From e7b553272196e6175b8a15f807cb59217ba2843a Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 29 Oct 2024 06:01:14 +0800
Subject: [PATCH] elf: Handle static PIE with non-zero load address [BZ #31799]
 
Reference:https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=e7b553272196e6175b8a15f807cb59217ba2843a
Conflict:The context of the modified content is slightly different.
 
For a static PIE with non-zero load address, its PT_DYNAMIC segment
entries contain the relocated values for the load address in static PIE.
Since static PIE usually doesn't have PT_PHDR segment, use p_vaddr of
the PT_LOAD segment with offset == 0 as the load address in static PIE
and adjust the entries of PT_DYNAMIC segment in static PIE by properly
setting the l_addr field for static PIE.  This fixes BZ #31799.
 
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
---
 configure                    | 73 ++++++++++++++++++++++++++++++++++++
 configure.ac                 | 36 ++++++++++++++++++
 elf/Makefile                 | 20 ++++++++++
 elf/dl-reloc-static-pie.c    | 30 +++++++++++----
 elf/tst-pie-address-static.c | 19 ++++++++++
 elf/tst-pie-address.c        | 28 ++++++++++++++
 6 files changed, 199 insertions(+), 7 deletions(-)
 create mode 100644 elf/tst-pie-address-static.c
 create mode 100644 elf/tst-pie-address.c

diff --git a/configure b/configure
index be2277b1..ae83d509 100755
--- a/configure
+++ b/configure
@@ -6925,6 +6925,79 @@ $as_echo "$libc_cv_cc_pie_default" >&6; }
 libc_cv_pie_default=$libc_cv_cc_pie_default
 
 
+# Get Position Dependent Executable (PDE) load address to be used to
+# load static Position Independent Executable (PIE) at a known working
+# non-zero load address.  This is only used by glibc tests to verify
+# that PIE and static PIE with non-zero load address work correctly.
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking PDE load address" >&5
+printf %s "checking PDE load address... " >&6; }
+if test ${libc_cv_pde_load_address+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) cat > conftest.S <<EOF
+.globl _start
+_start:
+.globl __start
+__start:
+EOF
+if test $libc_cv_cc_pie_default = yes; then
+  pde_ld_flags="-no-pie"
+fi
+if ${CC-cc} $pde_ld_flags $CFLAGS $CPPFLAGS $LDFLAGS \
+	    -nostartfiles -nostdlib $no_ssp \
+	    -o conftest conftest.S 1>&5 2>&5; then
+  # Get the load address of the first PT_LOAD segment.
+  libc_cv_pde_load_address=$(LC_ALL=C $READELF -Wl conftest \
+			     | $AWK '/LOAD/ { print $3; exit 0; }')
+else
+  as_fn_error $? "${CC-cc} can not create PDE" "$LINENO" 5
+fi
+rm -f conftest* ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_pde_load_address" >&5
+printf "%s\n" "$libc_cv_pde_load_address" >&6; }
+config_vars="$config_vars
+pde-load-address = $libc_cv_pde_load_address"
+
+# Get the linker command-line option to load executable at a non-zero
+# load address.  This is only used by glibc tests to verify that PIE and
+# static PIE with non-zero load address work correctly.
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for linker that supports -Ttext-segment=$libc_cv_pde_load_address" >&5
+printf %s "checking for linker that supports -Ttext-segment=$libc_cv_pde_load_address... " >&6; }
+libc_linker_feature=no
+cat > conftest.c <<EOF
+int _start (void) { return 42; }
+EOF
+if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp
+		  -Wl,-Ttext-segment=$libc_cv_pde_load_address -nostdlib -nostartfiles
+		  -fPIC -shared -o conftest.so conftest.c
+		  1>&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then
+  if ${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp -Wl,-Ttext-segment=$libc_cv_pde_load_address -nostdlib \
+      -nostartfiles -fPIC -shared -o conftest.so conftest.c 2>&1 \
+      | grep "warning: -Ttext-segment=$libc_cv_pde_load_address ignored" > /dev/null 2>&1; then
+    true
+  else
+    libc_linker_feature=yes
+  fi
+fi
+rm -f conftest*
+if test $libc_linker_feature = yes; then
+  libc_cv_load_address_ldflag=-Wl,-Ttext-segment
+else
+  libc_cv_load_address_ldflag=
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5
+printf "%s\n" "$libc_linker_feature" >&6; }
+config_vars="$config_vars
+load-address-ldflag = $libc_cv_load_address_ldflag"
 
