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sysklogd/ksym.c

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/*
ksym.c - functions for kernel address->symbol translation
Copyright (c) 1995, 1996 Dr. G.W. Wettstein <greg@wind.rmcc.com>
Copyright (c) 1996 Enjellic Systems Development
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.
*/
/*
* This file contains functions which handle the translation of kernel
* numeric addresses into symbols for the klogd utility.
*
* Sat Oct 28 09:00:14 CDT 1995: Dr. Wettstein
* Initial Version.
*
* Fri Nov 24 12:50:52 CST 1995: Dr. Wettstein
* Added VERBOSE_DEBUGGING define to make debugging output more
* manageable.
*
* Added support for verification of the loaded kernel symbols. If
* no version information can be be found in the mapfile a warning
* message is issued but translation will still take place. This
* will be the default case if kernel versions < 1.3.43 are used.
*
* If the symbols in the mapfile are of the same version as the kernel
* that is running an informative message is issued. If the symbols
* in the mapfile do not match the current kernel version a warning
* message is issued and translation is disabled.
*
* Wed Dec 6 16:14:11 CST 1995: Dr. Wettstein
* Added /boot/System.map to the list of symbol maps to search for.
* Also made this map the first item in the search list. I am open
* to CONSTRUCTIVE suggestions for any additions or corrections to
* the list of symbol maps to search for. Be forewarned that the
* list in use is the consensus agreement between myself, Linus and
* some package distributers. It is a given that no list will suit
* everyone's taste. If you have rabid concerns about the list
* please feel free to edit the system_maps array and compile your
* own binaries.
*
* Added support for searching of the list of symbol maps. This
* allows support for access to multiple symbol maps. The theory
* behind this is that a production kernel may have a system map in
* /boot/System.map. If a test kernel is booted this system map
* would be skipped in favor of one found in /usr/src/linux.
*
* Thu Jan 18 11:18:31 CST 1996: Dr. Wettstein
* Added patch from beta-testers to allow for reading of both
* ELF and a.out map files.
*
* Wed Aug 21 09:15:49 CDT 1996: Dr. Wettstein
* Reloading of kernel module symbols is now turned on by the
* SetParanoiaLevel function. The default behavior is to NOT reload
* the kernel module symbols when a protection fault is detected.
*
* Added support for freeing of the current kernel module symbols.
* This was necessary to support reloading of the kernel module symbols.
*
* When a matching static symbol table is loaded the kernel version
* number is printed.
*
* Mon Jun 9 17:12:42 CST 1997: Martin Schulze
* Added #1 and #2 to some error messages in order to being able
* to divide them (ulmo@Q.Net)
*
* Fri Jun 13 10:50:23 CST 1997: Martin Schulze
* Changed definition of LookupSymbol to non-static because it is
* used in klogd.c, too.
*
* Fri Jan 9 23:00:08 CET 1998: Martin Schulze <joey@infodrom.north.de>
* Fixed bug that caused klogd to die if there is no System.map available.
*
* Sun 29 Mar 18:14:07 BST 1998: Mark Simon Phillips <M.S.Phillips@nortel.co.uk>
* Switched to fgets() as gets() is not buffer overrun secure.
*
* Mon Apr 13 18:18:45 CEST 1998: Martin Schulze <joey@infodrom.north.de>
* Modified loop for detecting the correct system map. Now it won't
* stop if a file has been found but doesn't contain the correct map.
* Special thanks go go Mark Simon Phillips for the hint.
*
* Mon Oct 12 00:42:30 CEST 1998: Martin Schulze <joey@infodrom.north.de>
* Modified CheckVersion()
* . Use shift to decode the kernel version
* . Compare integers of kernel version
* . extract major.minor.patch from utsname.release via sscanf()
* The reason lays in possible use of kernel flavours which
* modify utsname.release but no the Version_ symbol.
*
* Sun Feb 21 22:27:49 EST 1999: Keith Owens <kaos@ocs.com.au>
* Fixed bug that caused klogd to die if there is no sym_array available.
