glibc/glibc-ld-readonly-revert.patch

Revert "ld.so: Replace DL_RO_DYN_SECTION with dl_relocate_ld [BZ #28340]"

This reverts commit b413280cfb16834450f66f554bc0d618bb513851 with changes to
adjust for the following subsequent commits:
490e6c62aa31a8 (elf: Avoid nested functions in the loader [BZ #27220])
4af6982e4c9fc4 (elf: Fix elf_get_dynamic_info definition)

It does not work on ppc64le:

“
Sorry, this does not appear to work: For !DONT_USE_BOOTSTRAP_MAP,
bootstrap_map.l_ld_readonly is not initialized during the initial
self-relocation.  This is visible as a valgrind failure on
powerpc64le-linux-gnu:

+ /builddir/build/BUILDROOT/glibc-2.34.9000-9.fc36.ppc64le/lib64/ld64.so.2 --library-path /builddir/build/BUILDROOT/glibc-2.34.9000-9.fc36.ppc64le/lib64 /usr/bin/valgrind --error-exitcode=1 /builddir/build/BUILDROOT/glibc-2.34.9000-9.fc36.ppc64le/lib64/ld64.so.2 --library-path /builddir/build/BUILDROOT/glibc-2.34.9000-9.fc36.ppc64le/lib64 /usr/bin/true
==1924587== Memcheck, a memory error detector
==1924587== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==1924587== Using Valgrind-3.17.0 and LibVEX; rerun with -h for copyright info
==1924587== Command: /builddir/build/BUILDROOT/glibc-2.34.9000-9.fc36.ppc64le/lib64/ld64.so.2 --library-path /builddir/build/BUILDROOT/glibc-2.34.9000-9.fc36.ppc64le/lib64 /usr/bin/true
==1924587== 
==1924587== Conditional jump or move depends on uninitialised value(s)
==1924587==    at 0x191620: elf_get_dynamic_info (get-dynamic-info.h:73)
==1924587==    by 0x191620: _dl_start (rtld.c:550)
==1924587==    by 0x190677: (below main) (in /builddir/build/BUILDROOT/glibc-2.34.9000-9.fc36.ppc64le/lib64/ld64.so.2)
==1924587== 

For DONT_USE_BOOTSTRAP_MAP, bootstrap_map.l_ld_readonly is always zero,
which is incorrect for RISC-V (which is PI_STATIC_AND_HIDDEN and thus
DONT_USE_BOOTSTRAP_MAP).
”

<https://sourceware.org/pipermail/libc-alpha/2021-September/131287.html>

diff --git a/elf/Makefile b/elf/Makefile
index 26986c0692..2236b6ec62 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -224,7 +224,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
 	 tst-tls-ie tst-tls-ie-dlmopen argv0test \
 	 tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask \
 	 tst-tls20 tst-tls21 tst-dlmopen-dlerror tst-dlmopen-gethostbyname \
-	 tst-dl-is_dso tst-ro-dynamic
+	 tst-dl-is_dso
 #	 reldep9
 tests-internal += loadtest unload unload2 circleload1 \
 	 neededtest neededtest2 neededtest3 neededtest4 \
@@ -360,7 +360,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		libmarkermod4-1 libmarkermod4-2 libmarkermod4-3 libmarkermod4-4 \
 		tst-tls20mod-bad tst-tls21mod tst-dlmopen-dlerror-mod \
 		tst-auxvalmod \
-		tst-dlmopen-gethostbyname-mod tst-ro-dynamic-mod \
+		tst-dlmopen-gethostbyname-mod \
 
 # Most modules build with _ISOMAC defined, but those filtered out
 # depend on internal headers.
@@ -1912,10 +1912,3 @@ $(objpfx)tst-getauxval-static.out: $(objpfx)tst-auxvalmod.so
 tst-getauxval-static-ENV = LD_LIBRARY_PATH=$(objpfx):$(common-objpfx)
 
 $(objpfx)tst-dlmopen-gethostbyname.out: $(objpfx)tst-dlmopen-gethostbyname-mod.so
-
-$(objpfx)tst-ro-dynamic: $(objpfx)tst-ro-dynamic-mod.so
-$(objpfx)tst-ro-dynamic-mod.so: $(objpfx)tst-ro-dynamic-mod.os \
-  tst-ro-dynamic-mod.map
-	$(LINK.o) -nostdlib -nostartfiles -shared -o $@ \
-		-Wl,--script=tst-ro-dynamic-mod.map \
-		$(objpfx)tst-ro-dynamic-mod.os
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 335c79fad5..a8e7f2e9cb 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1154,7 +1154,6 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
 		 such a segment to avoid a crash later.  */
 	      l->l_ld = (void *) ph->p_vaddr;
 	      l->l_ldnum = ph->p_memsz / sizeof (ElfW(Dyn));
-	      l->l_ld_readonly = (ph->p_flags & PF_W) == 0;
 	    }
 	  break;
 
