elf/dl-tunable-types.h

   1 /* Internal representation of tunables.
   2
   3    Copyright (C) 2016-2023 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _TUNABLE_TYPES_H_
  21 #define _TUNABLE_TYPES_H_
  22
  23 /* Note: This header is included in the generated dl-tunables-list.h and
  24    only used internally in the tunables implementation in dl-tunables.c.  */
  25
  26 #include <stdbool.h>
  27 #include <stddef.h>
  28 #include <stdint.h>
  29
  30 typedef enum
  31 {
  32   TUNABLE_TYPE_INT_32,
  33   TUNABLE_TYPE_UINT_64,
  34   TUNABLE_TYPE_SIZE_T,
  35   TUNABLE_TYPE_STRING
  36 } tunable_type_code_t;
  37
  38 typedef struct
  39 {
  40   tunable_type_code_t type_code;
  41   tunable_num_t min;
  42   tunable_num_t max;
  43 } tunable_type_t;
  44
  45 /* Security level for tunables.  This decides what to do with individual
  46    tunables for AT_SECURE binaries.  */
  47 typedef enum
  48 {
  49   /* Erase the tunable for AT_SECURE binaries so that child processes don't
  50      read it.  */
  51   TUNABLE_SECLEVEL_SXID_ERASE = 0,
  52   /* Ignore the tunable for AT_SECURE binaries, but don't erase it, so that
  53      child processes can read it.  */
  54   TUNABLE_SECLEVEL_SXID_IGNORE = 1,
  55   /* Read the tunable.  */
  56   TUNABLE_SECLEVEL_NONE = 2,
  57 } tunable_seclevel_t;
  58
  59 /* A tunable.  */
  60 struct _tunable
  61 {
  62   const char name[TUNABLE_NAME_MAX];    /* Internal name of the tunable.  */
  63   tunable_type_t type;                  /* Data type of the tunable.  */
  64   tunable_val_t val;                    /* The value.  */
  65   bool initialized;                     /* Flag to indicate that the tunable is
  66                                            initialized.  */
  67   tunable_seclevel_t security_level;    /* Specify the security level for the
  68                                            tunable with respect to AT_SECURE
  69                                            programs.  See description of
  70                                            tunable_seclevel_t to see a
  71                                            description of the values.
  72
  73                                            Note that even if the tunable is
  74                                            read, it may not get used by the
  75                                            target module if the value is
  76                                            considered unsafe.  */
  77   /* Compatibility elements.  */
  78   const char env_alias[TUNABLE_ALIAS_MAX]; /* The compatibility environment
  79                                            variable name.  */
  80 };
  81
  82 typedef struct _tunable tunable_t;
  83
  84 static __always_inline bool
  85 unsigned_tunable_type (tunable_type_code_t t)
  86 {
  87   switch (t)
  88     {
  89     case TUNABLE_TYPE_INT_32:
  90       return false;
  91     case TUNABLE_TYPE_UINT_64:
  92     case TUNABLE_TYPE_SIZE_T:
  93       return true;
  94     case TUNABLE_TYPE_STRING:
  95     default:
  96       break;
  97     }
  98   __builtin_unreachable ();
  99 }
 100
 101 #endif