1/* Operating system support for run-time dynamic linker. Generic Unix version.
2 Copyright (C) 1995-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19/* We conditionalize the whole of this file rather than simply eliding it
20 from the static build, because other sysdeps/ versions of this file
21 might define things needed by a static build. */
22
23#ifdef SHARED
24
25#include <assert.h>
26#include <elf.h>
27#include <errno.h>
28#include <fcntl.h>
29#include <libintl.h>
30#include <stdlib.h>
31#include <string.h>
32#include <unistd.h>
33#include <sys/types.h>
34#include <sys/stat.h>
35#include <sys/mman.h>
36#include <ldsodefs.h>
37#include <_itoa.h>
38#include <fpu_control.h>
39
40#include <entry.h>
41#include <dl-machine.h>
42#include <dl-procinfo.h>
43#include <dl-osinfo.h>
44#include <hp-timing.h>
45#include <tls.h>
46
47extern char **_environ attribute_hidden;
48extern char _end[] attribute_hidden;
49
50/* Protect SUID program against misuse of file descriptors. */
51extern void __libc_check_standard_fds (void);
52
53#ifdef NEED_DL_BASE_ADDR
54ElfW(Addr) _dl_base_addr;
55#endif
56int __libc_enable_secure attribute_relro = 0;
57rtld_hidden_data_def (__libc_enable_secure)
58int __libc_multiple_libcs = 0; /* Defining this here avoids the inclusion
59 of init-first. */
60/* This variable contains the lowest stack address ever used. */
61void *__libc_stack_end attribute_relro = NULL;
62rtld_hidden_data_def(__libc_stack_end)
63void *_dl_random attribute_relro = NULL;
64
65#ifndef DL_FIND_ARG_COMPONENTS
66# define DL_FIND_ARG_COMPONENTS(cookie, argc, argv, envp, auxp) \
67 do { \
68 void **_tmp; \
69 (argc) = *(long int *) cookie; \
70 (argv) = (char **) ((long int *) cookie + 1); \
71 (envp) = (argv) + (argc) + 1; \
72 for (_tmp = (void **) (envp); *_tmp; ++_tmp) \
73 continue; \
74 (auxp) = (void *) ++_tmp; \
75 } while (0)
76#endif
77
78#ifndef DL_STACK_END
79# define DL_STACK_END(cookie) ((void *) (cookie))
80#endif
81
82ElfW(Addr)
83_dl_sysdep_start (void **start_argptr,
84 void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
85 ElfW(Addr) *user_entry, ElfW(auxv_t) *auxv))
86{
87 const ElfW(Phdr) *phdr = NULL;
88 ElfW(Word) phnum = 0;
89 ElfW(Addr) user_entry;
90 ElfW(auxv_t) *av;
91#ifdef HAVE_AUX_SECURE
92# define set_seen(tag) (tag) /* Evaluate for the side effects. */
93# define set_seen_secure() ((void) 0)
94#else
95 uid_t uid = 0;
96 gid_t gid = 0;
97 unsigned int seen = 0;
98# define set_seen_secure() (seen = -1)
99# ifdef HAVE_AUX_XID
100# define set_seen(tag) (tag) /* Evaluate for the side effects. */
101# else
102# define M(type) (1 << (type))
103# define set_seen(tag) seen |= M ((tag)->a_type)
104# endif
105#endif
106#ifdef NEED_DL_SYSINFO
107 uintptr_t new_sysinfo = 0;
108#endif
109
110 __libc_stack_end = DL_STACK_END (start_argptr);
111 DL_FIND_ARG_COMPONENTS (start_argptr, _dl_argc, _dl_argv, _environ,
112 GLRO(dl_auxv));
113
114 user_entry = (ElfW(Addr)) ENTRY_POINT;
115 GLRO(dl_platform) = NULL; /* Default to nothing known about the platform. */
116
117 for (av = GLRO(dl_auxv); av->a_type != AT_NULL; set_seen (av++))
118 switch (av->a_type)
119 {
120 case AT_PHDR:
121 phdr = (void *) av->a_un.a_val;
122 break;
123 case AT_PHNUM:
124 phnum = av->a_un.a_val;
125 break;
126 case AT_PAGESZ:
127 GLRO(dl_pagesize) = av->a_un.a_val;
128 break;
