/* $OpenBSD: kern_exec.c,v 1.92 2005/04/11 20:05:51 deraadt Exp $ */ /* $NetBSD: kern_exec.c,v 1.75 1996/02/09 18:59:28 christos Exp $ */ /*- * Copyright (C) 1993, 1994 Christopher G. Demetriou * Copyright (C) 1992 Wolfgang Solfrank. * Copyright (C) 1992 TooLs GmbH. * 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 TooLs GmbH. * 4. The name of TooLs GmbH may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``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 TOOLS GMBH 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 #include #include #include #include #include #include #include #include #include #include #include #ifdef SYSVSHM #include #endif #include #include #include #include #include #include "systrace.h" #if NSYSTRACE > 0 #include #endif /* * Map the shared signal code. */ int exec_sigcode_map(struct proc *, struct emul *); /* * stackgap_random specifies if the stackgap should have a random size added * to it. Must be a n^2. If non-zero, the stack gap will be calculated as: * (arc4random() * ALIGNBYTES) & (stackgap_random - 1) + STACKGAPLEN. */ int stackgap_random = STACKGAP_RANDOM; /* * check exec: * given an "executable" described in the exec package's namei info, * see what we can do with it. * * ON ENTRY: * exec package with appropriate namei info * proc pointer of exec'ing proc * NO SELF-LOCKED VNODES * * ON EXIT: * error: nothing held, etc. exec header still allocated. * ok: filled exec package, one locked vnode. * * EXEC SWITCH ENTRY: * Locked vnode to check, exec package, proc. * * EXEC SWITCH EXIT: * ok: return 0, filled exec package, one locked vnode. * error: destructive: * everything deallocated execept exec header. * non-destructive: * error code, locked vnode, exec header unmodified */ int check_exec(p, epp) struct proc *p; struct exec_package *epp; { int error, i; struct vnode *vp; struct nameidata *ndp; size_t resid; ndp = epp->ep_ndp; ndp->ni_cnd.cn_nameiop = LOOKUP; ndp->ni_cnd.cn_flags = FOLLOW | LOCKLEAF | SAVENAME; /* first get the vnode */ if ((error = namei(ndp)) != 0) return (error); epp->ep_vp = vp = ndp->ni_vp; /* check for regular file */ if (vp->v_type == VDIR) { error = EISDIR; goto bad1; } if (vp->v_type != VREG) { error = EACCES; goto bad1; } /* get attributes */ if ((error = VOP_GETATTR(vp, epp->ep_vap, p->p_ucred, p)) != 0) goto bad1; /* Check mount point */ if (vp->v_mount->mnt_flag & MNT_NOEXEC) { error = EACCES; goto bad1; } if ((vp->v_mount->mnt_flag & MNT_NOSUID)) epp->ep_vap->va_mode &= ~(VSUID | VSGID); /* check access. for root we have to see if any exec bit on */ if ((error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p)) != 0) goto bad1; if ((epp->ep_vap->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0) { error = EACCES; goto bad1; } /* try to open it */ if ((error = VOP_OPEN(vp, FREAD, p->p_ucred, p)) != 0) goto bad1; /* unlock vp, we need it unlocked from here */ VOP_UNLOCK(vp, 0, p); /* now we have the file, get the exec header */ error = vn_rdwr(UIO_READ, vp, epp->ep_hdr, epp->ep_hdrlen, 0, UIO_SYSSPACE, 0, p->p_ucred, &resid, p); if (error) goto bad2; epp->ep_hdrvalid = epp->ep_hdrlen - resid; /* * set up the vmcmds for creation of the process * address space */ error = ENOEXEC; for (i = 0; i < nexecs && error != 0; i++) { int newerror; if (execsw[i].es_check == NULL) continue; newerror = (*execsw[i].es_check)(p, epp); if (!newerror && !