Commit Graph

8 Commits

Author SHA1 Message Date
Alexey Makhalov
cebcb9f864 Fix range check in do_tunable_update_val
Current implementation of tunables does not set arena_max and arena_test
values. Any value provided by glibc.malloc.arena_max and
glibc.malloc.arena_test parameters is ignored.

These tunables have minval value set to 1 (see elf/dl-tunables.list file)
and undefined maxval value. In that case default value (which is 0. see
scripts/gen-tunables.awk) is being used to set maxval.

For instance, generated tunable_list[] entry for arena_max is:
(gdb) p *cur
$1 = {name = 0x7ffff7df6217 "glibc.malloc.arena_max",
 type = {type_code = TUNABLE_TYPE_SIZE_T, min = 1, max = 0},
  val = {numval = 0, strval = 0x0}, initialized = false,
   security_level = TUNABLE_SECLEVEL_SXID_IGNORE,
    env_alias = 0x7ffff7df622e "MALLOC_ARENA_MAX"}

As a result, any value of glibc.malloc.arena_max is ignored by
TUNABLE_SET_VAL_IF_VALID_RANGE macro
  __type min = (__cur)->type.min;                    <- initialized to 1
  __type max = (__cur)->type.max;                    <- initialized to 0!
  if (min == max)                                    <- false
    {
      min = __default_min;
      max = __default_max;
    }
  if ((__type) (__val) >= min && (__type) (val) <= max)  <- false
    {
      (__cur)->val.numval = val;
      (__cur)->initialized = true;
    }

Assigning correct min/max values at a build time fixes a problem.
Plus, a bit of optimization: Setting of default min/max values for the
given type at a run time might be eliminated.

	* elf/dl-tunables.c (do_tunable_update_val): Range checking fix.
	* scripts/gen-tunables.awk: Set unspecified minval and/or maxval
	values to correct default value for given type.
2017-09-27 02:44:09 +05:30
Adhemerval Zanella
a4de0a9008 Fix gen-tunables.awk to work with older awk
Awk 3.1.x does not support multi-dimensional arrays, so fix up to make
sure that gen-tunables.awk works on it.

	* scripts/gen-tunables.awk: Avoid multi-dimensional arrays.
2017-06-19 14:47:22 +05:30
Siddhesh Poyarekar
ea9b0ecbf0 tunables: Add LD_HWCAP_MASK to tunables
Add LD_HWCAP_MASK to tunables in preparation of it being removed from
rtld.c.  This allows us to read LD_HWCAP_MASK much earlier so that it
can influence IFUNC resolution in aarch64.

This patch does not actually do anything other than read the
LD_HWCAP_MASK variable and add the tunables way to set the
LD_HWCAP_MASK, i.e. via the glibc.tune.hwcap_mask tunable.  In a
follow-up patch, the _dl_hwcap_mask will be replaced with
glibc.tune.hwcap_mask to complete the transition.

	* elf/dl-tunables.list: Add glibc.tune.hwcap_mask.
	* scripts/gen-tunables.awk: Include dl-procinfo.h.
	* manual/tunables.texi: Document glibc.tune.hwcap_mask.
2017-06-07 11:11:37 +05:30
Siddhesh Poyarekar
d13103074a tunables: Specify a default value for tunables
Enhance dl-tunables.list to allow specifying a default value for a
tunable that it would be initialized to.

	* scripts/gen-tunables.awk: Recognize 'default' keyword in
	dl-tunables.list.
	* README.tunables: Document it.
2017-05-17 13:11:00 +05:30
Siddhesh Poyarekar
17284d650e tunables: Make tunable_list relro
As of now we don't need tunables to be writable after they have been
set initially, so there is no point in having them writable.  Put
tunable_list in .data.rel.ro so that it is set as read-only after
relocation.  This also allows us to move some of the dl_* variables
that are tunables controlled into the tunables infrastructure instead
of having two copies.

In future if we ever need specific tunables to be writable at runtime,
we can split the tunable_list into two.

Regression tested on x86_64 to verify that tests continue to pass.

	* scripts/gen-tunables.awk: Add attribute_relro to
	tunable_list.
2017-05-11 20:15:56 +05:30
Sunyeop Lee
65eff7fbdb Update old tunables framework document/script.
Since commit 8b9e9c3c0b, security_level replaces
is_secure. There were some old files need to be updated.

