/* $NetBSD: headers.c,v 1.65.2.1 2020/03/08 10:22:29 martin Exp $ */ /* * Copyright 1996 John D. Polstra. * Copyright 1996 Matt Thomas * Copyright 2002 Charles M. Hannum * All rights reserved. * * 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by John Polstra. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * 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. */ /* * Dynamic linker for ELF. * * John Polstra . */ #include #ifndef lint __RCSID("$NetBSD: headers.c,v 1.65.2.1 2020/03/08 10:22:29 martin Exp $"); #endif /* not lint */ #include #include #include #include #include #include #include #include #include #include #include #include #include "debug.h" #include "rtld.h" /* * Process a shared object's DYNAMIC section, and save the important * information in its Obj_Entry structure. */ void _rtld_digest_dynamic(const char *execname, Obj_Entry *obj) { Elf_Dyn *dynp; Needed_Entry **needed_tail = &obj->needed; const Elf_Dyn *dyn_soname = NULL; const Elf_Dyn *dyn_rpath = NULL; bool use_pltrel = false; bool use_pltrela = false; Elf_Addr relsz = 0, relasz = 0; Elf_Addr pltrel = 0, pltrelsz = 0; #ifdef RTLD_LOADER Elf_Addr init = 0, fini = 0; #endif dbg(("headers: digesting PT_DYNAMIC at %p", obj->dynamic)); for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; ++dynp) { dbg((" d_tag %ld at %p", (long)dynp->d_tag, dynp)); switch (dynp->d_tag) { case DT_REL: obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_RELSZ: relsz = dynp->d_un.d_val; break; case DT_RELENT: assert(dynp->d_un.d_val == sizeof(Elf_Rel)); break; case DT_JMPREL: pltrel = dynp->d_un.d_ptr; break; case DT_PLTRELSZ: pltrelsz = dynp->d_un.d_val; break; case DT_RELA: obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_RELASZ: relasz = dynp->d_un.d_val; break; case DT_RELAENT: assert(dynp->d_un.d_val == sizeof(Elf_Rela)); break; case DT_PLTREL: use_pltrel = dynp->d_un.d_val == DT_REL; use_pltrela = dynp->d_un.d_val == DT_RELA; assert(use_pltrel || use_pltrela); break; case DT_SYMTAB: obj->symtab = (const Elf_Sym *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_SYMENT: assert(dynp->d_un.d_val == sizeof(Elf_Sym)); break; case DT_STRTAB: obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_STRSZ: obj->strsize = dynp->d_un.d_val; break; case DT_VERNEED: obj->verneed = (const Elf_Verneed *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_VERNEEDNUM: obj->verneednum = dynp->d_un.d_val; break; case DT_VERDEF: obj->verdef = (const Elf_Verdef *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_VERDEFNUM: obj->verdefnum = dynp->d_un.d_val; break; case DT_VERSYM: obj->versyms = (const Elf_Versym *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_HASH: { const Elf_Symindx *hashtab = (const Elf_Symindx *) (obj->relocbase + dynp->d_un.d_ptr); if (hashtab[0] > UINT32_MAX) obj->nbuckets = UINT32_MAX; else obj->nbuckets = hashtab[0]; obj->nchains = hashtab[1]; obj->buckets = hashtab + 2; obj->chains = obj->buckets + obj->nbuckets; /* * Should really be in _rtld_relocate_objects, * but _rtld_symlook_obj might be used before. */ if (obj->nbuckets) { fast_divide32_prepare(obj->nbuckets, &obj->nbuckets_m, &obj->nbuckets_s1, &obj->nbuckets_s2); } } break; case