/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2007 Robert N. M. Watson
* 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 AUTHOR 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 AUTHOR 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.
*/
/*-
* Kernel text-dump support: write a series of text files to the dump
* partition for later recovery, including captured DDB output, kernel
* configuration, message buffer, and panic message. This allows for a more
* compact representation of critical debugging information than traditional
* binary dumps, as well as allowing dump information to be used without
* access to kernel symbols, source code, etc.
*
* Storage Layout
* --------------
*
* Crash dumps are aligned to the end of the dump or swap partition in order
* to minimize the chances of swap duing fsck eating into the dump. However,
* unlike a memory dump, we don't know the size of the textdump a priori, so
* can't just write it out sequentially in order from a known starting point
* calculated with respect to the end of the partition. In order to address
* this, we actually write out the textdump in reverse block order, allowing
* us to directly align it to the end of the partition and then write out the
* dump header and trailer before and after it once done. savecore(8) must
* know to reverse the order of the blocks in order to produce a readable
* file.
*
* Data is written out in the ustar file format so that we can write data
* incrementally as a stream without reference to previous files.
*
* TODO
* ----
*
* - Allow subsystems to register to submit files for inclusion in the text
* dump in a generic way.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_config.h"
#include "opt_ddb.h"
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/kernel.h>
#include <sys/kerneldump.h>
#include <sys/msgbuf.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <ddb/ddb.h>
#include <ddb/db_lex.h>
static SYSCTL_NODE(_debug_ddb, OID_AUTO, textdump, CTLFLAG_RW, 0,
"DDB textdump options");
/*
* Don't touch the first SIZEOF_METADATA bytes on the dump device. This is
* to protect us from metadata and metadata from us.
*/
#define SIZEOF_METADATA (64*1024)
/*
* Data is written out as a series of files in the ustar tar format. ustar
* is a simple streamed format consiting of a series of files prefixed with
* headers, and all padded to 512-byte block boundaries, which maps
* conveniently to our requirements.
*/
struct ustar_header {
char uh_filename[100];
char uh_mode[8];
char uh_tar_owner[8];
char uh_tar_group[8];
char uh_size[12];
char uh_mtime[12];
char uh_sum[8];
char uh_type;
char uh_linkfile[100];
char uh_ustar[6];
char uh_version[2];
char uh_owner[32];
char uh_group[32];
char uh_major[8];
char uh_minor[8];
char uh_filenameprefix[155];
char uh_zeropad[12];
} __packed;
/*
* Various size assertions -- pretty much everything must be one block in
* size.
*/
CTASSERT(sizeof(struct kerneldumpheader) == TEXTDUMP_BLOCKSIZE);
CTASSERT(sizeof(struct ustar_header) == TEXTDUMP_BLOCKSIZE);
/*
* Is a textdump scheduled? If so, the shutdown code will invoke our dumpsys
* routine instead of the machine-dependent kernel dump routine.
*/
#ifdef TEXTDUMP_PREFERRED
int textdump_pending = 1;
#else
int textdump_pending = 0;
#endif
SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, pending, CTLFLAG_RW,
&textdump_pending, 0,
"Perform textdump instead of regular kernel dump.");
/*
* Various constants for tar headers and contents.
*/
#define TAR_USER "root"
#define TAR_GROUP "wheel"
#define TAR_UID "0"
#define TAR_GID "0"
#define TAR_MODE "0600"
#define TAR_USTAR "ustar"
#define TAR_CONFIG_FILENAME "config.txt" /* Kernel configuration. */
#define TAR_MSGBUF_FILENAME "msgbuf.txt" /* Kernel messsage buffer. */
#define TAR_PANIC_FILENAME "panic.txt" /* Panic message. */
#define TAR_VERSION_FILENAME "version.txt" /* Kernel version. */
/*
* Configure which files will be dumped.
