[v4] ld.so: Replace DL_RO_DYN_SECTION with dl_relocate_ld
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Commit Message
Changes in v4:
1. Change l_ld_readonly to bitfield.
Changes in v3:
1. Remove DL_RO_DYN_TEMP_CNT.
2. Update comments for dl_relocate_ld.
Changes in v2:
1. Replace DL_RO_DYN_SECTION with dl_relocate_ld so that MIPS and RISC-V
won't relocate dynamic section even if it is writable.
2. Add a run-time testcase.
We can't relocate entries in dynamic section if it is readonly:
1. Add a l_ld_readonly field to struct link_map to indicate if dynamic
section is readonly and set it based on p_flags of PT_DYNAMIC segment.
2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic
section should be relocated.
3. Remove DL_RO_DYN_TEMP_CNT.
4. Don't use a static dynamic section to make readonly dynamic section
in vDSO writable.
5. Remove the temp argument from elf_get_dynamic_info.
---
elf/Makefile | 11 +++++++++--
elf/dl-load.c | 3 ++-
elf/dl-reloc-static-pie.c | 12 +++++++++++-
elf/get-dynamic-info.h | 21 +++------------------
elf/rtld.c | 6 ++++--
elf/setup-vdso.h | 5 ++---
elf/tst-ro-dynamic-mod.c | 19 +++++++++++++++++++
elf/tst-ro-dynamic-mod.map | 16 ++++++++++++++++
elf/tst-ro-dynamic.c | 31 +++++++++++++++++++++++++++++++
include/link.h | 3 +++
sysdeps/generic/dl-relocate-ld.h | 32 ++++++++++++++++++++++++++++++++
sysdeps/generic/ldsodefs.h | 7 ++-----
sysdeps/mips/dl-relocate-ld.h | 32 ++++++++++++++++++++++++++++++++
sysdeps/mips/ldsodefs.h | 4 ----
sysdeps/riscv/dl-relocate-ld.h | 32 ++++++++++++++++++++++++++++++++
sysdeps/riscv/ldsodefs.h | 5 -----
16 files changed, 198 insertions(+), 41 deletions(-)
create mode 100644 elf/tst-ro-dynamic-mod.c
create mode 100644 elf/tst-ro-dynamic-mod.map
create mode 100644 elf/tst-ro-dynamic.c
create mode 100644 sysdeps/generic/dl-relocate-ld.h
create mode 100644 sysdeps/mips/dl-relocate-ld.h
create mode 100644 sysdeps/riscv/dl-relocate-ld.h
Comments
On 9/19/21 21:58, H.J. Lu wrote:
> Changes in v4:
>
> 1. Change l_ld_readonly to bitfield.
>
> Changes in v3:
>
> 1. Remove DL_RO_DYN_TEMP_CNT.
> 2. Update comments for dl_relocate_ld.
>
> Changes in v2:
>
> 1. Replace DL_RO_DYN_SECTION with dl_relocate_ld so that MIPS and RISC-V
> won't relocate dynamic section even if it is writable.
> 2. Add a run-time testcase.
>
> We can't relocate entries in dynamic section if it is readonly:
>
> 1. Add a l_ld_readonly field to struct link_map to indicate if dynamic
> section is readonly and set it based on p_flags of PT_DYNAMIC segment.
> 2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic
> section should be relocated.
> 3. Remove DL_RO_DYN_TEMP_CNT.
> 4. Don't use a static dynamic section to make readonly dynamic section
> in vDSO writable.
> 5. Remove the temp argument from elf_get_dynamic_info.
