panic_string.c revision 1.1.2.2
1 1.1.2.2 pgoyette /* $NetBSD: panic_string.c,v 1.1.2.2 2018/06/25 07:26:05 pgoyette Exp $ */ 2 1.1.2.2 pgoyette 3 1.1.2.2 pgoyette /*- 4 1.1.2.2 pgoyette * Copyright (c) 2018 The NetBSD Foundation, Inc. 5 1.1.2.2 pgoyette * All rights reserved. 6 1.1.2.2 pgoyette * 7 1.1.2.2 pgoyette * Redistribution and use in source and binary forms, with or without 8 1.1.2.2 pgoyette * modification, are permitted provided that the following conditions 9 1.1.2.2 pgoyette * are met: 10 1.1.2.2 pgoyette * 1. Redistributions of source code must retain the above copyright 11 1.1.2.2 pgoyette * notice, this list of conditions and the following disclaimer. 12 1.1.2.2 pgoyette * 2. Redistributions in binary form must reproduce the above copyright 13 1.1.2.2 pgoyette * notice, this list of conditions and the following disclaimer in the 14 1.1.2.2 pgoyette * documentation and/or other materials provided with the distribution. 15 1.1.2.2 pgoyette * 16 1.1.2.2 pgoyette * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 1.1.2.2 pgoyette * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 1.1.2.2 pgoyette * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 1.1.2.2 pgoyette * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 1.1.2.2 pgoyette * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 1.1.2.2 pgoyette * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 1.1.2.2 pgoyette * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 1.1.2.2 pgoyette * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 1.1.2.2 pgoyette * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 1.1.2.2 pgoyette * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 1.1.2.2 pgoyette * POSSIBILITY OF SUCH DAMAGE. 27 1.1.2.2 pgoyette */ 28 1.1.2.2 pgoyette 29 1.1.2.2 pgoyette 30 1.1.2.2 pgoyette #include <sys/cdefs.h> 31 1.1.2.2 pgoyette __KERNEL_RCSID(0, "$NetBSD: panic_string.c,v 1.1.2.2 2018/06/25 07:26:05 pgoyette Exp $"); 32 1.1.2.2 pgoyette 33 1.1.2.2 pgoyette #include <sys/param.h> 34 1.1.2.2 pgoyette #include <sys/types.h> 35 1.1.2.2 pgoyette #include <sys/conf.h> 36 1.1.2.2 pgoyette #include <sys/device.h> 37 1.1.2.2 pgoyette #include <sys/filedesc.h> 38 1.1.2.2 pgoyette #include <sys/kernel.h> 39 1.1.2.2 pgoyette #include <sys/kmem.h> 40 1.1.2.2 pgoyette #include <sys/lwp.h> 41 1.1.2.2 pgoyette #include <sys/module.h> 42 1.1.2.2 pgoyette #include <sys/vfs_syscalls.h> 43 1.1.2.2 pgoyette 44 1.1.2.2 pgoyette /* 45 1.1.2.2 pgoyette * Create a device /dev/panic from which you can read sequential 46 1.1.2.2 pgoyette * user input. 47 1.1.2.2 pgoyette * 48 1.1.2.2 pgoyette * To use this device you need to do: 49 1.1.2.2 pgoyette * mknod /dev/panic c 210 0 50 1.1.2.2 pgoyette * 51 1.1.2.2 pgoyette * To write to the device you might need: 52 1.1.2.2 pgoyette * chmod 666 /dev/panic 53 1.1.2.2 pgoyette * 54 1.1.2.2 pgoyette * Commentary: 55 1.1.2.2 pgoyette * This module manages the device /dev/panic, 56 1.1.2.2 pgoyette * tranfers a string from userspace to kernel space 57 1.1.2.2 pgoyette * and calls kernel panic with the passed string. 