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61117bfa1b
The TUNABLE_SET interface took a primitive C type argument, which resulted in inconsistent type conversions internally due to incorrect dereferencing of types, especialy on 32-bit architectures. This change simplifies the TUNABLE setting logic along with the interfaces. Now all numeric tunable values are stored as signed numbers in tunable_num_t, which is intmax_t. All calls to set tunables cast the input value to its primitive type and then to tunable_num_t for storage. This relies on gcc-specific (although I suspect other compilers woul also do the same) unsigned to signed integer conversion semantics, i.e. the bit pattern is conserved. The reverse conversion is guaranteed by the standard.
85 lines
2.6 KiB
C
85 lines
2.6 KiB
C
/* Internal representation of tunables.
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Copyright (C) 2016-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _TUNABLE_TYPES_H_
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#define _TUNABLE_TYPES_H_
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/* Note: This header is included in the generated dl-tunables-list.h and
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only used internally in the tunables implementation in dl-tunables.c. */
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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typedef enum
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{
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TUNABLE_TYPE_INT_32,
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TUNABLE_TYPE_UINT_64,
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TUNABLE_TYPE_SIZE_T,
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TUNABLE_TYPE_STRING
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} tunable_type_code_t;
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typedef struct
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{
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tunable_type_code_t type_code;
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tunable_num_t min;
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tunable_num_t max;
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} tunable_type_t;
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/* Security level for tunables. This decides what to do with individual
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tunables for AT_SECURE binaries. */
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typedef enum
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{
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/* Erase the tunable for AT_SECURE binaries so that child processes don't
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read it. */
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TUNABLE_SECLEVEL_SXID_ERASE = 0,
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/* Ignore the tunable for AT_SECURE binaries, but don't erase it, so that
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child processes can read it. */
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TUNABLE_SECLEVEL_SXID_IGNORE = 1,
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/* Read the tunable. */
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TUNABLE_SECLEVEL_NONE = 2,
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} tunable_seclevel_t;
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/* A tunable. */
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struct _tunable
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{
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const char name[TUNABLE_NAME_MAX]; /* Internal name of the tunable. */
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tunable_type_t type; /* Data type of the tunable. */
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tunable_val_t val; /* The value. */
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bool initialized; /* Flag to indicate that the tunable is
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initialized. */
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tunable_seclevel_t security_level; /* Specify the security level for the
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tunable with respect to AT_SECURE
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programs. See description of
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tunable_seclevel_t to see a
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description of the values.
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Note that even if the tunable is
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read, it may not get used by the
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target module if the value is
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considered unsafe. */
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/* Compatibility elements. */
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const char env_alias[TUNABLE_ALIAS_MAX]; /* The compatibility environment
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variable name. */
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};
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typedef struct _tunable tunable_t;
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#endif
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