1 /* $OpenBSD: init.c,v 1.8 2020/07/06 13:33:05 pirofti Exp $ */ 2 /* 3 * Copyright (c) 2014,2015 Philip Guenther <guenther@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 19 #define _DYN_LOADER 20 21 #include <sys/types.h> 22 #include <sys/syscall.h> 23 #include <sys/timetc.h> /* timekeep */ 24 25 #ifndef PIC 26 #include <sys/mman.h> 27 #endif 28 29 #include <tib.h> 30 #include <limits.h> /* NAME_MAX */ 31 #include <link.h> 32 #include <stdlib.h> /* atexit */ 33 #include <string.h> 34 #include <unistd.h> 35 36 #include "init.h" 37 38 #define MAX(a,b) (((a)>(b))?(a):(b)) 39 40 #ifdef TIB_EXTRA_ALIGN 41 # define TIB_ALIGN MAX(__alignof__(struct tib), TIB_EXTRA_ALIGN) 42 #else 43 # define TIB_ALIGN __alignof__(struct tib) 44 #endif 45 46 /* XXX should be in an include file shared with csu */ 47 char ***_csu_finish(char **_argv, char **_envp, void (*_cleanup)(void)); 48 49 /* provide definitions for these */ 50 int _pagesize = 0; 51 struct timekeep *_timekeep; 52 53 /* 54 * In dynamicly linked binaries environ and __progname are overriden by 55 * the definitions in ld.so. 56 */ 57 char **environ __attribute__((weak)) = NULL; 58 char *__progname __attribute__((weak)) = NULL; 59 60 61 #ifndef PIC 62 struct dl_phdr_info _static_phdr_info __relro = { .dlpi_name = "a.out" }; 63 64 static inline void early_static_init(char **_argv, char **_envp); 65 static inline void setup_static_tib(Elf_Phdr *_phdr, int _phnum); 66 67 /* provided by the linker */ 68 extern Elf_Ehdr __executable_start[] __attribute__((weak)); 69 #endif /* PIC */ 70 71 /* provide definitions for these */ 72 const dl_cb *_dl_cb __relro = NULL; 73 74 void _libc_preinit(int, char **, char **, dl_cb_cb *) __dso_hidden; 75 void 76 _libc_preinit(int argc, char **argv, char **envp, dl_cb_cb *cb) 77 { 78 AuxInfo *aux; 79 #ifndef PIC 80 Elf_Phdr *phdr = NULL; 81 int phnum = 0; 82 83 /* static libc in a static link? */ 84 if (cb == NULL) 85 early_static_init(argv, envp); 86 #endif /* !PIC */ 87 88 if (cb != NULL) 89 _dl_cb = cb(DL_CB_CUR); 90 91 /* Extract useful bits from the auxiliary vector */ 92 while (*envp++ != NULL) 93 ; 94 for (aux = (void *)envp; aux->au_id != AUX_null; aux++) { 95 switch (aux->au_id) { 96 case AUX_pagesz: 97 _pagesize = aux->au_v; 98 break; 99 #ifndef PIC 100 case AUX_base: 101 _static_phdr_info.dlpi_addr = aux->au_v; 102 break; 103 case AUX_phdr: 104 phdr = (void *)aux->au_v; 105 break; 106 case AUX_phnum: 107 phnum = aux->au_v; 108 break; 109 #endif /* !PIC */ 110 case AUX_openbsd_timekeep: 111 if (_tc_get_timecount) { 112 _timekeep = (void *)aux->au_v; 113 if (_timekeep && 114 _timekeep->tk_version != TK_VERSION) 115 _timekeep = NULL; 116 } 117 break; 118 } 119 } 120 121 #ifndef PIC 122 if (cb == NULL && phdr == NULL && __executable_start != NULL) { 123 /* 124 * Static non-PIE processes don't get an AUX vector, 125 * so find the phdrs through the ELF header 126 */ 127 _static_phdr_info.dlpi_addr = (Elf_Addr)__executable_start; 128 phdr = (void *)((char *)__executable_start + 129 __executable_start->e_phoff); 130 phnum = __executable_start->e_phnum; 131 } 132 _static_phdr_info.dlpi_phdr = phdr; 133 _static_phdr_info.dlpi_phnum = phnum; 134 135 /* static libc in a static link? */ 136 if (cb == NULL) 137 setup_static_tib(phdr, phnum); 138 #endif /* !PIC */ 139 } 140 141 /* ARM just had to be different... */ 142 #ifndef __arm__ 143 # define TYPE "@" 144 #else 145 # define TYPE "%" 146 #endif 147 148 #ifdef __LP64__ 149 # define VALUE_ALIGN ".balign 8" 150 # define VALUE_DIRECTIVE ".quad" 151 #else 152 # define VALUE_ALIGN ".balign 4" 153 # ifdef __hppa__ 154 /* hppa just had to be different: func pointers prefix with 'P%' */ 155 # define VALUE_DIRECTIVE ".int P%" 156 # else 157 # define VALUE_DIRECTIVE ".int" 158 # endif 159 #endif 160 161 #define ADD_TO_ARRAY(func, which) \ 162 __asm( " .section ."#which",\"a\","TYPE#which"\n " \ 163 VALUE_ALIGN"\n "VALUE_DIRECTIVE" "#func"\n .previous") 164 165 #ifdef PIC 166 ADD_TO_ARRAY(_libc_preinit, init_array); 167 #else 168 ADD_TO_ARRAY(_libc_preinit, preinit_array); 169 #endif 170 171 /* 172 * In dynamic links, invoke ld.so's dl_clean_boot() callback, if any, 173 * and register its cleanup. 