 # Set the `multidir' variable by grabbing the variable from the compiler.
 # We do it once and save the result in a generated makefile.
diff --git a/configure.ac b/configure.ac
index fa34af26..0ea4cbe9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1853,6 +1853,42 @@ libc_cv_pie_default=$libc_cv_cc_pie_default
 AC_SUBST(libc_cv_cc_pie_default)
 AC_SUBST(libc_cv_pie_default)
 
+# Get Position Dependent Executable (PDE) load address to be used to
+# load static Position Independent Executable (PIE) at a known working
+# non-zero load address.  This is only used by glibc tests to verify
+# that PIE and static PIE with non-zero load address work correctly.
+AC_CACHE_CHECK([PDE load address],
+	       libc_cv_pde_load_address, [dnl
+cat > conftest.S <<EOF
+.globl _start
+_start:
+.globl __start
+__start:
+EOF
+if test $libc_cv_cc_pie_default = yes; then
+  pde_ld_flags="-no-pie"
+fi
+if ${CC-cc} $pde_ld_flags $CFLAGS $CPPFLAGS $LDFLAGS \
+	    -nostartfiles -nostdlib $no_ssp \
+	    -o conftest conftest.S 1>&AS_MESSAGE_LOG_FD 2>&AS_MESSAGE_LOG_FD; then
+  # Get the load address of the first PT_LOAD segment.
+  libc_cv_pde_load_address=$(LC_ALL=C $READELF -Wl conftest \
+			     | $AWK '/LOAD/ { print $3; exit 0; }')
+else
+  AC_MSG_ERROR([${CC-cc} can not create PDE])
+fi
+rm -f conftest*])
+LIBC_CONFIG_VAR([pde-load-address], [$libc_cv_pde_load_address])
+
+# Get the linker command-line option to load executable at a non-zero
+# load address.  This is only used by glibc tests to verify that PIE and
+# static PIE with non-zero load address work correctly.
+LIBC_LINKER_FEATURE([-Ttext-segment=$libc_cv_pde_load_address],
+		    [-Wl,-Ttext-segment=$libc_cv_pde_load_address],
+		    [libc_cv_load_address_ldflag=-Wl,-Ttext-segment],
+		    [libc_cv_load_address_ldflag=])
+LIBC_CONFIG_VAR([load-address-ldflag], [$libc_cv_load_address_ldflag])
+
 # Set the `multidir' variable by grabbing the variable from the compiler.
 # We do it once and save the result in a generated makefile.
 libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory`
diff --git a/elf/Makefile b/elf/Makefile
index 89ab30cd..e6f78d7f 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -844,6 +844,25 @@ modules-names += tst-piemod1
 tests += tst-pie1 tst-pie2 tst-dlopen-pie tst-dlopen-tlsmodid-pie \
   tst-dlopen-self-pie
 tests-pie += tst-pie1 tst-pie2 tst-dlopen-tlsmodid-pie tst-dlopen-self-pie
+ifneq (,$(load-address-ldflag))
+tests += \
+  tst-pie-address \
+  # tests
+tests-pie += \
+  tst-pie-address \
+  # tests-pie
+LDFLAGS-tst-pie-address += $(load-address-ldflag)=$(pde-load-address)
+ifeq (yes,$(enable-static-pie))
+tests += \
+  tst-pie-address-static \
+  # tests
+tests-static += \
+  tst-pie-address-static \
+  # tests-static
+LDFLAGS-tst-pie-address-static += \
+  $(load-address-ldflag)=$(pde-load-address)
+endif
+endif
 ifeq (yes,$(have-protected-data))
 tests += vismain
 tests-pie += vismain
@@ -1622,6 +1641,7 @@ $(objpfx)tst-array5-static-cmp.out: tst-array5-static.exp \
 
