/* $OpenBSD: boot.h,v 1.29 2018/11/22 21:37:29 guenther Exp $ */ /* * Copyright (c) 1998 Per Fogelstrom, Opsycon AB * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * */ /* * IMPORTANT: any functions below are NOT protected by SSP. Please * do not add anything except what is required to reach GOT with * an adjustment. */ #define _DYN_LOADER #include #include #include #include #include #include #include #include "syscall.h" #include "archdep.h" #include "path.h" #include "resolve.h" #include "sod.h" #include "stdlib.h" /* * Use the internal, hidden name for any syscalls we need, to avoid * accidental override by application code */ #define REDIRECT_SYSCALL(x) typeof(x) x asm("_libc_"#x) __dso_hidden REDIRECT_SYSCALL(mprotect); #ifdef RCRT0 #define DT_PROC(n) ((n) - DT_LOPROC) #if RELOC_TAG == DT_RELA typedef Elf_RelA RELOC_TYPE; #elif RELOC_TAG == DT_REL typedef Elf_Rel RELOC_TYPE; #else # error "unknown RELOC_TAG" #endif /* The set of dynamic tags that we're interested in for bootstrapping */ struct boot_dyn { RELOC_TYPE *dt_reloc; /* DT_RELA or DT_REL */ Elf_Addr dt_relocsz; /* DT_RELASZ or DT_RELSZ */ Elf_Addr *dt_pltgot; Elf_Addr dt_pltrelsz; const Elf_Sym *dt_symtab; RELOC_TYPE *dt_jmprel; #if DT_PROCNUM > 0 u_long dt_proc[DT_PROCNUM]; #endif }; /* * Local decls. */ void _dl_boot_bind(const long, long *, Elf_Dyn *); void _dl_boot_bind(const long sp, long *dl_data, Elf_Dyn *dynamicp) { struct boot_dyn dynld; /* Resolver data for the loader */ AuxInfo *auxstack; long *stack; Elf_Dyn *dynp; int n, argc; char **argv, **envp; long loff; RELOC_TYPE *rp; Elf_Phdr *phdp; Elf_Addr i; /* * Scan argument and environment vectors. Find dynamic * data vector put after them. */ stack = (long *)sp; argc = *stack++; argv = (char **)stack; envp = &argv[argc + 1]; stack = (long *)envp; while (*stack++ != 0L) ; /* * Zero out dl_data. */ for (n = 0; n <= AUX_entry; n++) dl_data[n] = 0; /* * Dig out auxiliary data set up by exec call. Move all known * tags to an indexed local table for easy access. */ for (auxstack = (AuxInfo *)stack; auxstack->au_id != AUX_null; auxstack++) { if (auxstack->au_id > AUX_entry) continue; dl_data[auxstack->au_id] = auxstack->au_v; } loff = dl_data[AUX_base]; /* XXX assumes ld.so is linked at 0x0 */ /* * We need to do 'selfreloc' in case the code weren't * loaded at the address it was linked to. * * Scan the DYNAMIC section for the loader. * Cache the data for easier access. */ dynp = dynamicp; _dl_memset(&dynld, 0, sizeof(dynld)); while (dynp->d_tag != DT_NULL) { /* first the tags that are pointers to be relocated */ if (dynp->d_tag == DT_PLTGOT) dynld.dt_pltgot = (void *)(dynp->d_un.d_ptr + loff); else if (dynp->d_tag == DT_SYMTAB) dynld.dt_symtab = (void *)(dynp->d_un.d_ptr + loff); else if (dynp->d_tag == RELOC_TAG) /* DT_{RELA,REL} */ dynld.dt_reloc = (void *)(dynp->d_un.d_ptr + loff); else if (dynp->d_tag == DT_JMPREL) dynld.dt_jmprel = (void *)(dynp->d_un.d_ptr + loff); /* Now for the tags that are just sizes or counts */ else if (dynp->d_tag == DT_PLTRELSZ) dynld.dt_pltrelsz = dynp->d_un.d_val; else if (dynp->d_tag == RELOC_TAG+1) /* DT_{RELA,REL}SZ */ dynld.dt_relocsz = dynp->d_un.d_val; #if DT_PROCNUM > 0 else if (dynp->d_tag >= DT_LOPROC && dynp->d_tag < DT_LOPROC + DT_PROCNUM) dynld.dt_proc[dynp->d_tag - DT_LOPROC] = dynp->d_un.d_val; #endif /* DT_PROCNUM */ dynp++; } rp = dynld.dt_jmprel; for (i = 0; i < dynld.dt_pltrelsz; i += sizeof *rp) { const Elf_Sym *sp; sp = dynld.dt_symtab + ELF_R_SYM(rp->r_info); if (!ELF_R_SYM(rp->r_info) || sp->st_value != 0) { #ifdef HAVE_JMPREL Elf_Addr *ra = (Elf_Addr *)(rp->r_offset + loff); RELOC_JMPREL(rp, sp, ra, loff, dynld.dt_pltgot); #else _dl_exit(6); #endif } rp++; } rp = dynld.dt_reloc; for (i = 0; i < dynld.dt_relocsz; i += sizeof *rp) { Elf_Addr *ra; const Elf_Sym *sp; sp = dynld.dt_symtab + ELF_R_SYM(rp->r_info); if (!ELF_R_SYM(rp->r_info) || sp->st_value != 0) { ra = (Elf_Addr *)(rp->r_offset + loff); RELOC_DYN(rp, sp, ra, loff); } rp++; } RELOC_GOT(&dynld, loff); /* * we have been fully relocated here, so most things no longer * need the loff adjustment */ /* * No further changes to the PLT and/or GOT are needed so make * them read-only. */ /* do any RWX -> RX fixups for executable PLTs and apply GNU_RELRO */ phdp = (Elf_Phdr *)dl_data[AUX_phdr]; for (i = 0; i < dl_data[AUX_phnum]; i++, phdp++) { switch (phdp->p_type) { #if defined(__alpha__) || defined(__hppa__) || defined(__powerpc__) || \ defined(__sparc64__) case PT_LOAD: if ((phdp->p_flags & (PF_X | PF_W)) != (PF_X | PF_W)) break; mprotect((void *)(phdp->p_vaddr + loff), phdp->p_memsz, PROT_READ); break; #endif case PT_GNU_RELRO: mprotect((void *)(phdp->p_vaddr + loff), phdp->p_memsz, PROT_READ); /* * GNU_RELRO (a) covers the GOT, and (b) comes after * all LOAD sections, so if we found it then we're done */ break; } } } #endif /* RCRT0 */