LGTM, thanks for doing this. AFAICT you've addressed their concerns but
please check with Florian and Carlos before committing.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
> ---
> elf/Makefile | 11 +++++++++--
> elf/dl-load.c | 3 ++-
> elf/dl-reloc-static-pie.c | 12 +++++++++++-
> elf/get-dynamic-info.h | 21 +++------------------
> elf/rtld.c | 6 ++++--
> elf/setup-vdso.h | 5 ++---
> elf/tst-ro-dynamic-mod.c | 19 +++++++++++++++++++
> elf/tst-ro-dynamic-mod.map | 16 ++++++++++++++++
> elf/tst-ro-dynamic.c | 31 +++++++++++++++++++++++++++++++
> include/link.h | 3 +++
> sysdeps/generic/dl-relocate-ld.h | 32 ++++++++++++++++++++++++++++++++
> sysdeps/generic/ldsodefs.h | 7 ++-----
> sysdeps/mips/dl-relocate-ld.h | 32 ++++++++++++++++++++++++++++++++
> sysdeps/mips/ldsodefs.h | 4 ----
> sysdeps/riscv/dl-relocate-ld.h | 32 ++++++++++++++++++++++++++++++++
> sysdeps/riscv/ldsodefs.h | 5 -----
> 16 files changed, 198 insertions(+), 41 deletions(-)
> create mode 100644 elf/tst-ro-dynamic-mod.c
> create mode 100644 elf/tst-ro-dynamic-mod.map
> create mode 100644 elf/tst-ro-dynamic.c
> create mode 100644 sysdeps/generic/dl-relocate-ld.h
> create mode 100644 sysdeps/mips/dl-relocate-ld.h
> create mode 100644 sysdeps/riscv/dl-relocate-ld.h
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 9f3fadc37e..eeb47145fc 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -223,7 +223,7 @@ 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-dl-is_dso tst-ro-dynamic
> # reldep9
> tests-internal += loadtest unload unload2 circleload1 \
> neededtest neededtest2 neededtest3 neededtest4 \
> @@ -359,7 +359,7 @@ 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-dlmopen-gethostbyname-mod tst-ro-dynamic-mod \
>
> # Most modules build with _ISOMAC defined, but those filtered out
> # depend on internal headers.
> @@ -1908,3 +1908,10 @@ $(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
Adding new test and options. OK.
> diff --git a/elf/dl-load.c b/elf/dl-load.c
> index 650e4edc35..4445c28ef3 100644
> --- a/elf/dl-load.c
> +++ b/elf/dl-load.c
> @@ -1149,6 +1149,7 @@ _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;
Mark read-only for DSOs. OK.
> }
> break;
>
> @@ -1292,7 +1293,7 @@ _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, NULL);
> + elf_get_dynamic_info (l);
>
> /* 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 d5bd2f31e9..2fb02d7276 100644
> --- a/elf/dl-reloc-static-pie.c
> +++ b/elf/dl-reloc-static-pie.c
> @@ -40,7 +40,17 @@ _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 ());
> - elf_get_dynamic_info (main_map, NULL);
> +
> + 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);
Mark read-only for static-pie. OK.
>
> # ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
> ELF_MACHINE_BEFORE_RTLD_RELOC (main_map->l_info);
> diff --git a/elf/get-dynamic-info.h b/elf/get-dynamic-info.h
> index d8ec32377d..4aa2058abf 100644
> --- a/elf/get-dynamic-info.h
> +++ b/elf/get-dynamic-info.h
> @@ -28,7 +28,7 @@ static
> auto
> #endif
> inline void __attribute__ ((unused, always_inline))
> -elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
> +elf_get_dynamic_info (struct link_map *l)
> {
> #if __ELF_NATIVE_CLASS == 32
> typedef Elf32_Word d_tag_utype;
> @@ -69,28 +69,15 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
> 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)
> + if (l->l_addr != 0 && dl_relocate_ld (l))
> {
> ElfW(Addr) l_addr = l->l_addr;
> - int cnt = 0;
>
> # define ADJUST_DYN_INFO(tag) \
> do \
> if (info[tag] != NULL) \
> - { \
> - 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; \
> - } \
> + info[tag]->d_un.d_ptr += l_addr; \
Simplify by using the readonly flag. OK.
> while (0)
>
> ADJUST_DYN_INFO (DT_HASH);
> @@ -107,9 +94,7 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
> 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 878e6480f4..88a78326c8 100644
> --- a/elf/rtld.c
> +++ b/elf/rtld.c
> @@ -463,6 +463,7 @@ _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;
> @@ -546,7 +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, NULL);
> + elf_get_dynamic_info (&bootstrap_map);
>
> #if NO_TLS_OFFSET != 0
> bootstrap_map.l_tls_offset = NO_TLS_OFFSET;
> @@ -1468,6 +1469,7 @@ 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
> @@ -1613,7 +1615,7 @@ 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, NULL);
> + elf_get_dynamic_info (main_map);
Mark read-only for main executable. OK.
