glibc/sysdeps/mach/hurd/dl-sysdep.c

/* Operating system support for run-time dynamic linker.  Hurd version.
   Copyright (C) 1995-2021 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

/* In the static library, this is all handled by dl-support.c
   or by the vanilla definitions in the rest of the C library.  */
#ifdef SHARED

#include <hurd.h>
#include <link.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <ldsodefs.h>
#include <sys/wait.h>
#include <assert.h>
#include <sysdep.h>
#include <mach/mig_support.h>
#include <mach/machine/vm_param.h>
#include "hurdstartup.h"
#include <hurd/lookup.h>
#include <hurd/auth.h>
#include <hurd/term.h>
#include <stdarg.h>
#include <ctype.h>
#include <sys/stat.h>
#include <sys/uio.h>

#include <entry.h>
#include <dl-machine.h>
#include <dl-procinfo.h>

#include <dl-tunables.h>
#include <not-errno.h>
#include <not-cancel.h>

extern void __mach_init (void);

extern int _dl_argc;
extern char **_dl_argv;
extern char **_environ;

int __libc_enable_secure = 0;
rtld_hidden_data_def (__libc_enable_secure)
/* This variable contains the lowest stack address ever used.  */
void *__libc_stack_end = NULL;
rtld_hidden_data_def(__libc_stack_end)

/* TODO: Initialize.  */
void *_dl_random attribute_relro = NULL;

struct hurd_startup_data *_dl_hurd_data;

#define FMH defined(__i386__)
#if ! FMH
# define fmh()		((void)0)
# define unfmh()	((void)0)
#else
/* XXX loser kludge for vm_map kernel bug, fixed by gnumach's 0650a4ee30e3 */
#undef	ELF_MACHINE_USER_ADDRESS_MASK
#define ELF_MACHINE_USER_ADDRESS_MASK	0
static vm_address_t fmha;
static vm_size_t fmhs;
static void unfmh(void){
__vm_deallocate(__mach_task_self(),fmha,fmhs);}
static void fmh(void) {
    error_t err;int x;vm_offset_t o;mach_port_t p;
    vm_address_t a=0x08000000U,max=VM_MAX_ADDRESS;
    while (!(err=__vm_region(__mach_task_self(),&a,&fmhs,&x,&x,&x,&x,&p,&o))){
      __mach_port_deallocate(__mach_task_self(),p);
      if (a+fmhs>=0x80000000U){
	max=a; break;}
      fmha=a+=fmhs;}
    if (err) assert(err==KERN_NO_SPACE);
    if (!fmha)fmhs=0;else{
    fmhs=max-fmha;
    err = __vm_map (__mach_task_self (),
		    &fmha, fmhs, 0, 0, MACH_PORT_NULL, 0, 1,
		    VM_PROT_NONE, VM_PROT_NONE, VM_INHERIT_COPY);
    assert_perror(err);}
  }
/* XXX loser kludge for vm_map kernel bug */
#endif


ElfW(Addr)
_dl_sysdep_start (void **start_argptr,
		  void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phent,
				   ElfW(Addr) *user_entry,
				   ElfW(auxv_t) *auxv))
{
  void go (intptr_t *argdata)
    {
      char *orig_argv0;
      char **p;

      /* Cache the information in various global variables.  */
      _dl_argc = *argdata;
      _dl_argv = 1 + (char **) argdata;
      _environ = &_dl_argv[_dl_argc + 1];
      for (p = _environ; *p++;); /* Skip environ pointers and terminator.  */

      orig_argv0 = _dl_argv[0];

      if ((void *) p == _dl_argv[0])
	{
	  static struct hurd_startup_data nodata;
	  _dl_hurd_data = &nodata;
	  nodata.user_entry = (vm_address_t) ENTRY_POINT;
	}
      else
	_dl_hurd_data = (void *) p;