(epp->ep_emul->e_flags & EMUL_ENABLED)) newerror = EPERM; /* make sure the first "interesting" error code is saved. */ if (!newerror || error == ENOEXEC) error = newerror; if (epp->ep_flags & EXEC_DESTR && error != 0) return (error); } if (!error) { /* check that entry point is sane */ if (epp->ep_entry > VM_MAXUSER_ADDRESS) { error = ENOEXEC; } /* check limits */ if ((epp->ep_tsize > MAXTSIZ) || (epp->ep_dsize > p->p_rlimit[RLIMIT_DATA].rlim_cur)) error = ENOMEM; if (!error) return (0); } /* * free any vmspace-creation commands, * and release their references */ kill_vmcmds(&epp->ep_vmcmds); bad2: /* * close the vnode, free the pathname buf, and punt. */ vn_close(vp, FREAD, p->p_ucred, p); pool_put(&namei_pool, ndp->ni_cnd.cn_pnbuf); return (error); bad1: /* * free the namei pathname buffer, and put the vnode * (which we don't yet have open). */ pool_put(&namei_pool, ndp->ni_cnd.cn_pnbuf); vput(vp); return (error); } /* * exec system call */ /* ARGSUSED */ int sys_execve(p, v, retval) register struct proc *p; void *v; register_t *retval; { struct sys_execve_args /* { syscallarg(const char *) path; syscallarg(char *const *) argp; syscallarg(char *const *) envp; } */ *uap = v; int error; struct exec_package pack; struct nameidata nid; struct vattr attr; struct ucred *cred = p->p_ucred; char *argp; char * const *cpp, *dp, *sp; long argc, envc; size_t len, sgap; #ifdef MACHINE_STACK_GROWS_UP size_t slen; #endif char *stack; struct ps_strings arginfo; struct vmspace *vm = p->p_vmspace; char **tmpfap; extern struct emul emul_native; #if NSYSTRACE > 0 int wassugid = ISSET(p->p_flag, P_SUGID) || ISSET(p->p_flag, P_SUGIDEXEC); char pathbuf[MAXPATHLEN]; size_t pathbuflen; #endif /* * Cheap solution to complicated problems. * Mark this process as "leave me alone, I'm execing". */ p->p_flag |= P_INEXEC; #if NSYSTRACE > 0 if (ISSET(p->p_flag, P_SYSTRACE)) systrace_execve0(p); error = copyinstr(SCARG(uap, path), pathbuf, MAXPATHLEN, &pathbuflen); if (error != 0) goto clrflag; NDINIT(&nid, LOOKUP, NOFOLLOW, UIO_SYSSPACE, pathbuf, p); #else /* init the namei data to point the file user's program name */ NDINIT(&nid, LOOKUP, NOFOLLOW, UIO_USERSPACE, SCARG(uap, path), p); #endif /* * initialize the fields of the exec package. */ #if NSYSTRACE > 0 pack.ep_name = pathbuf; #else pack.ep_name = (char *)SCARG(uap, path); #endif pack.ep_hdr = malloc(exec_maxhdrsz, M_EXEC, M_WAITOK); pack.ep_hdrlen = exec_maxhdrsz; pack.ep_hdrvalid = 0; pack.ep_ndp = &nid; pack.ep_interp = NULL; pack.ep_emul_arg = NULL; VMCMDSET_INIT(&pack.ep_vmcmds); pack.ep_vap = &attr; pack.ep_emul = &emul_native; pack.ep_flags = 0; /* see if we can run it. */ if ((error = check_exec(p, &pack)) != 0) { goto freehdr; } /* XXX -- THE FOLLOWING SECTION NEEDS MAJOR CLEANUP */ /* allocate an argument buffer */ argp = (char *) uvm_km_valloc_wait(exec_map, NCARGS); #ifdef DIAGNOSTIC if (argp == NULL) panic("execve: argp == NULL"); #endif dp = argp; argc = 0; /* copy the fake args list, if there's one, freeing it as we go */ if (pack.ep_flags & EXEC_HASARGL) { tmpfap = pack.ep_fa; while (*tmpfap != NULL) { char *cp; cp = *tmpfap; while (*cp) *dp++ = *cp++; dp++; free(*tmpfap, M_EXEC); tmpfap++; argc++; } FREE(pack.ep_fa, M_EXEC); pack.ep_flags &= ~EXEC_HASARGL; } /* Now get argv & environment */ if (!