>
> /* 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 86c491e49c..f44748bc98 100644
> --- a/elf/setup-vdso.h
> +++ b/elf/setup-vdso.h
> @@ -33,8 +33,6 @@ 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;
> @@ -45,6 +43,7 @@ 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;
Mark read-only for vdso. OK.
> }
> else if (ph->p_type == PT_LOAD)
> {
> @@ -65,7 +64,7 @@ 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, dyn_temp);
> + elf_get_dynamic_info (l);
> _dl_setup_hash (l);
> l->l_relocated = 1;
>
> diff --git a/elf/tst-ro-dynamic-mod.c b/elf/tst-ro-dynamic-mod.c
> new file mode 100644
> index 0000000000..6d99925964
> --- /dev/null
> +++ b/elf/tst-ro-dynamic-mod.c
> @@ -0,0 +1,19 @@
> +/* 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
> new file mode 100644
> index 0000000000..2fe4a2998c
> --- /dev/null
> +++ b/elf/tst-ro-dynamic-mod.map
> @@ -0,0 +1,16 @@
> +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
> new file mode 100644
> index 0000000000..3a18f8789a
> --- /dev/null
> +++ b/elf/tst-ro-dynamic.c
> @@ -0,0 +1,31 @@
> +/* 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>
New test. OK.
> diff --git a/include/link.h b/include/link.h
> index 4af16cb596..c46aced9f7 100644
> --- a/include/link.h
> +++ b/include/link.h
> @@ -205,6 +205,7 @@ 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. */
Flag bit. OK.
>
> /* NODELETE status of the map. Only valid for maps of type
> lt_loaded. Lazy binding sets l_nodelete_active directly,
> @@ -342,6 +343,8 @@ 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
> new file mode 100644
> index 0000000000..5fae206db9
> --- /dev/null
> +++ b/sysdeps/generic/dl-relocate-ld.h
> @@ -0,0 +1,32 @@
> +/* 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;
> +}
Depend on read-only flag for all architectures except those that
override this definition. OK.
> +
> +#endif /* _DL_RELOCATE_LD_H */
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index fd67871f4b..eafa308047 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -75,11 +75,8 @@ __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. */
> -#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
> +#define D_PTR(map, i) \
> + ((map)->i->d_un.d_ptr + (dl_relocate_ld (map) ? 0 : (map)->l_addr))
Simplify D_PTR to add l_addr for read-only maps.
>
> /* 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
> new file mode 100644
> index 0000000000..0c18d9a567
> --- /dev/null
> +++ b/sysdeps/mips/dl-relocate-ld.h
> @@ -0,0 +1,32 @@
> +/* 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;
> +}
mips does not like relocating the dynamic section at all. OK.
> +
> +#endif /* _DL_RELOCATE_LD_H */
> diff --git a/sysdeps/mips/ldsodefs.h b/sysdeps/mips/ldsodefs.h
> index 4db7c60e38..36fd09a8bd 100644
> --- a/sysdeps/mips/ldsodefs.h
> +++ b/sysdeps/mips/ldsodefs.h
> @@ -75,10 +75,6 @@ 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
> new file mode 100644
> index 0000000000..10327454b1
> --- /dev/null
> +++ b/sysdeps/riscv/dl-relocate-ld.h
> @@ -0,0 +1,32 @@
> +/* 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;
> +}
Neither does risc-v. OK.
> +
> +#endif /* _DL_RELOCATE_LD_H */
> diff --git a/sysdeps/riscv/ldsodefs.h b/sysdeps/riscv/ldsodefs.h
> index 0c696714a7..8947ffe4b5 100644
> --- a/sysdeps/riscv/ldsodefs.h
> +++ b/sysdeps/riscv/ldsodefs.h
> @@ -38,11 +38,6 @@ 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
>
* H. J. Lu:
> We can't relocate entries in dynamic section if it is readonly:
>
> 1. Add a l_ld_readonly field to struct link_map to indicate if dynamic
> section is readonly and set it based on p_flags of PT_DYNAMIC segment.