      GLRO(dl_platform) = NULL; /* Default to nothing known about the platform.  */

      __libc_enable_secure = _dl_hurd_data->flags & EXEC_SECURE;

      __tunables_init (_environ);

#ifdef DL_SYSDEP_INIT
      DL_SYSDEP_INIT;
#endif

#ifdef SHARED
#ifdef DL_PLATFORM_INIT
      DL_PLATFORM_INIT;
#endif

      /* Determine the length of the platform name.  */
      if (GLRO(dl_platform) != NULL)
	GLRO(dl_platformlen) = strlen (GLRO(dl_platform));
#endif

      if (_dl_hurd_data->flags & EXEC_STACK_ARGS
	  && _dl_hurd_data->user_entry == 0)
	_dl_hurd_data->user_entry = (vm_address_t) ENTRY_POINT;

unfmh();			/* XXX */

#if 0				/* XXX make this work for real someday... */
      if (_dl_hurd_data->user_entry == (vm_address_t) ENTRY_POINT)
	/* We were invoked as a command, not as the program interpreter.
	   The generic ld.so code supports this: it will parse the args
	   as "ld.so PROGRAM [ARGS...]".  For booting the Hurd, we
	   support an additional special syntax:
	     ld.so [-LIBS...] PROGRAM [ARGS...]
	   Each LIBS word consists of "FILENAME=MEMOBJ";
	   for example "-/lib/libc.so=123" says that the contents of
	   /lib/libc.so are found in a memory object whose port name
	   in our task is 123.  */
	while (_dl_argc > 2 && _dl_argv[1][0] == '-' && _dl_argv[1][1] != '-')
	  {
	    char *lastslash, *memobjname, *p;
	    struct link_map *l;
	    mach_port_t memobj;
	    error_t err;

	    ++_dl_skip_args;
	    --_dl_argc;
	    p = _dl_argv++[1] + 1;

	    memobjname = strchr (p, '=');
	    if (! memobjname)
	      _dl_sysdep_fatal ("Bogus library spec: ", p, "\n", NULL);
	    *memobjname++ = '\0';
	    memobj = 0;
	    while (*memobjname != '\0')
	      memobj = (memobj * 10) + (*memobjname++ - '0');

	    /* Add a user reference on the memory object port, so we will
	       still have one after _dl_map_object_from_fd calls our
	       `close'.  */
	    err = __mach_port_mod_refs (__mach_task_self (), memobj,
					MACH_PORT_RIGHT_SEND, +1);
	    assert_perror (err);

	    lastslash = strrchr (p, '/');
	    l = _dl_map_object_from_fd (lastslash ? lastslash + 1 : p, NULL,
					memobj, strdup (p), 0);

	    /* Squirrel away the memory object port where it
	       can be retrieved by the program later.  */
	    l->l_info[DT_NULL] = (void *) memobj;
	  }
#endif

      /* Call elf/rtld.c's main program.  It will set everything
	 up and leave us to transfer control to USER_ENTRY.  */
      (*dl_main) ((const ElfW(Phdr) *) _dl_hurd_data->phdr,
		  _dl_hurd_data->phdrsz / sizeof (ElfW(Phdr)),
		  (ElfW(Addr) *) &_dl_hurd_data->user_entry, NULL);

      /* The call above might screw a few things up.

	 P is the location after the terminating NULL of the list of
	 environment variables.  It has to point to the Hurd startup
	 data or if that's missing then P == ARGV[0] must hold. The
	 startup code in init-first.c will get confused if this is not
	 the case, so we must rearrange things to make it so.  We'll
	 recompute P and move the Hurd data or the new ARGV[0] there.

	 Note: directly invoked ld.so can move arguments and env vars.