*/
#ifdef INCLUDE_CONFIG_FILE
static int textdump_do_config = 1;
SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_config, CTLFLAG_RW,
&textdump_do_config, 0, "Dump kernel configuration in textdump");
#endif
static int textdump_do_ddb = 1;
SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_ddb, CTLFLAG_RW,
&textdump_do_ddb, 0, "Dump DDB captured output in textdump");
static int textdump_do_msgbuf = 1;
SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_msgbuf, CTLFLAG_RW,
&textdump_do_msgbuf, 0, "Dump kernel message buffer in textdump");
static int textdump_do_panic = 1;
SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_panic, CTLFLAG_RW,
&textdump_do_panic, 0, "Dump kernel panic message in textdump");
static int textdump_do_version = 1;
SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_version, CTLFLAG_RW,
&textdump_do_version, 0, "Dump kernel version string in textdump");
/*
* State related to incremental writing of blocks to disk.
*/
static off_t textdump_offset; /* Offset of next sequential write. */
static int textdump_error; /* Carried write error, if any. */
/*
* Statically allocate space to prepare block-sized headers and data.
*/
char textdump_block_buffer[TEXTDUMP_BLOCKSIZE];
static struct kerneldumpheader kdh;
/*
* Calculate and fill in the checksum for a ustar header.
*/
static void
ustar_checksum(struct ustar_header *uhp)
{
u_int sum;
int i;
for (i = 0; i < sizeof(uhp->uh_sum); i++)
uhp->uh_sum[i] = ' ';
sum = 0;
for (i = 0; i < sizeof(*uhp); i++)
sum += ((u_char *)uhp)[i];
snprintf(uhp->uh_sum, sizeof(uhp->uh_sum), "%6o", sum);
}
/*
* Each file in the tarball has a block-sized header with its name and other,
* largely hard-coded, properties.
*/
void
textdump_mkustar(char *block_buffer, const char *filename, u_int size)
{
struct ustar_header *uhp;
#ifdef TEXTDUMP_VERBOSE
if (textdump_error == 0)
printf("textdump: creating '%s'.\n", filename);
#endif
uhp = (struct ustar_header *)block_buffer;
bzero(uhp, sizeof(*uhp));
strlcpy(uhp->uh_filename, filename, sizeof(uhp->uh_filename));
strlcpy(uhp->uh_mode, TAR_MODE, sizeof(uhp->uh_mode));
snprintf(uhp->uh_size, sizeof(uhp->uh_size), "%o", size);
strlcpy(uhp->uh_tar_owner, TAR_UID, sizeof(uhp->uh_tar_owner));
strlcpy(uhp->uh_tar_group, TAR_GID, sizeof(uhp->uh_tar_group));
strlcpy(uhp->uh_owner, TAR_USER, sizeof(uhp->uh_owner));
strlcpy(uhp->uh_group, TAR_GROUP, sizeof(uhp->uh_group));
snprintf(uhp->uh_mtime, sizeof(uhp->uh_mtime), "%lo",
(unsigned long)time_second);
uhp->uh_type = 0;
strlcpy(uhp->uh_ustar, TAR_USTAR, sizeof(uhp->uh_ustar));
ustar_checksum(uhp);
}
/*
* textdump_writeblock() writes TEXTDUMP_BLOCKSIZE-sized blocks of data to
* the space between di->mediaoffset and di->mediaoffset + di->mediasize. It
* accepts an offset relative to di->mediaoffset. If we're carrying any
* error from previous I/O, return that error and don't continue to try to
* write. Most writers ignore the error and forge ahead on the basis that
* there's not much you can do.
*/
static int
textdump_writeblock(struct dumperinfo *di, off_t offset, char *buffer)
{
if (textdump_error)
return (textdump_error);
if (offset + TEXTDUMP_BLOCKSIZE > di->mediasize)
return (EIO);
if (offset < SIZEOF_METADATA)
return (ENOSPC);
textdump_error = dump_write(di, buffer, 0, offset + di->mediaoffset,
TEXTDUMP_BLOCKSIZE);
if (textdump_error)
printf("textdump_writeblock: offset %jd, error %d\n", (intmax_t)offset,
textdump_error);
return (textdump_error);
}
/*
* Interfaces to save and restore the dump offset, so that printers can go
* back to rewrite a header if required, while avoiding their knowing about
* the global layout of the blocks.
*
* If we ever want to support writing textdumps to tape or other
* stream-oriented target, we'll need to remove this.
*/
void
textdump_saveoff(off_t *offsetp)
{
*offsetp = textdump_offset;
}
void
textdump_restoreoff(off_t offset)
{
textdump_offset = offset;
}
/*
* Interface to write the "next block" relative to the current offset; since
* we write backwards from the end of the partition, we subtract, but there's
* no reason for the caller to know this.