> 2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic
> section should be relocated.
> 3. Remove DL_RO_DYN_TEMP_CNT.
> 4. Don't use a static dynamic section to make readonly dynamic section
> in vDSO writable.
> 5. Remove the temp argument from elf_get_dynamic_info.
I don't have any objections to this patch.
Thanks,
Florian
This breaks aarch64.
gcc -nostdlib -nostartfiles -shared -o /home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/elf/ld.so.new \
-Wl,-z,combreloc -Wl,-z,relro -Wl,--hash-style=both -Wl,-z,force-bti,--fatal-warnings -Wl,-z,defs -Wl,-z,now \
/home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/elf/librtld.os -Wl,--version-script=/home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/ld.map \
-Wl,-soname=ld-linux-aarch64.so.1 \
-Wl,-defsym=_begin=0
/usr/lib64/gcc/aarch64-suse-linux/11/../../../../aarch64-suse-linux/bin/ld: /home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/elf/librtld.os: warning: BTI turned on by -z force-bti when all inputs do not have BTI in NOTE section.
collect2: error: ld returned 1 exit status
make[2]: *** [Makefile:607: /home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/elf/ld.so] Error 1
Andreas.
* Andreas Schwab:
> This breaks aarch64.
>
> gcc -nostdlib -nostartfiles -shared -o /home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/elf/ld.so.new \
> -Wl,-z,combreloc -Wl,-z,relro -Wl,--hash-style=both -Wl,-z,force-bti,--fatal-warnings -Wl,-z,defs -Wl,-z,now \
> /home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/elf/librtld.os -Wl,--version-script=/home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/ld.map \
> -Wl,-soname=ld-linux-aarch64.so.1 \
> -Wl,-defsym=_begin=0
> /usr/lib64/gcc/aarch64-suse-linux/11/../../../../aarch64-suse-linux/bin/ld: /home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/elf/librtld.os: warning: BTI turned on by -z force-bti when all inputs do not have BTI in NOTE section.
> collect2: error: ld returned 1 exit status
> make[2]: *** [Makefile:607: /home/abuild/rpmbuild/BUILD/glibc-2.34.9000.109.ga93d9e03a3/cc-base/elf/ld.so] Error 1
This is rather odd because the patch does not change the set of linker
input files or its attributes.
Or is this about commit a93d9e03a31ec14405cb3a09aa95413b67067380
("Extend struct r_debug to support multiple namespaces [BZ #15971]")?
Thanks,
Florian
On Sep 20 2021, Florian Weimer wrote:
> Or is this about commit a93d9e03a31ec14405cb3a09aa95413b67067380
> ("Extend struct r_debug to support multiple namespaces [BZ #15971]")?
Yes, that's the commit I meant indeed.
Andreas.
* Andreas Schwab:
> On Sep 20 2021, Florian Weimer wrote:
>
>> Or is this about commit a93d9e03a31ec14405cb3a09aa95413b67067380
>> ("Extend struct r_debug to support multiple namespaces [BZ #15971]")?
>
> Yes, that's the commit I meant indeed.
Okay, I'm testing a patch.
Thanks,
Florian
On Sun, Sep 19, 2021 at 8:28 PM Siddhesh Poyarekar
<siddhesh@sourceware.org> wrote:
>
> On 9/19/21 21:58, H.J. Lu wrote:
> > Changes in v4:
> >
> > 1. Change l_ld_readonly to bitfield.
> >
> > Changes in v3:
> >
> > 1. Remove DL_RO_DYN_TEMP_CNT.
> > 2. Update comments for dl_relocate_ld.
> >
> > Changes in v2:
> >
> > 1. Replace DL_RO_DYN_SECTION with dl_relocate_ld so that MIPS and RISC-V
> > won't relocate dynamic section even if it is writable.
> > 2. Add a run-time testcase.
> >
> > We can't relocate entries in dynamic section if it is readonly:
> >
> > 1. Add a l_ld_readonly field to struct link_map to indicate if dynamic
> > section is readonly and set it based on p_flags of PT_DYNAMIC segment.
> > 2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic
> > section should be relocated.
> > 3. Remove DL_RO_DYN_TEMP_CNT.
