/* $OpenBSD: exec_elf.c,v 1.19 1996/12/23 02:42:43 deraadt Exp $ */ /* * Copyright (c) 1996 Per Fogelstrom * All rights reserved. * * Copyright (c) 1994 Christos Zoulas * 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. 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. * */ #include #include #include #include #include #include #include #include #include #if defined(_KERN_DO_ELF) #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef COMPAT_LINUX #include #endif #ifdef COMPAT_SVR4 #include #endif int (*elf_probe_funcs[]) __P((struct proc *, struct exec_package *, char *, u_long *)) = { #ifdef COMPAT_SVR4 svr4_elf_probe, #endif #ifdef COMPAT_LINUX linux_elf_probe #endif }; int elf_load_file __P((struct proc *, char *, struct exec_package *, struct elf_args *, u_long *)); int elf_check_header __P((Elf32_Ehdr *, int)); int olf_check_header __P((Elf32_Ehdr *, int)); int elf_read_from __P((struct proc *, struct vnode *, u_long, caddr_t, int)); void elf_load_psection __P((struct exec_vmcmd_set *, struct vnode *, Elf32_Phdr *, u_long *, u_long *, int *)); int exec_elf_fixup __P((struct proc *, struct exec_package *)); #define ELF_ALIGN(a, b) ((a) & ~((b) - 1)) /* * This is the basic elf emul. elf_probe_funcs may change to other emuls. */ extern char sigcode[], esigcode[]; #ifdef SYSCALL_DEBUG extern char *syscallnames[]; #endif struct emul emul_elf = { "native", NULL, sendsig, SYS_syscall, SYS_MAXSYSCALL, sysent, #ifdef SYSCALL_DEBUG syscallnames, #else NULL, #endif sizeof(AuxInfo) * ELF_AUX_ENTRIES, elf_copyargs, setregs, exec_elf_fixup, sigcode, esigcode, }; /* * Copy arguments onto the stack in the normal way, but add some * space for extra information in case of dynamic binding. */ void * elf_copyargs(pack, arginfo, stack, argp) struct exec_package *pack; struct ps_strings *arginfo; void *stack; void *argp; { stack = copyargs(pack, arginfo, stack, argp); if (!stack) return NULL; /* * Push space for extra arguments on the stack needed by * dynamically linked binaries */ if (pack->ep_interp != NULL) { pack->ep_emul_argp = stack; stack += ELF_AUX_ENTRIES * sizeof (AuxInfo); } return stack; } /* * elf_check_header(): * * Check header for validity; return 0 for ok, ENOEXEC if error */ int elf_check_header(ehdr, type) Elf32_Ehdr *ehdr; int type; { /* * We need to check magic, class size, endianess, and version before * we look at the rest of the Elf32_Ehdr structure. These few elements * are represented in a machine independant fashion. */ if (!IS_ELF(*ehdr) || ehdr->e_ident[EI_CLASS] != ELF_TARG_CLASS || ehdr->e_ident[EI_DATA] != ELF_TARG_DATA || ehdr->e_ident[EI_VERSION] != ELF_TARG_VER) return ENOEXEC; /* Now check the machine dependant header */ if (ehdr->e_machine != ELF_TARG_MACH || ehdr->e_version != ELF_TARG_VER) return ENOEXEC; /* Check the type */ if (ehdr->e_type != type) return ENOEXEC; return 0; } /* * olf_check_header(): * * Check header for validity; return 0 for ok, ENOEXEC if error */ int olf_check_header(ehdr, type) Elf32_Ehdr *ehdr; int type; { /* * We need to check magic, class size, endianess, version, and OS * before we look at the rest of the Elf32_Ehdr structure. These few * elements are represented in a machine independant fashion. */ if (!IS_OLF(*ehdr) || ehdr->e_ident[OI_CLASS] != ELF_TARG_CLASS || ehdr->e_ident[OI_DATA] != ELF_TARG_DATA || ehdr->e_ident[OI_VERSION] != ELF_TARG_VER || ehdr->e_ident[OI_OS] != OOS_OPENBSD) return