/* * Copyright (c) 1993, David Greenman * 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. * * $FreeBSD$ */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); static register_t *exec_copyout_strings __P((struct image_params *)); /* XXX This should be vm_size_t. */ static u_long ps_strings = PS_STRINGS; SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); /* XXX This should be vm_size_t. */ static u_long usrstack = USRSTACK; SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); u_long ps_arg_cache_limit = PAGE_SIZE / 16; SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, &ps_arg_cache_limit, 0, ""); int ps_argsopen = 1; SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); /* * Each of the items is a pointer to a `const struct execsw', hence the * double pointer here. */ static const struct execsw **execsw; #ifndef _SYS_SYSPROTO_H_ struct execve_args { char *fname; char **argv; char **envv; }; #endif /* * execve() system call. * * MPSAFE */ int execve(td, uap) struct thread *td; register struct execve_args *uap; { struct proc *p = td->td_proc; struct nameidata nd, *ndp; struct ucred *newcred, *oldcred; register_t *stack_base; int error, len, i; struct image_params image_params, *imgp; struct vattr attr; int (*img_first) __P((struct image_params *)); struct pargs *pa; imgp = &image_params; /* * Lock the process and set the P_INEXEC flag to indicate that * it should be left alone until we're done here. This is * necessary to avoid race conditions - e.g. in ptrace() - * that might allow a local user to illicitly obtain elevated * privileges. */ mtx_lock(&Giant); PROC_LOCK(p); KASSERT((p->p_flag & P_INEXEC) == 0, (__FUNCTION__ "(): process already has P_INEXEC flag")); p->p_flag |= P_INEXEC; PROC_UNLOCK(p); /* XXXKSE */ /* !!!!!!!! we need abort all the other threads of this process before we */ /* proceed beyond his point! */ /* * Initialize part of the common data */ imgp->proc = p; imgp->uap = uap; imgp->attr = &attr; imgp->argc = imgp->envc = 0; imgp->argv0 = NULL; imgp->entry_addr = 0; imgp->vmspace_destroyed = 0; imgp->interpreted = 0; imgp->interpreter_name[0] = '\0'; imgp->auxargs = NULL; imgp->vp = NULL; imgp->firstpage = NULL; imgp->ps_strings = 0; imgp->auxarg_size = 0; /* * Allocate temporary demand zeroed space for argument and * environment strings */ imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE); if (imgp->stringbase == NULL) { error = ENOMEM; goto exec_fail; } imgp->stringp = imgp->stringbase; imgp->stringspace = ARG_MAX; imgp->image_header = imgp->stringbase + ARG_MAX; /* * Translate the file name. namei() returns a vnode pointer * in ni_vp amoung other things. */ ndp = &nd; NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, UIO_USERSPACE, uap->fname, td); interpret: error = namei(ndp); if (error) { kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, ARG_MAX + PAGE_SIZE); goto exec_fail; } imgp->vp = ndp->ni_vp; imgp->fname = uap->fname; /* * Check file permissions (also 'opens' file) */ error = exec_check_permissions(imgp); if (error) { VOP_UNLOCK(imgp->vp, 0, td); goto exec_fail_dealloc; } error = exec_map_first_page(imgp); VOP_UNLOCK(imgp->vp, 0, td); if (error) goto exec_fail_dealloc; /* * If the current process has a special image activator it * wants to try first, call it. For example, emulating shell * scripts differently. */ error = -1; if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) error = img_first(imgp); /* * Loop through the list of image activators, calling each one. * An activator returns -1 if there is no match, 0 on success, * and an error otherwise. */ for (i = 0; error == -1 && execsw[i]; ++i) { if (execsw[i]->ex_imgact == NULL || execsw[i]->ex_imgact == img_first) { continue; } error = (*execsw[i]->ex_imgact)(imgp); } if (error) { if (error == -1) error = ENOEXEC; goto exec_fail_dealloc; } /* * Special interpreter operation, cleanup and loop up to try to * activate the interpreter. */ if (imgp->interpreted) { exec_unmap_first_page(imgp); /* free name buffer and old vnode */ NDFREE(ndp, NDF_ONLY_PNBUF); vrele(ndp->ni_vp); /* set new name to that of the interpreter */ NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, UIO_SYSSPACE, imgp->interpreter_name, td); goto interpret; } /* * Copy out strings (args and env) and initialize stack base */ stack_base = exec_copyout_strings(imgp); p->p_vmspace->vm_minsaddr = (char *)stack_base; /* * If custom stack fixup routine present for this process * let it do the stack setup. * Else stuff argument count as first item on stack */ if (p->p_sysent->sv_fixup) (*p->p_sysent->sv_fixup)(&stack_base, imgp); else suword(--stack_base, imgp->argc); /* * For security and other reasons, the file descriptor table cannot * be shared after an exec. */ if (p->p_fd->fd_refcnt > 1) { struct filedesc *tmp; tmp = fdcopy(td); fdfree(td); p->p_fd = tmp; } /* * For security and other reasons, signal handlers cannot * be shared after an exec. The new process gets a copy of the old * handlers. In execsigs(), the new process will have its signals * reset. */ if (p->p_procsig->ps_refcnt > 1) { struct procsig *newprocsig; MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), M_SUBPROC, M_WAITOK); bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); p->p_procsig->ps_refcnt--; p->p_procsig = newprocsig; p->p_procsig->ps_refcnt = 1; if (p->p_sigacts == &p->p_uarea->u_sigacts) panic("shared procsig but private sigacts?"); p->p_uarea->u_sigacts = *p->p_sigacts; p->p_sigacts = &p->p_uarea->u_sigacts; } /* Stop profiling */ stopprofclock(p); /* close files on exec */ fdcloseexec(td); /* reset caught signals */ execsigs(p); /* name this process - nameiexec(p, ndp) */ len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); p->p_comm[len] = 0; /* * mark as execed, wakeup the process that vforked (if any) and tell * it that it now has its own resources back */ PROC_LOCK(p); p->p_flag |= P_EXEC; if (p->p_pptr && (p->p_flag & P_PPWAIT)) { p->p_flag &= ~P_PPWAIT; wakeup((caddr_t)p->p_pptr); } /* * Implement image setuid/setgid. * * Don't honor setuid/setgid if the filesystem prohibits it or if * the process is being traced. */ oldcred = p->p_ucred; newcred = NULL; if ((((attr.va_mode & VSUID) && oldcred->cr_uid != attr.va_uid) || ((attr.va_mode & VSGID) && oldcred->cr_gid != attr.va_gid)) && (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && (p->p_flag & P_TRACED) == 0) { PROC_UNLOCK(p); /* * Turn off syscall tracing for set-id programs, except for * root. Record any set-id flags first to make sure that * we do not regain any tracing during a possible block. */ setsugid(p); if (p->p_tracep && suser_xxx(oldcred, NULL, PRISON_ROOT)) { struct vnode *vtmp; if ((vtmp = p->p_tracep) != NULL) { p->p_tracep = NULL; p->p_traceflag = 0; vrele(vtmp); } } /* * Set the new credentials. */ newcred = crdup(oldcred); if (attr.va_mode & VSUID) change_euid(newcred, attr.va_uid); if (attr.va_mode & VSGID) change_egid(newcred, attr.va_gid); setugidsafety(td); } else { if (oldcred->cr_uid == oldcred->cr_ruid && oldcred->cr_gid == oldcred->cr_rgid) p->p_flag &= ~P_SUGID; PROC_UNLOCK(p); } /* * Implement correct POSIX saved-id behavior. * * XXX: It's not clear that the existing behavior is * POSIX-compliant. A number of sources indicate that the saved * uid/gid should only be updated if the new ruid is not equal to * the old ruid, or the new euid is not equal to the old euid and * the new euid is not equal to the old ruid. The FreeBSD code * always updates the saved uid/gid. Also, this code uses the new * (replaced) euid and egid as