129 case AT_ENTRY:
130 user_entry = av->a_un.a_val;
131 break;
132#ifdef NEED_DL_BASE_ADDR
133 case AT_BASE:
134 _dl_base_addr = av->a_un.a_val;
135 break;
136#endif
137#ifndef HAVE_AUX_SECURE
138 case AT_UID:
139 case AT_EUID:
140 uid ^= av->a_un.a_val;
141 break;
142 case AT_GID:
143 case AT_EGID:
144 gid ^= av->a_un.a_val;
145 break;
146#endif
147 case AT_SECURE:
148#ifndef HAVE_AUX_SECURE
149 seen = -1;
150#endif
151 __libc_enable_secure = av->a_un.a_val;
152 break;
153 case AT_PLATFORM:
154 GLRO(dl_platform) = (void *) av->a_un.a_val;
155 break;
156 case AT_HWCAP:
157 GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
158 break;
159 case AT_HWCAP2:
160 GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
161 break;
162 case AT_CLKTCK:
163 GLRO(dl_clktck) = av->a_un.a_val;
164 break;
165 case AT_FPUCW:
166 GLRO(dl_fpu_control) = av->a_un.a_val;
167 break;
168#ifdef NEED_DL_SYSINFO
169 case AT_SYSINFO:
170 new_sysinfo = av->a_un.a_val;
171 break;
172#endif
173#ifdef NEED_DL_SYSINFO_DSO
174 case AT_SYSINFO_EHDR:
175 GLRO(dl_sysinfo_dso) = (void *) av->a_un.a_val;
176 break;
177#endif
178 case AT_RANDOM:
179 _dl_random = (void *) av->a_un.a_val;
180 break;
181#ifdef DL_PLATFORM_AUXV
182 DL_PLATFORM_AUXV
183#endif
184 }
185
186#ifndef HAVE_AUX_SECURE
187 if (seen != -1)
188 {
189 /* Fill in the values we have not gotten from the kernel through the
190 auxiliary vector. */
191# ifndef HAVE_AUX_XID
192# define SEE(UID, var, uid) \
193 if ((seen & M (AT_##UID)) == 0) var ^= __get##uid ()
194 SEE (UID, uid, uid);
195 SEE (EUID, uid, euid);
196 SEE (GID, gid, gid);
197 SEE (EGID, gid, egid);
198# endif
199
200 /* If one of the two pairs of IDs does not match this is a setuid
201 or setgid run. */
202 __libc_enable_secure = uid | gid;
203 }
204#endif
205
206#ifndef HAVE_AUX_PAGESIZE
207 if (GLRO(dl_pagesize) == 0)
208 GLRO(dl_pagesize) = __getpagesize ();
209#endif
210
211#ifdef NEED_DL_SYSINFO
212 if (new_sysinfo != 0)
213 {
214# ifdef NEED_DL_SYSINFO_DSO
215 /* Only set the sysinfo value if we also have the vsyscall DSO. */
216 if (GLRO(dl_sysinfo_dso) != 0)
217# endif
218 GLRO(dl_sysinfo) = new_sysinfo;
219 }
220#endif
221
222#ifdef DL_SYSDEP_INIT
223 DL_SYSDEP_INIT;
224#endif
225
226#ifdef DL_PLATFORM_INIT
227 DL_PLATFORM_INIT;
228#endif
229
230 /* Determine the length of the platform name. */
231 if (GLRO(dl_platform) != NULL)
232 GLRO(dl_platformlen) = strlen (GLRO(dl_platform));
233
234 if (__sbrk (0) == _end)
235 /* The dynamic linker was run as a program, and so the initial break
236 starts just after our bss, at &_end. The malloc in dl-minimal.c
237 will consume the rest of this page, so tell the kernel to move the
238 break up that far. When the user program examines its break, it
239 will see this new value and not clobber our data. */
240 __sbrk (GLRO(dl_pagesize)
241 - ((_end - (char *) 0) & (GLRO(dl_pagesize) - 1)));
242
243 /* If this is a SUID program we make sure that FDs 0, 1, and 2 are
244 allocated. If necessary we are doing it ourself. If it is not
245 possible we stop the program. */
246 if (__builtin_expect (__libc_enable_secure, 0))
247 __libc_check_standard_fds ();
248
249 (*dl_main) (phdr, phnum, &user_entry, GLRO(dl_auxv));
250 return user_entry;
251}
252
253void
254internal_function
255_dl_sysdep_start_cleanup (void)
256{
257}
258
259void