*/
int
textdump_writenextblock(struct dumperinfo *di, char *buffer)
{
int error;
error = textdump_writeblock(di, textdump_offset, buffer);
textdump_offset -= TEXTDUMP_BLOCKSIZE;
return (error);
}
#ifdef INCLUDE_CONFIG_FILE
extern char kernconfstring[];
/*
* Dump kernel configuration.
*/
static void
textdump_dump_config(struct dumperinfo *di)
{
u_int count, fullblocks, len;
len = strlen(kernconfstring);
textdump_mkustar(textdump_block_buffer, TAR_CONFIG_FILENAME, len);
(void)textdump_writenextblock(di, textdump_block_buffer);
/*
* Write out all full blocks directly from the string, and handle any
* left-over bits by copying it to out to the local buffer and
* zero-padding it.
*/
fullblocks = len / TEXTDUMP_BLOCKSIZE;
for (count = 0; count < fullblocks; count++)
(void)textdump_writenextblock(di, kernconfstring + count *
TEXTDUMP_BLOCKSIZE);
if (len % TEXTDUMP_BLOCKSIZE != 0) {
bzero(textdump_block_buffer, TEXTDUMP_BLOCKSIZE);
bcopy(kernconfstring + count * TEXTDUMP_BLOCKSIZE,
textdump_block_buffer, len % TEXTDUMP_BLOCKSIZE);
(void)textdump_writenextblock(di, textdump_block_buffer);
}
}
#endif /* INCLUDE_CONFIG_FILE */
/*
* Dump kernel message buffer.
*/
static void
textdump_dump_msgbuf(struct dumperinfo *di)
{
off_t end_offset, tarhdr_offset;
u_int i, len, offset, seq, total_len;
char buf[16];
/*
* Write out a dummy tar header to advance the offset; we'll rewrite
* it later once we know the true size.
*/
textdump_saveoff(&tarhdr_offset);
textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 0);
(void)textdump_writenextblock(di, textdump_block_buffer);
/*
* Copy out the data in small chunks, but don't copy nuls that may be
* present if the message buffer has not yet completely filled at
* least once.
*/
total_len = 0;
offset = 0;
msgbuf_peekbytes(msgbufp, NULL, 0, &seq);
while ((len = msgbuf_peekbytes(msgbufp, buf, sizeof(buf), &seq)) > 0) {
for (i = 0; i < len; i++) {
if (buf[i] == '\0')
continue;
textdump_block_buffer[offset] = buf[i];
offset++;
if (offset != sizeof(textdump_block_buffer))
continue;
(void)textdump_writenextblock(di,
textdump_block_buffer);
total_len += offset;
offset = 0;
}
}
total_len += offset; /* Without the zero-padding. */
if (offset != 0) {
bzero(textdump_block_buffer + offset,
sizeof(textdump_block_buffer) - offset);
(void)textdump_writenextblock(di, textdump_block_buffer);
}
/*
* Rewrite tar header to reflect how much was actually written.
*/
textdump_saveoff(&end_offset);
textdump_restoreoff(tarhdr_offset);
textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME,
total_len);
(void)textdump_writenextblock(di, textdump_block_buffer);
textdump_restoreoff(end_offset);
}
static void
textdump_dump_panic(struct dumperinfo *di)
{
u_int len;
/*
* Write out tar header -- we store up to one block of panic message.
*/
len = min(strlen(panicstr), TEXTDUMP_BLOCKSIZE);
textdump_mkustar(textdump_block_buffer, TAR_PANIC_FILENAME, len);
(void)textdump_writenextblock(di, textdump_block_buffer);
/*
* Zero-pad the panic string and write out block.
*/
bzero(textdump_block_buffer, sizeof(textdump_block_buffer));
bcopy(panicstr, textdump_block_buffer, len);
(void)textdump_writenextblock(di, textdump_block_buffer);
}
static void
textdump_dump_version(struct dumperinfo *di)
{
u_int len;
/*
* Write out tar header -- at most one block of version information.
