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sysklogd/klogd.c
Joey Schulze 67383f9931 * Fixed little mistake which prevented klogd from accepting a console 
log level of 8 to get <7> alias KERN_DEBUG displayed.
1997-08-21 10:14:52 +00:00

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/*
klogd.c - main program for Linux kernel log daemon.
Copyright (c) 1995 Dr. G.W. Wettstein <greg@wind.rmcc.com>
This file is part of the sysklogd package, a kernel and system log daemon.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* Steve Lord (lord@cray.com) 7th Nov 92
*
* Modified to check for kernel info by Dr. G.W. Wettstein 02/17/93.
*
* Fri Mar 12 16:53:56 CST 1993: Dr. Wettstein
* Modified LogLine to use a newline as the line separator in
* the kernel message buffer.
*
* Added debugging code to dump the contents of the kernel message
* buffer at the start of the LogLine function.
*
* Thu Jul 29 11:40:32 CDT 1993: Dr. Wettstein
* Added syscalls to turn off logging of kernel messages to the
* console when klogd becomes responsible for kernel messages.
*
* klogd now catches SIGTERM and SIGKILL signals. Receipt of these
* signals cases the clean_up function to be called which shuts down
* kernel logging and re-enables logging of messages to the console.
*
* Sat Dec 11 11:54:22 CST 1993: Dr. Wettstein
* Added fixes to allow compilation with no complaints with -Wall.
*
* When the daemon catches a fatal signal (SIGTERM, SIGKILL) a
* message is output to the logfile advising that the daemon is
* going to terminate.
*
* Thu Jan 6 11:54:10 CST 1994: Dr. Wettstein
* Major re-write/re-organization of the code.
*
* Klogd now assigns kernel messages to priority levels when output
* to the syslog facility is requested. The priority level is
* determined by decoding the prioritization sequence which is
* tagged onto the start of the kernel messages.
*
* Added the following program options: -f arg -c arg -s -o -d
*
* The -f switch can be used to specify that output should
* be written to the named file.
*
* The -c switch is used to specify the level of kernel
* messages which are to be directed to the console.
*
* The -s switch causes the program to use the syscall
* interface to the kernel message facility. This can be
* used to override the presence of the /proc filesystem.
*
* The -o switch causes the program to operate in 'one-shot'
* mode. A single call will be made to read the complete
* kernel buffer. The contents of the buffer will be
* output and the program will terminate.
*
* The -d switch causes 'debug' mode to be activated. This
* will cause the daemon to generate LOTS of output to stderr.
*
* The buffer decomposition function (LogLine) was re-written to
* squash a bug which was causing only partial kernel messages to
* be written to the syslog facility.
*
* The signal handling code was modified to properly differentiate
* between the STOP and TSTP signals.
*
* Added pid saving when the daemon detaches into the background. Thank
* you to Juha Virtanen (jiivee@hut.fi) for providing this patch.
*
* Mon Feb 6 07:31:29 CST 1995: Dr. Wettstein
* Significant re-organization of the signal handling code. The
* signal handlers now only set variables. Not earth shaking by any
* means but aesthetically pleasing to the code purists in the group.
*
* Patch to make things more compliant with the file system standards.
* Thanks to Chris Metcalf for prompting this helpful change.
*
* The routines responsible for reading the kernel log sources now
* initialize the buffers before reading. I think that this will
* solve problems with non-terminated kernel messages producing
* output of the form: new old old old
*
* This may also help influence the occassional reports of klogd
* failing under significant load. I think that the jury may still
* be out on this one though. My thanks to Joerg Ahrens for initially
* tipping me off to the source of this problem. Also thanks to
* Michael O'Reilly for tipping me off to the best fix for this problem.
* And last but not least Mark Lord for prompting me to try this as
* a means of attacking the stability problem.
*
* Specifying a - as the arguement to the -f switch will cause output
* to be directed to stdout rather than a filename of -. Thanks to
* Randy Appleton for a patch which prompted me to do this.
*
* Wed Feb 22 15:37:37 CST 1995: Dr. Wettstein
* Added version information to logging startup messages.