260internal_function
261_dl_show_auxv (void)
262{
263 char buf[64];
264 ElfW(auxv_t) *av;
265
266 /* Terminate string. */
267 buf[63] = '\0';
268
269 /* The following code assumes that the AT_* values are encoded
270 starting from 0 with AT_NULL, 1 for AT_IGNORE, and all other values
271 close by (otherwise the array will be too large). In case we have
272 to support a platform where these requirements are not fulfilled
273 some alternative implementation has to be used. */
274 for (av = GLRO(dl_auxv); av->a_type != AT_NULL; ++av)
275 {
276 static const struct
277 {
278 const char label[17];
279 enum { unknown = 0, dec, hex, str, ignore } form : 8;
280 } auxvars[] =
281 {
282 [AT_EXECFD - 2] = { "EXECFD: ", dec },
283 [AT_EXECFN - 2] = { "EXECFN: ", str },
284 [AT_PHDR - 2] = { "PHDR: 0x", hex },
285 [AT_PHENT - 2] = { "PHENT: ", dec },
286 [AT_PHNUM - 2] = { "PHNUM: ", dec },
287 [AT_PAGESZ - 2] = { "PAGESZ: ", dec },
288 [AT_BASE - 2] = { "BASE: 0x", hex },
289 [AT_FLAGS - 2] = { "FLAGS: 0x", hex },
290 [AT_ENTRY - 2] = { "ENTRY: 0x", hex },
291 [AT_NOTELF - 2] = { "NOTELF: ", hex },
292 [AT_UID - 2] = { "UID: ", dec },
293 [AT_EUID - 2] = { "EUID: ", dec },
294 [AT_GID - 2] = { "GID: ", dec },
295 [AT_EGID - 2] = { "EGID: ", dec },
296 [AT_PLATFORM - 2] = { "PLATFORM: ", str },
297 [AT_HWCAP - 2] = { "HWCAP: ", hex },
298 [AT_CLKTCK - 2] = { "CLKTCK: ", dec },
299 [AT_FPUCW - 2] = { "FPUCW: ", hex },
300 [AT_DCACHEBSIZE - 2] = { "DCACHEBSIZE: 0x", hex },
301 [AT_ICACHEBSIZE - 2] = { "ICACHEBSIZE: 0x", hex },
302 [AT_UCACHEBSIZE - 2] = { "UCACHEBSIZE: 0x", hex },
303 [AT_IGNOREPPC - 2] = { "IGNOREPPC", ignore },
304 [AT_SECURE - 2] = { "SECURE: ", dec },
305 [AT_BASE_PLATFORM - 2] = { "BASE_PLATFORM:", str },
306 [AT_SYSINFO - 2] = { "SYSINFO: 0x", hex },
307 [AT_SYSINFO_EHDR - 2] = { "SYSINFO_EHDR: 0x", hex },
308 [AT_RANDOM - 2] = { "RANDOM: 0x", hex },
309 [AT_HWCAP2 - 2] = { "HWCAP2: 0x", hex },
310 };
311 unsigned int idx = (unsigned int) (av->a_type - 2);
312
313 if ((unsigned int) av->a_type < 2u
314 || (idx < sizeof (auxvars) / sizeof (auxvars[0])
315 && auxvars[idx].form == ignore))
316 continue;
317
318 assert (AT_NULL == 0);
319 assert (AT_IGNORE == 1);
320
321 if (av->a_type == AT_HWCAP || av->a_type == AT_HWCAP2)
322 {
323 /* These are handled in a special way per platform. */
324 if (_dl_procinfo (av->a_type, av->a_un.a_val) == 0)
325 continue;
326 }
327
328 if (idx < sizeof (auxvars) / sizeof (auxvars[0])
329 && auxvars[idx].form != unknown)
330 {
331 const char *val = (char *) av->a_un.a_val;
332
333 if (__builtin_expect (auxvars[idx].form, dec) == dec)
334 val = _itoa ((unsigned long int) av->a_un.a_val,
335 buf + sizeof buf - 1, 10, 0);
336 else if (__builtin_expect (auxvars[idx].form, hex) == hex)
337 val = _itoa ((unsigned long int) av->a_un.a_val,
338 buf + sizeof buf - 1, 16, 0);
339
340 _dl_printf ("AT_%s%s\n", auxvars[idx].label, val);
341
342 continue;
343 }
344
345 /* Unknown value: print a generic line. */
346 char buf2[17];
347 buf2[sizeof (buf2) - 1] = '\0';
348 const char *val2 = _itoa ((unsigned long int) av->a_un.a_val,
349 buf2 + sizeof buf2 - 1, 16, 0);
350 const char *val = _itoa ((unsigned long int) av->a_type,
351 buf + sizeof buf - 1, 16, 0);
352 _dl_printf ("AT_??? (0x%s): 0x%s\n", val, val2);
353 }
354}
355
356#endif
357