121 lines
3.6 KiB
C
121 lines
3.6 KiB
C
/* Copyright (C) 1998, 1999 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <errno.h>
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#include <fcntl.h>
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#include <paths.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/ioctl.h>
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#include <elf/ldsodefs.h>
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extern void __libc_init_first (int argc, char **argv, char **envp);
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extern int _dl_starting_up;
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weak_extern (_dl_starting_up)
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extern int __libc_multiple_libcs;
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extern void *__libc_stack_end;
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/* Prototype for local function. */
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static void check_standard_fds (void);
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int
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__libc_start_main (int (*main) (int, char **, char **), int argc,
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char **argv, void (*init) (void), void (*fini) (void),
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void (*rtld_fini) (void), void *stack_end)
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{
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#ifndef PIC
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/* The next variable is only here to work around a bug in gcc <= 2.7.2.2.
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If the address would be taken inside the expression the optimizer
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would try to be too smart and throws it away. Grrr. */
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int *dummy_addr = &_dl_starting_up;
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__libc_multiple_libcs = dummy_addr && !_dl_starting_up;
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#endif
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/* Store the lowest stack address. */
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__libc_stack_end = stack_end;
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/* Set the global _environ variable correctly. */
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__environ = &argv[argc + 1];
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/* Some security at this point. Prevent starting a SUID binary where
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the standard file descriptors are not opened. */
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if (__libc_enable_secure)
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check_standard_fds ();
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/* Register the destructor of the dynamic linker if there is any. */
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if (rtld_fini != NULL)
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atexit (rtld_fini);
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/* Call the initializer of the libc. */
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#ifdef PIC
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if (_dl_debug_impcalls)
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_dl_debug_message (1, "\ninitialize libc\n\n", NULL);
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#endif
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__libc_init_first (argc, argv, __environ);
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/* Register the destructor of the program, if any. */
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if (fini)
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atexit (fini);
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/* Call the initializer of the program, if any. */
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#ifdef PIC
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if (_dl_debug_impcalls)
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_dl_debug_message (1, "\ninitialize program: ", argv[0], "\n\n", NULL);
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#endif
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if (init)
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(*init) ();
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#ifdef PIC
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if (_dl_debug_impcalls)
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_dl_debug_message (1, "\ntransferring control: ", argv[0], "\n\n", NULL);
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#endif
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exit ((*main) (argc, argv, __environ));
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}
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/* Should other OSes (e.g., Hurd) have different versions which can
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be written in a better way? */
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static void
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check_one_fd (int fd, int mode)
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{
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if (__libc_fcntl (fd, F_GETFD) == -1 && errno == EBADF)
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{
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/* Something is wrong with this descriptor, it's probably not
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opened. Open /dev/null so that the SUID program we are
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about to start does not accidently use this descriptor. */
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int nullfd = __libc_open (_PATH_DEVNULL, mode);
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if (nullfd == -1)
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/* We cannot even given an error message here since it would
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run into the same problems. */
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abort ();
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}
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}
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static void
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check_standard_fds (void)
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{
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/* Check all three standard file descriptors. */
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check_one_fd (STDIN_FILENO, O_RDONLY);
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check_one_fd (STDOUT_FILENO, O_RDWR);
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check_one_fd (STDERR_FILENO, O_RDWR);
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}
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