> > 4. Don't use a static dynamic section to make readonly dynamic section
> > in vDSO writable.
> > 5. Remove the temp argument from elf_get_dynamic_info.
>
> LGTM, thanks for doing this. AFAICT you've addressed their concerns but
> please check with Florian and Carlos before committing.
Carlos, do you have any comments?
>
> Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
>
> > ---
> > elf/Makefile | 11 +++++++++--
> > elf/dl-load.c | 3 ++-
> > elf/dl-reloc-static-pie.c | 12 +++++++++++-
> > elf/get-dynamic-info.h | 21 +++------------------
> > elf/rtld.c | 6 ++++--
> > elf/setup-vdso.h | 5 ++---
> > elf/tst-ro-dynamic-mod.c | 19 +++++++++++++++++++
> > elf/tst-ro-dynamic-mod.map | 16 ++++++++++++++++
> > elf/tst-ro-dynamic.c | 31 +++++++++++++++++++++++++++++++
> > include/link.h | 3 +++
> > sysdeps/generic/dl-relocate-ld.h | 32 ++++++++++++++++++++++++++++++++
> > sysdeps/generic/ldsodefs.h | 7 ++-----
> > sysdeps/mips/dl-relocate-ld.h | 32 ++++++++++++++++++++++++++++++++
> > sysdeps/mips/ldsodefs.h | 4 ----
> > sysdeps/riscv/dl-relocate-ld.h | 32 ++++++++++++++++++++++++++++++++
> > sysdeps/riscv/ldsodefs.h | 5 -----
> > 16 files changed, 198 insertions(+), 41 deletions(-)
> > create mode 100644 elf/tst-ro-dynamic-mod.c
> > create mode 100644 elf/tst-ro-dynamic-mod.map
> > create mode 100644 elf/tst-ro-dynamic.c
> > create mode 100644 sysdeps/generic/dl-relocate-ld.h
> > create mode 100644 sysdeps/mips/dl-relocate-ld.h
> > create mode 100644 sysdeps/riscv/dl-relocate-ld.h
> >
> > diff --git a/elf/Makefile b/elf/Makefile
> > index 9f3fadc37e..eeb47145fc 100644
> > --- a/elf/Makefile
> > +++ b/elf/Makefile
> > @@ -223,7 +223,7 @@ 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-dl-is_dso tst-ro-dynamic
> > # reldep9
> > tests-internal += loadtest unload unload2 circleload1 \
> > neededtest neededtest2 neededtest3 neededtest4 \
> > @@ -359,7 +359,7 @@ 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-dlmopen-gethostbyname-mod tst-ro-dynamic-mod \
> >
> > # Most modules build with _ISOMAC defined, but those filtered out
> > # depend on internal headers.
> > @@ -1908,3 +1908,10 @@ $(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
>
> Adding new test and options. OK.
>
> > diff --git a/elf/dl-load.c b/elf/dl-load.c
> > index 650e4edc35..4445c28ef3 100644
> > --- a/elf/dl-load.c
> > +++ b/elf/dl-load.c
> > @@ -1149,6 +1149,7 @@ _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;
>
> Mark read-only for DSOs. OK.
>
> > }
> > break;
> >
> > @@ -1292,7 +1293,7 @@ _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, NULL);
> > + elf_get_dynamic_info (l);
> >
> > /* 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 d5bd2f31e9..2fb02d7276 100644
> > --- a/elf/dl-reloc-static-pie.c
> > +++ b/elf/dl-reloc-static-pie.c
> > @@ -40,7 +40,17 @@ _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 ());
> > - elf_get_dynamic_info (main_map, NULL);
> > +
> > + 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);
>
> Mark read-only for static-pie. OK.