 CFLAGS-tst-pie1.c += $(pie-ccflag)
 CFLAGS-tst-pie2.c += $(pie-ccflag)
+CFLAGS-tst-pie-address.c += $(pie-ccflag)
 
 $(objpfx)tst-piemod1.so: $(libsupport)
 $(objpfx)tst-pie1: $(objpfx)tst-piemod1.so
diff --git a/elf/dl-reloc-static-pie.c b/elf/dl-reloc-static-pie.c
index 2fb02d72..f4013e55 100644
--- a/elf/dl-reloc-static-pie.c
+++ b/elf/dl-reloc-static-pie.c
@@ -35,21 +35,37 @@ _dl_relocate_static_pie (void)
 # define RESOLVE_MAP(sym, version, flags) BOOTSTRAP_MAP
 # include "dynamic-link.h"
 
-  /* Figure out the run-time load address of static PIE.  */
-  main_map->l_addr = elf_machine_load_address ();
-
-  /* Read our own dynamic section and fill in the info array.  */
-  main_map->l_ld = ((void *) main_map->l_addr + elf_machine_dynamic ());
-
+  /* NB: elf_machine_load_address () returns the run-time load address
+     of static PIE.  The l_addr field contains the difference between the
+     link-time load address in the ELF file and the run-time load address
+     in memory.  We must subtract the link-time load address of static PIE,
+     which can be non-zero, when computing the l_addr field.  Since static
+     PIE usually doesn't have PT_PHDR segment, use p_vaddr of the PT_LOAD
+     segment with offset == 0 as the load address of static PIE.  */
+  ElfW(Addr) file_p_vaddr = 0;
   const ElfW(Phdr) *ph, *phdr = GL(dl_phdr);
   size_t phnum = GL(dl_phnum);
   for (ph = phdr; ph < &phdr[phnum]; ++ph)
-    if (ph->p_type == PT_DYNAMIC)
+    switch (ph->p_type)
       {
+      case PT_LOAD:
+	if (ph->p_offset == 0)
+	  file_p_vaddr = ph->p_vaddr;
+	break;
+      case PT_DYNAMIC:
 	main_map->l_ld_readonly = (ph->p_flags & PF_W) == 0;
 	break;
+      default:
+	break;
       }
 
+  /* Figure out the run-time load address of static PIE.  */
+  ElfW(Addr) l_addr = elf_machine_load_address ();
+  main_map->l_addr = l_addr - file_p_vaddr;
+
+  /* Read our own dynamic section and fill in the info array.  */
+  main_map->l_ld = ((void *) l_addr + elf_machine_dynamic ());
+
   elf_get_dynamic_info (main_map);
 
 # ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
diff --git a/elf/tst-pie-address-static.c b/elf/tst-pie-address-static.c
new file mode 100644
index 00000000..be2831e9
--- /dev/null
+++ b/elf/tst-pie-address-static.c
@@ -0,0 +1,19 @@
+/* Test static PIE with non-zero load address.
+   Copyright (C) 2024 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 "tst-pie-address.c"
diff --git a/elf/tst-pie-address.c b/elf/tst-pie-address.c
new file mode 100644
index 00000000..aa1ca0a9
--- /dev/null
+++ b/elf/tst-pie-address.c
@@ -0,0 +1,28 @@
+/* Test PIE with non-zero load address.
+   Copyright (C) 2024 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 <stdio.h>
+
+static int
+do_test (void)
+{
+  printf ("Hello\n");
+  return 0;
+}
+
+#include <support/test-driver.c>
-- 
2.27.0