*
* Tue Sep 12 23:48:12 CEST 2000: Martin Schulze <joey@infodrom.ffis.de>
* Close symbol file in InitKsyms() when an error occurred.
*
* Thu Apr 29 18:07:16 CEST 2004: Dmitry Levin <ldv@altlinux.org>
* Close file descriptor in FindSymbolFile() in order not to leak
* file descriptors.
*
* Fri Jul 16 08:32:49 CEST 2004: Ulf H<>rnhammar <Ulf.Harnhammar.9485@student.uu.se>
* Added boundary check for fscanf() in InitKsyms() and
* CheckMapVersion() to prevent an unintended crash when reading
* an incorrect System.map.
*
* Mon May 28 08:27:51 CEST 2007: Martin Schulze <joey@infodrom.org>
* Added back /usr/src/linux/System.map as fall-back location.
*/
/* Includes. */
#include <stdlib.h>
#include <malloc.h>
#include <sys/utsname.h>
#include "klogd.h"
#include "ksyms.h"
#define VERBOSE_DEBUGGING 0
/* Variables static to this module. */
struct sym_table
{
unsigned long value;
char *name;
};
static int num_syms = 0;
static int i_am_paranoid = 0;
static char vstring[12];
static struct sym_table *sym_array = (struct sym_table *) 0;
static char *system_maps[] =
{
"/boot/System.map",
"/System.map",
"/usr/src/linux/System.map",
#if defined(TEST)
"./System.map",
#endif
(char *) 0
};
#if defined(TEST)
int debugging;
#else
extern int debugging;
#endif
/* Function prototypes. */
static char * FindSymbolFile(void);
static int AddSymbol(unsigned long, char*);
static void FreeSymbols(void);
static int CheckVersion(char *);
static int CheckMapVersion(char *);
/**************************************************************************
* Function: InitKsyms
*
* Purpose: This function is responsible for initializing and loading
* the data tables used by the kernel address translations.
*
* Arguements: (char *) mapfile
*
* mapfile:-> A pointer to a complete path
* specification of the file containing
* the kernel map to use.
*
* Return: int
*
* A boolean style context is returned. The return value will
* be true if initialization was successful. False if not.
**************************************************************************/
extern int InitKsyms(mapfile)
char *mapfile;
{
auto char type,
sym[512];
auto int version = 0;
auto unsigned long int address;
auto FILE *sym_file;
/* Check and make sure that we are starting with a clean slate. */
if ( num_syms > 0 )
FreeSymbols();
/*
* Search for and open the file containing the kernel symbols.
*/
if ( mapfile != (char *) 0 )
{
if ( (sym_file = fopen(mapfile, "r")) == (FILE *) 0 )
{
Syslog(LOG_WARNING, "Cannot open map file: %s.", \
mapfile);
return(0);
}
}
else
{
if ( (mapfile = FindSymbolFile()) == (char *) 0 )
{
Syslog(LOG_WARNING, "Cannot find map file.");
if ( debugging )
fputs("Cannot find map file.\n", stderr);
return(0);
}
if ( (sym_file = fopen(mapfile, "r")) == (FILE *) 0 )
{
Syslog(LOG_WARNING, "Cannot open map file.");
if ( debugging )
fputs("Cannot open map file.\n", stderr);
return(0);
}
}
/*
* Read the kernel symbol table file and add entries for each
* line. I suspect that the use of fscanf is not really in vogue
* but it was quick and dirty and IMHO suitable for fixed format
* data such as this. If anybody doesn't agree with this please
* e-mail me a diff containing a parser with suitable political
* correctness -- GW.