ENOEXEC; /* Now check the machine dependant header */ if (ehdr->e_machine != ELF_TARG_MACH || ehdr->e_version != ELF_TARG_VER) return ENOEXEC; /* Check the type */ if (ehdr->e_type != type) return ENOEXEC; return 0; } /* * elf_load_psection(): * * Load a psection at the appropriate address */ void elf_load_psection(vcset, vp, ph, addr, size, prot) struct exec_vmcmd_set *vcset; struct vnode *vp; Elf32_Phdr *ph; u_long *addr; u_long *size; int *prot; { u_long uaddr, msize, psize, rm, rf; long diff, offset; /* * If the user specified an address, then we load there. */ if (*addr != ELF32_NO_ADDR) { if (ph->p_align > 1) { *addr = ELF_ALIGN(*addr + ph->p_align, ph->p_align); uaddr = ELF_ALIGN(ph->p_vaddr, ph->p_align); } else uaddr = ph->p_vaddr; diff = ph->p_vaddr - uaddr; } else { *addr = uaddr = ph->p_vaddr; if (ph->p_align > 1) *addr = ELF_ALIGN(uaddr, ph->p_align); diff = uaddr - *addr; } *prot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0; *prot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0; *prot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0; offset = ph->p_offset - diff; *size = ph->p_filesz + diff; msize = ph->p_memsz + diff; psize = round_page(*size); /* * Because the pagedvn pager can't handle zero fill of the last * data page if it's not page aligned we map the las page readvn. */ if(ph->p_flags & PF_W) { psize = trunc_page(*size); NEW_VMCMD(vcset, vmcmd_map_pagedvn, psize, *addr, vp, offset, *prot); if(psize != *size) { NEW_VMCMD(vcset, vmcmd_map_readvn, *size - psize, *addr + psize, vp, offset + psize, *prot); } } else { NEW_VMCMD(vcset, vmcmd_map_pagedvn, psize, *addr, vp, offset, *prot); } /* * Check if we need to extend the size of the segment */ rm = round_page(*addr + msize); rf = round_page(*addr + *size); if (rm != rf) { NEW_VMCMD(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 0, *prot); *size = msize; } } /* * elf_read_from(): * * Read from vnode into buffer at offset. */ int elf_read_from(p, vp, off, buf, size) struct proc *p; struct vnode *vp; u_long off; caddr_t buf; int size; { int error; int resid; if ((error = vn_rdwr(UIO_READ, vp, buf, size, off, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p)) != 0) return error; /* * See if we got all of it */ if (resid != 0) return ENOEXEC; return 0; } /* * elf_load_file(): * * Load a file (interpreter/library) pointed to by path * [stolen from coff_load_shlib()]. Made slightly generic * so it might be used externally. */ int elf_load_file(p, path, epp, ap, last) struct proc *p; char *path; struct exec_package *epp; struct elf_args *ap; u_long *last; { int error, i; struct nameidata nd; Elf32_Ehdr eh; Elf32_Phdr *ph = NULL; u_long phsize; char *bp = NULL; u_long addr = *last; struct vnode *vp; bp = path; NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, path, p); if ((error = namei(&nd)) != 0) { return error; } vp = nd.ni_vp; if (vp->v_type != VREG) { error = EACCES; goto bad; } if ((error = VOP_GETATTR(vp, epp->ep_vap, p->p_ucred, p)) != 0) goto bad; if (vp->v_mount->mnt_flag & MNT_NOEXEC) { error = EACCES; goto bad; } if ((error = VOP_ACCESS(vp, VREAD, p->p_ucred, p)) != 0) goto bad1; if ((error = elf_read_from(p, nd.ni_vp, 0, (caddr_t) &eh, sizeof(eh))) != 0) goto bad1; if (elf_check_header(&eh, ET_DYN) && olf_check_header(&eh, ET_DYN)) { error = ENOEXEC; goto bad1; } phsize = eh.e_phnum * sizeof(Elf32_Phdr); ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK); if ((error = elf_read_from(p, nd.ni_vp, eh.e_phoff, (caddr_t) ph, phsize)) != 0) goto bad1; /* * Load all the necessary sections */ for (i = 0; i < eh.e_phnum; i++) { u_long size = 0; int prot = 0; #ifdef mips if (*last == ELF32_NO_ADDR) addr = ELF32_NO_ADDR; /* GRRRRR!!!!! */ #endif switch (ph[i].p_type) { case PT_LOAD: elf_load_psection(&epp->ep_vmcmds, nd.ni_vp, &ph[i], &addr, &size, &prot); /* If entry is within this section it must be text */ if (eh.e_entry >= ph[i].p_vaddr && eh.e_entry < (ph[i].p_vaddr + size)) { epp->ep_entry = addr + eh.e_entry - ELF_ALIGN(ph[i].p_vaddr,ph[i].p_align); ap->arg_interp = addr; } addr += size; break; case PT_DYNAMIC: case PT_PHDR: case PT_NOTE: break; default: break; } } bad1: VOP_CLOSE(nd.ni_vp, FREAD, p->p_ucred, p); bad: if (ph != NULL) free((char *) ph, M_TEMP); *last = addr; vput(nd.ni_vp); return error; } /* * exec_elf_makecmds(): Prepare an Elf binary's exec package * * First, set of the various offsets/lengths in the exec package. * * Then, mark the text image busy (so it can be demand paged) or error * out if this is not possible. Finally, set up vmcmds for the * text, data, bss, and stack segments. * */ int exec_elf_makecmds(p, epp) struct proc *p; struct exec_package *epp; { Elf32_Ehdr *eh = epp->ep_hdr; Elf32_Phdr *ph, *pp; Elf32_Addr phdr = 0; int error, i, n, nload; char interp[MAXPATHLEN]; u_long pos = 0, phsize; if (epp->ep_hdrvalid < sizeof(Elf32_Ehdr)) return ENOEXEC; if (elf_check_header(eh, ET_EXEC) && olf_check_header(eh, ET_EXEC)) return ENOEXEC; /* * check if vnode is in open for writing, because we want to * demand-page out of it. if it is, don't do it, for various * reasons */ if (epp->ep_vp->v_writecount != 0) { #ifdef DIAGNOSTIC if (epp->ep_vp->v_flag & VTEXT) panic("exec: a VTEXT vnode has writecount != 0\n"); #endif return ETXTBSY; } /* * Allocate space to hold all the program headers, and read them * from the file */ phsize = eh->e_phnum * sizeof(Elf32_Phdr); ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK); if ((error = elf_read_from(p, epp->ep_vp, eh->e_phoff, (caddr_t) ph, phsize)) != 0) goto bad; epp->ep_tsize = ELF32_NO_ADDR; epp->ep_dsize = ELF32_NO_ADDR; interp[0] = '\0'; for (i = 0; i < eh->e_phnum; i++) { pp = &ph[i]; if (pp->p_type == PT_INTERP) { if (pp->p_filesz >= sizeof(interp)) goto bad; if ((error = elf_read_from(p, epp->ep_vp, pp->p_offset, (caddr_t) interp, pp->p_filesz)) != 0) goto bad; break; } } /* * OK, we want a slightly different twist of the * standard emulation package for "real" elf. */ epp->ep_emul = &emul_elf; pos = ELF32_NO_ADDR; /* * On the same architecture, we may be emulating different systems. * See which one will accept this executable. This currently only * applies to Linux and SVR4 on the i386. * * Probe functions would normally see if the interpreter (if any) * exists. Emulation packages may possibly replace the interpreter in * interp[] with a changed path (/emul/xxx/), and also * set the ep_emul field in the exec package structure. */ if ((n = sizeof elf_probe_funcs / sizeof elf_probe_funcs[0])) { error = ENOEXEC; for (i = 0; i < n && error; i++) error = elf_probe_funcs[i](p, epp, interp, &pos); if (error) goto bad; } /* * Load all the necessary sections */ for (i = nload = 0; i < eh->e_phnum; i++) { u_long addr = ELF32_NO_ADDR, size = 0; int prot = 0; pp = &ph[i]; switch (ph[i].p_type) { case PT_LOAD: /* * XXX * Can handle