>
> >
> > # ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
> > ELF_MACHINE_BEFORE_RTLD_RELOC (main_map->l_info);
> > diff --git a/elf/get-dynamic-info.h b/elf/get-dynamic-info.h
> > index d8ec32377d..4aa2058abf 100644
> > --- a/elf/get-dynamic-info.h
> > +++ b/elf/get-dynamic-info.h
> > @@ -28,7 +28,7 @@ static
> > auto
> > #endif
> > inline void __attribute__ ((unused, always_inline))
> > -elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
> > +elf_get_dynamic_info (struct link_map *l)
> > {
> > #if __ELF_NATIVE_CLASS == 32
> > typedef Elf32_Word d_tag_utype;
> > @@ -69,28 +69,15 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
> > 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)
> > + if (l->l_addr != 0 && dl_relocate_ld (l))
> > {
> > ElfW(Addr) l_addr = l->l_addr;
> > - int cnt = 0;
> >
> > # define ADJUST_DYN_INFO(tag) \
> > do \
> > if (info[tag] != NULL) \
> > - { \
> > - 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; \
> > - } \
> > + info[tag]->d_un.d_ptr += l_addr; \
>
> Simplify by using the readonly flag. OK.
>
> > while (0)
> >
> > ADJUST_DYN_INFO (DT_HASH);
> > @@ -107,9 +94,7 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
> > 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 878e6480f4..88a78326c8 100644
> > --- a/elf/rtld.c
> > +++ b/elf/rtld.c
> > @@ -463,6 +463,7 @@ _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;
> > @@ -546,7 +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, NULL);
> > + elf_get_dynamic_info (&bootstrap_map);
> >
> > #if NO_TLS_OFFSET != 0
> > bootstrap_map.l_tls_offset = NO_TLS_OFFSET;
> > @@ -1468,6 +1469,7 @@ 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
> > @@ -1613,7 +1615,7 @@ 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, NULL);
> > + elf_get_dynamic_info (main_map);
>
> Mark read-only for main executable. OK.
>
> >
> > /* 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 86c491e49c..f44748bc98 100644
> > --- a/elf/setup-vdso.h
> > +++ b/elf/setup-vdso.h
> > @@ -33,8 +33,6 @@ 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;
> > @@ -45,6 +43,7 @@ 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;
>
> Mark read-only for vdso. OK.
>
> > }
> > else if (ph->p_type == PT_LOAD)
> > {
> > @@ -65,7 +64,7 @@ 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, dyn_temp);
> > + elf_get_dynamic_info (l);
> > _dl_setup_hash (l);
> > l->l_relocated = 1;
> >
> > diff --git a/elf/tst-ro-dynamic-mod.c b/elf/tst-ro-dynamic-mod.c
> > new file mode 100644
> > index 0000000000..6d99925964
> > --- /dev/null
> > +++ b/elf/tst-ro-dynamic-mod.c
> > @@ -0,0 +1,19 @@
> > +/* 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
> > new file mode 100644
> > index 0000000000..2fe4a2998c
> > --- /dev/null
> > +++ b/elf/tst-ro-dynamic-mod.map
> > @@ -0,0 +1,16 @@
> > +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
> > new file mode 100644
> > index 0000000000..3a18f8789a
> > --- /dev/null
> > +++ b/elf/tst-ro-dynamic.c
> > @@ -0,0 +1,31 @@
> > +/* 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>
>
> New test. OK.
>
> > diff --git a/include/link.h b/include/link.h
> > index 4af16cb596..c46aced9f7 100644
> > --- a/include/link.h
> > +++ b/include/link.h
> > @@ -205,6 +205,7 @@ 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. */
>
> Flag bit. OK.
>
> >
> > /* NODELETE status of the map. Only valid for maps of type
> > lt_loaded. Lazy binding sets l_nodelete_active directly,
> > @@ -342,6 +343,8 @@ 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
> > new file mode 100644
> > index 0000000000..5fae206db9
> > --- /dev/null
> > +++ b/sysdeps/generic/dl-relocate-ld.h
> > @@ -0,0 +1,32 @@
> > +/* 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;
> > +}
>
> Depend on read-only flag for all architectures except those that
> override this definition. OK.
>
> > +
> > +#endif /* _DL_RELOCATE_LD_H */
> > diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> > index fd67871f4b..eafa308047 100644
> > --- a/sysdeps/generic/ldsodefs.h
> > +++ b/sysdeps/generic/ldsodefs.h
> > @@ -75,11 +75,8 @@ __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. */
> > -#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
> > +#define D_PTR(map, i) \
> > + ((map)->i->d_un.d_ptr + (dl_relocate_ld (map) ? 0 : (map)->l_addr))
>
> Simplify D_PTR to add l_addr for read-only maps.