*
* Wed Jul 26 18:57:23 MET DST 1995: Martin Schulze
* Added an commandline argument "-n" to avoid forking. This obsoletes
* the compiler define NO_FORK. It's more useful to have this as an
* argument as there are many binary versions and one doesn't need to
* recompile the daemon.
*
* Thu Aug 10 19:01:08 MET DST 1995: Martin Schulze
* Added my pidfile.[ch] to it to perform a better handling with pidfiles.
* Now both, syslogd and klogd, can only be started once. They check the
* pidfile.
*
* Fri Nov 17 15:05:43 CST 1995: Dr. Wettstein
* Added support for kernel address translation. This required moving
* some definitions and includes to the new klogd.h file. Some small
* code cleanups and modifications.
*
* Mon Nov 20 10:03:39 MET 1995
* Added -v option to print the version and exit.
*
* Thu Jan 18 11:19:46 CST 1996: Dr. Wettstein
* Added suggested patches from beta-testers. These address two
* two problems. The first is segmentation faults which occur with
* the ELF libraries. This was caused by passing a null pointer to
* the strcmp function.
*
* Added a second patch to remove the pidfile as part of the
* termination cleanup sequence. This minimizes the potential for
* conflicting pidfiles causing immediate termination at boot time.
*
* Wed Aug 21 09:13:03 CDT 1996: Dr. Wettstein
* Added ability to reload static symbols and kernel module symbols
* under control of SIGUSR1 and SIGUSR2 signals.
*
* Added -p switch to select 'paranoid' behavior with respect to the
* loading of kernel module symbols.
*
* Informative line now printed whenever a state change occurs due
* to signal reception by the daemon.
*
* Added the -i and -I command line switches to signal the currently
* executing daemon.
*
* Tue Nov 19 10:15:36 PST 1996: Leland Olds <olds@eskimo.com>
* Corrected vulnerability to buffer overruns by rewriting LogLine
* routine. Obscenely long kernel messages will now be broken up
* into lines no longer than LOG_LINE_LENGTH.
*
* The last version of LogLine was vulnerable to buffer overruns:
* - Kernel messages longer than LOG_LINE_LENGTH caused a buffer
* overrun.
* - If a line was determined to be shorter than LOG_LINE_LENGTH,
* the routine "ExpandKadds" could cause the line grow by
* an unknown amount and overrun a buffer.
* I turned these routines into a little parsing state machine that
* should not have these problems.
*
* Sun Jun 15 16:23:29 MET DST 1997: Michael Alan Dorman
* Some more glibc patches made by <mdorman@debian.org>.
*
* Thu Aug 21 12:11:27 MET DST 1997: Martin Schulze <joey@infodrom.north.de>
* Fixed little mistake which prevented klogd from accepting a
* console log
*/
/* Includes. */
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#if !defined(__GLIBC__)
#include <linux/time.h>
#endif /* __GLIBC__ */
#include <stdarg.h>
#include <paths.h>
#include <stdlib.h>
#include "klogd.h"
#include "ksyms.h"
#include "pidfile.h"
#include "version.h"
#define __LIBRARY__
#include <linux/unistd.h>
#if !defined(__GLIBC__)
# define __NR_ksyslog __NR_syslog
_syscall3(int,ksyslog,int, type, char *, buf, int, len);
#else
#include <sys/klog.h>
#define ksyslog klogctl
#endif
#define LOG_BUFFER_SIZE 4096
#define LOG_LINE_LENGTH 1024
#if defined(FSSTND)
static char *PidFile = _PATH_VARRUN "klogd.pid";
#else
static char *PidFile = "/etc/klogd.pid";
#endif
static int kmsg,
change_state = 0,
terminate = 0,
caught_TSTP = 0,
reload_symbols = 0,
console_log_level = 6;
static int use_syscall = 0,
one_shot = 0,
NoFork = 0; /* don't fork - don't run in daemon mode */
static char *symfile = (char *) 0,