*/
while ( !feof(sym_file) )
{
if ( fscanf(sym_file, "%lx %c %511s\n", &address, &type, sym)
!= 3 )
{
Syslog(LOG_ERR, "Error in symbol table input (#1).");
fclose(sym_file);
return(0);
}
if ( VERBOSE_DEBUGGING && debugging )
fprintf(stderr, "Address: %lx, Type: %c, Symbol: %s\n",
address, type, sym);
if ( AddSymbol(address, sym) == 0 )
{
Syslog(LOG_ERR, "Error adding symbol - %s.", sym);
fclose(sym_file);
return(0);
}
if ( version == 0 )
version = CheckVersion(sym);
}
Syslog(LOG_INFO, "Loaded %d symbols from %s.", num_syms, mapfile);
switch ( version )
{
case -1:
Syslog(LOG_WARNING, "Symbols do not match kernel version.");
num_syms = 0;
break;
case 0:
Syslog(LOG_WARNING, "Cannot verify that symbols match " \
"kernel version.");
break;
case 1:
Syslog(LOG_INFO, "Symbols match kernel version %s.", vstring);
break;
}
fclose(sym_file);
return(1);
}
/**************************************************************************
* Function: FindSymbolFile
*
* Purpose: This function is responsible for encapsulating the search
* for a valid symbol file. Encapsulating the search for
* the map file in this function allows an intelligent search
* process to be implemented.
*
* The list of symbol files will be searched until either a
* symbol file is found whose version matches the currently
* executing kernel or the end of the list is encountered. If
* the end of the list is encountered the first available
* symbol file is returned to the caller.
*
* This strategy allows klogd to locate valid symbol files
* for both a production and an experimental kernel. For
* example a map for a production kernel could be installed
* in /boot. If an experimental kernel is loaded the map
* in /boot will be skipped and the map in /usr/src/linux would
* be used if its version number matches the executing kernel.
*
* Arguements: None specified.
*
* Return: char *
*
* If a valid system map cannot be located a null pointer
* is returned to the caller.
*
* If the search is succesful a pointer is returned to the
* caller which points to the name of the file containing
* the symbol table to be used.
**************************************************************************/
static char * FindSymbolFile()
{
auto char *file = (char *) 0,
**mf = system_maps;
auto struct utsname utsname;
static char symfile[100];
auto FILE *sym_file = (FILE *) 0;
if ( uname(&utsname) < 0 )
{
Syslog(LOG_ERR, "Cannot get kernel version information.");
return(0);
}
if ( debugging )
fputs("Searching for symbol map.\n", stderr);
for (mf = system_maps; *mf != (char *) 0 && file == (char *) 0; ++mf)
{
sprintf (symfile, "%s-%s", *mf, utsname.release);
if ( debugging )
fprintf(stderr, "Trying %s.\n", symfile);
if ( (sym_file = fopen(symfile, "r")) != (FILE *) 0 ) {
if (CheckMapVersion(symfile) == 1)
file = symfile;
fclose (sym_file);
}
if (sym_file == (FILE *) 0 || file == (char *) 0) {
sprintf (symfile, "%s", *mf);
if ( debugging )
fprintf(stderr, "Trying %s.\n", symfile);
if ( (sym_file = fopen(symfile, "r")) != (FILE *) 0 ) {
if (CheckMapVersion(symfile) == 1)
file = symfile;
fclose (sym_file);
}
}
}
/*
* At this stage of the game we are at the end of the symbol
* tables.
*/
if ( debugging )
fprintf(stderr, "End of search list encountered.\n");
return(file);
}
/**************************************************************************
* Function: CheckVersion
*
* Purpose: This function is responsible for determining whether or
* the system map being loaded matches the version of the
* currently running kernel.
*
* The kernel version is checked by examing a variable which
* is of the form: _Version_66347 (a.out) or Version_66437 (ELF).
*
* The suffix of this variable is the current kernel version
* of the kernel encoded in base 256. For example the
* above variable would be decoded as:
*
* (66347 = 1*65536 + 3*256 + 43 = 1.3.43)
*
* (Insert appropriate deities here) help us if Linus ever
* needs more than 255 patch levels to get a kernel out the
* door... :-)
*
* Arguements: (char *) version
*
* version:-> A pointer to the string which
* is to be decoded as a kernel
* version variable.
*
* Return: int
*
* -1:-> The currently running kernel version does
* not match this version string.
*
* 0:-> The string is not a kernel version variable.
*
* 1:-> The executing kernel is of the same version
* as the version string.