@@ -1298,7 +1297,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
   else
     l->l_ld = (ElfW(Dyn) *) ((ElfW(Addr)) l->l_ld + l->l_addr);
 
-  elf_get_dynamic_info (l, false);
+  elf_get_dynamic_info (l, NULL, false);
 
   /* Make sure we are not dlopen'ing an object that has the
      DF_1_NOOPEN flag set, or a PIE object.  */
diff --git a/elf/dl-reloc-static-pie.c b/elf/dl-reloc-static-pie.c
index 8a99c4995b..efffc411cd 100644
--- a/elf/dl-reloc-static-pie.c
+++ b/elf/dl-reloc-static-pie.c
@@ -42,17 +42,7 @@ _dl_relocate_static_pie (void)
 
   /* Read our own dynamic section and fill in the info array.  */
   main_map->l_ld = ((void *) main_map->l_addr + elf_machine_dynamic ());
-
-  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)
-      {
-	main_map->l_ld_readonly = (ph->p_flags & PF_W) == 0;
-	break;
-      }
-
-  elf_get_dynamic_info (main_map, false);
+  elf_get_dynamic_info (main_map, NULL, false);
 
 # ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
   ELF_MACHINE_BEFORE_RTLD_RELOC (main_map, main_map->l_info);
diff --git a/elf/get-dynamic-info.h b/elf/get-dynamic-info.h
index d169099fbc..061466af71 100644
--- a/elf/get-dynamic-info.h
+++ b/elf/get-dynamic-info.h
@@ -25,7 +25,7 @@
 #include <libc-diag.h>
 
 static inline void __attribute__ ((unused, always_inline))
-elf_get_dynamic_info (struct link_map *l, bool check)
+elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp, bool check)
 {
 #if __ELF_NATIVE_CLASS == 32
   typedef Elf32_Word d_tag_utype;
@@ -66,15 +66,28 @@ elf_get_dynamic_info (struct link_map *l, bool check)
       info[i] = dyn;
     }
 
+#define DL_RO_DYN_TEMP_CNT	8
+
+#ifndef DL_RO_DYN_SECTION
   /* Don't adjust .dynamic unnecessarily.  */
-  if (l->l_addr != 0 && dl_relocate_ld (l))
+  if (l->l_addr != 0)
     {
       ElfW(Addr) l_addr = l->l_addr;
+      int cnt = 0;
 
 # define ADJUST_DYN_INFO(tag) \
       do								      \
 	if (info[tag] != NULL)						      \
-         info[tag]->d_un.d_ptr += l_addr;				      \
+	  {								      \
+	    if (temp)							      \
+	      {								      \
+		temp[cnt].d_tag = info[tag]->d_tag;			      \
+		temp[cnt].d_un.d_ptr = info[tag]->d_un.d_ptr + l_addr;	      \
+		info[tag] = temp + cnt++;				      \
+	      }								      \
+	    else							      \
+	      info[tag]->d_un.d_ptr += l_addr;				      \
+	  }								      \
       while (0)
 
       ADJUST_DYN_INFO (DT_HASH);
@@ -91,7 +104,9 @@ elf_get_dynamic_info (struct link_map *l, bool check)
       ADJUST_DYN_INFO (VERSYMIDX (DT_VERSYM));
       ADJUST_DYN_INFO (ADDRIDX (DT_GNU_HASH));
 # undef ADJUST_DYN_INFO
+      assert (cnt <= DL_RO_DYN_TEMP_CNT);
     }
+#endif
   if (info[DT_PLTREL] != NULL)
     {
 #if ELF_MACHINE_NO_RELA
diff --git a/elf/rtld.c b/elf/rtld.c
index fe5ee9ec4d..de731a90d9 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -464,7 +464,6 @@ _dl_start_final (void *arg, struct dl_start_final_info *info)
 #ifndef DONT_USE_BOOTSTRAP_MAP
   GL(dl_rtld_map).l_addr = info->l.l_addr;
   GL(dl_rtld_map).l_ld = info->l.l_ld;
-  GL(dl_rtld_map).l_ld_readonly = info->l.l_ld_readonly;
   memcpy (GL(dl_rtld_map).l_info, info->l.l_info,
 	  sizeof GL(dl_rtld_map).l_info);
   GL(dl_rtld_map).l_mach = info->l.l_mach;
@@ -548,7 +547,7 @@ _dl_start (void *arg)
 
   /* Read our own dynamic section and fill in the info array.  */
   bootstrap_map.l_ld = (void *) bootstrap_map.l_addr + elf_machine_dynamic ();
-  elf_get_dynamic_info (&bootstrap_map, true);
+  elf_get_dynamic_info (&bootstrap_map, NULL, true);
 
