summary refs log tree commit diff
path: root/sysdeps/generic/dl-sysdep.c
blob: 36349a5658dc63a7c845c9fa1a1def9096c5ac11 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
/* Operating system support for run-time dynamic linker.  Generic Unix version.
Copyright (C) 1995, 96 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., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <elf.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <link.h>
#include <unistd.h>
#include <stdarg.h>
#include <string.h>


extern int _dl_argc;
extern char **_dl_argv;
extern char **_environ;
extern void _start (void);

int __libc_enable_secure;

ElfW(Addr)
_dl_sysdep_start (void **start_argptr,
		  void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
				   ElfW(Addr) *user_entry))
{
  const ElfW(Phdr) *phdr;
  ElfW(Word) phnum;
  ElfW(Addr) user_entry;
  ElfW(auxv_t) *av;
  uid_t uid, euid;
  gid_t gid, egid;
  unsigned int seen;

  user_entry = (ElfW(Addr)) &_start;
  _dl_argc = *(long *) start_argptr;
  _dl_argv = (char **) start_argptr + 1;
  _environ = &_dl_argv[_dl_argc + 1];
  start_argptr = (void **) _environ;
  while (*start_argptr)
    ++start_argptr;

  seen = 0;
#define M(type) (1 << (type))

  for (av = (void *) ++start_argptr;
       av->a_type != AT_NULL;
       seen |= M ((++av)->a_type))
    switch (av->a_type)
      {
      case AT_PHDR:
	phdr = av->a_un.a_ptr;
	break;
      case AT_PHNUM:
	phnum = av->a_un.a_val;
	break;
      case AT_ENTRY:
	user_entry = av->a_un.a_val;
	break;
      case AT_UID:
	uid = av->a_un.a_val;
	break;
      case AT_GID:
	gid = av->a_un.a_val;
	break;
      case AT_EUID:
	euid = av->a_un.a_val;
	break;
      case AT_EGID:
	egid = av->a_un.a_val;
	break;
      }

  /* Linux doesn't provide us with any of these values on the stack
     when the dynamic linker is run directly as a program.  */

#define SEE(UID, uid) if ((seen & M (AT_##UID)) == 0) uid = __get##uid ()
  SEE (UID, uid);
  SEE (GID, gid);
  SEE (EUID, euid);
  SEE (EGID, egid);


  __libc_enable_secure = uid != euid || gid != egid;

#ifdef DL_SYSDEP_INIT
  DL_SYSDEP_INIT;
#endif

  (*dl_main) (phdr, phnum, &user_entry);
  return user_entry;
}

void
_dl_sysdep_start_cleanup (void)
{
}

#ifndef MAP_ANON
/* This is only needed if the system doesn't support MAP_ANON.  */

int
_dl_sysdep_open_zero_fill (void)
{
  return __open ("/dev/zero", O_RDONLY);
}
#endif

/* Read the whole contents of FILE into new mmap'd space with given
   protections.  *SIZEP gets the size of the file.  */

void *
_dl_sysdep_read_whole_file (const char *file, size_t *sizep, int prot)
{
  void *result;
  struct stat st;
  int fd = __open (file, O_RDONLY);
  if (fd < 0)
    return NULL;
  if (__fstat (fd, &st) < 0)
    result = NULL;
  else
    {
      /* Map a copy of the file contents.  */
      result = __mmap (0, st.st_size, prot,
#ifdef MAP_COPY
		       MAP_COPY
#else
		       MAP_PRIVATE
#endif
#ifdef MAP_FILE
		       | MAP_FILE
#endif
		       , fd, 0);
      if (result == (void *) -1)
	result = NULL;
      else
	*sizep = st.st_size;
    }
  __close (fd);
  return result;
}

void
_dl_sysdep_fatal (const char *msg, ...)
{
  va_list ap;

  va_start (ap, msg);
  do
    {
      size_t len = strlen (msg);
      __write (STDERR_FILENO, msg, len);
      msg = va_arg (ap, const char *);
    } while (msg);
  va_end (ap);

  _exit (127);
}


void
_dl_sysdep_message (const char *msg, ...)
{
  va_list ap;

  va_start (ap, msg);
  do
    {
      size_t len = strlen (msg);
      __write (STDOUT_FILENO, msg, len);
      msg = va_arg (ap, const char *);
    } while (msg);
  va_end (ap);
}