**************************************************************************/
static int CheckVersion(version)
char *version;
{
auto int vnum,
major,
minor,
patch;
#ifndef TESTING
int kvnum;
auto struct utsname utsname;
#endif
static char *prefix = { "Version_" };
/* Early return if there is no hope. */
if ( strncmp(version, prefix, strlen(prefix)) == 0 /* ELF */ ||
(*version == '_' &&
strncmp(++version, prefix, strlen(prefix)) == 0 ) /* a.out */ )
;
else
return(0);
/*
* Since the symbol looks like a kernel version we can start
* things out by decoding the version string into its component
* parts.
*/
vnum = atoi(version + strlen(prefix));
patch = vnum & 0x000000FF;
minor = (vnum >> 8) & 0x000000FF;
major = (vnum >> 16) & 0x000000FF;
if ( debugging )
fprintf(stderr, "Version string = %s, Major = %d, " \
"Minor = %d, Patch = %d.\n", version +
strlen(prefix), major, minor, \
patch);
sprintf(vstring, "%d.%d.%d", major, minor, patch);
#ifndef TESTING
/*
* We should now have the version string in the vstring variable in
* the same format that it is stored in by the kernel. We now
* ask the kernel for its version information and compare the two
* values to determine if our system map matches the kernel
* version level.
*/
if ( uname(&utsname) < 0 )
{
Syslog(LOG_ERR, "Cannot get kernel version information.");
return(0);
}
if ( debugging )
fprintf(stderr, "Comparing kernel %s with symbol table %s.\n",\
utsname.release, vstring);
if ( sscanf (utsname.release, "%d.%d.%d", &major, &minor, &patch) < 3 )
{
Syslog(LOG_ERR, "Kernel send bogus release string `%s'.",
utsname.release);
return(0);
}
/* Compute the version code from data sent by the kernel */
kvnum = (major << 16) | (minor << 8) | patch;
/* Failure. */
if ( vnum != kvnum )
return(-1);
/* Success. */
#endif
return(1);
}
/**************************************************************************
* Function: CheckMapVersion
*
* Purpose: This function is responsible for determining whether or
* the system map being loaded matches the version of the
* currently running kernel. It uses CheckVersion as
* backend.
*
* Arguements: (char *) fname
*
* fname:-> A pointer to the string which
* references the system map file to
* be used.
*
* Return: int
*
* -1:-> The currently running kernel version does
* not match the version in the given file.
*
* 0:-> No system map file or no version information.
*
* 1:-> The executing kernel is of the same version
* as the version of the map file.
**************************************************************************/
static int CheckMapVersion(fname)
char *fname;
{
int version;
FILE *sym_file;
auto unsigned long int address;
auto char type,
sym[512];
if ( (sym_file = fopen(fname, "r")) != (FILE *) 0 ) {
/*
* At this point a map file was successfully opened. We
* now need to search this file and look for version
* information.
*/
Syslog(LOG_INFO, "Inspecting %s", fname);
version = 0;
while ( !feof(sym_file) && (version == 0) )
{
if ( fscanf(sym_file, "%lx %c %511s\n", &address, \
&type, sym) != 3 )
{
Syslog(LOG_ERR, "Error in symbol table input (#2).");
fclose(sym_file);
return(0);
}
if ( VERBOSE_DEBUGGING && debugging )
fprintf(stderr, "Address: %lx, Type: %c, " \
"Symbol: %s\n", address, type, sym);
version = CheckVersion(sym);
}
fclose(sym_file);
switch ( version )
{
case -1:
Syslog(LOG_ERR, "Symbol table has incorrect " \
"version number.\n");
break;
case 0:
if ( debugging )
fprintf(stderr, "No version information " \
"found.\n");
break;
case 1:
if ( debugging )
fprintf(stderr, "Found table with " \
"matching version number.\n");
break;
}
return(version);
}
return(0);
}
/**************************************************************************
* Function: AddSymbol
*
* Purpose: This function is responsible for adding a symbol name
* and its address to the symbol table.
*
* Arguements: (unsigned long) address, (char *) symbol
*
* Return: int
*
* A boolean value is assumed. True if the addition is
* successful. False if not.