	 We use memmove, since the locations might overlap.  */

      char **newp;
      for (newp = _environ; *newp++;);

      if (newp != p || _dl_argv[0] != orig_argv0)
	{
	  if (orig_argv0 == (char *) p)
	    {
	      if ((char *) newp != _dl_argv[0])
		{
		  assert ((char *) newp < _dl_argv[0]);
		  _dl_argv[0] = memmove ((char *) newp, _dl_argv[0],
					 strlen (_dl_argv[0]) + 1);
		}
	    }
	  else
	    {
	      if ((void *) newp != _dl_hurd_data)
		memmove (newp, _dl_hurd_data, sizeof (*_dl_hurd_data));
	    }
	}

      {
	extern void _dl_start_user (void);
	/* Unwind the stack to ARGDATA and simulate a return from _dl_start
	   to the RTLD_START code which will run the user's entry point.  */
	RETURN_TO (argdata, &_dl_start_user, _dl_hurd_data->user_entry);
      }
    }

  /* Set up so we can do RPCs.  */
  __mach_init ();

  /* Initialize frequently used global variable.  */
  GLRO(dl_pagesize) = __getpagesize ();

fmh();				/* XXX */

  /* See hurd/hurdstartup.c; this deals with getting information
     from the exec server and slicing up the arguments.
     Then it will call `go', above.  */
  _hurd_startup (start_argptr, &go);

  LOSE;
  abort ();
}

void
_dl_sysdep_start_cleanup (void)
{
  /* Deallocate the reply port and task port rights acquired by
     __mach_init.  We are done with them now, and the user will
     reacquire them for himself when he wants them.  */
  __mig_dealloc_reply_port (MACH_PORT_NULL);
  __mach_port_deallocate (__mach_task_self (), __mach_host_self_);
  __mach_port_deallocate (__mach_task_self (), __mach_task_self_);
}

/* Minimal open/close/mmap/etc. implementation sufficient for initial loading of
   shared libraries.  These are weak definitions so that when the
   dynamic linker re-relocates itself to be user-visible (for -ldl),
   it will get the user's definition (i.e. usually libc's).

   They also need to be set in the libc and ld section of
   sysdeps/mach/hurd/Versions, to be overridable, and in libc.abilist and
   ld.abilist to be checked. */

/* This macro checks that the function does not get renamed to be hidden: we do
   need these to be overridable by libc's.  */
#define check_no_hidden(name)				\
  __typeof (name) __check_##name##_no_hidden		\
       __attribute__ ((alias (#name)))			\
       __attribute_copy__ (name);

/* Open FILE_NAME and return a Hurd I/O for it in *PORT, or return an
   error.  If STAT is non-zero, stat the file into that stat buffer.  */
static error_t
open_file (const char *file_name, int flags,
	   mach_port_t *port, struct stat64 *stat)
{
  enum retry_type doretry;
  char retryname[1024];		/* XXX string_t LOSES! */
  file_t startdir;
  error_t err;

  error_t use_init_port (int which, error_t (*operate) (file_t))
    {
      return (which < _dl_hurd_data->portarraysize
	      ? ((*operate) (_dl_hurd_data->portarray[which]))
	      : EGRATUITOUS);
    }
  file_t get_dtable_port (int fd)
    {
      if ((unsigned int) fd < _dl_hurd_data->dtablesize
	  && _dl_hurd_data->dtable[fd] != MACH_PORT_NULL)
	{
	  __mach_port_mod_refs (__mach_task_self (), _dl_hurd_data->dtable[fd],
				MACH_PORT_RIGHT_SEND, +1);
	  return _dl_hurd_data->dtable[fd];
	}
      errno = EBADF;
      return MACH_PORT_NULL;
    }

  assert (!(flags & ~(O_READ | O_CLOEXEC)));

  startdir = _dl_hurd_data->portarray[file_name[0] == '/'
				      ? INIT_PORT_CRDIR : INIT_PORT_CWDIR];

  while (file_name[0] == '/')
    file_name++;

  err = __dir_lookup (startdir, (char *)file_name, O_RDONLY, 0,
		      &doretry, retryname, port);

