1 /* $NetBSD: subr_exec_fd.c,v 1.5 2011/02/15 15:54:28 pooka Exp $ */ 2 3 /*- 4 * Copyright (c) 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __KERNEL_RCSID(0, "$NetBSD: subr_exec_fd.c,v 1.5 2011/02/15 15:54:28 pooka Exp $"); 31 32 #include <sys/param.h> 33 #include <sys/file.h> 34 #include <sys/filedesc.h> 35 #include <sys/mutex.h> 36 #include <sys/namei.h> 37 #include <sys/syslog.h> 38 #include <sys/vnode.h> 39 40 /* 41 * It is unsafe for set[ug]id processes to be started with file 42 * descriptors 0..2 closed, as these descriptors are given implicit 43 * significance in the Standard C library. fdcheckstd() will create a 44 * descriptor referencing /dev/null for each of stdin, stdout, and 45 * stderr that is not already open. 46 */ 47 #define CHECK_UPTO 3 48 int 49 fd_checkstd(void) 50 { 51 struct proc *p; 52 struct pathbuf *pb; 53 struct nameidata nd; 54 filedesc_t *fdp; 55 file_t *fp; 56 fdtab_t *dt; 57 struct proc *pp; 58 int fd, i, error, flags = FREAD|FWRITE; 59 char closed[CHECK_UPTO * 3 + 1], which[3 + 1]; 60 61 p = curproc; 62 closed[0] = '\0'; 63 if ((fdp = p->p_fd) == NULL) 64 return (0); 65 dt = fdp->fd_dt; 66 for (i = 0; i < CHECK_UPTO; i++) { 67 KASSERT(i >= NDFDFILE || 68 dt->dt_ff[i] == (fdfile_t *)fdp->fd_dfdfile[i]); 69 if (dt->dt_ff[i]->ff_file != NULL) 70 continue; 71 snprintf(which, sizeof(which), ",%d", i); 72 strlcat(closed, which, sizeof(closed)); 73 if ((error = fd_allocfile(&fp, &fd)) != 0) 74 return (error); 75 KASSERT(fd < CHECK_UPTO); 76 pb = pathbuf_create("/dev/null"); 77 if (pb == NULL) { 78 return ENOMEM; 79 } 80 NDINIT(&nd, LOOKUP, FOLLOW, pb); 81 if ((error = vn_open(&nd, flags, 0)) != 0) { 82 pathbuf_destroy(pb); 83 fd_abort(p, fp, fd); 84 return (error); 85 } 86 fp->f_data = nd.ni_vp; 87 fp->f_flag = flags; 88 fp->f_ops = &vnops; 89 fp->f_type = DTYPE_VNODE; 90 VOP_UNLOCK(nd.ni_vp); 91 fd_affix(p, fp, fd); 92 pathbuf_destroy(pb); 93 } 94 if (closed[0] != '\0') { 95 mutex_enter(proc_lock); 96 pp = p->p_pptr; 97 mutex_enter(pp->p_lock); 98 log(LOG_WARNING, "set{u,g}id pid %d (%s) " 99 "was invoked by uid %d ppid %d (%s) " 100 "with fd %s closed\n", 101 p->p_pid, p->p_comm, kauth_cred_geteuid(pp->p_cred), 102 pp->p_pid, pp->p_comm, &closed[1]); 103 mutex_exit(pp->p_lock); 104 mutex_exit(proc_lock); 105 } 106 return (0); 107 } 108 #undef CHECK_UPTO 109