Re: [PATCH v2 03/19] elf: Ignore GLIBC_TUNABLES for setuid/setgid binaries

[Siddhesh Poyarekar <siddhesh@sourceware.org>]

On 2023-10-18 09:04, Siddhesh Poyarekar wrote:
> On 2023-10-17 09:05, Adhemerval Zanella wrote:
>> The tunable privilege levels were a retrofit to try and keep the malloc
>> tunable environment variables' behavior unchanged across security
>> boundaries.  However, CVE-2023-4911 shows how tricky can be
>> tunable parsing in a security-sensitive environment.
>>
>> Not only parsing, but the malloc tunable essentially changes some
>> semantics on setuid/setgid processes.  Although it is not a direct
>> security issue, allowing users to change setuid/setgid semantics is not
>> a good security practice, and requires extra code and analysis to check
>> if each tunable is safe to use on all security boundaries.
>>
>> It also means that security opt-in features, like aarch64 MTE, would
>> need to be explicit enabled by an administrator with a wrapper script
>> or with a possible future system-wide tunable setting.
>>
>> Co-authored-by: Siddhesh Poyarekar  <siddhesh@sourceware.org>
> 
> I'll leave this for someone else to review since I wrote some parts of 
> this.

Carlos, can you please review this?

Thanks,
Sid

> 
> Thanks,
> Sid
> 
>> ---
>>   elf/Makefile                       |   5 +-
>>   elf/dl-tunable-types.h             |  10 --
>>   elf/dl-tunables.c                  | 127 ++++-----------
>>   elf/dl-tunables.list               |   9 --
>>   elf/tst-env-setuid-tunables.c      |  29 +++-
>>   elf/tst-tunables.c                 | 244 +++++++++++++++++++++++++++++
>>   manual/README.tunables             |   9 --
>>   scripts/gen-tunables.awk           |  18 +--
>>   sysdeps/x86_64/64/dl-tunables.list |   1 -
>>   9 files changed, 299 insertions(+), 153 deletions(-)
>>   create mode 100644 elf/tst-tunables.c
>>
>> diff --git a/elf/Makefile b/elf/Makefile
>> index 9176cbf1e3..c824f7dab7 100644
>> --- a/elf/Makefile
>> +++ b/elf/Makefile
>> @@ -263,7 +263,6 @@ tests-static-normal := \
>>     tst-dl-iter-static \
>>     tst-dst-static \
>>     tst-env-setuid \
>> -  tst-env-setuid-tunables \
>>     tst-getauxval-static \
>>     tst-linkall-static \
>>     tst-single_threaded-pthread-static \
>> @@ -276,10 +275,12 @@ tests-static-normal := \
>>   tests-static-internal := \
>>     tst-dl-printf-static \
>>     tst-dl_find_object-static \
>> +  tst-env-setuid-tunables \
>>     tst-ptrguard1-static \
>>     tst-stackguard1-static \
>>     tst-tls1-static \
>>     tst-tls1-static-non-pie \
>> +  tst-tunables \
>>     # tests-static-internal
>>   CRT-tst-tls1-static-non-pie := $(csu-objpfx)crt1.o
>> @@ -2696,6 +2697,8 @@ $(objpfx)tst-glibc-hwcaps-mask.out: \
>>   # tst-glibc-hwcaps-cache.
>>   $(objpfx)tst-glibc-hwcaps-cache.out: $(objpfx)tst-glibc-hwcaps
>> +tst-tunables-ARGS = -- $(host-test-program-cmd)
>> +
>>   $(objpfx)list-tunables.out: tst-rtld-list-tunables.sh $(objpfx)ld.so
>>       $(SHELL) $< $(objpfx)ld.so '$(test-wrapper-env)' \
>>           '$(run_program_env)' > $(objpfx)/tst-rtld-list-tunables.out
>> diff --git a/elf/dl-tunable-types.h b/elf/dl-tunable-types.h
>> index c88332657e..62d6d9e629 100644
>> --- a/elf/dl-tunable-types.h
>> +++ b/elf/dl-tunable-types.h
>> @@ -64,16 +64,6 @@ struct _tunable
>>     tunable_val_t val;            /* The value.  */
>>     bool initialized;            /* Flag to indicate that the tunable is
>>                          initialized.  */
>> -  tunable_seclevel_t security_level;    /* Specify the security level 
>> for the
>> -                       tunable with respect to AT_SECURE
>> -                       programs.  See description of
>> -                       tunable_seclevel_t to see a
>> -                       description of the values.