  if (!err)
    err = __hurd_file_name_lookup_retry (use_init_port, get_dtable_port,
					 __dir_lookup, doretry, retryname,
					 O_RDONLY, 0, port);
  if (!err && stat)
    {
      err = __io_stat (*port, stat);
      if (err)
	__mach_port_deallocate (__mach_task_self (), *port);
    }

  return err;
}

check_no_hidden(__open);
check_no_hidden (__open64);
check_no_hidden (__open_nocancel);
int weak_function
__open (const char *file_name, int mode, ...)
{
  mach_port_t port;
  error_t err = open_file (file_name, mode, &port, 0);
  if (err)
    return __hurd_fail (err);
  else
    return (int)port;
}
weak_alias (__open, __open64)
weak_alias (__open, __open_nocancel)

check_no_hidden(__close);
check_no_hidden(__close_nocancel);
int weak_function
__close (int fd)
{
  if (fd != (int) MACH_PORT_NULL)
    __mach_port_deallocate (__mach_task_self (), (mach_port_t) fd);
  return 0;
}
weak_alias (__close, __close_nocancel)

check_no_hidden(__pread64);
check_no_hidden(__pread64_nocancel);
__ssize_t weak_function
__pread64 (int fd, void *buf, size_t nbytes, off64_t offset)
{
  error_t err;
  char *data;
  mach_msg_type_number_t nread;

  data = buf;
  nread = nbytes;
  err = __io_read ((mach_port_t) fd, &data, &nread, offset, nbytes);
  if (err)
    return __hurd_fail (err);

  if (data != buf)
    {
      memcpy (buf, data, nread);
      __vm_deallocate (__mach_task_self (), (vm_address_t) data, nread);
    }

  return nread;
}
libc_hidden_weak (__pread64)
weak_alias (__pread64, __pread64_nocancel)

check_no_hidden(__read);
check_no_hidden(__read_nocancel);
__ssize_t weak_function
__read (int fd, void *buf, size_t nbytes)
{
  return __pread64 (fd, buf, nbytes, -1);
}
libc_hidden_weak (__read)
weak_alias (__read, __read_nocancel)

check_no_hidden(__write);
check_no_hidden(__write_nocancel);
__ssize_t weak_function
__write (int fd, const void *buf, size_t nbytes)
{
  error_t err;
  mach_msg_type_number_t nwrote;

  assert (fd < _hurd_init_dtablesize);

  err = __io_write (_hurd_init_dtable[fd], buf, nbytes, -1, &nwrote);
  if (err)
    return __hurd_fail (err);

  return nwrote;
}
libc_hidden_weak (__write)
  weak_alias (__write, __write_nocancel)

/* This is only used for printing messages (see dl-misc.c).  */
check_no_hidden(__writev);
__ssize_t weak_function
__writev (int fd, const struct iovec *iov, int niov)
{
  if (fd >= _hurd_init_dtablesize)
    {
      errno = EBADF;
      return -1;
    }

  int i;
  size_t total = 0;
  for (i = 0; i < niov; ++i)
    total += iov[i].iov_len;

  if (total != 0)
    {
      char buf[total], *bufp = buf;
      error_t err;
      mach_msg_type_number_t nwrote;

      for (i = 0; i < niov; ++i)
	bufp = (memcpy (bufp, iov[i].iov_base, iov[i].iov_len)
		+ iov[i].iov_len);

      err = __io_write (_hurd_init_dtable[fd], buf, total, -1, &nwrote);
      if (err)
	return __hurd_fail (err);

      return nwrote;
    }
  return 0;
}

check_no_hidden(__libc_lseek64);
off64_t weak_function
__libc_lseek64 (int fd, off64_t offset, int whence)
{
  error_t err;

  err = __io_seek ((mach_port_t) fd, offset, whence, &offset);
  if (err)
    return __hurd_fail (err);

