freebsd-nq/module/zfs/zfs_debug.c
Sara Hartse a887d653b3 Restrict kstats and print real pointers
There are several places where we use zfs_dbgmsg and %p to
print pointers. In the Linux kernel, these values obfuscated
to prevent information leaks which means the pointers aren't
very useful for debugging crash dumps. We decided to restrict
the permissions of dbgmsg (and some other kstats while we were
at it) and print pointers with %px in zfs_dbgmsg as well as
spl_dumpstack

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Gallagher <john.gallagher@delphix.com>
Signed-off-by: sara hartse <sara.hartse@delphix.com>
Closes #8467 
Closes #8476
2019-04-04 18:57:06 -07:00

254 lines
5.8 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2014 by Delphix. All rights reserved.
*/
#include <sys/zfs_context.h>
typedef struct zfs_dbgmsg {
procfs_list_node_t zdm_node;
time_t zdm_timestamp;
int zdm_size;
char zdm_msg[1]; /* variable length allocation */
} zfs_dbgmsg_t;
procfs_list_t zfs_dbgmsgs;
int zfs_dbgmsg_size = 0;
int zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
/*
* Internal ZFS debug messages are enabled by default.
*
* # Print debug messages
* cat /proc/spl/kstat/zfs/dbgmsg
*
* # Disable the kernel debug message log.
* echo 0 > /sys/module/zfs/parameters/zfs_dbgmsg_enable
*
* # Clear the kernel debug message log.
* echo 0 >/proc/spl/kstat/zfs/dbgmsg
*/
int zfs_dbgmsg_enable = 1;
static int
zfs_dbgmsg_show_header(struct seq_file *f)
{
seq_printf(f, "%-12s %-8s\n", "timestamp", "message");
return (0);
}
static int
zfs_dbgmsg_show(struct seq_file *f, void *p)
{
zfs_dbgmsg_t *zdm = (zfs_dbgmsg_t *)p;
seq_printf(f, "%-12llu %-s\n",
(u_longlong_t)zdm->zdm_timestamp, zdm->zdm_msg);
return (0);
}
static void
zfs_dbgmsg_purge(int max_size)
{
while (zfs_dbgmsg_size > max_size) {
zfs_dbgmsg_t *zdm = list_remove_head(&zfs_dbgmsgs.pl_list);
if (zdm == NULL)
return;
int size = zdm->zdm_size;
kmem_free(zdm, size);
zfs_dbgmsg_size -= size;
}
}
static int
zfs_dbgmsg_clear(procfs_list_t *procfs_list)
{
mutex_enter(&zfs_dbgmsgs.pl_lock);
zfs_dbgmsg_purge(0);
mutex_exit(&zfs_dbgmsgs.pl_lock);
return (0);
}
void
zfs_dbgmsg_init(void)
{
procfs_list_install("zfs",
"dbgmsg",
0600,
&zfs_dbgmsgs,
zfs_dbgmsg_show,
zfs_dbgmsg_show_header,
zfs_dbgmsg_clear,
offsetof(zfs_dbgmsg_t, zdm_node));
}
void
zfs_dbgmsg_fini(void)
{
procfs_list_uninstall(&zfs_dbgmsgs);
zfs_dbgmsg_purge(0);
/*
* TODO - decide how to make this permanent
*/
#ifdef _KERNEL
procfs_list_destroy(&zfs_dbgmsgs);
#endif
}
void
__set_error(const char *file, const char *func, int line, int err)
{
/*
* To enable this:
*
* $ echo 512 >/sys/module/zfs/parameters/zfs_flags
*/
if (zfs_flags & ZFS_DEBUG_SET_ERROR)
__dprintf(B_FALSE, file, func, line, "error %lu", err);
}
void
__zfs_dbgmsg(char *buf)
{
int size = sizeof (zfs_dbgmsg_t) + strlen(buf);
zfs_dbgmsg_t *zdm = kmem_zalloc(size, KM_SLEEP);
zdm->zdm_size = size;
zdm->zdm_timestamp = gethrestime_sec();
strcpy(zdm->zdm_msg, buf);
mutex_enter(&zfs_dbgmsgs.pl_lock);
procfs_list_add(&zfs_dbgmsgs, zdm);
zfs_dbgmsg_size += size;
zfs_dbgmsg_purge(MAX(zfs_dbgmsg_maxsize, 0));
mutex_exit(&zfs_dbgmsgs.pl_lock);
}
#ifdef _KERNEL
void
__dprintf(boolean_t dprint, const char *file, const char *func,
int line, const char *fmt, ...)
