYSCALL, so there is no need to set their type.  */
+# ifdef HAVE_SIGTRAMP_RT64
+PROCINFO_CLASS void *_dl_vdso_sigtramp_rt64 RELRO;
+# endif
+# ifdef HAVE_SIGTRAMP_RT32
+PROCINFO_CLASS void *_dl_vdso_sigtramp_rt32 RELRO;
+# endif
+# ifdef HAVE_SIGTRAMP_32
+PROCINFO_CLASS void *_dl_vdso_sigtramp_32 RELRO;
+# endif
+#endif
+
+#undef RELRO
+#undef PROCINFO_DECL
+#undef PROCINFO_CLASS
diff --git a/sysdeps/unix/sysv/linux/dl-vdso-setup.h b/sysdeps/unix/sysv/linux/dl-vdso-setup.h
new file mode 100644
index 0000000000..9f5e4a3b0b
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dl-vdso-setup.h
@@ -0,0 +1,55 @@
+/* ELF symbol initialization functions for VDSO objects.  Linux version.
+   Copyright (C) 2020 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_VDSO_INIT_H
+#define _DL_VDSO_INIT_H
+
+/* Initialize the VDSO functions pointers.  */
+static inline void __attribute__ ((always_inline))
+setup_vdso_pointers (void)
+{
+#ifdef HAVE_CLOCK_GETTIME_VSYSCALL
+  GLRO(dl_vdso_clock_gettime) = dl_vdso_vsym (HAVE_CLOCK_GETTIME_VSYSCALL);
+#endif
+#ifdef HAVE_GETTIMEOFDAY_VSYSCALL
+  GLRO(dl_vdso_gettimeofday) = dl_vdso_vsym (HAVE_GETTIMEOFDAY_VSYSCALL);
+#endif
+#ifdef HAVE_TIME_VSYSCALL
+  GLRO(dl_vdso_time) = dl_vdso_vsym (HAVE_TIME_VSYSCALL);
+#endif
+#ifdef HAVE_GETCPU_VSYSCALL
+  GLRO(dl_vdso_getcpu) = dl_vdso_vsym (HAVE_GETCPU_VSYSCALL);
+#endif
+#ifdef HAVE_CLOCK_GETRES_VSYSCALL
+  GLRO(dl_vdso_clock_getres) = dl_vdso_vsym (HAVE_CLOCK_GETRES_VSYSCALL);
+#endif
+#ifdef HAVE_GET_TBFREQ
+  GLRO(dl_vdso_get_tbfreq) = dl_vdso_vsym (HAVE_GET_TBFREQ);
+#endif
+#ifdef HAVE_SIGTRAMP_RT64
+  GLRO(dl_vdso_sigtramp_rt64) = dl_vdso_vsym (HAVE_SIGTRAMP_RT64);
+#endif
+#ifdef HAVE_SIGTRAMP_RT32
+  GLRO(dl_vdso_sigtramp_rt32) = dl_vdso_vsym (HAVE_SIGTRAMP_RT32);
+#endif
+#ifdef HAVE_SIGTRAMP_32
+  GLRO(dl_vdso_sigtramp_32) = dl_vdso_vsym (HAVE_SIGTRAMP_32);
+#endif
+}
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/dl-vdso.c b/sysdeps/unix/sysv/linux/