  return offset;
}

check_no_hidden(__mmap);
void *weak_function
__mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset)
{
  error_t err;
  vm_prot_t vmprot;
  vm_address_t mapaddr;
  mach_port_t memobj_rd, memobj_wr;

  vmprot = VM_PROT_NONE;
  if (prot & PROT_READ)
    vmprot |= VM_PROT_READ;
  if (prot & PROT_WRITE)
    vmprot |= VM_PROT_WRITE;
  if (prot & PROT_EXEC)
    vmprot |= VM_PROT_EXECUTE;

  if (flags & MAP_ANON)
    memobj_rd = MACH_PORT_NULL;
  else
    {
      assert (!(flags & MAP_SHARED));
      err = __io_map ((mach_port_t) fd, &memobj_rd, &memobj_wr);
      if (err)
	return __hurd_fail (err), MAP_FAILED;
      if (memobj_wr != MACH_PORT_NULL)
	__mach_port_deallocate (__mach_task_self (), memobj_wr);
    }

  mapaddr = (vm_address_t) addr;
  err = __vm_map (__mach_task_self (),
		  &mapaddr, (vm_size_t) len, ELF_MACHINE_USER_ADDRESS_MASK,
		  !(flags & MAP_FIXED),
		  memobj_rd,
		  (vm_offset_t) offset,
		  flags & (MAP_COPY|MAP_PRIVATE),
		  vmprot, VM_PROT_ALL,
		  (flags & MAP_SHARED) ? VM_INHERIT_SHARE : VM_INHERIT_COPY);
  if (err == KERN_NO_SPACE && (flags & MAP_FIXED))
    {
      /* XXX this is not atomic as it is in unix! */
      /* The region is already allocated; deallocate it first.  */
      err = __vm_deallocate (__mach_task_self (), mapaddr, len);
      if (! err)
	err = __vm_map (__mach_task_self (),
			&mapaddr, (vm_size_t) len,
			ELF_MACHINE_USER_ADDRESS_MASK,
			!(flags & MAP_FIXED),
			memobj_rd, (vm_offset_t) offset,
			flags & (MAP_COPY|MAP_PRIVATE),
			vmprot, VM_PROT_ALL,
			(flags & MAP_SHARED)
			? VM_INHERIT_SHARE : VM_INHERIT_COPY);
    }

  if ((flags & MAP_ANON) == 0)
    __mach_port_deallocate (__mach_task_self (), memobj_rd);

  if (err)
    return __hurd_fail (err), MAP_FAILED;
  return (void *) mapaddr;
}

check_no_hidden(__fstat64);
int weak_function
__fstat64 (int fd, struct stat64 *buf)
{
  error_t err;

  err = __io_stat ((mach_port_t) fd, buf);
  if (err)
    return __hurd_fail (err);

  return 0;
}
libc_hidden_def (__fstat64)

check_no_hidden(__stat64);
int weak_function
__stat64 (const char *file, struct stat64 *buf)
{
  error_t err;
  mach_port_t port;

  err = open_file (file, 0, &port, buf);
  if (err)
    return __hurd_fail (err);

  __mach_port_deallocate (__mach_task_self (), port);

  return 0;
}
libc_hidden_def (__stat64)

/* This function is called by the dynamic linker (rtld.c) to check
   whether debugging malloc is allowed even for SUID binaries.  This
   stub will always fail, which means that malloc-debugging is always
   disabled for SUID binaries.  */
check_no_hidden(__access);
int weak_function
__access (const char *file, int type)
{
  errno = ENOSYS;
  return -1;
}
check_no_hidden(__access_noerrno);
int weak_function
__access_noerrno (const char *file, int type)
{
  return -1;
}

check_no_hidden(__getpid);
pid_t weak_function
__getpid (void)
{
  pid_t pid, ppid;
  int orphaned;

  if (__proc_getpids (_dl_hurd_data->portarray[INIT_PORT_PROC],
		      &pid, &ppid, &orphaned))
    return -1;

  return pid;
}

/* We need this alias to satisfy references from libc_pic.a objects
   that were affected by the libc_hidden_proto declaration for __getpid.  */
strong_alias (__getpid, __GI___getpid)