>> -
>> -                       Note that even if the tunable is
>> -                       read, it may not get used by the
>> -                       target module if the value is
>> -                       considered unsafe.  */
>>     /* Compatibility elements.  */
>>     const char env_alias[TUNABLE_ALIAS_MAX]; /* The compatibility 
>> environment
>>                          variable name.  */
>> diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
>> index 24252af22c..a83bd2b8bc 100644
>> --- a/elf/dl-tunables.c
>> +++ b/elf/dl-tunables.c
>> @@ -154,50 +154,51 @@ __tunable_set_val (tunable_id_t id, 
>> tunable_val_t *valp, tunable_num_t *minp,
>>     do_tunable_update_val (cur, valp, minp, maxp);
>>   }
>> -/* Parse the tunable string TUNESTR and adjust it to drop any 
>> tunables that may
>> -   be unsafe for AT_SECURE processes so that it can be used as the new
>> -   environment variable value for GLIBC_TUNABLES.  VALSTRING is the 
>> original
>> -   environment variable string which we use to make NULL terminated 
>> values so
>> -   that we don't have to allocate memory again for it.  */
>> +/* Parse the tunable string VALSTRING.  VALSTRING is a duplicated 
>> values,
>> +   where delimiters ':' are replaced with '\0', so string tunables 
>> are null
>> +   terminated.  */
>>   static void
>> -parse_tunables (char *tunestr, char *valstring)
>> +parse_tunables (char *valstring)
>>   {
>> -  if (tunestr == NULL || *tunestr == '\0')
>> +  if (valstring == NULL || *valstring == '\0')
>>       return;
>> -  char *p = tunestr;
>> -  size_t off = 0;
>> +  char *p = valstring;
>> +  bool done = false;
>> -  while (true)
>> +  while (!done)
>>       {
>>         char *name = p;
>> -      size_t len = 0;
>>         /* First, find where the name ends.  */
>> -      while (p[len] != '=' && p[len] != ':' && p[len] != '\0')
>> -    len++;
>> +      while (*p != '=' && *p != ':' && *p != '\0')
>> +    p++;
>>         /* If we reach the end of the string before getting a valid 
>> name-value
>>        pair, bail out.  */
>> -      if (p[len] == '\0')
>> +      if (*p == '\0')
>>       break;
>>         /* We did not find a valid name-value pair before encountering 
>> the
>>        colon.  */
>> -      if (p[len]== ':')
>> +      if (*p == ':')
>>       {
>> -      p += len + 1;
>> +      p++;
>>         continue;
>>       }
>> -      p += len + 1;
>> +      /* Skip the ':' or '='.  */
>> +      p++;
>> -      /* Take the value from the valstring since we need to NULL 
>> terminate it.  */
>> -      char *value = &valstring[p - tunestr];
>> -      len = 0;
>> +      const char *value = p;
>> -      while (p[len] != ':' && p[len] != '\0')
>> -    len++;
>> +      while (*p != ':' && *p != '\0')
>> +    p++;
>> +
>> +      if (*p == '\0')
>> +    done = true;
>> +      else
>> +    *p++ = '\0';
>>         /* Add the tunable if it exists.  */
>>         for (size_t i = 0; i < sizeof (tunable_list) / sizeof 
>> (tunable_t); i++)
>> @@ -206,50 +207,11 @@ parse_tunables (char *tunestr, char *valstring)
>>         if (tunable_is_name (cur->name, name))
>>           {
>> -          /* If we are in a secure context (AT_SECURE) then ignore the
>> -         tunable unless it is explicitly marked as secure.  Tunable
>> -         values take precedence over their envvar aliases.  We write
>> -         the tunables that are not SXID_ERASE back to TUNESTR, thus
>> -         dropping all SXID_ERASE tunables and any invalid or
>> -         unrecognized tunables.  */
>> -          if (__libc_enable_secure)
>> -        {
>> -          if (cur->security_level != TUNABLE_SECLEVEL_SXID_ERASE)
