[2/2] Add run-time chesk for indirect external access
Checks
| Context |
Check |
Description |
| dj/TryBot-apply_patch |
success
|
Patch applied to master at the time it was sent
|
| dj/TryBot-32bit |
success
|
Build for i686
|
Commit Message
When performing symbol lookup for references in executable without
indirect external access:
1. Disallow copy relocations in executable against protected data symbols
in a shared object with indirect external access.
2. Disallow non-zero symbol values of undefined function symbols in
executable, which are used as the function pointer, against protected
function symbols in a shared object with indirect external access.
---
elf/dl-lookup.c | 5 ++++
sysdeps/generic/dl-protected.h | 54 ++++++++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)
create mode 100644 sysdeps/generic/dl-protected.h
Comments
On Tue, Aug 3, 2021 at 2:59 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> When performing symbol lookup for references in executable without
> indirect external access:
>
> 1. Disallow copy relocations in executable against protected data symbols
> in a shared object with indirect external access.
> 2. Disallow non-zero symbol values of undefined function symbols in
> executable, which are used as the function pointer, against protected
> function symbols in a shared object with indirect external access.
PING:
https://sourceware.org/pipermail/libc-alpha/2021-August/129798.html
https://sourceware.org/pipermail/libc-alpha/2021-August/129799.html
On 03/08/2021 18:59, H.J. Lu via Libc-alpha wrote:
> When performing symbol lookup for references in executable without
> indirect external access:
>
> 1. Disallow copy relocations in executable against protected data symbols
> in a shared object with indirect external access.
> 2. Disallow non-zero symbol values of undefined function symbols in
> executable, which are used as the function pointer, against protected
> function symbols in a shared object with indirect external access.
How hard would to add some testcases for both cases? To simplify we may
want to build it iff binutins supports noindirect-extern-access.
The rest LGTM, just a nit below due an ununsed variable.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> elf/dl-lookup.c | 5 ++++
> sysdeps/generic/dl-protected.h | 54 ++++++++++++++++++++++++++++++++++
> 2 files changed, 59 insertions(+)
> create mode 100644 sysdeps/generic/dl-protected.h
>
> diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
> index eea217eb28..430359af39 100644
> --- a/elf/dl-lookup.c
> +++ b/elf/dl-lookup.c
> @@ -24,6 +24,7 @@
> #include <ldsodefs.h>
> #include <dl-hash.h>
> #include <dl-machine.h>
> +#include <dl-protected.h>
> #include <sysdep-cancel.h>
> #include <libc-lock.h>
> #include <tls.h>
> @@ -527,6 +528,10 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
> if (__glibc_unlikely (dl_symbol_visibility_binds_local_p (sym)))
> goto skip;
>
> + if (ELFW(ST_VISIBILITY) (sym->st_other) == STV_PROTECTED)
> + _dl_check_protected_symbol (undef_name, undef_map, ref, map,
> + type_class);
> +
> switch (ELFW(ST_BIND) (sym->st_info))
> {
> case STB_WEAK:
Ok.
> diff --git a/sysdeps/generic/dl-protected.h b/sysdeps/generic/dl-protected.h
> new file mode 100644
> index 0000000000..244d020dc4
> --- /dev/null
> +++ b/sysdeps/generic/dl-protected.h
> @@ -0,0 +1,54 @@
> +/* Support for STV_PROTECTED visibility. 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_PROTECTED_H
> +#define _DL_PROTECTED_H
> +
> +static inline void __attribute__ ((always_inline))
> +_dl_check_protected_symbol (const char *undef_name,
This argument seems unused.