(cpp = SCARG(uap, argp))) { error = EFAULT; goto bad; } if (pack.ep_flags & EXEC_SKIPARG) cpp++; while (1) { len = argp + ARG_MAX - dp; if ((error = copyin(cpp, &sp, sizeof(sp))) != 0) goto bad; if (!sp) break; if ((error = copyinstr(sp, dp, len, &len)) != 0) { if (error == ENAMETOOLONG) error = E2BIG; goto bad; } dp += len; cpp++; argc++; } envc = 0; /* environment does not need to be there */ if ((cpp = SCARG(uap, envp)) != NULL ) { while (1) { len = argp + ARG_MAX - dp; if ((error = copyin(cpp, &sp, sizeof(sp))) != 0) goto bad; if (!sp) break; if ((error = copyinstr(sp, dp, len, &len)) != 0) { if (error == ENAMETOOLONG) error = E2BIG; goto bad; } dp += len; cpp++; envc++; } } dp = (char *)ALIGN(dp); sgap = STACKGAPLEN; if (stackgap_random != 0) sgap += (arc4random() * ALIGNBYTES) & (stackgap_random - 1); /* Now check if args & environ fit into new stack */ len = ((argc + envc + 2 + pack.ep_emul->e_arglen) * sizeof(char *) + sizeof(long) + dp + sgap + sizeof(struct ps_strings)) - argp; len = ALIGN(len); /* make the stack "safely" aligned */ if (len > pack.ep_ssize) { /* in effect, compare to initial limit */ error = ENOMEM; goto bad; } /* adjust "active stack depth" for process VSZ */ pack.ep_ssize = len; /* maybe should go elsewhere, but... */ /* * Prepare vmspace for remapping. Note that uvmspace_exec can replace * p_vmspace! */ uvmspace_exec(p, VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS); vm = p->p_vmspace; /* Now map address space */ vm->vm_taddr = (char *)pack.ep_taddr; vm->vm_tsize = btoc(pack.ep_tsize); vm->vm_daddr = (char *)pack.ep_daddr; vm->vm_dsize = btoc(pack.ep_dsize); vm->vm_ssize = btoc(pack.ep_ssize); vm->vm_maxsaddr = (char *)pack.ep_maxsaddr; vm->vm_minsaddr = (char *)pack.ep_minsaddr; /* create the new process's VM space by running the vmcmds */ #ifdef DIAGNOSTIC if (pack.ep_vmcmds.evs_used == 0) panic("execve: no vmcmds"); #endif error = exec_process_vmcmds(p, &pack); /* if an error happened, deallocate and punt */ if (error) goto exec_abort; /* remember information about the process */ arginfo.ps_nargvstr = argc; arginfo.ps_nenvstr = envc; #ifdef MACHINE_STACK_GROWS_UP stack = (char *)USRSTACK + sizeof(arginfo); slen = len - sizeof(arginfo); #else stack = (char *)(USRSTACK - len); #endif /* Now copy argc, args & environ to new stack */ if (!(*pack.ep_emul->e_copyargs)(&pack, &arginfo, stack, argp)) goto exec_abort; /* copy out the process's ps_strings structure */ if (copyout(&arginfo, (char *)PS_STRINGS, sizeof(arginfo))) goto exec_abort; stopprofclock(p); /* stop profiling */ fdcloseexec(p); /* handle close on exec */ execsigs(p); /* reset catched signals */ /* set command name & other accounting info */ len = min(nid.ni_cnd.cn_namelen, MAXCOMLEN); bcopy(nid.ni_cnd.cn_nameptr, p->p_comm, len); p->p_comm[len] = 0; p->p_acflag &= ~AFORK; /* record proc's vnode, for use by procfs and others */ if (p->p_textvp) vrele(p->p_textvp); VREF(pack.ep_vp); p->p_textvp = pack.ep_vp; p->p_flag |= P_EXEC; if (p->p_flag & P_PPWAIT) { p->p_flag &= ~P_PPWAIT; wakeup((caddr_t)p->p_pptr); } /* * If process does execve() while it has a mismatched real, * effective, or saved uid/gid, we set P_SUGIDEXEC. */ if (p->p_ucred->cr_uid != p->p_cred->p_ruid || p->p_ucred->cr_uid != p->p_cred->p_svuid || p->p_ucred->cr_gid != p->p_cred->p_rgid || p->p_ucred->cr_gid != p->p_cred->p_svgid) p->p_flag |= P_SUGIDEXEC; else p->p_flag &= ~P_SUGIDEXEC; /* * deal with set[ug]id. * MNT_NOEXEC has already been used to disable s[ug]id. */ if ((attr.va_mode & (VSUID | VSGID)) && proc_cansugid(p)) { int i; p->p_flag |= P_SUGID; p->p_flag |= P_SUGIDEXEC; #ifdef KTRACE /* * If process is being ktraced, turn off - unless * root set it. */ if (p->p_tracep && !