>> -            {
>> -              if (off > 0)
>> -            tunestr[off++] = ':';
>> -
>> -              const char *n = cur->name;
>> -
>> -              while (*n != '\0')
>> -            tunestr[off++] = *n++;
>> -
>> -              tunestr[off++] = '=';
>> -
>> -              for (size_t j = 0; j < len; j++)
>> -            tunestr[off++] = value[j];
>> -            }
>> -
>> -          if (cur->security_level != TUNABLE_SECLEVEL_NONE)
>> -            break;
>> -        }
>> -
>> -          value[len] = '\0';
>>             tunable_initialize (cur, value);
>>             break;
>>           }
>>       }
>> -
>> -      /* We reached the end while processing the tunable string.  */
>> -      if (p[len] == '\0')
>> -    break;
>> -
>> -      p += len + 1;
>>       }
>> -
>> -  /* Terminate tunestr before we leave.  */
>> -  if (__libc_enable_secure)
>> -    tunestr[off] = '\0';
>>   }
>>   /* Initialize the tunables list from the environment.  For now we 
>> only use the
>> @@ -263,16 +225,16 @@ __tunables_init (char **envp)
>>     size_t len = 0;
>>     char **prev_envp = envp;
>> +  /* Ignore tunables for AT_SECURE programs.  */
>> +  if (__libc_enable_secure)
>> +    return;
>> +
>>     while ((envp = get_next_env (envp, &envname, &len, &envval,
>>                      &prev_envp)) != NULL)
>>       {
>>         if (tunable_is_name ("GLIBC_TUNABLES", envname))
>>       {
>> -      char *new_env = tunables_strdup (envname);
>> -      if (new_env != NULL)
>> -        parse_tunables (new_env + len + 1, envval);
>> -      /* Put in the updated envval.  */
>> -      *prev_envp = new_env;
>> +      parse_tunables (tunables_strdup (envval));
>>         continue;
>>       }
>> @@ -290,39 +252,6 @@ __tunables_init (char **envp)
>>         /* We have a match.  Initialize and move on to the next line.  */
>>         if (tunable_is_name (name, envname))
>>           {
>> -          /* For AT_SECURE binaries, we need to check the security 
>> settings of
>> -         the tunable and decide whether we read the value and also 
>> whether
>> -         we erase the value so that child processes don't inherit 
>> them in
>> -         the environment.  */
>> -          if (__libc_enable_secure)
>> -        {
>> -          if (cur->security_level == TUNABLE_SECLEVEL_SXID_ERASE)
>> -            {
>> -              /* Erase the environment variable.  */
>> -              char **ep = prev_envp;
>> -
>> -              while (*ep != NULL)
>> -            {
>> -              if (tunable_is_name (name, *ep))
>> -                {
>> -                  char **dp = ep;
>> -
>> -                  do
>> -                dp[0] = dp[1];
>> -                  while (*dp++);
>> -                }
>> -              else
>> -                ++ep;
>> -            }
>> -              /* Reset the iterator so that we read the environment 
>> again
>> -             from the point we erased.  */
>> -              envp = prev_envp;
>> -            }
>> -
>> -          if (cur->security_level != TUNABLE_SECLEVEL_NONE)
>> -            continue;
>> -        }
>> -
>>             tunable_initialize (cur, envval);
>>             break;
>>           }
>> diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
>> index 695ba7192e..471895af7b 100644
>> --- a/elf/dl-tunables.list
>> +++ b/elf/dl-tunables.list
>> @@ -21,14 +21,6 @@
>>   # minval: Optional minimum acceptable value
>>   # maxval: Optional maximum acceptable value
>>   # env_alias: An alias environment variable
>> -# security_level: Specify security level of the tunable for AT_SECURE 
>> binaries.
