/* $OpenBSD: init.c,v 1.22 2024/01/21 17:18:13 kettenis Exp $ */ /* * Copyright (c) 2014,2015 Philip Guenther * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #define _DYN_LOADER #include #include #include /* timekeep */ #ifndef PIC #include #endif #include #include /* NAME_MAX */ #include #include /* atexit */ #include #include #include "init.h" #define MAX(a,b) (((a)>(b))?(a):(b)) #ifdef TIB_EXTRA_ALIGN # define TIB_ALIGN MAX(__alignof__(struct tib), TIB_EXTRA_ALIGN) #else # define TIB_ALIGN __alignof__(struct tib) #endif /* XXX should be in an include file shared with csu */ char ***_csu_finish(char **_argv, char **_envp, void (*_cleanup)(void)); /* provide definitions for these */ int _pagesize = 0; struct timekeep *_timekeep; /* * In dynamically linked binaries environ and __progname are overridden by * the definitions in ld.so. */ char **environ __attribute__((weak)) = NULL; char *__progname __attribute__((weak)) = NULL; #ifndef PIC struct dl_phdr_info _static_phdr_info __relro = { .dlpi_name = "a.out" }; static inline void early_static_init(char **_argv, char **_envp); static inline void setup_static_tib(Elf_Phdr *_phdr, int _phnum); /* provided by the linker */ extern Elf_Ehdr __executable_start[] __attribute__((weak)); #endif /* PIC */ /* provide definitions for these */ const dl_cb *_dl_cb __relro = NULL; int HIDDEN(execve)(const char *, char *const *, char *const *) __attribute__((weak)); void _libc_preinit(int, char **, char **, dl_cb_cb *) __dso_hidden; void _libc_preinit(int argc, char **argv, char **envp, dl_cb_cb *cb) { AuxInfo *aux; #ifndef PIC Elf_Phdr *phdr = NULL; int phnum = 0; /* static libc in a static link? */ if (cb == NULL) early_static_init(argv, envp); #endif /* !PIC */ if (cb != NULL) _dl_cb = cb(DL_CB_CUR); /* Extract useful bits from the auxiliary vector */ while (*envp++ != NULL) ; for (aux = (void *)envp; aux->au_id != AUX_null; aux++) { switch (aux->au_id) { case AUX_pagesz: _pagesize = aux->au_v; break; #ifndef PIC case AUX_base: _static_phdr_info.dlpi_addr = aux->au_v; break; case AUX_phdr: phdr = (void *)aux->au_v; break; case AUX_phnum: phnum = aux->au_v; break; #endif /* !PIC */ case AUX_openbsd_timekeep: if (_tc_get_timecount) { _timekeep = (void *)aux->au_v; if (_timekeep && _timekeep->tk_version != TK_VERSION) _timekeep = NULL; } if (issetugid() == 0 && getenv("LIBC_NOUSERTC")) _timekeep = NULL; break; } } #ifndef PIC if (cb == NULL && phdr == NULL && __executable_start != NULL) { /* * Static non-PIE processes don't get an AUX vector, * so find the phdrs through the ELF header */ phdr = (void *)((char *)__executable_start + __executable_start->e_phoff); phnum = __executable_start->e_phnum; } _static_phdr_info.dlpi_phdr = phdr; _static_phdr_info.dlpi_phnum = phnum; /* static libc in a static link? */ if (cb == NULL) setup_static_tib(phdr, phnum); /* * If a static binary has text relocations (DT_TEXT), then un-writeable * segments were not made immutable by the kernel. Textrel and RELRO * changes have now been completed and permissions corrected, so these * regions can become immutable. */ if (phdr) { int i; for (i = 0; i < phnum; i++) { if (phdr[i].p_type == PT_LOAD && (phdr[i].p_flags & PF_W) == 0) mimmutable((void *)(_static_phdr_info.dlpi_addr + phdr[i].p_vaddr), phdr[i].p_memsz); } } #endif /* !PIC */ } /* ARM just had to be different... */ #ifndef __arm__ # define TYPE "@" #else # define TYPE "%" #endif #ifdef __LP64__ # define VALUE_ALIGN ".balign 8" # define VALUE_DIRECTIVE ".quad" #else # define VALUE_ALIGN ".balign 4" # ifdef __hppa__ /* hppa just had to be different: func pointers prefix with 'P%' */ # define VALUE_DIRECTIVE ".int P%" # else # define VALUE_DIRECTIVE ".int" # endif #endif #define ADD_TO_ARRAY(func, which) \ __asm( " .section ."