(p->p_traceflag & KTRFAC_ROOT)) { p->p_traceflag = 0; ktrsettracevnode(p, NULL); } #endif p->p_ucred = crcopy(cred); if (attr.va_mode & VSUID) p->p_ucred->cr_uid = attr.va_uid; if (attr.va_mode & VSGID) p->p_ucred->cr_gid = attr.va_gid; /* * For set[ug]id processes, a few caveats apply to * stdin, stdout, and stderr. */ for (i = 0; i < 3; i++) { struct file *fp = NULL; /* * NOTE - This will never return NULL because of * unmature fds. The file descriptor table is not * shared because we're suid. */ fp = fd_getfile(p->p_fd, i); #ifdef PROCFS /* * Close descriptors that are writing to procfs. */ if (fp && fp->f_type == DTYPE_VNODE && ((struct vnode *)(fp->f_data))->v_tag == VT_PROCFS && (fp->f_flag & FWRITE)) { fdrelease(p, i); fp = NULL; } #endif /* * Ensure that stdin, stdout, and stderr are already * allocated. We do not want userland to accidentally * allocate descriptors in this range which has implied * meaning to libc. */ if (fp == NULL) { short flags = FREAD | (i == 0 ? 0 : FWRITE); struct vnode *vp; int indx; if ((error = falloc(p, &fp, &indx)) != 0) goto exec_abort; #ifdef DIAGNOSTIC if (indx != i) panic("sys_execve: falloc indx != i"); #endif if ((error = cdevvp(getnulldev(), &vp)) != 0) { fdremove(p->p_fd, indx); closef(fp, p); goto exec_abort; } if ((error = VOP_OPEN(vp, flags, p->p_ucred, p)) != 0) { fdremove(p->p_fd, indx); closef(fp, p); vrele(vp); goto exec_abort; } if (flags & FWRITE) vp->v_writecount++; fp->f_flag = flags; fp->f_type = DTYPE_VNODE; fp->f_ops = &vnops; fp->f_data = (caddr_t)vp; FILE_SET_MATURE(fp); } } } else p->p_flag &= ~P_SUGID; p->p_cred->p_svuid = p->p_ucred->cr_uid; p->p_cred->p_svgid = p->p_ucred->cr_gid; if (p->p_flag & P_SUGIDEXEC) { int i, s = splclock(); timeout_del(&p->p_realit_to); timerclear(&p->p_realtimer.it_interval); timerclear(&p->p_realtimer.it_value); for (i = 0; i < sizeof(p->p_stats->p_timer) / sizeof(p->p_stats->p_timer[0]); i++) { timerclear(&p->p_stats->p_timer[i].it_interval); timerclear(&p->p_stats->p_timer[i].it_value); } splx(s); } uvm_km_free_wakeup(exec_map, (vaddr_t) argp, NCARGS); pool_put(&namei_pool, nid.ni_cnd.cn_pnbuf); vn_close(pack.ep_vp, FREAD, cred, p); /* * notify others that we exec'd */ KNOTE(&p->p_klist, NOTE_EXEC); /* setup new registers and do misc. setup. */ if (pack.ep_emul->e_fixup != NULL) { if ((*pack.ep_emul->e_fixup)(p, &pack) != 0) goto free_pack_abort; } #ifdef MACHINE_STACK_GROWS_UP (*pack.ep_emul->e_setregs)(p, &pack, (u_long)stack + slen, retval); #else (*pack.ep_emul->e_setregs)(p, &pack, (u_long)stack, retval); #endif /* map the process's signal trampoline code */ if (exec_sigcode_map(p, pack.ep_emul)) goto free_pack_abort; if (p->p_flag & P_TRACED) psignal(p, SIGTRAP); free(pack.ep_hdr, M_EXEC); /* * Call emulation specific exec hook. This can setup per-process * p->p_emuldata or do any other per-process stuff an emulation needs. * * If we are executing process of different emulation than the * original forked process, call e_proc_exit() of the old emulation * first, then e_proc_exec() of new emulation. If the emulation is * same, the exec hook code should deallocate any old emulation * resources held previously by this process. */ if (p->p_emul && p->p_emul->e_proc_exit && p->p_emul != pack.ep_emul) (*p->p_emul->e_proc_exit)(p); /* * Call exec hook. Emulation code may NOT store reference to anything * from &pack. */ if (pack.ep_emul->e_proc_exec) (*pack.ep_emul->e_proc_exec)(p, &pack); /* update p_emul, the old value is no longer needed */ p->p_emul = pack.ep_emul; #ifdef KTRACE if (KTRPOINT(p, KTR_EMUL)) ktremul(p, p->p_emul->e_name); #endif p->p_flag &= ~P_INEXEC; #if NSYSTRACE > 0 if (ISSET(p->p_flag, P_SYSTRACE) && wassugid && !ISSET(p->p_flag, P_SUGID) && !ISSET(p->p_flag, P_SUGIDEXEC)) systrace_execve1(pathbuf, p); #endif return (0); bad: /* free the vmspace-creation commands, and release their references */ kill_vmcmds(&pack.ep_vmcmds); /* kill any opened file descriptor, if necessary */ if (pack.ep_flags & EXEC_HASFD) { pack.ep_flags &= ~EXEC_HASFD; (void) fdrelease(p, pack.ep_fd); } if (pack.ep_interp != NULL) FREE(pack.ep_interp, M_TEMP); if (pack.ep_emul_arg != NULL) FREE(pack.ep_emul_arg, M_TEMP); /* close and put the exec'd file */ vn_close(pack.ep_vp, FREAD, cred, p); pool_put(&namei_pool, nid.ni_cnd.cn_pnbuf); uvm_km_free_wakeup(exec_map, (vaddr_t) argp, NCARGS); freehdr: free(pack.ep_hdr, M_EXEC); #if NSYSTRACE > 0 clrflag: #endif p->p_flag &= ~P_INEXEC; return (error); exec_abort: /* * the old process doesn't exist anymore. exit gracefully. * get rid of the (new) address space we have created, if any, get rid * of our namei data and vnode, and exit noting failure */ uvm_deallocate(&vm->vm_map, VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS - VM_MIN_ADDRESS); if (pack.ep_interp != NULL) FREE(pack.ep_interp, M_TEMP); if (pack.ep_emul_arg != NULL) FREE(pack.ep_emul_arg, M_TEMP); pool_put(&namei_pool, nid.ni_cnd.cn_pnbuf); vn_close(pack.ep_vp, FREAD, cred, p); uvm_km_free_wakeup(exec_map, (vaddr_t) argp, NCARGS); free_pack_abort: free(pack.ep_hdr, M_EXEC); exit1(p, W_EXITCODE(0, SIGABRT)); /* NOTREACHED */ p->p_flag &= ~P_INEXEC; return (0); } void * copyargs(pack, arginfo, stack, argp) struct exec_package *pack; struct ps_strings *arginfo; void *stack; void *argp; { char **cpp = stack; char *dp, *sp; size_t len; void *nullp = NULL; long argc = arginfo->ps_nargvstr; int envc = arginfo->ps_nenvstr; if (copyout(&argc, cpp++, sizeof(argc))) return (NULL); dp = (char *) (cpp + argc + envc + 2 + pack->ep_emul->e_arglen); sp = argp; /* XXX don't copy them out, remap them! */ arginfo->ps_argvstr = cpp; /* remember location of argv for later */ for (; --argc >= 0; sp += len, dp += len) if (copyout(&dp, cpp++, sizeof(dp)) || copyoutstr(sp, dp, ARG_MAX, &len)) return (NULL); if (copyout(&nullp, cpp++, sizeof(nullp))) return (NULL); arginfo->ps_envstr = cpp; /* remember location of envp for later */ for (; --envc >= 0; sp += len, dp += len) if (copyout(&dp, cpp++, sizeof(dp)) || copyoutstr(sp, dp, ARG_MAX, &len)) return (NULL); if (copyout(&nullp, cpp++, sizeof(nullp))) return (NULL); return (cpp); } int exec_sigcode_map(struct proc *p, struct emul *e) { vsize_t sz; sz = (vaddr_t)e->e_esigcode - (vaddr_t)e->e_sigcode; /* * If we don't have a sigobject for this emulation, create one. * * sigobject is an anonymous memory object (just like SYSV shared * memory) that we keep a permanent reference to and that we map * in all processes that need this sigcode. The creation is simple, * we create an object, add a permanent reference to it, map it in * kernel space, copy out the sigcode to it and unmap it. * Then we map it with PROT_READ|PROT_EXEC into the process just * the way sys_mmap would map it. */ if (e->e_sigobject == NULL) { vaddr_t va; int r; e->e_sigobject = uao_create(sz, 0); uao_reference(e->e_sigobject); /* permanent reference */ va = vm_map_min(kernel_map); /* hint */ if ((r = uvm_map(kernel_map, &va, round_page(sz), e->e_sigobject, 0, 0, UVM_MAPFLAG(UVM_PROT_RW, UVM_PROT_RW, UVM_INH_SHARE, UVM_ADV_RANDOM, 0)))) { printf("kernel mapping failed %d\n", r); uao_detach(e->e_sigobject); return (ENOMEM); } memcpy((void *)va, e->e_sigcode, sz); uvm_unmap(kernel_map, va, va + round_page(sz)); } /* Just a hint to uvm_mmap where to put it. */ p->p_sigcode = uvm_map_hint(p, VM_PROT_READ|VM_PROT_EXECUTE); uao_reference(e->e_sigobject); if (uvm_map(&p->p_vmspace->vm_map, &p->p_sigcode, round_page(sz), e->e_sigobject, 0, 0, UVM_MAPFLAG(UVM_PROT_RX, UVM_PROT_RX, UVM_INH_SHARE, UVM_ADV_RANDOM, 0))) { printf("user mapping failed\n"); uao_detach(e->e_sigobject); return (ENOMEM); } return (0); }