/* This is called only in some strange cases trying to guess a value
   for $ORIGIN for the executable.  The dynamic linker copes with
   getcwd failing (dl-object.c), and it's too much hassle to include
   the functionality here.  (We could, it just requires duplicating or
   reusing getcwd.c's code but using our special lookup function as in
   `open', above.)  */
check_no_hidden(__getcwd);
char *weak_function
__getcwd (char *buf, size_t size)
{
  errno = ENOSYS;
  return NULL;
}

/* This is used by dl-tunables.c to strdup strings.  We can just make this a
   mere allocation.  */
check_no_hidden(__sbrk);
void *weak_function
__sbrk (intptr_t increment)
{
  vm_address_t addr;
  __vm_allocate (__mach_task_self (), &addr, increment, 1);
  return (void *) addr;
}

/* This is only used by hurdlookup for the /dev/fd/nnn magic.
 * We avoid pulling the whole libc implementation, and we can keep this hidden.  */
unsigned long int weak_function
__strtoul_internal (const char *nptr, char **endptr, int base, int group)
{
  assert (base == 0 || base == 10);
  assert (group == 0);
  return _dl_strtoul (nptr, endptr);
}

/* We need this alias to satisfy references from libc_pic.a objects
   that were affected by the libc_hidden_proto declaration for __strtoul_internal.  */
strong_alias (__strtoul_internal, __GI___strtoul_internal)
strong_alias (__strtoul_internal, __GI_____strtoul_internal)

check_no_hidden(_exit);
void weak_function attribute_hidden
_exit (int status)
{
  __proc_mark_exit (_dl_hurd_data->portarray[INIT_PORT_PROC],
		    W_EXITCODE (status, 0), 0);
  while (__task_terminate (__mach_task_self ()))
    __mach_task_self_ = (__mach_task_self) ();

  LOSE;
  abort ();
}
/* We need this alias to satisfy references from libc_pic.a objects
   that were affected by the libc_hidden_proto declaration for _exit.  */
strong_alias (_exit, __GI__exit)

/* 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

check_no_hidden(abort);
void weak_function
abort (void)
{
  /* Try to abort using the system specific command.  */
  ABORT_INSTRUCTION;

  /* If the abort instruction failed, exit.  */
  _exit (127);

  /* If even this fails, make sure we never return.  */
  while (1)
    /* Try for ever and ever.  */
    ABORT_INSTRUCTION;
}

/* We need this alias to satisfy references from libc_pic.a objects
   that were affected by the libc_hidden_proto declaration for abort.  */
strong_alias (abort, __GI_abort)
strong_alias (abort, __GI___fortify_fail)
strong_alias (abort, __GI___assert_fail)
strong_alias (abort, __GI___assert_perror_fail)

/* This function is called by interruptible RPC stubs.  For initial
   dynamic linking, just use the normal mach_msg.  Since this defn is
   weak, the real defn in libc.so will override it if we are linked into
   the user program (-ldl).  */

error_t weak_function
_hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
			 mach_msg_option_t option,
			 mach_msg_size_t send_size,
			 mach_msg_size_t rcv_size,
			 mach_port_t rcv_name,
			 mach_msg_timeout_t timeout,
			 mach_port_t notify)
{
  return __mach_msg (msg, option, send_size, rcv_size, rcv_name,
		     timeout, notify);
}


void
_dl_show_auxv (void)
{
  /* There is nothing to print.  Hurd has no auxiliary vector.  */
}


void weak_function
_dl_init_first (int argc, ...)
{
  /* This no-op definition only gets used if libc is not linked in.  */
}

#endif /* SHARED */