> + const struct link_map *undef_map,
> + const ElfW(Sym) *ref,
> + const struct link_map *map,
> + int type_class)
> +{
> + if (undef_map != NULL
> + && undef_map->l_type == lt_executable
> + && !(undef_map->l_1_needed
> + & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS)
> + && (map->l_1_needed
> + & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS))
> + {
> + if ((type_class & ELF_RTYPE_CLASS_COPY))
> + /* Disallow copy relocations in executable against protected
> + data symbols in a shared object which needs indirect external
> + access. */
> + _dl_signal_error (0, map->l_name, undef_name,
> + N_("copy relocation against non-copyable protected symbol"));
> + else if (ref->st_value != 0
> + && ref->st_shndx == SHN_UNDEF
> + && (type_class & ELF_RTYPE_CLASS_PLT))
> + /* Disallow non-zero symbol values of undefined symbols in
> + executable, which are used as the function pointer, against
> + protected function symbols in a shared object with indirect
> + external access. */
> + _dl_signal_error (0, map->l_name, undef_name,
> + N_("non-canonical reference to canonical protected function"));
> + }
> +}
> +
> +#endif /* _DL_PROTECTED_H */
>
Ok.
On Thu, Oct 7, 2021 at 9:58 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 03/08/2021 18:59, H.J. Lu via Libc-alpha wrote:
> > When performing symbol lookup for references in executable without
> > indirect external access:
> >
> > 1. Disallow copy relocations in executable against protected data symbols
> > in a shared object with indirect external access.
> > 2. Disallow non-zero symbol values of undefined function symbols in
> > executable, which are used as the function pointer, against protected
> > function symbols in a shared object with indirect external access.
>
> How hard would to add some testcases for both cases? To simplify we may
> want to build it iff binutins supports noindirect-extern-access.
I will submit followup patches with testcases from
users/hjl/indirect/master branch:
https://gitlab.com/x86-glibc/glibc/-/tree/users/hjl/indirect/master
including adding LD_DEBUG=protected to check copy relocations against
protected data and non-canonical reference to protected function.
> The rest LGTM, just a nit below due an ununsed variable.
>
> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>
> > ---
> > elf/dl-lookup.c | 5 ++++
> > sysdeps/generic/dl-protected.h | 54 ++++++++++++++++++++++++++++++++++
> > 2 files changed, 59 insertions(+)
> > create mode 100644 sysdeps/generic/dl-protected.h
> >
> > diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
> > index eea217eb28..430359af39 100644
> > --- a/elf/dl-lookup.c
> > +++ b/elf/dl-lookup.c
> > @@ -24,6 +24,7 @@
> > #include <ldsodefs.h>
> > #include <dl-hash.h>
> > #include <dl-machine.h>
> > +#include <dl-protected.h>
> > #include <sysdep-cancel.h>
> > #include <libc-lock.h>
> > #include <tls.h>
> > @@ -527,6 +528,10 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
> > if (__glibc_unlikely (dl_symbol_visibility_binds_local_p (sym)))
> > goto skip;
> >
> > + if (ELFW(ST_VISIBILITY) (sym->st_other) == STV_PROTECTED)
> > + _dl_check_protected_symbol (undef_name, undef_map, ref, map,
> > + type_class);
> > +
> > switch (ELFW(ST_BIND) (sym->st_info))
> > {
> > case STB_WEAK:
>
> Ok.
>
> > diff --git a/sysdeps/generic/dl-protected.h b/sysdeps/generic/dl-protected.h
> > new file mode 100644
> > index 0000000000..244d020dc4
> > --- /dev/null
> > +++ b/sysdeps/generic/dl-protected.h
> > @@ -0,0 +1,54 @@
> > +/* Support for STV_PROTECTED visibility. 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_PROTECTED_H
> > +#define _DL_PROTECTED_H
> > +
> > +static inline void __attribute__ ((always_inline))
> > +_dl_check_protected_symbol (const char *undef_name,
>
> This argument seems unused.
