aarch64: Move and update the definition of MTE_ENABLED
[glibc.git] / elf / dl-sysdep.c
blob0658c17da632efa58a0c2068039ea3adbf26a88b
1 /* Operating system support for run-time dynamic linker. Generic Unix version.
2 Copyright (C) 1995-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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 <https://www.gnu.org/licenses/>. */
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. */
23 #ifdef SHARED
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>
40 #include <entry.h>
41 #include <dl-machine.h>
42 #include <dl-procinfo.h>
43 #include <dl-osinfo.h>
44 #include <libc-internal.h>
45 #include <tls.h>
47 #include <dl-tunables.h>
48 #include <dl-auxv.h>
50 extern char **_environ attribute_hidden;
51 extern char _end[] attribute_hidden;
53 /* Protect SUID program against misuse of file descriptors. */
54 extern void __libc_check_standard_fds (void);
56 #ifdef NEED_DL_BASE_ADDR
57 ElfW(Addr) _dl_base_addr;
58 #endif
59 int __libc_enable_secure attribute_relro = 0;
60 rtld_hidden_data_def (__libc_enable_secure)
61 /* This variable contains the lowest stack address ever used. */
62 void *__libc_stack_end attribute_relro = NULL;
63 rtld_hidden_data_def(__libc_stack_end)
64 void *_dl_random attribute_relro = NULL;
66 #ifndef DL_FIND_ARG_COMPONENTS
67 # define DL_FIND_ARG_COMPONENTS(cookie, argc, argv, envp, auxp) \
68 do { \
69 void **_tmp; \
70 (argc) = *(long int *) cookie; \
71 (argv) = (char **) ((long int *) cookie + 1); \
72 (envp) = (argv) + (argc) + 1; \
73 for (_tmp = (void **) (envp); *_tmp; ++_tmp) \
74 continue; \
75 (auxp) = (void *) ++_tmp; \
76 } while (0)
77 #endif
79 #ifndef DL_STACK_END
80 # define DL_STACK_END(cookie) ((void *) (cookie))
81 #endif
83 ElfW(Addr)
84 _dl_sysdep_start (void **start_argptr,
85 void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
86 ElfW(Addr) *user_entry, ElfW(auxv_t) *auxv))
88 const ElfW(Phdr) *phdr = NULL;
89 ElfW(Word) phnum = 0;
90 ElfW(Addr) user_entry;
91 ElfW(auxv_t) *av;
92 #ifdef HAVE_AUX_SECURE
93 # define set_seen(tag) (tag) /* Evaluate for the side effects. */
94 # define set_seen_secure() ((void) 0)
95 #else
96 uid_t uid = 0;
97 gid_t gid = 0;
98 unsigned int seen = 0;
99 # define set_seen_secure() (seen = -1)
100 # ifdef HAVE_AUX_XID
101 # define set_seen(tag) (tag) /* Evaluate for the side effects. */
102 # else
103 # define M(type) (1 << (type))
104 # define set_seen(tag) seen |= M ((tag)->a_type)
105 # endif
106 #endif
107 #ifdef NEED_DL_SYSINFO
108 uintptr_t new_sysinfo = 0;
109 #endif
111 __libc_stack_end = DL_STACK_END (start_argptr);
112 DL_FIND_ARG_COMPONENTS (start_argptr, _dl_argc, _dl_argv, _environ,
113 GLRO(dl_auxv));
115 user_entry = (ElfW(Addr)) ENTRY_POINT;
116 GLRO(dl_platform) = NULL; /* Default to nothing known about the platform. */
118 for (av = GLRO(dl_auxv); av->a_type != AT_NULL; set_seen (av++))
119 switch (av->a_type)
121 case AT_PHDR:
122 phdr = (void *) av->a_un.a_val;
123 break;
124 case AT_PHNUM:
125 phnum = av->a_un.a_val;
126 break;
127 case AT_PAGESZ:
128 GLRO(dl_pagesize) = av->a_un.a_val;
129 break;
130 case AT_ENTRY:
131 user_entry = av->a_un.a_val;
132 break;
133 #ifdef NEED_DL_BASE_ADDR
134 case AT_BASE:
135 _dl_base_addr = av->a_un.a_val;
136 break;
137 #endif
138 #ifndef HAVE_AUX_SECURE
139 case AT_UID:
140 case AT_EUID:
141 uid ^= av->a_un.a_val;
142 break;
143 case AT_GID:
144 case AT_EGID:
145 gid ^= av->a_un.a_val;
146 break;
147 #endif
148 case AT_SECURE:
149 #ifndef HAVE_AUX_SECURE
150 seen = -1;
151 #endif
152 __libc_enable_secure = av->a_un.a_val;
153 break;
154 case AT_PLATFORM:
155 GLRO(dl_platform) = (void *) av->a_un.a_val;
156 break;
157 case AT_HWCAP:
158 GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
159 break;
160 case AT_HWCAP2:
161 GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
162 break;
163 case AT_CLKTCK:
164 GLRO(dl_clktck) = av->a_un.a_val;
165 break;
166 case AT_FPUCW:
167 GLRO(dl_fpu_control) = av->a_un.a_val;
168 break;
169 #ifdef NEED_DL_SYSINFO
170 case AT_SYSINFO:
171 new_sysinfo = av->a_un.a_val;
172 break;
173 #endif
174 #ifdef NEED_DL_SYSINFO_DSO
175 case AT_SYSINFO_EHDR:
176 GLRO(dl_sysinfo_dso) = (void *) av->a_un.a_val;
177 break;
178 #endif
179 case AT_RANDOM:
180 _dl_random = (void *) av->a_un.a_val;
181 break;
182 DL_PLATFORM_AUXV
185 #ifndef HAVE_AUX_SECURE
186 if (seen != -1)
188 /* Fill in the values we have not gotten from the kernel through the
189 auxiliary vector. */
190 # ifndef HAVE_AUX_XID
191 # define SEE(UID, var, uid) \
192 if ((seen & M (AT_##UID)) == 0) var ^= __get##uid ()
193 SEE (UID, uid, uid);
194 SEE (EUID, uid, euid);
195 SEE (GID, gid, gid);
196 SEE (EGID, gid, egid);
197 # endif
199 /* If one of the two pairs of IDs does not match this is a setuid
200 or setgid run. */
201 __libc_enable_secure = uid | gid;
203 #endif
205 #ifndef HAVE_AUX_PAGESIZE
206 if (GLRO(dl_pagesize) == 0)
207 GLRO(dl_pagesize) = __getpagesize ();
208 #endif
210 #ifdef NEED_DL_SYSINFO
211 if (new_sysinfo != 0)
213 # ifdef NEED_DL_SYSINFO_DSO
214 /* Only set the sysinfo value if we also have the vsyscall DSO. */
215 if (GLRO(dl_sysinfo_dso) != 0)
216 # endif
217 GLRO(dl_sysinfo) = new_sysinfo;
219 #endif
221 __tunables_init (_environ);
223 #ifdef DL_SYSDEP_INIT
224 DL_SYSDEP_INIT;
225 #endif
227 #ifdef DL_PLATFORM_INIT
228 DL_PLATFORM_INIT;
229 #endif
231 /* Determine the length of the platform name. */
232 if (GLRO(dl_platform) != NULL)
233 GLRO(dl_platformlen) = strlen (GLRO(dl_platform));
235 if (__sbrk (0) == _end)
236 /* The dynamic linker was run as a program, and so the initial break
237 starts just after our bss, at &_end. The malloc in dl-minimal.c
238 will consume the rest of this page, so tell the kernel to move the
239 break up that far. When the user program examines its break, it
240 will see this new value and not clobber our data. */
241 __sbrk (GLRO(dl_pagesize)
242 - ((_end - (char *) 0) & (GLRO(dl_pagesize) - 1)));
244 /* If this is a SUID program we make sure that FDs 0, 1, and 2 are
245 allocated. If necessary we are doing it ourself. If it is not
246 possible we stop the program. */
247 if (__builtin_expect (__libc_enable_secure, 0))
248 __libc_check_standard_fds ();
250 (*dl_main) (phdr, phnum, &user_entry, GLRO(dl_auxv));
251 return user_entry;
254 void
255 _dl_sysdep_start_cleanup (void)
259 void
260 _dl_show_auxv (void)
262 char buf[64];
263 ElfW(auxv_t) *av;
265 /* Terminate string. */
266 buf[63] = '\0';
268 /* The following code assumes that the AT_* values are encoded
269 starting from 0 with AT_NULL, 1 for AT_IGNORE, and all other values
270 close by (otherwise the array will be too large). In case we have