>> -#           Valid values are:
>> -#
>> -#          SXID_ERASE: (default) Do not read and do not pass on to
>> -#          child processes.
>> -#          SXID_IGNORE: Do not read, but retain for non-AT_SECURE
>> -#          subprocesses.
>> -#          NONE: Read all the time.
>>   glibc {
>>     malloc {
>> @@ -158,7 +150,6 @@ glibc {
>>         type: INT_32
>>         minval: 0
>>         maxval: 255
>> -      security_level: SXID_IGNORE
>>       }
>>     }
>> diff --git a/elf/tst-env-setuid-tunables.c 
>> b/elf/tst-env-setuid-tunables.c
>> index 2603007b7b..ca02dbba58 100644
>> --- a/elf/tst-env-setuid-tunables.c
>> +++ b/elf/tst-env-setuid-tunables.c
>> @@ -15,14 +15,10 @@
>>      License along with the GNU C Library; if not, see
>>      <https://www.gnu.org/licenses/>.  */
>> -/* Verify that tunables correctly filter out unsafe tunables like
>> -   glibc.malloc.check and glibc.malloc.mmap_threshold but also retain
>> -   glibc.malloc.mmap_threshold in an unprivileged child.  */
>> -
>> -#define _LIBC 1
>> -#include "config.h"
>> -#undef _LIBC
>> +/* Verify that GLIBC_TUNABLES is kept unchanged but no tunable is 
>> actually
>> +   enabled for AT_SECURE processes.  */
>> +#include <dl-tunables.h>
>>   #include <errno.h>
>>   #include <fcntl.h>
>>   #include <stdlib.h>
>> @@ -40,7 +36,7 @@
>>   #include <support/test-driver.h>
>>   #include <support/capture_subprocess.h>
>> -const char *teststrings[] =
>> +static const char *teststrings[] =
>>   {
>>     "glibc.malloc.check=2:glibc.malloc.mmap_threshold=4096",
>>     
>> "glibc.malloc.check=2:glibc.malloc.check=2:glibc.malloc.mmap_threshold=4096",
>> @@ -74,6 +70,23 @@ test_child (int off)
>>       ret = 0;
>>     fflush (stdout);
>> +  /* Also check if the set tunables are effectively unchanged.  */
>> +  int32_t check = TUNABLE_GET_FULL (glibc, malloc, check, int32_t, 
>> NULL);
>> +  size_t mmap_threshold = TUNABLE_GET_FULL (glibc, malloc, 
>> mmap_threshold,
>> +                        size_t, NULL);
>> +  int32_t perturb = TUNABLE_GET_FULL (glibc, malloc, perturb, 
>> int32_t, NULL);
>> +
>> +  printf ("    [%d] glibc.malloc.check=%d\n", off, check);
>> +  fflush (stdout);
>> +  printf ("    [%d] glibc.malloc.mmap_threshold=%zu\n", off, 
>> mmap_threshold);
>> +  fflush (stdout);
>> +  printf ("    [%d] glibc.malloc.perturb=%d\n", off, perturb);
>> +  fflush (stdout);
>> +
>> +  ret |= check != 0;
>> +  ret |= mmap_threshold != 0;
>> +  ret |= perturb != 0;
>> +
>>     return ret;
>>   }
>> diff --git a/elf/tst-tunables.c b/elf/tst-tunables.c
>> new file mode 100644
>> index 0000000000..57cf532fc4
>> --- /dev/null
>> +++ b/elf/tst-tunables.c
>> @@ -0,0 +1,244 @@
>> +/* Check GLIBC_TUNABLES parsing.