58 1.1.2.2 pgoyette * 59 1.1.2.2 pgoyette * echo 'string' > /dev/panic 60 1.1.2.2 pgoyette * will do the trick after loading the module. 61 1.1.2.2 pgoyette */ 62 1.1.2.2 pgoyette 63 1.1.2.2 pgoyette dev_type_open(panic_string_open); 64 1.1.2.2 pgoyette dev_type_close(panic_string_close); 65 1.1.2.2 pgoyette dev_type_write(panic_string_write); 66 1.1.2.2 pgoyette 67 1.1.2.2 pgoyette static struct cdevsw panic_string_cdevsw = { 68 1.1.2.2 pgoyette .d_open = panic_string_open, 69 1.1.2.2 pgoyette .d_close = panic_string_close, 70 1.1.2.2 pgoyette .d_read = noread, 71 1.1.2.2 pgoyette .d_write = panic_string_write, 72 1.1.2.2 pgoyette .d_ioctl = noioctl, 73 1.1.2.2 pgoyette .d_stop = nostop, 74 1.1.2.2 pgoyette .d_tty = notty, 75 1.1.2.2 pgoyette .d_poll = nopoll, 76 1.1.2.2 pgoyette .d_mmap = nommap, 77 1.1.2.2 pgoyette .d_kqfilter = nokqfilter, 78 1.1.2.2 pgoyette .d_discard = nodiscard, 79 1.1.2.2 pgoyette .d_flag = D_OTHER 80 1.1.2.2 pgoyette }; 81 1.1.2.2 pgoyette 82 1.1.2.2 pgoyette static struct panic_string_softc { 83 1.1.2.2 pgoyette int refcnt; 84 1.1.2.2 pgoyette } sc; 85 1.1.2.2 pgoyette 86 1.1.2.2 pgoyette /* 87 1.1.2.2 pgoyette * A function similar to strnlen + isprint 88 1.1.2.2 pgoyette * 89 1.1.2.2 pgoyette * Detect length of the printable and non-whitespace string in the buffer. 90 1.1.2.2 pgoyette * A string is accepted if it contains any non-space character. 91 1.1.2.2 pgoyette */ 92 1.1.2.2 pgoyette 93 1.1.2.2 pgoyette static size_t 94 1.1.2.2 pgoyette printable_length(const char *str, size_t len) 95 1.1.2.2 pgoyette { 96 1.1.2.2 pgoyette size_t n; 97 1.1.2.2 pgoyette bool accepted; 98 1.1.2.2 pgoyette 99 1.1.2.2 pgoyette n = 0; 100 1.1.2.2 pgoyette accepted = false; 101 1.1.2.2 pgoyette 102 1.1.2.2 pgoyette while (len > n) { 103 1.1.2.2 pgoyette if (str[n] >= 0x20 && str[n] <= 0x7e) { 104 1.1.2.2 pgoyette if (str[n] != 0x20 /* space */) 105 1.1.2.2 pgoyette accepted = true; 106 1.1.2.2 pgoyette n++; 107 1.1.2.2 pgoyette } else 108 1.1.2.2 pgoyette break; 109 1.1.2.2 pgoyette } 110 1.1.2.2 pgoyette 111 1.1.2.2 pgoyette if (accepted) 112 1.1.2.2 pgoyette return n; 113 1.1.2.2 pgoyette else 114 1.1.2.2 pgoyette return 0; 115 1.1.2.2 pgoyette } 116 1.1.2.2 pgoyette 117 1.1.2.2 pgoyette int 118 1.1.2.2 pgoyette panic_string_open(dev_t self __unused, int flag __unused, int mod __unused, struct lwp *l) 119 1.1.2.2 pgoyette { 120 1.1.2.2 pgoyette 121 1.1.2.2 pgoyette /* Make sure the device is opened once at a time */ 122 1.1.2.2 pgoyette if (sc.refcnt > 0) 123 1.1.2.2 pgoyette return EBUSY; 124 1.1.2.2 pgoyette 125 1.1.2.2 pgoyette ++sc.refcnt; 126 1.1.2.2 pgoyette 127 1.1.2.2 