 #if NO_TLS_OFFSET != 0
   bootstrap_map.l_tls_offset = NO_TLS_OFFSET;
@@ -1470,7 +1469,6 @@ dl_main (const ElfW(Phdr) *phdr,
 	/* This tells us where to find the dynamic section,
 	   which tells us everything we need to do.  */
 	main_map->l_ld = (void *) main_map->l_addr + ph->p_vaddr;
-	main_map->l_ld_readonly = (ph->p_flags & PF_W) == 0;
 	break;
       case PT_INTERP:
 	/* This "interpreter segment" was used by the program loader to
@@ -1616,7 +1614,7 @@ dl_main (const ElfW(Phdr) *phdr,
   if (! rtld_is_main)
     {
       /* Extract the contents of the dynamic section for easy access.  */
-      elf_get_dynamic_info (main_map, false);
+      elf_get_dynamic_info (main_map, NULL, false);
 
       /* If the main map is libc.so, update the base namespace to
 	 refer to this map.  If libc.so is loaded later, this happens
diff --git a/elf/setup-vdso.h b/elf/setup-vdso.h
index 6fdffafcca..97de0f56a0 100644
--- a/elf/setup-vdso.h
+++ b/elf/setup-vdso.h
@@ -33,6 +33,8 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
 				       0, LM_ID_BASE);
   if (__glibc_likely (l != NULL))
     {
+      static ElfW(Dyn) dyn_temp[DL_RO_DYN_TEMP_CNT] attribute_relro;
+
       l->l_phdr = ((const void *) GLRO(dl_sysinfo_dso)
 		   + GLRO(dl_sysinfo_dso)->e_phoff);
       l->l_phnum = GLRO(dl_sysinfo_dso)->e_phnum;
@@ -43,7 +45,6 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
 	    {
 	      l->l_ld = (void *) ph->p_vaddr;
 	      l->l_ldnum = ph->p_memsz / sizeof (ElfW(Dyn));
-	      l->l_ld_readonly = (ph->p_flags & PF_W) == 0;
 	    }
 	  else if (ph->p_type == PT_LOAD)
 	    {
@@ -64,7 +65,7 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
       l->l_map_end += l->l_addr;
       l->l_text_end += l->l_addr;
       l->l_ld = (void *) ((ElfW(Addr)) l->l_ld + l->l_addr);
-      elf_get_dynamic_info (l, false);
+      elf_get_dynamic_info (l, dyn_temp, false);
       _dl_setup_hash (l);
       l->l_relocated = 1;
 
diff --git a/elf/tst-ro-dynamic-mod.c b/elf/tst-ro-dynamic-mod.c
deleted file mode 100644
index 6d99925964..0000000000
--- a/elf/tst-ro-dynamic-mod.c
+++ /dev/null
@@ -1,19 +0,0 @@
-/* Test case for DSO with readonly dynamic section.
-   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/>.  */
-
-int foo = -1;
diff --git a/elf/tst-ro-dynamic-mod.map b/elf/tst-ro-dynamic-mod.map
deleted file mode 100644
index 2fe4a2998c..0000000000
--- a/elf/tst-ro-dynamic-mod.map
+++ /dev/null
@@ -1,16 +0,0 @@
-SECTIONS
-{
- . = SIZEOF_HEADERS;
- .dynamic : { *(.dynamic) } :text :dynamic
- .rodata : { *(.data*) *(.bss*) } :text
- /DISCARD/ : {
-  *(.note.gnu.property)
- }
- .note : { *(.note.*) } :text :note
-}
-PHDRS
-{
- text PT_LOAD FLAGS(5) FILEHDR PHDRS;
- dynamic PT_DYNAMIC FLAGS(4);
- note PT_NOTE FLAGS(4);
-}
diff --git a/elf/tst-ro-dynamic.c b/elf/tst-ro-dynamic.c
deleted file mode 100644
index 3a18f8789a..0000000000
--- a/elf/tst-ro-dynamic.c
+++ /dev/null
@@ -1,31 +0,0 @@
-/* Test case for DSO with readonly dynamic section.
-   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 <support/check.h>
-#include <support/test-driver.h>
-
-extern int foo;
-
-static int
-do_test (void)
-{
-  TEST_COMPARE (foo, -1);
-  return 0;
-}
-
-#include <support/test-driver.c>
diff --git a/include/link.h b/include/link.h
index 484ee6cb1b..7b8250db36 100644
--- a/include/link.h
+++ b/include/link.h
@@ -205,7 +205,6 @@ struct link_map
     unsigned int l_free_initfini:1; /* Nonzero if l_initfini can be
 				       freed, ie. not allocated with
 				       the dummy malloc in ld.so.  */
-    unsigned int l_ld_readonly:1; /* Nonzero if dynamic section is readonly.  */
 