*/
len = min(strlen(version), TEXTDUMP_BLOCKSIZE);
textdump_mkustar(textdump_block_buffer, TAR_VERSION_FILENAME, len);
(void)textdump_writenextblock(di, textdump_block_buffer);
/*
* Zero pad the version string and write out block.
*/
bzero(textdump_block_buffer, sizeof(textdump_block_buffer));
bcopy(version, textdump_block_buffer, len);
(void)textdump_writenextblock(di, textdump_block_buffer);
}
/*
* Commit text dump to disk.
*/
void
textdump_dumpsys(struct dumperinfo *di)
{
struct kerneldumpcrypto *kdc;
off_t dumplen, trailer_offset;
if (di->blocksize != TEXTDUMP_BLOCKSIZE) {
printf("Dump partition block size (%ju) not textdump "
"block size (%ju)", (uintmax_t)di->blocksize,
(uintmax_t)TEXTDUMP_BLOCKSIZE);
return;
}
/*
* We don't know a priori how large the dump will be, but we do know
* that we need to reserve space for metadata and that we need two
* dump headers. Also leave room for one ustar header and one block
* of data.
*/
if (di->mediasize < SIZEOF_METADATA + 2 * sizeof(kdh)) {
printf("Insufficient space on dump partition for minimal textdump.\n");
return;
}
textdump_error = 0;
/*
* Disable EKCD because we don't provide encrypted textdumps.
*/
kdc = di->kdcrypto;
di->kdcrypto = NULL;
/*
* Position the start of the dump so that we'll write the kernel dump
* trailer immediately before the end of the partition, and then work
* our way back. We will rewrite this header later to reflect the
* true size if things go well.
*/
textdump_offset = di->mediasize - sizeof(kdh);
textdump_saveoff(&trailer_offset);
dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 0);
(void)textdump_writenextblock(di, (char *)&kdh);
/*
* Write a series of files in ustar format.
*/
if (textdump_do_ddb)
db_capture_dump(di);
#ifdef INCLUDE_CONFIG_FILE
if (textdump_do_config)
textdump_dump_config(di);
#endif
if (textdump_do_msgbuf)
textdump_dump_msgbuf(di);
if (textdump_do_panic && panicstr != NULL)
textdump_dump_panic(di);
if (textdump_do_version)
textdump_dump_version(di);
/*
* Now that we know the true size, we can write out the header, then
* seek back to the end and rewrite the trailer with the correct
* size.
*/
dumplen = trailer_offset - (textdump_offset + TEXTDUMP_BLOCKSIZE);
dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION,
dumplen);
(void)textdump_writenextblock(di, (char *)&kdh);
textdump_restoreoff(trailer_offset);
(void)textdump_writenextblock(di, (char *)&kdh);
/*
* Terminate the dump, report any errors, and clear the pending flag.
*/
if (textdump_error == 0)
(void)dump_write(di, NULL, 0, 0, 0);
if (textdump_error == ENOSPC)
printf("Textdump: Insufficient space on dump partition\n");
else if (textdump_error != 0)
printf("Textdump: Error %d writing dump\n", textdump_error);
else
printf("Textdump complete.\n");
textdump_pending = 0;
/*
* Restore EKCD status.
*/
di->kdcrypto = kdc;
}
/*-
* DDB(4) command to manage textdumps:
*
* textdump set - request a textdump
* textdump status - print DDB output textdump status
* textdump unset - clear textdump request
*/
static void
db_textdump_usage(void)
{
db_printf("textdump [unset|set|status|dump]\n");
}
void
db_textdump_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif)
{
int t;
t = db_read_token();
if (t != tIDENT) {
db_textdump_usage();
return;
}
if (db_read_token() != tEOL) {
db_textdump_usage();
return;
}
if (strcmp(db_tok_string, "set") == 0) {
textdump_pending = 1;
db_printf("textdump set\n");
} else if (strcmp(db_tok_string, "status") == 0) {
if (textdump_pending)
db_printf("textdump is set\n");
else
db_printf("textdump is not set\n");
} else if (strcmp(db_tok_string, "unset") == 0) {
textdump_pending = 0;
db_printf("textdump unset\n");
} else if (strcmp(db_tok_string, "dump") == 0) {
textdump_pending = 1;
doadump(true);
} else {
db_textdump_usage();
}
}
