[glibc/maskray/relr] ld.so: Initialize bootstrap_map.l_ld_readonly [BZ #28340]

[glibc/maskray/relr] ld.so: Initialize bootstrap_map.l_ld_readonly [BZ #28340]

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2ec99d8c42b2ff1a1231e4df462a0910a9b7fdef

commit 2ec99d8c42b2ff1a1231e4df462a0910a9b7fdef
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Sep 23 09:06:49 2021 -0700

    ld.so: Initialize bootstrap_map.l_ld_readonly [BZ #28340]
    
    1. Define DL_RO_DYN_SECTION to initalize bootstrap_map.l_ld_readonly
    before calling elf_get_dynamic_info to get dynamic info in bootstrap_map,
    2. Define a single
    
    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 || DL_RO_DYN_SECTION);
    }
    
    This updates BZ #28340 fix.

Diff:
---
 elf/rtld.c                       |  1 +
 sysdeps/generic/dl-relocate-ld.h | 11 ++---------
 sysdeps/generic/ldsodefs.h       | 10 ++++++++++
 sysdeps/mips/dl-relocate-ld.h    | 11 ++---------
 sysdeps/riscv/dl-relocate-ld.h   | 11 ++---------
 5 files changed, 17 insertions(+), 27 deletions(-)

diff --git a/elf/rtld.c b/elf/rtld.c
index c66a1d00bc..b8ba2d8836 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -547,6 +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 ();
+  bootstrap_map.l_ld_readonly = DL_RO_DYN_SECTION;
   elf_get_dynamic_info (&bootstrap_map, true, false);
 
 #if NO_TLS_OFFSET != 0
diff --git a/sysdeps/generic/dl-relocate-ld.h b/sysdeps/generic/dl-relocate-ld.h
index 5fae206db9..cfb86c2d6a 100644
--- a/sysdeps/generic/dl-relocate-ld.h
+++ b/sysdeps/generic/dl-relocate-ld.h
@@ -19,14 +19,7 @@
 #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;
-}
+/* The dynamic section is writable.  */
+#define DL_RO_DYN_SECTION 0
 
 #endif /* _DL_RELOCATE_LD_H */
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 9ec1511bb0..0410f777a6 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -69,6 +69,16 @@ __BEGIN_DECLS
    `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'.  */
 #define ELFW(type)	_ElfW (ELF, __ELF_NATIVE_CLASS, type)
 
+/* 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 || DL_RO_DYN_SECTION);
+}
+
 /* All references to the value of l_info[DT_PLTGOT],
   l_info[DT_STRTAB], l_info[DT_SYMTAB], l_info[DT_RELA],
   l_info[DT_REL], l_info[DT_JMPREL], and l_info[VERSYMIDX (DT_VERSYM)]
diff --git a/sysdeps/mips/dl-relocate-ld.h b/sysdeps/mips/dl-relocate-ld.h
index 0c18d9a567..376ad75dd1 100644
--- a/sysdeps/mips/dl-relocate-ld.h
+++ b/sysdeps/mips/dl-relocate-ld.h
@@ -19,14 +19,7 @@
 #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;
-}
+/* The dynamic section is readonly.  */
+#define DL_RO_DYN_SECTION 1
 
 #endif /* _DL_RELOCATE_LD_H */
diff --git a/sysdeps/riscv/dl-relocate-ld.h b/sysdeps/riscv/dl-relocate-ld.h
index 10327454b1..2ab2b8ac6c 100644
--- a/sysdeps/riscv/dl-relocate-ld.h
+++ b/sysdeps/riscv/dl-relocate-ld.h
@@ -19,14 +19,7 @@
 #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;
-}
+/* The dynamic section is readonly for ABI compatibility.  */
+#define DL_RO_DYN_SECTION 1
 
 #endif /* _DL_RELOCATE_LD_H */