pgoyette return 0; 128 1.1.2.2 pgoyette } 129 1.1.2.2 pgoyette 130 1.1.2.2 pgoyette int 131 1.1.2.2 pgoyette panic_string_close(dev_t self __unused, int flag __unused, int mod __unused, struct lwp *l __unused) 132 1.1.2.2 pgoyette { 133 1.1.2.2 pgoyette 134 1.1.2.2 pgoyette --sc.refcnt; 135 1.1.2.2 pgoyette return 0; 136 1.1.2.2 pgoyette } 137 1.1.2.2 pgoyette 138 1.1.2.2 pgoyette int 139 1.1.2.2 pgoyette panic_string_write(dev_t self, struct uio *uio, int flags) 140 1.1.2.2 pgoyette { 141 1.1.2.2 pgoyette size_t len, printlen; 142 1.1.2.2 pgoyette char *buffer; 143 1.1.2.2 pgoyette 144 1.1.2.2 pgoyette /* Buffer length */ 145 1.1.2.2 pgoyette len = uio->uio_iov->iov_len; 146 1.1.2.2 pgoyette 147 1.1.2.2 pgoyette /* Allocate a local buffer to store the string */ 148 1.1.2.2 pgoyette buffer = (char *)kmem_alloc(len, KM_SLEEP); 149 1.1.2.2 pgoyette 150 1.1.2.2 pgoyette /* Move the string from user to kernel space and store it locally */ 151 1.1.2.2 pgoyette uiomove(buffer, len, uio); 152 1.1.2.2 pgoyette 153 1.1.2.2 pgoyette printlen = printable_length(buffer, len); 154 1.1.2.2 pgoyette 155 1.1.2.2 pgoyette if (printlen > 0) { 156 1.1.2.2 pgoyette /* Flushing disk changes */ 157 1.1.2.2 pgoyette do_sys_sync(curlwp); 158 1.1.2.2 pgoyette 159 1.1.2.2 pgoyette panic("panic string: %.*s\n", (int)printlen, buffer); 160 1.1.2.2 pgoyette // printf("panic string: %.*s\n", (int)printlen, buffer); 161 1.1.2.2 pgoyette 162 1.1.2.2 pgoyette /* NOTREACHED */ 163 1.1.2.2 pgoyette } 164 1.1.2.2 pgoyette 165 1.1.2.2 pgoyette kmem_free(buffer, len); 166 1.1.2.2 pgoyette return 0; 167 1.1.2.2 pgoyette } 168 1.1.2.2 pgoyette 169 1.1.2.2 pgoyette MODULE(MODULE_CLASS_MISC, panic_string, NULL); 170 1.1.2.2 pgoyette 171 1.1.2.2 pgoyette static int 172 1.1.2.2 pgoyette panic_string_modcmd(modcmd_t cmd, void *arg __unused) 173 1.1.2.2 pgoyette { 174 1.1.2.2 pgoyette /* The major should be verified and changed if needed to avoid 175 1.1.2.2 pgoyette * conflicts with other devices. */ 176 1.1.2.2 pgoyette int cmajor = 210, bmajor = -1; 177 1.1.2.2 pgoyette 178 1.1.2.2 pgoyette switch (cmd) { 179 1.1.2.2 pgoyette case MODULE_CMD_INIT: 180 1.1.2.2 pgoyette printf("Panic String module loaded.\n"); 181 1.1.2.2 pgoyette if (devsw_attach("panic", NULL, &bmajor, &panic_string_cdevsw, 182 1.1.2.2 pgoyette &cmajor)) 183 1.1.2.2 pgoyette return ENXIO; 184 1.1.2.2 pgoyette return 0; 185 1.1.2.2 pgoyette 186 1.1.2.2 pgoyette case MODULE_CMD_FINI: 187 1.1.2.2 pgoyette printf("Panic String module unloaded.\n"); 188 1.1.2.2 pgoyette if (sc.refcnt > 0) 189 1.1.2.2 pgoyette return EBUSY; 190 1.1.2.2 pgoyette 191 1.1.2.2 pgoyette devsw_detach(NULL, &panic_string_cdevsw); 192 1.1.2.2 pgoyette return 0; 193 1.1.2.2 pgoyette default: 194 1.1.2.2 pgoyette return ENOTTY; 195 1.1.2.2 pgoyette } 196 1.1.2.2 pgoyette } 197
Indexes created Tue Sep 23 07:09:52 GMT 2025