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8e1472d2c1
GLRO (_rtld_global_ro) is read-only after initialization and can therefore not be patched at run time, unlike the hook table addresses and their contents, so this is a desirable hardening feature. The hooks are only needed if ld.so has not been initialized, and this happens only after static dlopen (dlmopen uses a single ld.so object across all namespaces). Reviewed-by: Carlos O'Donell <carlos@redhat.com>
80 lines
2.2 KiB
C
80 lines
2.2 KiB
C
/* Load a shared object at run time.
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Copyright (C) 1995-2017 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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<http://www.gnu.org/licenses/>. */
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#include <dlfcn.h>
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#include <stddef.h>
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#include <unistd.h>
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#include <ldsodefs.h>
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/* This file is for compatibility with glibc 2.0. Compile it only if
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versioning is used. */
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#include <shlib-compat.h>
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#if SHLIB_COMPAT (libdl, GLIBC_2_0, GLIBC_2_1)
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struct dlopen_args
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{
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/* The arguments for dlopen_doit. */
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const char *file;
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int mode;
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/* The return value of dlopen_doit. */
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void *new;
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/* Address of the caller. */
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const void *caller;
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};
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/* Non-shared code has no support for multiple namespaces. */
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#ifdef SHARED
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# define NS __LM_ID_CALLER
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#else
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# define NS LM_ID_BASE
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#endif
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static void
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dlopen_doit (void *a)
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{
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struct dlopen_args *args = (struct dlopen_args *) a;
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args->new = GLRO(dl_open) (args->file ?: "", args->mode | __RTLD_DLOPEN,
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args->caller,
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args->file == NULL ? LM_ID_BASE : NS,
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__dlfcn_argc, __dlfcn_argv, __environ);
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}
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extern void *__dlopen_nocheck (const char *file, int mode);
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void *
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__dlopen_nocheck (const char *file, int mode)
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{
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struct dlopen_args args;
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args.file = file;
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args.caller = RETURN_ADDRESS (0);
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if ((mode & RTLD_BINDING_MASK) == 0)
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/* By default assume RTLD_LAZY. */
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mode |= RTLD_LAZY;
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args.mode = mode;
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if (!rtld_active ())
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return _dlfcn_hook->dlopen (file, mode, RETURN_ADDRESS (0));
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return _dlerror_run (dlopen_doit, &args) ? NULL : args.new;
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}
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compat_symbol (libdl, __dlopen_nocheck, dlopen, GLIBC_2_0);
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#endif
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