>> +   Copyright (C) 2023 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 <array_length.h>
>> +#include <dl-tunables.h>
>> +#include <getopt.h>
>> +#include <intprops.h>
>> +#include <stdint.h>
>> +#include <stdlib.h>
>> +#include <support/capture_subprocess.h>
>> +#include <support/check.h>
>> +
>> +static int restart;
>> +#define CMDLINE_OPTIONS \
>> +  { "restart", no_argument, &restart, 1 },
>> +
>> +static const struct test_t
>> +{
>> +  const char *env;
>> +  int32_t expected_malloc_check;
>> +  size_t expected_mmap_threshold;
>> +  int32_t expected_perturb;
>> +} tests[] =
>> +{
>> +  /* Expected tunable format.  */
>> +  {
>> +    "glibc.malloc.check=2",
>> +    2,
>> +    0,
>> +    0,
>> +  },
>> +  {
>> +    "glibc.malloc.check=2:glibc.malloc.mmap_threshold=4096",
>> +    2,
>> +    4096,
>> +    0,
>> +  },
>> +  /* Empty tunable are ignored.  */
>> +  {
>> +    "glibc.malloc.check=2::glibc.malloc.mmap_threshold=4096",
>> +    2,
>> +    4096,
>> +    0,
>> +  },
>> +  /* As well empty values.  */
>> +  {
>> +    "glibc.malloc.check=:glibc.malloc.mmap_threshold=4096",
>> +    0,
>> +    4096,
>> +    0,
>> +  },
>> +  /* Tunable are processed from left to right, so last one is the one 
>> set.  */
>> +  {
>> +    "glibc.malloc.check=1:glibc.malloc.check=2",
>> +    2,
>> +    0,
>> +    0,
>> +  },
>> +  {
>> +    
>> "glibc.malloc.check=2:glibc.malloc.check=2:glibc.malloc.mmap_threshold=4096",
>> +    2,
>> +    4096,
>> +    0,
>> +  },
>> +  {
>> +    
>> "glibc.malloc.check=2:glibc.malloc.mmap_threshold=4096:glibc.malloc.check=2",
>> +    2,
>> +    4096,
>> +    0,
>> +  },
>> +  /* 0x800 is larger than tunable maxval (0xff), so the tunable is 
>> unchanged.  */
>> +  {
>> +    "glibc.malloc.perturb=0x800",
>> +    0,
>> +    0,
>> +    0,
>> +  },
>> +  {
>> +    "glibc.malloc.perturb=0x55",
>> +    0,
>> +    0,
>> +    0x55,
>> +  },
>> +  /* Out of range values are just ignored.  */
>> +  {
>> +    "glibc.malloc.perturb=0x800:glibc.malloc.mmap_threshold=4096",
>> +    0,
>> +    4096,
>> +    0,
>> +  },
>> +  /* Invalid keys are ignored.  */
>> +  {
>> +    ":glibc.malloc.garbage=2:glibc.malloc.check=1",
>> +    1,
>> +    0,
>> +    0,
>> +  },
>> +  {
>> +    
>> "glibc.malloc.perturb=0x800:not_valid.malloc.check=2:glibc.malloc.mmap_threshold=4096",
>> +    0,
>> +    4096,
>> +    0,
>> +  },
>> +  {
>> +    "glibc.not_valid.check=2:glibc.malloc.mmap_threshold=4096",
>> +    0,
>> +    4096,
>> +    0,
>> +  },
>> +  {
>> +    "not_valid.malloc.check=2:glibc.malloc.mmap_threshold=4096",
>> +    0,
>> +    4096,
>> +    0,
>> +  },
>> +  /* Invalid subkeys are ignored.  */
>> +  {
>> +    
>> "glibc.malloc.garbage=2:glibc.maoc.mmap_threshold=4096:glibc.malloc.check=2",
>> +    2,
>> +    0,
>> +    0,
>> +  },
>> +  {
>> +    
>> "glibc.malloc.check=4:glibc.malloc.garbage=2:glibc.maoc.mmap_threshold=4096",
>> +    0,
>> +    0,
>> +    0,
>> +  },
>> +  {
>> +    "not_valid.malloc.check=2",
>> +    0,
>> +    0,
>> +    0,
>> +  },
>> +  {
>> +    "glibc.not_valid.check=2",
>> +    0,
>> +    0,
>> +    0,
>> +  },
>> +  /* An ill-formatted tunable in the for key=key=value will considere 