log_buffer[LOG_BUFFER_SIZE];
static FILE *output_file = (FILE *) 0;
static enum LOGSRC {none, proc, kernel} logsrc;
int debugging = 0;
/* Function prototypes. */
extern int ksyslog(int type, char *buf, int len);
static void CloseLogSrc(void);
extern void restart(int sig);
extern void stop_logging(int sig);
extern void stop_daemon(int sig);
extern void reload_daemon(int sig);
static void Terminate(void);
static void SignalDaemon(int);
static void ReloadSymbols(void);
static void ChangeLogging(void);
static enum LOGSRC GetKernelLogSrc(void);
static void LogLine(char *ptr, int len);
static void LogKernelLine(void);
static void LogProcLine(void);
extern int main(int argc, char *argv[]);
static void CloseLogSrc()
{
/* Turn on logging of messages to console. */
ksyslog(7, NULL, 0);
/* Shutdown the log sources. */
switch ( logsrc )
{
case kernel:
ksyslog(0, 0, 0);
Syslog(LOG_INFO, "Kernel logging (ksyslog) stopped.");
break;
case proc:
close(kmsg);
Syslog(LOG_INFO, "Kernel logging (proc) stopped.");
break;
case none:
break;
}
if ( output_file != (FILE *) 0 )
fflush(output_file);
return;
}
void restart(sig)
int sig;
{
signal(SIGCONT, restart);
change_state = 1;
caught_TSTP = 0;
return;
}
void stop_logging(sig)
int sig;
{
signal(SIGTSTP, stop_logging);
change_state = 1;
caught_TSTP = 1;
return;
}
void stop_daemon(sig)
int sig;
{
change_state = 1;
terminate = 1;
return;
}
void reload_daemon(sig)
int sig;
{
change_state = 1;
reload_symbols = 1;
if ( sig == SIGUSR2 )
{
++reload_symbols;
signal(SIGUSR2, reload_daemon);
}
else
signal(SIGUSR1, reload_daemon);
return;
}
static void Terminate()
{
CloseLogSrc();
Syslog(LOG_INFO, "Kernel log daemon terminating.");
sleep(1);
if ( output_file != (FILE *) 0 )
fclose(output_file);
closelog();
(void) remove_pid(PidFile);
exit(1);
}
static void SignalDaemon(sig)
int sig;
{
auto int pid = check_pid(PidFile);
kill(pid, sig);
return;
}
static void ReloadSymbols()
{
if ( reload_symbols > 1 )
InitKsyms(symfile);
InitMsyms();
reload_symbols = change_state = 0;
return;
}
static void ChangeLogging(void)
{
/* Terminate kernel logging. */
if ( terminate == 1 )
Terminate();
/* Indicate that something is happening. */
Syslog(LOG_INFO, "klogd %s-%s, ---------- state change ----------\n", \
VERSION, PATCHLEVEL);
/* Reload symbols. */
if ( reload_symbols > 0 )
{
ReloadSymbols();
return;
}
/* Stop kernel logging. */
if ( caught_TSTP == 1 )
{
CloseLogSrc();
logsrc = none;
change_state = 0;
return;
}
/*
* The rest of this function is responsible for restarting
* kernel logging after it was stopped.
*
* In the following section we make a decision based on the
* kernel log state as to what is causing us to restart. Somewhat
* groady but it keeps us from creating another static variable.
*/
if ( logsrc != none )
{
Syslog(LOG_INFO, "Kernel logging re-started after SIGSTOP.");
change_state = 0;
return;
}
/* Restart logging. */
logsrc = GetKernelLogSrc();
change_state = 0;
return;
}
static enum LOGSRC GetKernelLogSrc(void)
{
auto struct stat sb;
/* Set level of kernel console messaging.. */
if ( (ksyslog(8, NULL, console_log_level) < 0) && \
(errno == EINVAL) )
{
/*
* An invalid arguement error probably indicates that
* a pre-0.14 kernel is being run. At this point we
* issue an error message and simply shut-off console
* logging completely.
*/
Syslog(LOG_WARNING, "Cannot set console log level - disabling "
"console output.");
ksyslog(6, NULL, 0);
}
/*
* First do a stat to determine whether or not the proc based
* file system is available to get kernel messages from.