#which",\"a\","TYPE#which"\n " \ VALUE_ALIGN"\n "VALUE_DIRECTIVE" "#func"\n .previous") #ifdef PIC ADD_TO_ARRAY(_libc_preinit, init_array); #else ADD_TO_ARRAY(_libc_preinit, preinit_array); #endif /* * In dynamic links, invoke ld.so's dl_clean_boot() callback, if any, * and register its cleanup. */ char *** _csu_finish(char **argv, char **envp, void (*cleanup)(void)) { if (_dl_cb != NULL && _dl_cb->dl_clean_boot != NULL) _dl_cb->dl_clean_boot(); if (cleanup != NULL) atexit(cleanup); return &environ; } #ifndef PIC /* * static libc in a static link? Then set up __progname and environ */ static inline void early_static_init(char **argv, char **envp) { static char progname_storage[NAME_MAX+1]; environ = envp; /* set up __progname */ if (*argv != NULL) { /* NULL ptr if argc = 0 */ const char *p = strrchr(*argv, '/'); if (p == NULL) p = *argv; else p++; strlcpy(progname_storage, p, sizeof(progname_storage)); } __progname = progname_storage; } /* * static TLS handling */ #define ELF_ROUND(x,malign) (((x) + (malign)-1) & ~((malign)-1)) /* for static binaries, the location and size of the TLS image */ static void *static_tls __relro; static size_t static_tls_fsize __relro; size_t _static_tls_size __relro = 0; int _static_tls_align __relro; int _static_tls_align_offset __relro; static inline void setup_static_tib(Elf_Phdr *phdr, int phnum) { struct tib *tib; char *base; int i; _static_tls_align = TIB_ALIGN; if (phdr != NULL) { for (i = 0; i < phnum; i++) { if (phdr[i].p_type != PT_TLS) continue; if (phdr[i].p_memsz == 0) break; if (phdr[i].p_memsz < phdr[i].p_filesz) break; /* invalid */ if (phdr[i].p_align > getpagesize()) break; /* nope */ _static_tls_align = MAX(phdr[i].p_align, TIB_ALIGN); #if TLS_VARIANT == 1 /* * Variant 1 places the data after the TIB. If the * TLS alignment is larger than the TIB alignment * then we may need to pad in front of the TIB to * place the TLS data on the proper alignment. * Example: p_align=16 sizeof(TIB)=52 align(TIB)=4 * - need to offset the TIB 12 bytes from the start * - to place ths TLS data at offset 64 */ _static_tls_size = phdr[i].p_memsz; _static_tls_align_offset = ELF_ROUND(sizeof(struct tib), _static_tls_align) - sizeof(struct tib); #elif TLS_VARIANT == 2 /* * Variant 2 places the data before the TIB * so we need to round up the size to the * TLS data alignment TIB's alignment. * Example A: p_memsz=24 p_align=16 align(TIB)=8 * - need to allocate 32 bytes for TLS as compiler * - will give the first TLS symbol an offset of -32 * Example B: p_memsz=4 p_align=4 align(TIB)=8 * - need to allocate 8 bytes so that the TIB is * - properly aligned */ _static_tls_size = ELF_ROUND(phdr[i].p_memsz, phdr[i].p_align); _static_tls_align_offset = ELF_ROUND(_static_tls_size, _static_tls_align) - _static_tls_size; #endif if (phdr[i].p_vaddr != 0 && phdr[i].p_filesz != 0) { static_tls = (void *)phdr[i].p_vaddr + _static_phdr_info.dlpi_addr; static_tls_fsize = phdr[i].p_filesz; } break; } } base = mmap(NULL, _static_tls_size + _static_tls_align_offset + sizeof *tib, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0); tib = _static_tls_init(base, NULL); tib->tib_tid = getthrid(); TCB_SET(TIB_TO_TCB(tib)); #if ! TCB_HAVE_MD_GET _libc_single_tcb = TIB_TO_TCB(tib); #endif } struct tib * _static_tls_init(char *base, void *thread) { struct tib *tib; base += _static_tls_align_offset; # if TLS_VARIANT == 1 tib = (struct tib *)base; base += sizeof(struct tib); # elif TLS_VARIANT == 2 tib = (struct tib *)(base + _static_tls_size); # endif if (_static_tls_size) { if (static_tls != NULL) memcpy(base, static_tls, static_tls_fsize); memset(base + static_tls_fsize, 0, _static_tls_size - static_tls_fsize); } TIB_INIT(tib, NULL, thread); return tib; } #endif /* !PIC */