the source, which may or may not be * the right ones to use. */ if (newcred == NULL) { if (oldcred->cr_svuid != oldcred->cr_uid || oldcred->cr_svgid != oldcred->cr_gid) { newcred = crdup(oldcred); change_svuid(newcred, newcred->cr_uid); change_svgid(newcred, newcred->cr_gid); } } else { change_svuid(newcred, newcred->cr_uid); change_svgid(newcred, newcred->cr_gid); } if (newcred != NULL) { PROC_LOCK(p); p->p_ucred = newcred; PROC_UNLOCK(p); crfree(oldcred); } /* * Store the vp for use in procfs */ if (p->p_textvp) /* release old reference */ vrele(p->p_textvp); VREF(ndp->ni_vp); p->p_textvp = ndp->ni_vp; /* * Notify others that we exec'd, and clear the P_INEXEC flag * as we're now a bona fide freshly-execed process. */ PROC_LOCK(p); KNOTE(&p->p_klist, NOTE_EXEC); p->p_flag &= ~P_INEXEC; /* * If tracing the process, trap to debugger so breakpoints * can be set before the program executes. */ _STOPEVENT(p, S_EXEC, 0); if (p->p_flag & P_TRACED) psignal(p, SIGTRAP); /* clear "fork but no exec" flag, as we _are_ execing */ p->p_acflag &= ~AFORK; /* Free any previous argument cache */ pa = p->p_args; p->p_args = NULL; PROC_UNLOCK(p); if (pa != NULL && --pa->ar_ref == 0) FREE(pa, M_PARGS); /* Set values passed into the program in registers. */ setregs(td, imgp->entry_addr, (u_long)(uintptr_t)stack_base, imgp->ps_strings); /* Cache arguments if they fit inside our allowance */ i = imgp->endargs - imgp->stringbase; if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { MALLOC(pa, struct pargs *, sizeof(struct pargs) + i, M_PARGS, M_WAITOK); pa->ar_ref = 1; pa->ar_length = i; bcopy(imgp->stringbase, pa->ar_args, i); PROC_LOCK(p); p->p_args = pa; PROC_UNLOCK(p); } exec_fail_dealloc: /* * free various allocated resources */ if (imgp->firstpage) exec_unmap_first_page(imgp); if (imgp->stringbase != NULL) kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, ARG_MAX + PAGE_SIZE); if (imgp->vp) { NDFREE(ndp, NDF_ONLY_PNBUF); vrele(imgp->vp); } if (error == 0) goto done2; exec_fail: /* we're done here, clear P_INEXEC */ PROC_LOCK(p); p->p_flag &= ~P_INEXEC; PROC_UNLOCK(p); if (imgp->vmspace_destroyed) { /* sorry, no more process anymore. exit gracefully */ exit1(td, W_EXITCODE(0, SIGABRT)); /* NOT REACHED */ error = 0; } done2: mtx_unlock(&Giant); return (error); } int exec_map_first_page(imgp) struct image_params *imgp; { int rv, i; int initial_pagein; vm_page_t ma[VM_INITIAL_PAGEIN]; vm_object_t object; GIANT_REQUIRED; if (imgp->firstpage) { exec_unmap_first_page(imgp); } VOP_GETVOBJECT(imgp->vp, &object); ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { initial_pagein = VM_INITIAL_PAGEIN; if (initial_pagein > object->size) initial_pagein = object->size; for (i = 1; i < initial_pagein; i++) { if ((ma[i] = vm_page_lookup(object, i)) != NULL) { if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) break; if (ma[i]->valid) break; vm_page_busy(ma[i]); } else { ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); if (ma[i] == NULL) break; } } initial_pagein = i; rv = vm_pager_get_pages(object, ma, initial_pagein, 0); ma[0] = vm_page_lookup(object, 0); if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { if (ma[0]) { vm_page_protect(ma[0], VM_PROT_NONE); vm_page_free(ma[0]); } return EIO; } } vm_page_wire(ma[0]); vm_page_wakeup(ma[0]); pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); imgp->firstpage = ma[0]; return 0; } void exec_unmap_first_page(imgp) struct image_params *imgp; { GIANT_REQUIRED; if (imgp->firstpage) { pmap_kremove((vm_offset_t) imgp->image_header); vm_page_unwire(imgp->firstpage, 1); imgp->firstpage = NULL; } } /* * Destroy old address space, and allocate a new stack * The new stack is only SGROWSIZ large because it is grown * automatically in trap.c. */ int exec_new_vmspace(imgp) struct