*/
if ( use_syscall ||
((stat(_PATH_KLOG, &sb) < 0) && (errno == ENOENT)) )
{
/* Initialize kernel logging. */
ksyslog(1, NULL, 0);
Syslog(LOG_INFO, "klogd %s-%s, log source = ksyslog "
"started.", VERSION, PATCHLEVEL);
return(kernel);
}
if ( (kmsg = open(_PATH_KLOG, O_RDONLY)) < 0 )
{
fprintf(stderr, "klogd: Cannot open proc file system, " \
"%d - %s.\n", errno, strerror(errno));
ksyslog(7, NULL, 0);
exit(1);
}
Syslog(LOG_INFO, "klogd %s-%s, log source = %s started.", \
VERSION, PATCHLEVEL, _PATH_KLOG);
return(proc);
}
extern void Syslog(int priority, char *fmt, ...)
{
va_list ap;
if ( debugging )
{
fputs("Logging line:\n", stderr);
fprintf(stderr, "\tLine: %s\n", fmt);
fprintf(stderr, "\tPriority: %d\n", priority);
}
/* Handle output to a file. */
if ( output_file != (FILE *) 0 )
{
va_start(ap, fmt);
vfprintf(output_file, fmt, ap);
va_end(ap);
fputc('\n', output_file);
fflush(output_file);
fsync(fileno(output_file));
return;
}
/* Output using syslog. */
if ( *fmt == '<' )
{
switch ( *(fmt+1) )
{
case '0':
priority = LOG_EMERG;
break;
case '1':
priority = LOG_ALERT;
break;
case '2':
priority = LOG_CRIT;
break;
case '3':
priority = LOG_ERR;
break;
case '4':
priority = LOG_WARNING;
break;
case '5':
priority = LOG_NOTICE;
break;
case '6':
priority = LOG_INFO;
break;
case '7':
default:
priority = LOG_DEBUG;
}
fmt += 3;
}
va_start(ap, fmt);
vsyslog(priority, fmt, ap);
va_end(ap);
return;
}
/*
* Copy characters from ptr to line until a char in the delim
* string is encountered or until min( space, len ) chars have
* been copied.
*
* Returns the actual number of chars copied.
*/
static int copyin( char *line, int space,
const char *ptr, int len,
const char *delim )
{
auto int i;
auto int count;
count = len < space ? len : space;
for(i=0; i<count && !strchr(delim, *ptr); i++ ) { *line++ = *ptr++; }
return( i );
}
/*
* Messages are separated by "\n". Messages longer than
* LOG_LINE_LENGTH are broken up.
*
* Kernel symbols show up in the input buffer as : "[<aaaaaa>]",
* where "aaaaaa" is the address. These are replaced with
* "[symbolname+offset/size]" in the output line - symbolname,
* offset, and size come from the kernel symbol table.
*
* If a kernel symbol happens to fall at the end of a message close
* in length to LOG_LINE_LENGTH, the symbol will not be expanded.
* (This should never happen, since the kernel should never generate
* messages that long.
*/
static void LogLine(char *ptr, int len)
{
enum parse_state_enum {
PARSING_TEXT,
PARSING_SYMSTART, /* at < */
PARSING_SYMBOL,
PARSING_SYMEND /* at ] */
};
static char line_buff[LOG_LINE_LENGTH];
static char *line =line_buff;
static enum parse_state_enum parse_state = PARSING_TEXT;
static int space = sizeof(line_buff)-1;
static char *sym_start; /* points at the '<' of a symbol */
auto int delta = 0; /* number of chars copied */
while( len > 0 )
