1 /* $OpenBSD: boot.c,v 1.14 2016/08/13 20:57:04 guenther Exp $ */ 2 3 /* 4 * Copyright (c) 1998 Per Fogelstrom, Opsycon AB 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 */ 28 29 /* 30 * IMPORTANT: any functions below are NOT protected by SSP. Please 31 * do not add anything except what is required to reach GOT with 32 * an adjustment. 33 */ 34 35 #define _DYN_LOADER 36 37 #include <sys/types.h> 38 #include <sys/mman.h> 39 #include <sys/exec.h> 40 #include <sys/sysctl.h> 41 #include <nlist.h> 42 #include <link.h> 43 #include <dlfcn.h> 44 45 #include "syscall.h" 46 #include "archdep.h" 47 #include "stdlib.h" 48 49 #include "../../lib/csu/os-note-elf.h" 50 51 #if RELOC_TAG == DT_RELA 52 typedef Elf_RelA RELOC_TYPE; 53 #elif RELOC_TAG == DT_REL 54 typedef Elf_Rel RELOC_TYPE; 55 #else 56 # error "unknown RELOC_TAG" 57 #endif 58 59 /* The set of dynamic tags that we're interested in for bootstrapping */ 60 struct boot_dyn { 61 RELOC_TYPE *dt_reloc; /* DT_RELA or DT_REL */ 62 Elf_Addr dt_relocsz; /* DT_RELASZ or DT_RELSZ */ 63 Elf_Addr *dt_pltgot; 64 Elf_Addr dt_pltrelsz; 65 const Elf_Sym *dt_symtab; 66 #ifdef HAVE_JMPREL 67 RELOC_TYPE *dt_jmprel; 68 #endif 69 #if DT_PROCNUM > 0 70 u_long dt_proc[DT_PROCNUM]; 71 #endif 72 }; 73 74 /* 75 * Local decls. 76 */ 77 void _dl_boot_bind(const long, long *, Elf_Dyn *); 78 79 void 80 _dl_boot_bind(const long sp, long *dl_data, Elf_Dyn *dynp) 81 { 82 struct boot_dyn dynld; /* Resolver data for the loader */ 83 AuxInfo *auxstack; 84 long *stack; 85 int n, argc; 86 char **argv, **envp; 87 long loff; 88 Elf_Addr i; 89 RELOC_TYPE *rp; 90 91 /* 92 * Scan argument and environment vectors. Find dynamic 93 * data vector put after them. 94 */ 95 stack = (long *)sp; 96 argc = *stack++; 97 argv = (char **)stack; 98 envp = &argv[argc + 1]; 99 stack = (long *)envp; 100 while (*stack++ != 0L) 101 ; 102 103 /* 104 * Zero out dl_data. 105 */ 106 for (n = 0; n <= AUX_entry; n++) 107 dl_data[n] = 0; 108 109 /* 110 * Dig out auxiliary data set up by exec call. Move all known 111 * tags to an indexed local table for easy access. 112 */ 113 for (auxstack = (AuxInfo *)stack; auxstack->au_id != AUX_null; 114 auxstack++) { 115 if (auxstack->au_id > AUX_entry) 116 continue; 117 dl_data[auxstack->au_id] = auxstack->au_v; 118 } 119 loff = dl_data[AUX_base]; /* XXX assumes ld.so is linked at 0x0 */ 120 121 /* 122 * We need to do 'selfreloc' in case the code weren't 123 * loaded at the address it was linked to. 124 * 125 * Scan the DYNAMIC section for the loader. 126 * Cache the data for easier access. 127 */ 128 _dl_memset(&dynld, 0, sizeof(dynld)); 129 while (dynp->d_tag != DT_NULL) { 130 /* first the tags that are pointers to be relocated */ 131 if (dynp->d_tag == DT_PLTGOT) 132 dynld.dt_pltgot = (void *)(dynp->d_un.d_ptr + loff); 133 else if (dynp->d_tag == DT_SYMTAB) 134 dynld.dt_symtab = (void *)(dynp->d_un.d_ptr + loff); 135 else if (dynp->d_tag == RELOC_TAG) /* DT_{RELA,REL} */ 136 dynld.dt_reloc = (void *)(dynp->d_un.d_ptr + loff); 137 #ifdef HAVE_JMPREL 138 else if (dynp->d_tag == DT_JMPREL) 139 dynld.dt_jmprel = (void *)(dynp->d_un.d_ptr + loff); 140 #endif 141 142 /* Now for the tags that are just sizes or counts */ 143 else if (dynp->d_tag == DT_PLTRELSZ) 144 dynld.dt_pltrelsz = dynp->d_un.d_val; 145 else if (dynp->d_tag == RELOC_TAG+1) /* DT_{RELA,REL}SZ */ 146 dynld.dt_relocsz = dynp->d_un.d_val; 147 #if DT_PROCNUM > 0 148 else if (dynp->d_tag >= DT_LOPROC && 149 dynp->d_tag < DT_LOPROC + DT_PROCNUM) 150 dynld.dt_proc[dynp->d_tag - DT_LOPROC] = 151 dynp->d_un.d_val; 152 #endif /* DT_PROCNUM */ 153 dynp++; 154 } 155 156 #ifdef HAVE_JMPREL 157 rp = dynld.dt_jmprel; 158 for (i = 0; i < dynld.dt_pltrelsz; i += sizeof *rp) { 159 Elf_Addr *ra; 160 const Elf_Sym *sp; 161 162 sp = dynld.dt_symtab + ELF_R_SYM(rp->r_info); 163 if (ELF_R_SYM(rp->r_info) && sp->st_value == 0) 164 _dl_exit(5); 165 166 ra = (Elf_Addr *)(rp->r_offset + loff); 167 RELOC_JMPREL(rp, sp, ra, loff, dynld.dt_pltgot); 168 rp++; 169 } 170 #endif /* HAVE_JMPREL */ 171 172 rp = dynld.dt_reloc; 173 for (i = 0; i < dynld.dt_relocsz; i += sizeof *rp) { 174 Elf_Addr *ra; 175 const Elf_Sym *sp; 176 177 sp = dynld.dt_symtab + ELF_R_SYM(rp->r_info); 178 if (ELF_R_SYM(rp->r_info) && sp->st_value == 0) 179 _dl_exit(6); 180 181 ra = (Elf_Addr *)(rp->r_offset + loff); 182 RELOC_DYN(rp, sp, ra, loff); 183 rp++; 184 } 185 186 RELOC_GOT(&dynld, loff); 187 188 /* 189 * we have been fully relocated here, so most things no longer 190 * need the loff adjustment 191 */ 192 } 193