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Diffstat (limited to 'sys/modules/examples/panic_string/panic_string.c')
-rw-r--r--sys/modules/examples/panic_string/panic_string.c196
1 files changed, 196 insertions, 0 deletions
diff --git a/sys/modules/examples/panic_string/panic_string.c b/sys/modules/examples/panic_string/panic_string.c
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index 00000000000..f27cde06b6c
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+++ b/sys/modules/examples/panic_string/panic_string.c
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+/* $NetBSD: panic_string.c,v 1.1 2018/05/29 16:53:56 kamil Exp $ */
+
+/*-
+ * Copyright (c) 2018 The NetBSD Foundation, Inc.
+ * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+
+
+#include <sys/cdefs.h>
+__KERNEL_RCSID(0, "$NetBSD: panic_string.c,v 1.1 2018/05/29 16:53:56 kamil Exp $");
+
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/conf.h>
+#include <sys/device.h>
+#include <sys/filedesc.h>
+#include <sys/kernel.h>
+#include <sys/kmem.h>
+#include <sys/lwp.h>
+#include <sys/module.h>
+#include <sys/vfs_syscalls.h>
+
+/*
+ * Create a device /dev/panic from which you can read sequential
+ * user input.
+ *
+ * To use this device you need to do:
+ * mknod /dev/panic c 210 0
+ *
+ * To write to the device you might need:
+ * chmod 666 /dev/panic
+ *
+ * Commentary:
+ * This module manages the device /dev/panic,
+ * tranfers a string from userspace to kernel space
+ * and calls kernel panic with the passed string.
+ *
+ * echo 'string' > /dev/panic
+ * will do the trick after loading the module.
+ */
+
+dev_type_open(panic_string_open);
+dev_type_close(panic_string_close);
+dev_type_write(panic_string_write);
+
+static struct cdevsw panic_string_cdevsw = {
+ .d_open = panic_string_open,
+ .d_close = panic_string_close,
+ .d_read = noread,
+ .d_write = panic_string_write,
+ .d_ioctl = noioctl,
+ .d_stop = nostop,
+ .d_tty = notty,
+ .d_poll = nopoll,
+ .d_mmap = nommap,
+ .d_kqfilter = nokqfilter,
+ .d_discard = nodiscard,
+ .d_flag = D_OTHER
+};
+
+static struct panic_string_softc {
+ int refcnt;
+} sc;
+
+/*
+ * A function similar to strnlen + isprint
+ *
+ * Detect length of the printable and non-whitespace string in the buffer.
+ * A string is accepted if it contains any non-space character.
+ */
+
+static size_t
+printable_length(const char *str, size_t len)
+{
+ size_t n;
+ bool accepted;
+
+ n = 0;
+ accepted = false;
+
+ while (len > n) {
+ if (str[n] >= 0x20 && str[n] <= 0x7e) {
+ if (str[n] != 0x20 /* space */)
+ accepted = true;
+ n++;
+ } else
+ break;
+ }
+
+ if (accepted)
+ return n;
+ else
+ return 0;
+}
+
+int
+panic_string_open(dev_t self __unused, int flag __unused, int mod __unused, struct lwp *l)
+{
+
+ /* Make sure the device is opened once at a time */
+ if (sc.refcnt > 0)
+ return EBUSY;
+
+ ++sc.refcnt;
+
+ return 0;
+}
+
+int
+panic_string_close(dev_t self __unused, int flag __unused, int mod __unused, struct lwp *l __unused)
+{
+
+ --sc.refcnt;
+ return 0;
+}
+
+int
+panic_string_write(dev_t self, struct uio *uio, int flags)
+{
+ size_t len, printlen;
+ char *buffer;
+
+ /* Buffer length */
+ len = uio->uio_iov->iov_len;
+
+ /* Allocate a local buffer to store the string */
+ buffer = (char *)kmem_alloc(len, KM_SLEEP);
+
+ /* Move the string from user to kernel space and store it locally */
+ uiomove(buffer, len, uio);
+
+ printlen = printable_length(buffer, len);
+
+ if (printlen > 0) {
+ /* Flushing disk changes */
+ do_sys_sync(curlwp);
+
+ panic("panic string: %.*s\n", (int)printlen, buffer);
+// printf("panic string: %.*s\n", (int)printlen, buffer);
+
+ /* NOTREACHED */
+ }
+
+ kmem_free(buffer, len);
+ return 0;
+}
+
+MODULE(MODULE_CLASS_MISC, panic_string, NULL);
+
+static int
+panic_string_modcmd(modcmd_t cmd, void *arg __unused)
+{
+ /* The major should be verified and changed if needed to avoid
+ * conflicts with other devices. */
+ int cmajor = 210, bmajor = -1;
+
+ switch (cmd) {
+ case MODULE_CMD_INIT:
+ printf("Panic String module loaded.\n");
+ if (devsw_attach("panic", NULL, &bmajor, &panic_string_cdevsw,
+ &cmajor))
+ return ENXIO;
+ return 0;
+
+ case MODULE_CMD_FINI:
+ printf("Panic String module unloaded.\n");
+ if (sc.refcnt > 0)
+ return EBUSY;
+
+ devsw_detach(NULL, &panic_string_cdevsw);
+ return 0;
+ default:
+ return ENOTTY;
+ }
+}