{
const char *newfile;
va_list adx;
size_t size;
char *buf;
char *nl;
int i;
char *prefix = (dprint) ? "dprintf: " : "";
size = 1024;
buf = kmem_alloc(size, KM_SLEEP);
/*
* Get rid of annoying prefix to filename.
*/
newfile = strrchr(file, '/');
if (newfile != NULL) {
newfile = newfile + 1; /* Get rid of leading / */
} else {
newfile = file;
}
i = snprintf(buf, size, "%s%s:%d:%s(): ", prefix, newfile, line, func);
if (i < size) {
va_start(adx, fmt);
(void) vsnprintf(buf + i, size - i, fmt, adx);
va_end(adx);
}
/*
* Get rid of trailing newline for dprintf logs.
*/
if (dprint && buf[0] != '\0') {
nl = &buf[strlen(buf) - 1];
if (*nl == '\n')
*nl = '\0';
}
/*
* To get this data enable the zfs__dprintf trace point as shown:
*
* # Enable zfs__dprintf tracepoint, clear the tracepoint ring buffer
* $ echo 1 > /sys/kernel/debug/tracing/events/zfs/enable
* $ echo 0 > /sys/kernel/debug/tracing/trace
*
* # Dump the ring buffer.
* $ cat /sys/kernel/debug/tracing/trace
*/
DTRACE_PROBE1(zfs__dprintf, char *, buf);
/*
* To get this data:
*
* $ cat /proc/spl/kstat/zfs/dbgmsg
*
* To clear the buffer:
* $ echo 0 > /proc/spl/kstat/zfs/dbgmsg
*/
__zfs_dbgmsg(buf);
kmem_free(buf, size);
}
#else
void
zfs_dbgmsg_print(const char *tag)
{
ssize_t ret __attribute__((unused));
/*
* We use write() in this function instead of printf()
* so it is safe to call from a signal handler.
*/
ret = write(STDOUT_FILENO, "ZFS_DBGMSG(", 11);
ret = write(STDOUT_FILENO, tag, strlen(tag));
ret = write(STDOUT_FILENO, ") START:\n", 9);
mutex_enter(&zfs_dbgmsgs.pl_lock);
for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs.pl_list); zdm != NULL;
zdm = list_next(&zfs_dbgmsgs.pl_list, zdm)) {
ret = write(STDOUT_FILENO, zdm->zdm_msg,
strlen(zdm->zdm_msg));
ret = write(STDOUT_FILENO, "\n", 1);
}
ret = write(STDOUT_FILENO, "ZFS_DBGMSG(", 11);
ret = write(STDOUT_FILENO, tag, strlen(tag));
ret = write(STDOUT_FILENO, ") END\n", 6);
mutex_exit(&zfs_dbgmsgs.pl_lock);
}
#endif /* _KERNEL */
#ifdef _KERNEL
module_param(zfs_dbgmsg_enable, int, 0644);
MODULE_PARM_DESC(zfs_dbgmsg_enable, "Enable ZFS debug message log");
module_param(zfs_dbgmsg_maxsize, int, 0644);
MODULE_PARM_DESC(zfs_dbgmsg_maxsize, "Maximum ZFS debug log size");
#endif