It is used in
_dl_signal_error (0, map->l_name, undef_name,
N_("non-canonical reference to canonical
protected function"));
> > + const struct link_map *undef_map,
> > + const ElfW(Sym) *ref,
> > + const struct link_map *map,
> > + int type_class)
> > +{
> > + if (undef_map != NULL
> > + && undef_map->l_type == lt_executable
> > + && !(undef_map->l_1_needed
> > + & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS)
> > + && (map->l_1_needed
> > + & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS))
> > + {
> > + if ((type_class & ELF_RTYPE_CLASS_COPY))
> > + /* Disallow copy relocations in executable against protected
> > + data symbols in a shared object which needs indirect external
> > + access. */
> > + _dl_signal_error (0, map->l_name, undef_name,
> > + N_("copy relocation against non-copyable protected symbol"));
> > + else if (ref->st_value != 0
> > + && ref->st_shndx == SHN_UNDEF
> > + && (type_class & ELF_RTYPE_CLASS_PLT))
> > + /* Disallow non-zero symbol values of undefined symbols in
> > + executable, which are used as the function pointer, against
> > + protected function symbols in a shared object with indirect
> > + external access. */
> > + _dl_signal_error (0, map->l_name, undef_name,
> > + N_("non-canonical reference to canonical protected function"));
> > + }
> > +}
> > +
> > +#endif /* _DL_PROTECTED_H */
> >
>
> Ok.
I will check it in ASIS.
Thanks.
On 07/10/2021 14:10, H.J. Lu wrote:
> On Thu, Oct 7, 2021 at 9:58 AM Adhemerval Zanella
> <adhemerval.zanella@linaro.org> wrote:
>>
>>
>>
>> On 03/08/2021 18:59, H.J. Lu via Libc-alpha wrote:
>>> When performing symbol lookup for references in executable without
>>> indirect external access:
>>>
>>> 1. Disallow copy relocations in executable against protected data symbols
>>> in a shared object with indirect external access.
>>> 2. Disallow non-zero symbol values of undefined function symbols in
>>> executable, which are used as the function pointer, against protected
>>> function symbols in a shared object with indirect external access.
>>
>> How hard would to add some testcases for both cases? To simplify we may
>> want to build it iff binutins supports noindirect-extern-access.
>
> I will submit followup patches with testcases from
> users/hjl/indirect/master branch:
>
> https://gitlab.com/x86-glibc/glibc/-/tree/users/hjl/indirect/master
>
> including adding LD_DEBUG=protected to check copy relocations against
> protected data and non-canonical reference to protected function.
>
>> The rest LGTM, just a nit below due an ununsed variable.
>>
>> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>>
>>> ---
>>> elf/dl-lookup.c | 5 ++++
>>> sysdeps/generic/dl-protected.h | 54 ++++++++++++++++++++++++++++++++++
>>> 2 files changed, 59 insertions(+)
>>> create mode 100644 sysdeps/generic/dl-protected.h
>>>
>>> diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
>>> index eea217eb28..430359af39 100644
>>> --- a/elf/dl-lookup.c
>>> +++ b/elf/dl-lookup.c
>>> @@ -24,6 +24,7 @@
>>> #include <ldsodefs.h>
>>> #include <dl-hash.h>
>>> #include <dl-machine.h>
>>> +#include <dl-protected.h>
>>> #include <sysdep-cancel.h>
>>> #include <libc-lock.h>
>>> #include <tls.h>
>>> @@ -527,6 +528,10 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
>>> if (__glibc_unlikely (dl_symbol_visibility_binds_local_p (sym)))
>>> goto skip;
>>>
>>> + if (ELFW(ST_VISIBILITY) (sym->st_other) == STV_PROTECTED)
>>> + _dl_check_protected_symbol (undef_name, undef_map, ref, map,
>>> + type_class);
>>> +
>>> switch (ELFW(ST_BIND) (sym->st_info))
>>> {
>>> case STB_WEAK:
>>
>> Ok.
>>
>>> diff --git a/sysdeps/generic/dl-protected.h b/sysdeps/generic/dl-protected.h
>>> new file mode 100644
>>> index 0000000000..244d020dc4
>>> --- /dev/null
>>> +++ b/sysdeps/generic/dl-protected.h
>>> @@ -0,0 +1,54 @@
>>> +/* Support for STV_PROTECTED visibility. 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_PROTECTED_H
>>> +#define _DL_PROTECTED_H
>>> +
>>> +static inline void __attribute__ ((always_inline))
>>> +_dl_check_protected_symbol (const char *undef_name,
>>
>> This argument seems unused.