>
> >
> > /* 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
> > new file mode 100644
> > index 0000000000..0c18d9a567
> > --- /dev/null
> > +++ b/sysdeps/mips/dl-relocate-ld.h
> > @@ -0,0 +1,32 @@
> > +/* 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;
> > +}
>
> mips does not like relocating the dynamic section at all. OK.
>
> > +
> > +#endif /* _DL_RELOCATE_LD_H */
> > diff --git a/sysdeps/mips/ldsodefs.h b/sysdeps/mips/ldsodefs.h
> > index 4db7c60e38..36fd09a8bd 100644
> > --- a/sysdeps/mips/ldsodefs.h
> > +++ b/sysdeps/mips/ldsodefs.h
> > @@ -75,10 +75,6 @@ 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
> > new file mode 100644
> > index 0000000000..10327454b1
> > --- /dev/null
> > +++ b/sysdeps/riscv/dl-relocate-ld.h
> > @@ -0,0 +1,32 @@
> > +/* 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;
> > +}
>
> Neither does risc-v. OK.
>
> > +
> > +#endif /* _DL_RELOCATE_LD_H */
> > diff --git a/sysdeps/riscv/ldsodefs.h b/sysdeps/riscv/ldsodefs.h
> > index 0c696714a7..8947ffe4b5 100644
> > --- a/sysdeps/riscv/ldsodefs.h
> > +++ b/sysdeps/riscv/ldsodefs.h
> > @@ -38,11 +38,6 @@ 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
> >
On Mon, Sep 20, 2021 at 1:54 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> > We can't relocate entries in dynamic section if it is readonly:
> >
> > 1. Add a l_ld_readonly field to struct link_map to indicate if dynamic
> > section is readonly and set it based on p_flags of PT_DYNAMIC segment.
> > 2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic
> > section should be relocated.
> > 3. Remove DL_RO_DYN_TEMP_CNT.
> > 4. Don't use a static dynamic section to make readonly dynamic section
> > in vDSO writable.
> > 5. Remove the temp argument from elf_get_dynamic_info.
>
> I don't have any objections to this patch.
>
> Thanks,
> Florian
>
I am checking in this patch now.
* H. J. Lu:
> We can't relocate entries in dynamic section if it is readonly:
>
> 1. Add a l_ld_readonly field to struct link_map to indicate if dynamic
> section is readonly and set it based on p_flags of PT_DYNAMIC segment.
> 2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic
> section should be relocated.
> 3. Remove DL_RO_DYN_TEMP_CNT.
> 4. Don't use a static dynamic section to make readonly dynamic section
> in vDSO writable.
> 5. Remove the temp argument from elf_get_dynamic_info.
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).
I don't see how to fix this without bringing back DL_RO_DYN_SECTION.
Thanks,
Florian
On Thu, Sep 23, 2021 at 3:22 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> > We can't relocate entries in dynamic section if it is readonly:
> >
> > 1. Add a l_ld_readonly field to struct link_map to indicate if dynamic
> > section is readonly and set it based on p_flags of PT_DYNAMIC segment.
> > 2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic
> > section should be relocated.
> > 3. Remove DL_RO_DYN_TEMP_CNT.
> > 4. Don't use a static dynamic section to make readonly dynamic section
> > in vDSO writable.
> > 5. Remove the temp argument from elf_get_dynamic_info.
>
> 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).
>
> I don't see how to fix this without bringing back DL_RO_DYN_SECTION.
We can define DL_RO_DYN_SECTION and do
diff --git a/elf/rtld.c b/elf/rtld.c
index 8d2bba3d43..83adf1c5f5 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);
#if NO_TLS_OFFSET != 0
Will this work?
* H. J. Lu:
> We can define DL_RO_DYN_SECTION and do
>
> diff --git a/elf/rtld.c b/elf/rtld.c
> index 8d2bba3d43..83adf1c5f5 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);
>
> #if NO_TLS_OFFSET != 0
>
> Will this work?
I think it should. We can use DL_RO_DYN_SECTION to define a single,
generic version of dl_relocate_ld, too.