DT_NEEDED: { Needed_Entry *nep = NEW(Needed_Entry); nep->name = dynp->d_un.d_val; nep->obj = NULL; nep->next = NULL; *needed_tail = nep; needed_tail = &nep->next; } break; case DT_PLTGOT: obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_TEXTREL: obj->textrel = true; break; case DT_SYMBOLIC: obj->symbolic = true; break; case DT_RPATH: case DT_RUNPATH: /* * We have to wait until later to process this, because * we might not have gotten the address of the string * table yet. */ dyn_rpath = dynp; break; case DT_SONAME: dyn_soname = dynp; break; case DT_INIT: #ifdef RTLD_LOADER init = dynp->d_un.d_ptr; #endif break; #ifdef HAVE_INITFINI_ARRAY case DT_INIT_ARRAY: obj->init_array = (Elf_Addr *)(obj->relocbase + dynp->d_un.d_ptr); dbg(("headers: DT_INIT_ARRAY at %p", obj->init_array)); break; case DT_INIT_ARRAYSZ: obj->init_arraysz = dynp->d_un.d_val / sizeof(fptr_t); dbg(("headers: DT_INIT_ARRAYZ %zu", obj->init_arraysz)); break; #endif case DT_FINI: #ifdef RTLD_LOADER fini = dynp->d_un.d_ptr; #endif break; #ifdef HAVE_INITFINI_ARRAY case DT_FINI_ARRAY: obj->fini_array = (Elf_Addr *)(obj->relocbase + dynp->d_un.d_ptr); dbg(("headers: DT_FINI_ARRAY at %p", obj->fini_array)); break; case DT_FINI_ARRAYSZ: obj->fini_arraysz = dynp->d_un.d_val / sizeof(fptr_t); dbg(("headers: DT_FINI_ARRAYZ %zu", obj->fini_arraysz)); break; #endif /* * Don't process DT_DEBUG on MIPS as the dynamic section * is mapped read-only. DT_MIPS_RLD_MAP is used instead. * XXX: n32/n64 may use DT_DEBUG, not sure yet. */ #ifndef __mips__ case DT_DEBUG: #ifdef RTLD_LOADER dynp->d_un.d_ptr = (Elf_Addr)&_rtld_debug; #endif break; #endif #ifdef __mips__ case DT_MIPS_LOCAL_GOTNO: obj->local_gotno = dynp->d_un.d_val; break; case DT_MIPS_SYMTABNO: obj->symtabno = dynp->d_un.d_val; break; case DT_MIPS_GOTSYM: obj->gotsym = dynp->d_un.d_val; break; case DT_MIPS_RLD_MAP: #ifdef RTLD_LOADER *((Elf_Addr *)(dynp->d_un.d_ptr)) = (Elf_Addr) &_rtld_debug; #endif break; #endif #ifdef __powerpc__ #ifdef _LP64 case DT_PPC64_GLINK: obj->glink = (Elf_Addr)(uintptr_t)obj->relocbase + dynp->d_un.d_ptr; break; #else case DT_PPC_GOT: obj->gotptr = (Elf_Addr *)(obj->relocbase + dynp->d_un.d_ptr); break; #endif #endif case DT_FLAGS_1: obj->z_now = ((dynp->d_un.d_val & DF_1_NOW) != 0); obj->z_nodelete = ((dynp->d_un.d_val & DF_1_NODELETE) != 0); obj->z_initfirst = ((dynp->d_un.d_val & DF_1_INITFIRST) != 0); obj->z_noopen = ((dynp->d_un.d_val & DF_1_NOOPEN) != 0); break; } } obj->rellim = (const Elf_Rel *)((const uint8_t *)obj->rel + relsz); obj->relalim = (const Elf_Rela *)((const uint8_t *)obj->rela + relasz); if (use_pltrel) { obj->pltrel = (const Elf_Rel *)(obj->relocbase + pltrel); obj->pltrellim = (const Elf_Rel *)(obj->relocbase + pltrel + pltrelsz); obj->pltrelalim = 0; /* On PPC and SPARC, at least, REL(A)SZ may include JMPREL. Trim rel(a)lim to save time later. */ if (obj->rellim && obj->pltrel && obj->rellim > obj->pltrel && obj->rellim <= obj->pltrellim) obj->rellim = obj->pltrel; } else if (use_pltrela) { obj->pltrela = (const Elf_Rela *)(obj->relocbase + pltrel); obj->pltrellim = 0; obj->pltrelalim = (const Elf_Rela *)(obj->relocbase + pltrel + pltrelsz); /* On PPC and SPARC, at least, REL(A)SZ may include JMPREL. Trim rel(a)lim to save time later. */ if (obj->relalim && obj->pltrela && obj->relalim > obj->pltrela && obj->relalim <= obj->pltrelalim) obj->relalim = obj->pltrela; } #ifdef RTLD_LOADER if (init != 0) obj->init = (Elf_Addr) obj->relocbase + init; if (fini != 0) obj->fini = (Elf_Addr) obj->relocbase + fini; #endif if (dyn_rpath != NULL) { _rtld_add_paths(execname, &obj->rpaths, obj->strtab + dyn_rpath->d_un.d_val); } if (dyn_soname != NULL) { _rtld_object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val); } } /* * Process a shared object's program header. This is used only for the * main program, when the kernel has already loaded the main program * into memory before calling the dynamic linker. It creates and * returns an Obj_Entry structure. */ Obj_Entry * _rtld_digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry) { Obj_Entry *obj; const Elf_Phdr *phlimit = phdr + phnum; const Elf_Phdr *ph; bool first_seg = true; Elf_Addr vaddr; size_t size; obj = _rtld_obj_new(); for (ph = phdr; ph < phlimit; ++ph) { if (ph->p_type != PT_PHDR) continue; obj->relocbase = (caddr_t)((uintptr_t)phdr - (uintptr_t)ph->p_vaddr); obj->phdr = phdr; /* Equivalent to relocbase + p_vaddr. */ obj->phsize = ph->p_memsz; dbg(("headers: phdr %p (%p) phsize %zu relocbase %p", obj->phdr, phdr, obj->phsize, obj->relocbase)); break; } for (ph = phdr; ph < phlimit; ++ph) { vaddr = (Elf_Addr)(uintptr_t)(obj->relocbase + ph->p_vaddr); switch (ph->p_type) { case PT_INTERP: obj->interp = (const char *)(uintptr_t)vaddr; dbg(("headers: %s %p phsize %" PRImemsz, "PT_INTERP", (void *)(uintptr_t)vaddr, ph->p_memsz)); break; case PT_LOAD: size = round_up(vaddr + ph->p_memsz) - obj->vaddrbase; if (first_seg) { /* First load segment */ obj->vaddrbase = round_down(vaddr); obj->mapbase = (caddr_t)(uintptr_t)obj->vaddrbase; obj->textsize = size; obj->mapsize = size; first_seg = false; } else { /* Last load segment */ obj->mapsize = MAX(obj->mapsize, size); } dbg(("headers: %s %p phsize %" PRImemsz, "PT_LOAD", (void *)(uintptr_t)vaddr, ph->p_memsz)); break; case PT_DYNAMIC: obj->dynamic = (Elf_Dyn *)(uintptr_t)vaddr; dbg(("headers: %s %p phsize %" PRImemsz, "PT_DYNAMIC", (void *)(uintptr_t)vaddr, ph->p_memsz)); break; #ifdef GNU_RELRO case PT_GNU_RELRO: /* rounding happens later. */ obj->relro_page = obj->relocbase + ph->p_vaddr; obj->relro_size = ph->p_memsz; dbg(("headers: %s %p phsize %" PRImemsz, "PT_GNU_RELRO", (void *)(uintptr_t)vaddr, ph->p_memsz)); break; #endif #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) case PT_TLS: obj->tlsindex = 1; obj->tlssize = ph->p_memsz; obj->tlsalign = ph->p_align; obj->tlsinitsize = ph->p_filesz; obj->tlsinit = (void *)(obj->relocbase + (uintptr_t)ph->p_vaddr); dbg(("headers: %s %p phsize %" PRImemsz, "PT_TLS", (void *)(uintptr_t)vaddr, ph->p_memsz)); break; #endif #ifdef __ARM_EABI__ case PT_ARM_EXIDX: obj->exidx_start = (void *)(uintptr_t)vaddr; obj->exidx_sz = ph->p_memsz; dbg(("headers: %s %p phsize %" PRImemsz, "PT_ARM_EXIDX", (void *)(uintptr_t)vaddr, ph->p_memsz)); break; #endif } } obj->entry = entry; return obj; }