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The hooks mechanism uses symbol sets for running lists of functions, which requires either extra linker directives to provide any hardening (such as RELRO) or additional code (such as pointer obfuscation via mangling with random value). Currently only hurd uses set-hooks.h so we remove it from the generic includes. The generic implementation uses direct function calls which provide hardening and good code generation, observability and debugging without the need for extra linking options or special code handling. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
97 lines
3.2 KiB
C
97 lines
3.2 KiB
C
/* Macros for using symbol sets for running lists of functions.
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Copyright (C) 1994-2023 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 _SET_HOOKS_H
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#define _SET_HOOKS_H 1
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#define __need_size_t
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#include <stddef.h>
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#include <sys/cdefs.h>
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#include <libc-symbols.h>
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#include "set-hooks-arch.h"
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#ifdef symbol_set_define
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/* Define a hook variable called NAME. Functions put on this hook take
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arguments described by PROTO. Use `text_set_element (NAME, FUNCTION)'
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from include/libc-symbols.h to add a function to the hook. */
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# define DEFINE_HOOK(NAME, PROTO) \
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typedef void __##NAME##_hook_function_t PROTO; \
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symbol_set_define (NAME)
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# define DECLARE_HOOK(NAME, PROTO) \
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typedef void __##NAME##_hook_function_t PROTO;\
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symbol_set_declare (NAME)
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/* Run all the functions hooked on the set called NAME.
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Each function is called like this: `function ARGS'. */
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# define RUN_HOOK(NAME, ARGS) \
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do { \
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void *const *ptr; \
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for (ptr = (void *const *) symbol_set_first_element (NAME); \
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! symbol_set_end_p (NAME, ptr); ++ptr) \
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(*(__##NAME##_hook_function_t *) *ptr) ARGS; \
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} while (0)
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/* Define a hook variable with NAME and PROTO, and a function called RUNNER
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which calls each function on the hook in turn, with ARGS. */
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# define DEFINE_HOOK_RUNNER(name, runner, proto, args) \
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DEFINE_HOOK (name, proto); \
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extern void runner proto; void runner proto { RUN_HOOK (name, args); }
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# ifdef SET_RELHOOK
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/* This is similar to RUN_RELHOOK, but the hooks were registered with
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* SET_RELHOOK so that a relative offset was computed by the linker
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* rather than an absolute address by the dynamic linker. */
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# define RUN_RELHOOK(NAME, ARGS) \
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do { \
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void *const *ptr; \
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for (ptr = (void *const *) symbol_set_first_element (NAME); \
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! symbol_set_end_p (NAME, ptr); ++ptr) { \
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__##NAME##_hook_function_t *f = \
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(void*) ((uintptr_t) ptr + (ptrdiff_t) *ptr); \
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(*f) ARGS; \
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} \
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} while (0)
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# else
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# define SET_RELHOOK(NAME, HOOK) text_set_element (NAME, HOOK)
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# define RUN_RELHOOK(NAME, ARGS) RUN_HOOK(NAME, ARGS)
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# endif
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#else
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/* The system does not provide necessary support for this. */
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# define DEFINE_HOOK(NAME, PROTO)
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# define DECLARE_HOOK(NAME, PROTO)
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# define RUN_HOOK(NAME, ARGS)
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# define DEFINE_HOOK_RUNNER(name, runner, proto, args)
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# define SET_RELHOOK(NAME, HOOK)
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# define RUN_RELHOOK(NAME, ARGS)
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#endif
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#endif /* set-hooks.h */
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