only 2 sections: text and data */ if (nload++ == 2) goto bad; elf_load_psection(&epp->ep_vmcmds, epp->ep_vp, &ph[i], &addr, &size, &prot); /* * Decide whether it's text or data by looking * at the entry point. */ if (eh->e_entry >= addr && eh->e_entry < (addr + size)){ epp->ep_taddr = addr; epp->ep_tsize = size; } else { epp->ep_daddr = addr; epp->ep_dsize = size; } break; case PT_SHLIB: error = ENOEXEC; goto bad; case PT_INTERP: /* Already did this one */ case PT_DYNAMIC: case PT_NOTE: break; case PT_PHDR: /* Note address of program headers (in text segment) */ phdr = pp->p_vaddr; break; default: /* * Not fatal, we don't need to understand everything :-) */ break; } } #if !defined(mips) /* * If no position to load the interpreter was set by a probe * function, pick the same address that a non-fixed mmap(0, ..) * would (i.e. something safely out of the way). */ if (pos == ELF32_NO_ADDR) pos = round_page(epp->ep_daddr + MAXDSIZ); #endif /* * Check if we found a dynamically linked binary and arrange to load * it's interpreter when the exec file is released. */ if (interp[0]) { char *ip; struct elf_args *ap; ip = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); ap = (struct elf_args *) malloc(sizeof(struct elf_args), M_TEMP, M_WAITOK); bcopy(interp, ip, MAXPATHLEN); epp->ep_interp = ip; epp->ep_interp_pos = pos; ap->arg_phaddr = phdr; ap->arg_phentsize = eh->e_phentsize; ap->arg_phnum = eh->e_phnum; ap->arg_entry = eh->e_entry; epp->ep_emul_arg = ap; epp->ep_entry = eh->e_entry; /* keep check_exec() happy */ } else { epp->ep_interp = NULL; epp->ep_entry = eh->e_entry; } #ifdef ELF_MAP_PAGE_ZERO /* Dell SVR4 maps page zero, yeuch! */ NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, NBPG, 0, epp->ep_vp, 0, VM_PROT_READ); #endif free((char *) ph, M_TEMP); epp->ep_vp->v_flag |= VTEXT; return exec_setup_stack(p, epp); bad: free((char *) ph, M_TEMP); kill_vmcmds(&epp->ep_vmcmds); return ENOEXEC; } /* * Phase II of load. It is now safe to load the interpreter. Info collected * when loading the program is available for setup of the interpreter. */ int exec_elf_fixup(p, epp) struct proc *p; struct exec_package *epp; { char *interp; int error, i; struct elf_args *ap; AuxInfo ai[ELF_AUX_ENTRIES], *a; u_long pos = epp->ep_interp_pos; if(epp->ep_interp == 0) { return 0; } interp = (char *)epp->ep_interp; ap = (struct elf_args *) epp->ep_emul_arg; if ((error = elf_load_file(p, interp, epp, ap, &pos)) != 0) { free((char *) ap, M_TEMP); free((char *) interp, M_TEMP); kill_vmcmds(&epp->ep_vmcmds); return error; } /* * We have to do this ourselfs... */ for (i = 0; i < epp->ep_vmcmds.evs_used && !error; i++) { struct exec_vmcmd *vcp; vcp = &epp->ep_vmcmds.evs_cmds[i]; error = (*vcp->ev_proc)(p, vcp); } kill_vmcmds(&epp->ep_vmcmds); /* * Push extra arguments on the stack needed by dynamically * linked binaries */ if(error == 0) { a = ai; a->au_id = AUX_phdr; a->au_v = ap->arg_phaddr; a++; a->au_id = AUX_phent; a->au_v = ap->arg_phentsize; a++; a->au_id = AUX_phnum; a->au_v = ap->arg_phnum; a++; a->au_id = AUX_pagesz; a->au_v = NBPG; a++; a->au_id = AUX_base; a->au_v = ap->arg_interp; a++; a->au_id = AUX_flags; a->au_v = 0; a++; a->au_id = AUX_entry; a->au_v = ap->arg_entry; a++; a->au_id = AUX_null; a->au_v = 0; a++; error = copyout(ai, epp->ep_emul_argp, sizeof ai); } free((char *) ap, M_TEMP); free((char *) interp, M_TEMP); return error; } #endif /* _KERN_DO_ELF */