2017-03-23  Sunyeop Lee  <sunyeop97@gmail.com>

	* README.tunables: Updated descriptions.
	* elf/dl-tunables.list: Fixed typo: SXID_NONE -> NONE.
	* scripts/gen-tunables.awk: Updated the code related to the commit.
2017-03-24 11:08:28 +05:30
Siddhesh Poyarekar
8b9e9c3c0b tunables: Fix environment variable processing for setuid binaries (bz #21073)
Florian Weimer pointed out that we have three different kinds of
environment variables (and hence tunables):

1. Variables that are removed for setxid processes
2. Variables that are ignored in setxid processes but is passed on to
   child processes
3. Variables that are passed on to child processes all the time

Tunables currently only does (2) and (3) when it should be doing (1)
for MALLOC_CHECK_.  This patch enhances the is_secure flag in tunables
to an enum value that can specify which of the above three categories
the tunable (and its envvar alias) belongs to.

The default is for tunables to be in (1).  Hence, all of the malloc
tunables barring MALLOC_CHECK_ are explicitly specified to belong to
category (2).  There were discussions around abolishing category (2)
completely but we can do that as a separate exercise in 2.26.

Tested on x86_64 to verify that there are no regressions.

	[BZ #21073]
	* elf/dl-tunable-types.h (tunable_seclevel_t): New enum.
	* elf/dl-tunables.c (tunables_strdup): Remove.
	(get_next_env): Also return the previous envp.
	(parse_tunables): Erase tunables of category
	TUNABLES_SECLEVEL_SXID_ERASE.
	(maybe_enable_malloc_check): Make MALLOC_CHECK_
	TUNABLE_SECLEVEL_NONE if /etc/setuid-debug is accessible.
	(__tunables_init)[TUNABLES_FRONTEND ==
	TUNABLES_FRONTEND_valstring]: Update GLIBC_TUNABLES envvar
	after parsing.
	[TUNABLES_FRONTEND != TUNABLES_FRONTEND_valstring]: Erase
	tunable envvars of category TUNABLES_SECLEVEL_SXID_ERASE.
	* elf/dl-tunables.h (struct _tunable): Change member is_secure
	to security_level.
	* elf/dl-tunables.list: Add security_level annotations for all
	tunables.
	* scripts/gen-tunables.awk: Recognize and generate enum values
	for security_level.
	* elf/tst-env-setuid.c: New test case.
	* elf/tst-env-setuid-tunables: new test case.
	* elf/Makefile (tests-static): Add them.
2017-02-02 15:50:16 +05:30
Siddhesh Poyarekar
67e58f3941 Add framework for tunables
The tunables framework allows us to uniformly manage and expose global
variables inside glibc as switches to users.  tunables/README has
instructions for glibc developers to add new tunables.

Tunables support can be enabled by passing the --enable-tunables
configure flag to the configure script.  This patch only adds a
framework and does not pose any limitations on how tunable values are
read from the user.  It also adds environment variables used in malloc
behaviour tweaking to the tunables framework as a PoC of the
compatibility interface.

	* manual/install.texi: Add --enable-tunables option.
	* INSTALL: Regenerate.
	* README.tunables: New file.
	* Makeconfig (CPPFLAGS): Define TOP_NAMESPACE.
	(before-compile): Generate dl-tunable-list.h early.
	* config.h.in: Add HAVE_TUNABLES.
	* config.make.in: Add have-tunables.
	* configure.ac: Add --enable-tunables option.
	* configure: Regenerate.
	* csu/init-first.c (__libc_init_first): Move
	__libc_init_secure earlier...
	* csu/init-first.c (LIBC_START_MAIN):... to here.
	Include dl-tunables.h, libc-internal.h.
	(LIBC_START_MAIN) [!SHARED]: Initialize tunables for static
	binaries.
	* elf/Makefile (dl-routines): Add dl-tunables.
	* elf/Versions (ld): Add __tunable_set_val to GLIBC_PRIVATE
	namespace.
	* elf/dl-support (_dl_nondynamic_init): Unset MALLOC_CHECK_
	only when !HAVE_TUNABLES.
	* elf/rtld.c (process_envvars): Likewise.
	* elf/dl-sysdep.c [HAVE_TUNABLES]: Include dl-tunables.h
	(_dl_sysdep_start): Call __tunables_init.
	* elf/dl-tunable-types.h: New file.
	* elf/dl-tunables.c: New file.
	* elf/dl-tunables.h: New file.
	* elf/dl-tunables.list: New file.
	* malloc/tst-malloc-usable-static.c: New test case.
	* malloc/Makefile (tests-static): Add it.
	* malloc/arena.c [HAVE_TUNABLES]: Include dl-tunables.h.
	Define TUNABLE_NAMESPACE.
	(DL_TUNABLE_CALLBACK (set_mallopt_check)): New function.
	(DL_TUNABLE_CALLBACK_FNDECL): New macro.  Use it to define
	callback functions.
	(ptmalloc_init): Set tunable values.
	* scripts/gen-tunables.awk: New file.
	* sysdeps/mach/hurd/dl-sysdep.c: Include dl-tunables.h.
	(_dl_sysdep_start): Call __tunables_init.
2016-12-31 23:49:24 +05:30