/* $OpenBSD: self_reloc.c,v 1.2 2019/05/11 19:14:41 mlarkin Exp $ */ /*- * Copyright (c) 2008-2010 Rui Paulo * 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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. */ #include #include #define ELFSIZE 32 #define ElfW_Rel Elf32_Rel #define ElfW_Dyn Elf32_Dyn #define ELFW_R_TYPE ELF32_R_TYPE #include #define RELOC_TYPE_NONE R_386_NONE #define RELOC_TYPE_RELATIVE R_386_RELATIVE /* * A simple elf relocator. */ void self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic) { Elf_Word relsz, relent; Elf_Addr *newaddr; ElfW_Rel *rel = NULL; ElfW_Dyn *dynp; /* * Find the relocation address, its size and the relocation entry. */ relsz = 0; relent = 0; for (dynp = dynamic; dynp->d_tag != DT_NULL; dynp++) { switch (dynp->d_tag) { case DT_REL: case DT_RELA: rel = (ElfW_Rel *)(dynp->d_un.d_ptr + baseaddr); break; case DT_RELSZ: case DT_RELASZ: relsz = dynp->d_un.d_val; break; case DT_RELENT: case DT_RELAENT: relent = dynp->d_un.d_val; break; default: break; } } /* * Perform the actual relocation. We rely on the object having been * linked at 0, so that the difference between the load and link * address is the same as the load address. */ for (; relsz > 0; relsz -= relent) { switch (ELFW_R_TYPE(rel->r_info)) { case RELOC_TYPE_NONE: /* No relocation needs be performed. */ break; case RELOC_TYPE_RELATIVE: newaddr = (Elf_Addr *)(rel->r_offset + baseaddr); #ifdef ELF_RELA /* Addend relative to the base address. */ *newaddr = baseaddr + rel->r_addend; #else /* Address relative to the base address. */ *newaddr += baseaddr; #endif break; default: /* XXX: do we need other relocations ? */ break; } rel = (ElfW_Rel *) ((caddr_t) rel + relent); } }