1 /* $NetBSD: subr_exec_fd.c,v 1.1 2008/11/18 13:01:41 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 /* 30 * File descriptor related subroutines for exec. 31 */ 32 33 #include <sys/cdefs.h> 34 __KERNEL_RCSID(0, "$NetBSD: subr_exec_fd.c,v 1.1 2008/11/18 13:01:41 pooka Exp $"); 35 36 #include <sys/param.h> 37 #include <sys/file.h> 38 #include <sys/filedesc.h> 39 #include <sys/mutex.h> 40 #include <sys/namei.h> 41 #include <sys/syslog.h> 42 #include <sys/vnode.h> 43 44 /* 45 * Close open files on exec. 46 */ 47 void 48 fd_closeexec(void) 49 { 50 proc_t *p; 51 filedesc_t *fdp; 52 fdfile_t *ff; 53 lwp_t *l; 54 int fd; 55 56 l = curlwp; 57 p = l->l_proc; 58 fdp = p->p_fd; 59 60 cwdunshare(p); 61 62 if (p->p_cwdi->cwdi_edir) { 63 vrele(p->p_cwdi->cwdi_edir); 64 } 65 66 if (fdp->fd_refcnt > 1) { 67 fdp = fd_copy(); 68 fd_free(); 69 p->p_fd = fdp; 70 l->l_fd = fdp; 71 } 72 if (!fdp->fd_exclose) { 73 return; 74 } 75 fdp->fd_exclose = false; 76 77 for (fd = 0; fd <= fdp->fd_lastfile; fd++) { 78 if ((ff = fdp->fd_ofiles[fd]) == NULL) { 79 KASSERT(fd >= NDFDFILE); 80 continue; 81 } 82 KASSERT(fd >= NDFDFILE || 83 ff == (fdfile_t *)fdp->fd_dfdfile[fd]); 84 if (ff->ff_file == NULL) 85 continue; 86 if (ff->ff_exclose) { 87 /* 88 * We need a reference to close the file. 89 * No other threads can see the fdfile_t at 90 * this point, so don't bother locking. 91 */ 92 KASSERT((ff->ff_refcnt & FR_CLOSING) == 0); 93 ff->ff_refcnt++; 94 fd_close(fd); 95 } 96 } 97 } 98 99 /* 100 * It is unsafe for set[ug]id processes to be started with file 101 * descriptors 0..2 closed, as these descriptors are given implicit 102 * significance in the Standard C library. fdcheckstd() will create a 103 * descriptor referencing /dev/null for each of stdin, stdout, and 104 * stderr that is not already open. 105 */ 106 #define CHECK_UPTO 3 107 int 108 fd_checkstd(void) 109 { 110 struct proc *p; 111 struct nameidata nd; 112 filedesc_t *fdp; 113 file_t *fp; 114 struct proc *pp; 115 int fd, i, error, flags = FREAD|FWRITE; 116 char closed[CHECK_UPTO * 3 + 1], which[3 + 1]; 117 118 p = curproc; 119 closed[0] = '\0'; 120 if ((fdp = p->p_fd) == NULL) 121 return (0); 122 for (i = 0; i < CHECK_UPTO; i++) { 123 KASSERT(i >= NDFDFILE || 124 fdp->fd_ofiles[i] == (fdfile_t *)fdp->fd_dfdfile[i]); 125 if (fdp->fd_ofiles[i]->ff_file != NULL) 126 continue; 127 snprintf(which, sizeof(which), ",%d", i); 128 strlcat(closed, which, sizeof(closed)); 129 if ((error = fd_allocfile(&fp, &fd)) != 0) 130 return (error); 131 KASSERT(fd < CHECK_UPTO); 132 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, "/dev/null"); 133 if ((error = vn_open(&nd, flags, 0)) != 0) { 134 fd_abort(p, fp, fd); 135 return (error); 136 } 137 fp->f_data = nd.ni_vp; 138 fp->f_flag = flags; 139 fp->f_ops = &vnops; 140 fp->f_type = DTYPE_VNODE; 141 VOP_UNLOCK(nd.ni_vp, 0); 142 fd_affix(p, fp, fd); 143 } 144 if (closed[0] != '\0') { 145 mutex_enter(proc_lock); 146 pp = p->p_pptr; 147 mutex_enter(pp->p_lock); 148 log(LOG_WARNING, "set{u,g}id pid %d (%s) " 149 "was invoked by uid %d ppid %d (%s) " 150 "with fd %s closed\n", 151 p->p_pid, p->p_comm, kauth_cred_geteuid(pp->p_cred), 152 pp->p_pid, pp->p_comm, &closed[1]); 153 mutex_exit(pp->p_lock); 154 mutex_exit(proc_lock); 155 } 156 return (0); 157 } 158 #undef CHECK_UPTO 159