>
> It is used in
>
> _dl_signal_error (0, map->l_name, undef_name,
> N_("non-canonical reference to canonical
> protected function"));
Indeed, you are right.
>
>>> + const struct link_map *undef_map,
>>> + const ElfW(Sym) *ref,
>>> + const struct link_map *map,
>>> + int type_class)
>>> +{
>>> + if (undef_map != NULL
>>> + && undef_map->l_type == lt_executable
>>> + && !(undef_map->l_1_needed
>>> + & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS)
>>> + && (map->l_1_needed
>>> + & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS))
>>> + {
>>> + if ((type_class & ELF_RTYPE_CLASS_COPY))
>>> + /* Disallow copy relocations in executable against protected
>>> + data symbols in a shared object which needs indirect external
>>> + access. */
>>> + _dl_signal_error (0, map->l_name, undef_name,
>>> + N_("copy relocation against non-copyable protected symbol"));
>>> + else if (ref->st_value != 0
>>> + && ref->st_shndx == SHN_UNDEF
>>> + && (type_class & ELF_RTYPE_CLASS_PLT))
>>> + /* Disallow non-zero symbol values of undefined symbols in
>>> + executable, which are used as the function pointer, against
>>> + protected function symbols in a shared object with indirect
>>> + external access. */
>>> + _dl_signal_error (0, map->l_name, undef_name,
>>> + N_("non-canonical reference to canonical protected function"));
>>> + }
>>> +}
>>> +
>>> +#endif /* _DL_PROTECTED_H */
>>>
>>
>> Ok.
>
> I will check it in ASIS.
>
> Thanks.
>
@@ -24,6 +24,7 @@
#include <ldsodefs.h>
#include <dl-hash.h>
#include <dl-machine.h>
+#include <dl-protected.h>
#include <sysdep-cancel.h>
#include <libc-lock.h>
#include <tls.h>
@@ -527,6 +528,10 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
if (__glibc_unlikely (dl_symbol_visibility_binds_local_p (sym)))
goto skip;
+ if (ELFW(ST_VISIBILITY) (sym->st_other) == STV_PROTECTED)
+ _dl_check_protected_symbol (undef_name, undef_map, ref, map,
+ type_class);
+
switch (ELFW(ST_BIND) (sym->st_info))
{
case STB_WEAK:
new file mode 100644
@@ -0,0 +1,54 @@
+/* Support for STV_PROTECTED visibility. 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_PROTECTED_H
+#define _DL_PROTECTED_H
+
+static inline void __attribute__ ((always_inline))
+_dl_check_protected_symbol (const char *undef_name,
+ const struct link_map *undef_map,
+ const ElfW(Sym) *ref,
+ const struct link_map *map,
+ int type_class)
+{
+ if (undef_map != NULL
+ && undef_map->l_type == lt_executable
+ && !(undef_map->l_1_needed
+ & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS)
+ && (map->l_1_needed
+ & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS))
+ {
+ if ((type_class & ELF_RTYPE_CLASS_COPY))
+ /* Disallow copy relocations in executable against protected
+ data symbols in a shared object which needs indirect external
+ access. */
+ _dl_signal_error (0, map->l_name, undef_name,
+ N_("copy relocation against non-copyable protected symbol"));
+ else if (ref->st_value != 0
+ && ref->st_shndx == SHN_UNDEF
+ && (type_class & ELF_RTYPE_CLASS_PLT))
+ /* Disallow non-zero symbol values of undefined symbols in
+ executable, which are used as the function pointer, against
+ protected function symbols in a shared object with indirect
+ external access. */
+ _dl_signal_error (0, map->l_name, undef_name,
+ N_("non-canonical reference to canonical protected function"));
+ }
+}
+
+#endif /* _DL_PROTECTED_H */