>> the
>> +     value as 'key=value' (which can not be parsed as an integer).  */
>> +  {
>> +    "glibc.malloc.mmap_threshold=glibc.malloc.mmap_threshold=4096",
>> +    0,
>> +    0,
>> +    0,
>> +  },
>> +  /* The ill-formatted tunable is also skipped.  */
>> +  {
>> +    
>> "glibc.malloc.mmap_threshold=glibc.malloc.mmap_threshold=4096:glibc.malloc.check=2",
>> +    2,
>> +    0,
>> +    0,
>> +  },
>> +  /* For an integer tunable, parse will stop on non number 
>> character.  */
>> +  {
>> +    "glibc.malloc.check=2=2",
>> +    2,
>> +    0,
>> +    0,
>> +  },
>> +  {
>> +    "glibc.malloc.check=2=2:glibc.malloc.mmap_threshold=4096",
>> +    2,
>> +    4096,
>> +    0,
>> +  }
>> +};
>> +
>> +static int
>> +handle_restart (int i)
>> +{
>> +  TEST_COMPARE (tests[i].expected_malloc_check,
>> +        TUNABLE_GET_FULL (glibc, malloc, check, int32_t, NULL));
>> +  TEST_COMPARE (tests[i].expected_mmap_threshold,
>> +        TUNABLE_GET_FULL (glibc, malloc, mmap_threshold, size_t, NULL));
>> +  TEST_COMPARE (tests[i].expected_perturb,
>> +        TUNABLE_GET_FULL (glibc, malloc, perturb, int32_t, NULL));
>> +  return 0;
>> +}
>> +
>> +static int
>> +do_test (int argc, char *argv[])
>> +{
>> +  /* We must have either:
>> +     - One our fource parameters left if called initially:
>> +       + path to ld.so         optional
>> +       + "--library-path"      optional
>> +       + the library path      optional
>> +       + the application name
>> +       + the test to check  */
>> +
>> +  TEST_VERIFY_EXIT (argc == 2 || argc == 5);
>> +
>> +  if (restart)
>> +    return handle_restart (atoi (argv[1]));
>> +
>> +  char nteststr[INT_BUFSIZE_BOUND (int)];
>> +
>> +  char *spargv[10];
>> +  {
>> +    int i = 0;
>> +    for (; i < argc - 1; i++)
>> +      spargv[i] = argv[i + 1];
>> +    spargv[i++] = (char *) "--direct";
>> +    spargv[i++] = (char *) "--restart";
>> +    spargv[i++] = nteststr;
>> +    spargv[i] = NULL;
>> +  }
>> +
>> +  for (int i = 0; i < array_length (tests); i++)
>> +    {
>> +      snprintf (nteststr, sizeof nteststr, "%d", i);
>> +
>> +      printf ("[%d] Spawned test for %s\n", i, tests[i].env);
>> +      setenv ("GLIBC_TUNABLES", tests[i].env, 1);
>> +      struct support_capture_subprocess result
>> +    = support_capture_subprogram (spargv[0], spargv);
>> +      support_capture_subprocess_check (&result, "tst-tunables", 0,
>> +                    sc_allow_stderr);
>> +      support_capture_subprocess_free (&result);
>> +    }
>> +
>> +  return 0;
>> +}
>> +
>> +#define TEST_FUNCTION_ARGV do_test
>> +#include <support/test-driver.c>
>> diff --git a/manual/README.tunables b/manual/README.tunables
>> index 605ddd78cd..72ae00dc02 100644
>> --- a/manual/README.tunables
>> +++ b/manual/README.tunables
>> @@ -59,15 +59,6 @@ The list of allowed attributes are:
>>   - env_alias:        An alias environment variable
>> -- security_level:    Specify security level of the tunable for AT_SECURE
>> -            binaries.  Valid values are:
>> -
>> -            SXID_ERASE: (default) Do not read and do not pass on to
>> -            child processes.