174 */ 175 char *** 176 _csu_finish(char **argv, char **envp, void (*cleanup)(void)) 177 { 178 if (_dl_cb != NULL && _dl_cb->dl_clean_boot != NULL) 179 _dl_cb->dl_clean_boot(); 180 181 if (cleanup != NULL) 182 atexit(cleanup); 183 184 return &environ; 185 } 186 187 #ifndef PIC 188 /* 189 * static libc in a static link? Then disable kbind and set up 190 * __progname and environ 191 */ 192 static inline void 193 early_static_init(char **argv, char **envp) 194 { 195 static char progname_storage[NAME_MAX+1]; 196 197 /* disable kbind */ 198 syscall(SYS_kbind, (void *)NULL, (size_t)0, (long long)0); 199 200 environ = envp; 201 202 /* set up __progname */ 203 if (*argv != NULL) { /* NULL ptr if argc = 0 */ 204 const char *p = strrchr(*argv, '/'); 205 206 if (p == NULL) 207 p = *argv; 208 else 209 p++; 210 strlcpy(progname_storage, p, sizeof(progname_storage)); 211 } 212 __progname = progname_storage; 213 } 214 215 /* 216 * static TLS handling 217 */ 218 #define ELF_ROUND(x,malign) (((x) + (malign)-1) & ~((malign)-1)) 219 220 /* for static binaries, the location and size of the TLS image */ 221 static void *static_tls __relro; 222 static size_t static_tls_fsize __relro; 223 224 size_t _static_tls_size __relro = 0; 225 int _static_tls_align __relro; 226 int _static_tls_align_offset __relro; 227 228 static inline void 229 setup_static_tib(Elf_Phdr *phdr, int phnum) 230 { 231 struct tib *tib; 232 char *base; 233 int i; 234 235 _static_tls_align = TIB_ALIGN; 236 if (phdr != NULL) { 237 for (i = 0; i < phnum; i++) { 238 if (phdr[i].p_type != PT_TLS) 239 continue; 240 if (phdr[i].p_memsz == 0) 241 break; 242 if (phdr[i].p_memsz < phdr[i].p_filesz) 243 break; /* invalid */ 244 if (phdr[i].p_align > getpagesize()) 245 break; /* nope */ 246 _static_tls_align = MAX(phdr[i].p_align, TIB_ALIGN); 247 #if TLS_VARIANT == 1 248 /* 249 * Variant 1 places the data after the TIB. If the 250 * TLS alignment is larger than the TIB alignment 251 * then we may need to pad in front of the TIB to 252 * place the TLS data on the proper alignment. 253 * Example: p_align=16 sizeof(TIB)=52 align(TIB)=4 254 * - need to offset the TIB 12 bytes from the start 255 * - to place ths TLS data at offset 64 256 */ 257 _static_tls_size = phdr[i].p_memsz; 258 _static_tls_align_offset = 259 ELF_ROUND(sizeof(struct tib), _static_tls_align) - 260 sizeof(struct tib); 261 #elif TLS_VARIANT == 2 262 /* 263 * Variant 2 places the data before the TIB 264 * so we need to round up the size to the 265 * TLS data alignment TIB's alignment. 266 * Example A: p_memsz=24 p_align=16 align(TIB)=8 267 * - need to allocate 32 bytes for TLS as compiler 268 * - will give the first TLS symbol an offset of -32 269 * Example B: p_memsz=4 p_align=4 align(TIB)=8 270 * - need to allocate 8 bytes so that the TIB is 271 * - properly aligned 272 */ 273 _static_tls_size = ELF_ROUND(phdr[i].p_memsz, 274 phdr[i].p_align); 275 _static_tls_align_offset = ELF_ROUND(_static_tls_size, 276 _static_tls_align) - _static_tls_size; 277 #endif 278 if (phdr[i].p_vaddr != 0 && phdr[i].p_filesz != 0) { 279 static_tls = (void *)phdr[i].p_vaddr + 280 _static_phdr_info.dlpi_addr; 281 static_tls_fsize = phdr[i].p_filesz; 282 } 283 break; 284 } 285 } 286 287 base = mmap(NULL, _static_tls_size + _static_tls_align_offset 288 + sizeof *tib, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0); 289 290 tib = _static_tls_init(base, NULL); 291 tib->tib_tid = getthrid(); 292 TCB_SET(TIB_TO_TCB(tib)); 293 #if ! TCB_HAVE_MD_GET 294 _libc_single_tcb = TIB_TO_TCB(tib); 295 #endif 296 } 297 298 struct tib * 299 _static_tls_init(char *base, void *thread) 300 { 301 struct tib *tib; 302 303 base += _static_tls_align_offset; 304 # if TLS_VARIANT == 1 305 tib = (struct tib *)base; 306 base += sizeof(struct tib); 307 # elif TLS_VARIANT == 2 308 tib = (struct tib *)(base + _static_tls_size); 309 # endif 310 311 if (_static_tls_size) { 312 if (static_tls != NULL) 313 memcpy(base, static_tls, static_tls_fsize); 314 memset(base + static_tls_fsize, 0, 315 _static_tls_size - static_tls_fsize); 316 } 317 318 TIB_INIT(tib, NULL, thread); 319 return tib; 320 } 321 #endif /* !PIC */ 322