image_params *imgp; { int error; struct vmspace *vmspace = imgp->proc->p_vmspace; vm_offset_t stack_addr = USRSTACK - maxssiz; vm_map_t map = &vmspace->vm_map; GIANT_REQUIRED; imgp->vmspace_destroyed = 1; /* * Blow away entire process VM, if address space not shared, * otherwise, create a new VM space so that other threads are * not disrupted */ if (vmspace->vm_refcnt == 1) { if (vmspace->vm_shm) shmexit(imgp->proc); pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); } else { vmspace_exec(imgp->proc); vmspace = imgp->proc->p_vmspace; map = &vmspace->vm_map; } /* Allocate a new stack */ error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, VM_PROT_ALL, VM_PROT_ALL, 0); if (error) return (error); #ifdef __ia64__ { /* * Allocate backing store. We really need something * similar to vm_map_stack which can allow the backing * store to grow upwards. This will do for now. */ vm_offset_t bsaddr; bsaddr = USRSTACK - 2*maxssiz; error = vm_map_find(&vmspace->vm_map, 0, 0, &bsaddr, 4*PAGE_SIZE, 0, VM_PROT_ALL, VM_PROT_ALL, 0); imgp->proc->p_thread.td_md.md_bspstore = bsaddr; } #endif /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the * VM_STACK case, but they are still used to monitor the size of the * process stack so we can check the stack rlimit. */ vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; return(0); } /* * Copy out argument and environment strings from the old process * address space into the temporary string buffer. */ int exec_extract_strings(imgp) struct image_params *imgp; { char **argv, **envv; char *argp, *envp; int error; size_t length; /* * extract arguments first */ argv = imgp->uap->argv; if (argv) { argp = (caddr_t) (intptr_t) fuword(argv); if (argp == (caddr_t) -1) return (EFAULT); if (argp) argv++; if (imgp->argv0) argp = imgp->argv0; if (argp) { do { if (argp == (caddr_t) -1) return (EFAULT); if ((error = copyinstr(argp, imgp->stringp, imgp->stringspace, &length))) { if (error == ENAMETOOLONG) return(E2BIG); return (error); } imgp->stringspace -= length; imgp->stringp += length; imgp->argc++; } while ((argp = (caddr_t) (intptr_t) fuword(argv++))); } } imgp->endargs = imgp->stringp; /* * extract environment strings */ envv = imgp->uap->envv; if (envv) { while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { if (envp == (caddr_t) -1) return (EFAULT); if ((error = copyinstr(envp, imgp->stringp, imgp->stringspace, &length))) { if (error == ENAMETOOLONG) return(E2BIG); return (error); } imgp->stringspace -= length; imgp->stringp += length; imgp->envc++; } } return (0); } /* * Copy strings out to the new process address space, constructing * new arg and env vector tables. Return a pointer to the base * so that it can be used as the initial stack pointer. */ register_t * exec_copyout_strings(imgp) struct image_params *imgp; { int argc, envc; char **vectp; char *stringp, *destp; register_t *stack_base; struct ps_strings *arginfo; int szsigcode; /* * Calculate string base and vector table pointers. * Also deal with signal trampoline code for this exec type. */ arginfo = (struct ps_strings *)PS_STRINGS; szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - roundup((ARG_MAX - imgp->stringspace), sizeof(char *)); /* * install sigcode */ if (szsigcode) copyout(imgp->proc->p_sysent->sv_sigcode, ((caddr_t)arginfo - szsigcode), szsigcode); /* * If we have a valid auxargs ptr, prepare some room * on the stack. */ if (imgp->auxargs) { /* * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for * lower compatibility. */ imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : (AT_COUNT * 2); /* * The '+ 2' is for the null pointers at the end of each of * the arg and env vector sets,and imgp->auxarg_size is room * for argument of Runtime loader. */ vectp = (char **) (destp - (imgp->argc + imgp->envc + 2 + imgp->auxarg_size) * sizeof(char *)); } else /* * The '+ 2' is for the null pointers at the end of each of * the arg and env vector sets */ vectp = (char **) (destp - (imgp->argc + imgp->envc + 2) * sizeof(char *)); /* * vectp also becomes our initial stack base */ stack_base = (register_t *)vectp; stringp = imgp->stringbase; argc = imgp->argc; envc = imgp->envc; /* * Copy out strings - arguments and environment. */ copyout(stringp, destp, ARG_MAX - imgp->stringspace); /* * Fill in "ps_strings" struct for ps, w, etc. */ suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); suword(&arginfo->ps_nargvstr, argc); /* * Fill in argument portion of vector table. */ for (; argc > 0; --argc) { suword(vectp++, (long)(intptr_t)destp); while (*stringp++ != 0) destp++; destp++; } /* a null vector table pointer separates the argp's from the envp's */ suword(vectp++, 0); suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); suword(&arginfo->ps_nenvstr, envc); /* * Fill in environment portion of vector table. */ for (; envc > 0; --envc) { suword(vectp++, (long)(intptr_t)destp); while (*stringp++ != 0) destp++; destp++; } /* end of vector table is a null pointer */ suword(vectp, 0); return (stack_base); } /* * Check permissions of file to execute. * Called with imgp->vp locked. * Return 0 for success or error code on failure. */ int exec_check_permissions(imgp) struct image_params *imgp; { struct proc *p = imgp->proc; struct vnode *vp = imgp->vp; struct vattr *attr = imgp->attr; int error; /* Get file attributes */ error = VOP_GETATTR(vp, attr, p->p_ucred, curthread); /* XXXKSE */ if (error) return (error); /* * 1) Check if file execution is disabled for the filesystem that this * file resides on. * 2) Insure that at least one execute bit is on - otherwise root * will always succeed, and we don't want to happen unless the * file really is executable. * 3) Insure that the file is a regular file. */ if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || ((attr->va_mode & 0111) == 0) || (attr->va_type != VREG)) { return (EACCES); } /* * Zero length files can't be exec'd */ if (attr->va_size == 0) return (ENOEXEC); /* * Check for execute permission to file based on current credentials. */ error = VOP_ACCESS(vp, VEXEC, p->p_ucred, curthread); /* XXXKSE */ if (error) return (error); /* * Check number of open-for-writes on the file and deny execution * if there are any. */ if (vp->v_writecount) return (ETXTBSY); /* * Call filesystem specific open routine (which does nothing in the * general case). */ error = VOP_OPEN(vp, FREAD, p->p_ucred, curthread); /* XXXKSE */ if (error) return (error); return (0); } /* * Exec handler registration */ int exec_register(execsw_arg) const struct execsw *execsw_arg; { const struct execsw **es, **xs, **newexecsw; int count = 2; /* New slot and trailing NULL */ if (execsw) for (es = execsw; *es; es++) count++; newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); if (newexecsw == NULL) return ENOMEM; xs = newexecsw; if (execsw) for (es = execsw; *es; es++) *xs++ = *es; *xs++ = execsw_arg; *xs = NULL; if (execsw) free(execsw, M_TEMP); execsw = newexecsw; return 0; } int exec_unregister(execsw_arg) const struct execsw *execsw_arg; { const struct execsw **es, **xs, **newexecsw; int count = 1; if (execsw == NULL) panic("unregister with no handlers left?\n"); for (es = execsw; *es; es++) { if (*es == execsw_arg) break; } if (*es == NULL) return ENOENT; for (es = execsw; *es; es++) if (*es != execsw_arg) count++; newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); if (newexecsw == NULL) return ENOMEM; xs = newexecsw; for (es = execsw; *es; es++) if (*es != execsw_arg) *xs++ = *es; *xs = NULL; if (execsw) free(execsw, M_TEMP); execsw = newexecsw; return 0; }