>> -            SXID_IGNORE: Do not read, but retain for non-AT_SECURE
>> -            child processes.
>> -            NONE: Read all the time.
>> -
>>   2. Use TUNABLE_GET/TUNABLE_SET/TUNABLE_SET_WITH_BOUNDS to get and 
>> set tunables.
>>   3. OPTIONAL: If tunables in a namespace are being used multiple 
>> times within a
>> diff --git a/scripts/gen-tunables.awk b/scripts/gen-tunables.awk
>> index d6de100df0..1e9d6b534e 100644
>> --- a/scripts/gen-tunables.awk
>> +++ b/scripts/gen-tunables.awk
>> @@ -61,9 +61,6 @@ $1 == "}" {
>>       if (!env_alias[top_ns,ns,tunable]) {
>>         env_alias[top_ns,ns,tunable] = "{0}"
>>       }
>> -    if (!security_level[top_ns,ns,tunable]) {
>> -      security_level[top_ns,ns,tunable] = "SXID_ERASE"
>> -    }
>>       len = length(top_ns"."ns"."tunable)
>>       if (len > max_name_len)
>>         max_name_len = len
>> @@ -118,17 +115,6 @@ $1 == "}" {
>>       if (len > max_alias_len)
>>         max_alias_len = len
>>     }
>> -  else if (attr == "security_level") {
>> -    if (val == "SXID_ERASE" || val == "SXID_IGNORE" || val == "NONE") {
>> -      security_level[top_ns,ns,tunable] = val
>> -    }
>> -    else {
>> -      printf("Line %d: Invalid value (%s) for security_level: %s, ", 
>> NR, val,
>> -         $0)
>> -      print("Allowed values are 'SXID_ERASE', 'SXID_IGNORE', or 'NONE'")
>> -      exit 1
>> -    }
>> -  }
>>     else if (attr == "default") {
>>       if (types[top_ns,ns,tunable] == "STRING") {
>>         default_val[top_ns,ns,tunable] = sprintf(".strval = \"%s\"", 
>> val);
>> @@ -177,9 +163,9 @@ END {
>>       n = indices[2];
>>       m = indices[3];
>>       printf ("  {TUNABLE_NAME_S(%s, %s, %s)", t, n, m)
>> -    printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, false, 
>> TUNABLE_SECLEVEL_%s, %s},\n",
>> +    printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, false, %s},\n",
>>           types[t,n,m], minvals[t,n,m], maxvals[t,n,m],
>> -        default_val[t,n,m], security_level[t,n,m], env_alias[t,n,m]);
>> +        default_val[t,n,m], env_alias[t,n,m]);
>>     }
>>     print "};"
>>     print "#endif"
>> diff --git a/sysdeps/x86_64/64/dl-tunables.list 
>> b/sysdeps/x86_64/64/dl-tunables.list
>> index 0aab52e662..54a216a461 100644
>> --- a/sysdeps/x86_64/64/dl-tunables.list
>> +++ b/sysdeps/x86_64/64/dl-tunables.list
>> @@ -23,7 +23,6 @@ glibc {
>>         minval: 0
>>         maxval: 1
>>         env_alias: LD_PREFER_MAP_32BIT_EXEC
>> -      security_level: SXID_IGNORE
>>       }
>>     }
>>   }
>