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| -rw-r--r-- | ChangeLog | 3 | ||||
| -rw-r--r-- | sysdeps/mach/hurd/check_fds.c | 108 |
2 files changed, 111 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog index f178cc0398..b8c16bdf1f 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,8 @@ 2000-07-10 Mark Kettenis <kettenis@gnu.org> + * sysdeps/mach/hurd/check_fds.c: New file. Implements + file descriptor checking in SUID programs for the Hurd. + * resolv/nss_dns/dns-host.c (_nss_dns_gethostbyname2_r): Use res_hostalias instead of __hostalias for thread-safety. diff --git a/sysdeps/mach/hurd/check_fds.c b/sysdeps/mach/hurd/check_fds.c new file mode 100644 index 0000000000..9aa5bad62b --- /dev/null +++ b/sysdeps/mach/hurd/check_fds.c @@ -0,0 +1,108 @@ +/* Copyright (C) 2000 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <fcntl.h> +#include <paths.h> +#include <unistd.h> + +#include <hurd.h> +#include <hurd/fd.h> + +#include <set-hooks.h> + +/* Try to get a machine dependent instruction which will make the + program crash. This is used in case everything else fails. */ +#include <abort-instr.h> +#ifndef ABORT_INSTRUCTION +/* No such instruction is available. */ +# define ABORT_INSTRUCTION +#endif + +static void +check_one_fd (int fd, int mode) +{ + struct hurd_fd *d; + + d = _hurd_fd_get (fd); + if (d == NULL) + { + /* This descriptor hasn't been opened. We try to allocate the + descriptor and open /dev/null on it so that the SUID program + we are about to start does not accidently use this + descriptor. */ + d = _hurd_alloc_fd (NULL, fd); + if (d != NULL) + { + mach_port_t port; + + port = __file_name_lookup (_PATH_DEVNULL, mode, 0); + if (port) + { + /* Since /dev/null isn't supposed to be a terminal, we + avoid any ctty magic. */ + d->port.port = port; + d->flags = 0; + + __spin_unlock (&d->port.lock); + return; + } + } + + /* We cannot even give an error message here since it would run + into the same problems. */ + while (1) + /* Try for ever and ever. */ + ABORT_INSTRUCTION; + } +} + +static void +check_standard_fds (void) +{ + /* Check all three standard file descriptors. */ + check_one_fd (STDIN_FILENO, O_RDONLY); + check_one_fd (STDOUT_FILENO, O_RDWR); + check_one_fd (STDERR_FILENO, O_RDWR); +} + +static void +init_standard_fds (void) +{ + /* Now that we have FDs, make sure that, if this is a SUID program, + FDs 0, 1 and 2 are allocated. If necessary we'll set them up + ourselves. If that's not possible we stop the program. */ + if (__builtin_expect (__libc_enable_secure, 0)) + check_standard_fds (); + + (void) &init_standard_fds; /* Avoid "defined but not used" warning. */ +} +text_set_element (_hurd_fd_subinit, init_standard_fds); + + +#ifndef SHARED +void +__libc_check_standard_fds (void) +{ + /* We don't check the standard file descriptors here. They will be + checked when we initialize the file descriptor table, as part of + the _hurd_fd_subinit hook. + + This function is only present to make sure that this module gets + linked in when part of the static libc. */ +} +#endif |