{
if( space == 0 ) /* line buffer is full */
{
/*
** Line too long. Start a new line.
*/
*line = 0; /* force null terminator */
if ( debugging )
{
fputs("Line buffer full:\n", stderr);
fprintf(stderr, "\tLine: %s\n", line);
}
Syslog( LOG_INFO, line_buff );
line = line_buff;
space = sizeof(line_buff)-1;
parse_state = PARSING_TEXT;
}
switch( parse_state )
{
case PARSING_TEXT:
delta = copyin( line, space, ptr, len, "\n[" );
line += delta;
ptr += delta;
space -= delta;
len -= delta;
if( space == 0 || len == 0 )
{
break; /* full line_buff or end of input buffer */
}
if( *ptr == '\n' ) /* newline */
{
*line++ = *ptr++; /* copy it in */
space -= 1;
len -= 1;
*line = 0; /* force null terminator */
Syslog( LOG_INFO, line_buff );
line = line_buff;
space = sizeof(line_buff)-1;
break;
}
if( *ptr == '[' ) /* possible kernel symbol */
{
*line++ = *ptr++;
space -= 1;
len -= 1;
parse_state = PARSING_SYMSTART; /* at < */
break;
}
break;
case PARSING_SYMSTART:
if( *ptr != '<' )
{
parse_state = PARSING_TEXT; /* not a symbol */
break;
}
/*
** Save this character for now. If this turns out to
** be a valid symbol, this char will be replaced later.
** If not, we'll just leave it there.
*/
sym_start = line; /* this will point at the '<' */
*line++ = *ptr++;
space -= 1;
len -= 1;
parse_state = PARSING_SYMBOL; /* symbol... */
break;
case PARSING_SYMBOL:
delta = copyin( line, space, ptr, len, ">\n[" );
line += delta;
ptr += delta;
space -= delta;
len -= delta;
if( space == 0 || len == 0 )
{
break; /* full line_buff or end of input buffer */
}
if( *ptr != '>' )
{
parse_state = PARSING_TEXT;
break;
}
*line++ = *ptr++; /* copy the '>' */
space -= 1;
len -= 1;
parse_state = PARSING_SYMEND;
break;
case PARSING_SYMEND:
if( *ptr != ']' )
{
parse_state = PARSING_TEXT; /* not a symbol */
break;
}
/*
** It's really a symbol! Replace address with the
** symbol text.
*/
{
auto int sym_space;
auto int value;
auto struct symbol sym;
auto char *symbol;
*(line-1) = 0; /* null terminate the address string */
value = strtol(sym_start+1, (char **) 0, 16);
*(line-1) = '>'; /* put back delim */
symbol = LookupSymbol(value, &sym);
if ( symbol == (char *) 0 )
{
parse_state = PARSING_TEXT;
break;
}
/*
** verify there is room in the line buffer
*/
sym_space = space + ( line - sym_start );
if( sym_space < strlen(symbol) + 30 ) /*(30 should be overkill)*/
{
parse_state = PARSING_TEXT; /* not enough space */
break;
}
delta = sprintf( sym_start, "%s+%d/%d]",
symbol, sym.offset, sym.size );
space = sym_space + delta;
line = sym_start + delta;
}
ptr++;
len--;
parse_state = PARSING_TEXT;
break;
default: /* Can't get here! */
parse_state = PARSING_TEXT;
}
}
return;
}
static void LogKernelLine(void)
{
auto int rdcnt;
/*
* Zero-fill the log buffer. This should cure a multitude of
* problems with klogd logging the tail end of the message buffer
* which will contain old messages. Then read the kernel log
* messages into this fresh buffer.
*/
memset(log_buffer, '\0', sizeof(log_buffer));
if ( (rdcnt = ksyslog(2, log_buffer, sizeof(log_buffer))) < 0 )
{
if ( errno == EINTR )
return;
fprintf(stderr, "klogd: Error return from sys_sycall: " \
"%d - %s\n", errno, strerror(errno));
}
LogLine(log_buffer, rdcnt);
return;
}
static void LogProcLine(void)
{
auto int rdcnt;
/*
* Zero-fill the log buffer. This should cure a multitude of
* problems with klogd logging the tail end of the message buffer
* which will contain old messages. Then read the kernel messages
* from the message pseudo-file into this fresh buffer.