Thanks,
Florian
On Thu, Sep 23, 2021 at 9:02 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> > We can define DL_RO_DYN_SECTION and do
> >
> > diff --git a/elf/rtld.c b/elf/rtld.c
> > index 8d2bba3d43..83adf1c5f5 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);
> >
> > #if NO_TLS_OFFSET != 0
> >
> > Will this work?
>
> I think it should. We can use DL_RO_DYN_SECTION to define a single,
> generic version of dl_relocate_ld, too.
Here is the patch:
https://sourceware.org/pipermail/libc-alpha/2021-September/131294.html
@@ -223,7 +223,7 @@ 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-dl-is_dso tst-ro-dynamic
# reldep9
tests-internal += loadtest unload unload2 circleload1 \
neededtest neededtest2 neededtest3 neededtest4 \
@@ -359,7 +359,7 @@ 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-dlmopen-gethostbyname-mod tst-ro-dynamic-mod \
# Most modules build with _ISOMAC defined, but those filtered out
# depend on internal headers.
@@ -1908,3 +1908,10 @@ $(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
@@ -1149,6 +1149,7 @@ _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;
@@ -1292,7 +1293,7 @@ _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, NULL);
+ elf_get_dynamic_info (l);
/* Make sure we are not dlopen'ing an object that has the
DF_1_NOOPEN flag set, or a PIE object. */
@@ -40,7 +40,17 @@ _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 ());
- elf_get_dynamic_info (main_map, NULL);
+
+ 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);
# ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
ELF_MACHINE_BEFORE_RTLD_RELOC (main_map->l_info);
@@ -28,7 +28,7 @@ static
auto
#endif
inline void __attribute__ ((unused, always_inline))
-elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
+elf_get_dynamic_info (struct link_map *l)
{
#if __ELF_NATIVE_CLASS == 32
typedef Elf32_Word d_tag_utype;
@@ -69,28 +69,15 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
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)
+ if (l->l_addr != 0 && dl_relocate_ld (l))
{
ElfW(Addr) l_addr = l->l_addr;
- int cnt = 0;
# define ADJUST_DYN_INFO(tag) \
do \
if (info[tag] != NULL) \
- { \
- 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; \
- } \
+ info[tag]->d_un.d_ptr += l_addr; \
while (0)
ADJUST_DYN_INFO (DT_HASH);
@@ -107,9 +94,7 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
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
@@ -463,6 +463,7 @@ _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;
@@ -546,7 +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, NULL);
+ elf_get_dynamic_info (&bootstrap_map);
#if NO_TLS_OFFSET != 0
bootstrap_map.l_tls_offset = NO_TLS_OFFSET;
@@ -1468,6 +1469,7 @@ 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
@@ -1613,7 +1615,7 @@ 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, NULL);
+ elf_get_dynamic_info (main_map);
/* If the main map is libc.so, update the base namespace to
refer to this map. If libc.so is loaded later, this happens
@@ -33,8 +33,6 @@ 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;
@@ -45,6 +43,7 @@ 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)
{
@@ -65,7 +64,7 @@ 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, dyn_temp);
+ elf_get_dynamic_info (l);
_dl_setup_hash (l);
l->l_relocated = 1;
new file mode 100644
@@ -0,0 +1,19 @@
+/* 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;
new file mode 100644
@@ -0,0 +1,16 @@
+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);
+}
new file mode 100644
@@ -0,0 +1,31 @@
+/* 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>
@@ -205,6 +205,7 @@ 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,
@@ -342,6 +343,8 @@ 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
new file mode 100644
@@ -0,0 +1,32 @@
+/* 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 */
@@ -75,11 +75,8 @@ __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. */
-#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
+#define D_PTR(map, i) \
+ ((map)->i->d_un.d_ptr + (dl_relocate_ld (map) ? 0 : (map)->l_addr))
/* Result of the lookup functions and how to retrieve the base address. */
typedef struct link_map *lookup_t;
new file mode 100644
@@ -0,0 +1,32 @@
+/* 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 */
@@ -75,10 +75,6 @@ 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
new file mode 100644
@@ -0,0 +1,32 @@
+/* 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 */
@@ -38,11 +38,6 @@ 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