271 to support a platform where these requirements are not fulfilled
272 some alternative implementation has to be used. */
273 for (av = GLRO(dl_auxv); av->a_type != AT_NULL; ++av)
275 static const struct
277 const char label[22];
278 enum { unknown = 0, dec, hex, str, ignore } form : 8;
279 } auxvars[] =
281 [AT_EXECFD - 2] = { "EXECFD: ", dec },
282 [AT_EXECFN - 2] = { "EXECFN: ", str },
283 [AT_PHDR - 2] = { "PHDR: 0x", hex },
284 [AT_PHENT - 2] = { "PHENT: ", dec },
285 [AT_PHNUM - 2] = { "PHNUM: ", dec },
286 [AT_PAGESZ - 2] = { "PAGESZ: ", dec },
287 [AT_BASE - 2] = { "BASE: 0x", hex },
288 [AT_FLAGS - 2] = { "FLAGS: 0x", hex },
289 [AT_ENTRY - 2] = { "ENTRY: 0x", hex },
290 [AT_NOTELF - 2] = { "NOTELF: ", hex },
291 [AT_UID - 2] = { "UID: ", dec },
292 [AT_EUID - 2] = { "EUID: ", dec },
293 [AT_GID - 2] = { "GID: ", dec },
294 [AT_EGID - 2] = { "EGID: ", dec },
295 [AT_PLATFORM - 2] = { "PLATFORM: ", str },
296 [AT_HWCAP - 2] = { "HWCAP: ", hex },
297 [AT_CLKTCK - 2] = { "CLKTCK: ", dec },
298 [AT_FPUCW - 2] = { "FPUCW: ", hex },
299 [AT_DCACHEBSIZE - 2] = { "DCACHEBSIZE: 0x", hex },
300 [AT_ICACHEBSIZE - 2] = { "ICACHEBSIZE: 0x", hex },
301 [AT_UCACHEBSIZE - 2] = { "UCACHEBSIZE: 0x", hex },
302 [AT_IGNOREPPC - 2] = { "IGNOREPPC", ignore },
303 [AT_SECURE - 2] = { "SECURE: ", dec },
304 [AT_BASE_PLATFORM - 2] = { "BASE_PLATFORM: ", str },
305 [AT_SYSINFO - 2] = { "SYSINFO: 0x", hex },
306 [AT_SYSINFO_EHDR - 2] = { "SYSINFO_EHDR: 0x", hex },
307 [AT_RANDOM - 2] = { "RANDOM: 0x", hex },
308 [AT_HWCAP2 - 2] = { "HWCAP2: 0x", hex },
309 [AT_L1I_CACHESIZE - 2] = { "L1I_CACHESIZE: ", dec },
310 [AT_L1I_CACHEGEOMETRY - 2] = { "L1I_CACHEGEOMETRY: 0x", hex },
311 [AT_L1D_CACHESIZE - 2] = { "L1D_CACHESIZE: ", dec },
312 [AT_L1D_CACHEGEOMETRY - 2] = { "L1D_CACHEGEOMETRY: 0x", hex },
313 [AT_L2_CACHESIZE - 2] = { "L2_CACHESIZE: ", dec },
314 [AT_L2_CACHEGEOMETRY - 2] = { "L2_CACHEGEOMETRY: 0x", hex },
315 [AT_L3_CACHESIZE - 2] = { "L3_CACHESIZE: ", dec },
316 [AT_L3_CACHEGEOMETRY - 2] = { "L3_CACHEGEOMETRY: 0x", hex },
318 unsigned int idx = (unsigned int) (av->a_type - 2);
320 if ((unsigned int) av->a_type < 2u
321 || (idx < sizeof (auxvars) / sizeof (auxvars[0])
322 && auxvars[idx].form == ignore))
323 continue;
325 assert (AT_NULL == 0);
326 assert (AT_IGNORE == 1);
328 /* Some entries are handled in a special way per platform. */
329 if (_dl_procinfo (av->a_type, av->a_un.a_val) == 0)
330 continue;
332 if (idx < sizeof (auxvars) / sizeof (auxvars[0])
333 && auxvars[idx].form != unknown)
335 const char *val = (char *) av->a_un.a_val;
337 if (__builtin_expect (auxvars[idx].form, dec) == dec)
338 val = _itoa ((unsigned long int) av->a_un.a_val,
339 buf + sizeof buf - 1, 10, 0);
340 else if (__builtin_expect (auxvars[idx].form, hex) == hex)
341 val = _itoa ((unsigned long int) av->a_un.a_val,
342 buf + sizeof buf - 1, 16, 0);
344 _dl_printf ("AT_%s%s\n", auxvars[idx].label, val);
346 continue;
349 /* Unknown value: print a generic line. */
350 char buf2[17];
351 buf2[sizeof (buf2) - 1] = '\0';
352 const char *val2 = _itoa ((unsigned long int) av->a_un.a_val,
353 buf2 + sizeof buf2 - 1, 16, 0);
354 const char *val = _itoa ((unsigned long int) av->a_type,
355 buf + sizeof buf - 1, 16, 0);
356 _dl_printf ("AT_??? (0x%s): 0x%s\n", val, val2);
360 #endif