*/
memset(log_buffer, '\0', sizeof(log_buffer));
if ( (rdcnt = read(kmsg, log_buffer, sizeof(log_buffer))) < 0 )
{
if ( errno == EINTR )
return;
Syslog(LOG_ERR, "Cannot read proc file system: %d - %s.", \
errno, strerror(errno));
}
LogLine(log_buffer, rdcnt);
return;
}
int main(argc, argv)
int argc;
char *argv[];
{
auto int ch,
use_output = 0;
auto char *log_level = (char *) 0,
*output = (char *) 0;
/* Parse the command-line. */
while ((ch = getopt(argc, argv, "c:df:iIk:nopsv")) != EOF)
switch((char)ch)
{
case 'c': /* Set console message level. */
log_level = optarg;
break;
case 'd': /* Activity debug mode. */
debugging = 1;
break;
case 'f': /* Define an output file. */
output = optarg;
use_output++;
break;
case 'i': /* Reload module symbols. */
SignalDaemon(SIGUSR1);
return(0);
case 'I':
SignalDaemon(SIGUSR2);
return(0);
case 'k': /* Kernel symbol file. */
symfile = optarg;
break;
case 'n': /* don't fork */
NoFork++;
break;
case 'o': /* One-shot mode. */
one_shot = 1;
break;
case 'p':
SetParanoiaLevel(1); /* Load symbols on oops. */
break;
case 's': /* Use syscall interface. */
use_syscall = 1;
break;
case 'v':
printf("klogd %s-%s\n", VERSION, PATCHLEVEL);
exit (1);
}
/* Set console logging level. */
if ( log_level != (char *) 0 )
{
if ( (strlen(log_level) > 1) || \
(strchr("12345678", *log_level) == (char *) 0) )
{
fprintf(stderr, "klogd: Invalid console logging "
"level <%s> specified.\n", log_level);
return(1);
}
console_log_level = *log_level - '0';
}
/*
* The following code allows klogd to auto-background itself.
* What happens is that the program forks and the parent quits.
* The child closes all its open file descriptors, and issues a
* call to setsid to establish itself as an independent session
* immune from control signals.
*
* fork() is only called if it should run in daemon mode, fork is
* not disabled with the command line argument and there's no
* such process running.
*/
if ( (!one_shot) && (!NoFork) )
{
if (!check_pid(PidFile))
{
if ( fork() == 0 )
{
auto int fl;
int num_fds = getdtablesize();
/* This is the child closing its file descriptors. */
for (fl= 0; fl <= num_fds; ++fl)
{
if ( fileno(stdout) == fl && use_output )
if ( strcmp(output, "-") == 0 )
continue;
close(fl);
}
setsid();
}
else
exit(0);
}
else
{
fputs("klogd: Already running.\n", stderr);
exit(1);
}
}
/* tuck my process id away */
if (!check_pid(PidFile))
{
if (!write_pid(PidFile))
Terminate();
}
else
{
fputs("klogd: Already running.\n", stderr);
Terminate();
}
/* Signal setups. */
for (ch= 1; ch < NSIG; ++ch)
signal(ch, SIG_IGN);
signal(SIGINT, stop_daemon);
signal(SIGKILL, stop_daemon);
signal(SIGTERM, stop_daemon);
signal(SIGHUP, stop_daemon);
signal(SIGTSTP, stop_logging);
signal(SIGCONT, restart);
signal(SIGUSR1, reload_daemon);
signal(SIGUSR2, reload_daemon);
/* Open outputs. */
if ( use_output )
{
if ( strcmp(output, "-") == 0 )
output_file = stdout;
else if ( (output_file = fopen(output, "w")) == (FILE *) 0 )
{
fprintf(stderr, "klogd: Cannot open output file " \
"%s - %s\n", output, strerror(errno));
return(1);
}
}
else
openlog("kernel", 0, LOG_KERN);
/* Handle one-shot logging. */
if ( one_shot )
{
InitKsyms(symfile);
InitMsyms();
if ( (logsrc = GetKernelLogSrc()) == kernel )
LogKernelLine();
else
LogProcLine();
Terminate();
}
/* Determine where kernel logging information is to come from. */
#if defined(KLOGD_DELAY)
sleep(KLOGD_DELAY);
#endif
logsrc = GetKernelLogSrc();
InitKsyms(symfile);
InitMsyms();
/* The main loop. */
while (1)
{
if ( change_state )
ChangeLogging();
switch ( logsrc )
{
case kernel:
LogKernelLine();
break;
case proc:
LogProcLine();
break;
case none:
pause();
break;
}
}
}
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