     /* NODELETE status of the map.  Only valid for maps of type
        lt_loaded.  Lazy binding sets l_nodelete_active directly,
@@ -343,8 +342,6 @@ struct link_map
     unsigned long long int l_serial;
   };
 
-#include <dl-relocate-ld.h>
-
 /* Information used by audit modules.  For most link maps, this data
    immediate follows the link map in memory.  For the dynamic linker,
    it is allocated separately.  See link_map_audit_state in
diff --git a/sysdeps/generic/dl-relocate-ld.h b/sysdeps/generic/dl-relocate-ld.h
deleted file mode 100644
index 5fae206db9..0000000000
--- a/sysdeps/generic/dl-relocate-ld.h
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Check if dynamic section should be relocated.  Generic version.
-   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_RELOCATE_LD_H
-#define _DL_RELOCATE_LD_H
-
-/* Return true if dynamic section in the shared library L should be
-   relocated.  */
-
-static inline bool
-dl_relocate_ld (const struct link_map *l)
-{
-  /* Don't relocate dynamic section if it is readonly  */
-  return !l->l_ld_readonly;
-}
-
-#endif /* _DL_RELOCATE_LD_H */
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 9ec1511bb0..637dfcc1e5 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -75,8 +75,11 @@ __BEGIN_DECLS
   have to be accessed via the D_PTR macro.  The macro is needed since for
   most architectures the entry is already relocated - but for some not
   and we need to relocate at access time.  */
-#define D_PTR(map, i) \
-  ((map)->i->d_un.d_ptr + (dl_relocate_ld (map) ? 0 : (map)->l_addr))
+#ifdef DL_RO_DYN_SECTION
+# define D_PTR(map, i) ((map)->i->d_un.d_ptr + (map)->l_addr)
+#else
+# define D_PTR(map, i) (map)->i->d_un.d_ptr
+#endif
 
 /* Result of the lookup functions and how to retrieve the base address.  */
 typedef struct link_map *lookup_t;
diff --git a/sysdeps/mips/dl-relocate-ld.h b/sysdeps/mips/dl-relocate-ld.h
deleted file mode 100644
index 0c18d9a567..0000000000
--- a/sysdeps/mips/dl-relocate-ld.h
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Check if dynamic section should be relocated.  MIPS version.
-   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_RELOCATE_LD_H
-#define _DL_RELOCATE_LD_H
-
-/* Return true if dynamic section in the shared library L should be
-   relocated.  */
-
-static inline bool
-dl_relocate_ld (const struct link_map *l)
-{
-  /* Never relocate dynamic section.  */
-  return false;
-}
-
-#endif /* _DL_RELOCATE_LD_H */
diff --git a/sysdeps/mips/ldsodefs.h b/sysdeps/mips/ldsodefs.h
index 36fd09a8bd..4db7c60e38 100644
--- a/sysdeps/mips/ldsodefs.h
+++ b/sysdeps/mips/ldsodefs.h
@@ -75,6 +75,10 @@ struct La_mips_64_retval;
 					  struct La_mips_64_retval *,	    \
 					  const char *);
 
+/* The MIPS ABI specifies that the dynamic section has to be read-only.  */
+
+#define DL_RO_DYN_SECTION 1
+
 #include_next <ldsodefs.h>
 
 /* The 64-bit MIPS ELF ABI uses an unusual reloc format.  Each
diff --git a/sysdeps/riscv/dl-relocate-ld.h b/sysdeps/riscv/dl-relocate-ld.h
deleted file mode 100644
index 10327454b1..0000000000
--- a/sysdeps/riscv/dl-relocate-ld.h
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Check if dynamic section should be relocated.  RISC-V version.
-   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_RELOCATE_LD_H
-#define _DL_RELOCATE_LD_H
-
-/* Return true if dynamic section in the shared library L should be
-   relocated.  */
-
-static inline bool
-dl_relocate_ld (const struct link_map *l)
-{
-  /* Never relocate dynamic section for ABI compatibility.  */
-  return false;
-}
-
-#endif /* _DL_RELOCATE_LD_H */
diff --git a/sysdeps/riscv/ldsodefs.h b/sysdeps/riscv/ldsodefs.h
index 8947ffe4b5..0c696714a7 100644
--- a/sysdeps/riscv/ldsodefs.h
+++ b/sysdeps/riscv/ldsodefs.h
@@ -38,6 +38,11 @@ struct La_riscv_retval;
 				       struct La_riscv_retval *,	\
 				       const char *);
 
+/* Although the RISC-V ABI does not specify that the dynamic section has
+   to be read-only, it needs to be kept for ABI compatibility.  */
+
+#define DL_RO_DYN_SECTION 1
+
 #include_next <ldsodefs.h>
 
 #endif
-- 
2.31.1