**************************************************************************/
static int AddSymbol(address, symbol)
unsigned long address;
char *symbol;
{
/* Allocate the the symbol table entry. */
sym_array = (struct sym_table *) realloc(sym_array, (num_syms+1) * \
sizeof(struct sym_table));
if ( sym_array == (struct sym_table *) 0 )
return(0);
/* Then the space for the symbol. */
sym_array[num_syms].name = (char *) malloc(strlen(symbol)*sizeof(char)\
+ 1);
if ( sym_array[num_syms].name == (char *) 0 )
return(0);
sym_array[num_syms].value = address;
strcpy(sym_array[num_syms].name, symbol);
++num_syms;
return(1);
}
/**************************************************************************
* Function: LookupSymbol
*
* Purpose: Find the symbol which is related to the given kernel
* address.
*
* Arguements: (long int) value, (struct symbol *) sym
*
* value:-> The address to be located.
*
* sym:-> A pointer to a structure which will be
* loaded with the symbol's parameters.
*
* Return: (char *)
*
* If a match cannot be found a diagnostic string is printed.
* If a match is found the pointer to the symbolic name most
* closely matching the address is returned.
**************************************************************************/
char * LookupSymbol(value, sym)
unsigned long value;
struct symbol *sym;
{
auto int lp;
auto char *last;
if (!sym_array)
return((char *) 0);
last = sym_array[0].name;
sym->offset = 0;
sym->size = 0;
if ( value < sym_array[0].value )
return((char *) 0);
for(lp= 0; lp <= num_syms; ++lp)
{
if ( sym_array[lp].value > value )
{
sym->offset = value - sym_array[lp-1].value;
sym->size = sym_array[lp].value - \
sym_array[lp-1].value;
return(last);
}
last = sym_array[lp].name;
}
if ( (last = LookupModuleSymbol(value, sym)) != (char *) 0 )
return(last);
return((char *) 0);
}
/**************************************************************************
* Function: FreeSymbols
*
* Purpose: This function is responsible for freeing all memory which
* has been allocated to hold the static symbol table. It
* also initializes the symbol count and in general prepares
* for a re-read of a static symbol table.
*
* Arguements: void
*
* Return: void
**************************************************************************/
static void FreeSymbols()
{
auto int lp;
/* Free each piece of memory allocated for symbol names. */
for(lp= 0; lp < num_syms; ++lp)
free(sym_array[lp].name);
/* Whack the entire array and initialize everything. */
free(sym_array);
sym_array = (struct sym_table *) 0;
num_syms = 0;
return;
}
/**************************************************************************
* Function: LogExpanded
*
* Purpose: This function is responsible for logging a kernel message
* line after all potential numeric kernel addresses have
* been resolved symolically.
*
* Arguements: (char *) line, (char *) el
*
* line:-> A pointer to the buffer containing the kernel
* message to be expanded and logged.
*
* el:-> A pointer to the buffer into which the expanded
* kernel line will be written.
*
* Return: void
**************************************************************************/
extern char * ExpandKadds(line, el)
char *line;
char *el;
{
auto char dlm,
*kp,
*sl = line,
*elp = el,
*symbol;
char num[15];
auto unsigned long int value;
auto struct symbol sym;
/*
* This is as handy a place to put this as anyplace.
*
* Since the insertion of kernel modules can occur in a somewhat
* dynamic fashion we need some mechanism to insure that the
* kernel symbol tables get read just prior to when they are
* needed.
*
* To accomplish this we look for the Oops string and use its
* presence as a signal to load the module symbols.
*
* This is not the best solution of course, especially if the
* kernel is rapidly going out to lunch. What really needs to
* be done is to somehow generate a callback from the
* kernel whenever a module is loaded or unloaded. I am
* open for patches.
*/
if ( i_am_paranoid &&
(strstr(line, "Oops:") != (char *) 0) && !InitMsyms() )
Syslog(LOG_WARNING, "Cannot load kernel module symbols.\n");
/*
* Early return if there do not appear to be any kernel
* messages in this line.
*/
if ( (num_syms == 0) ||
(kp = strstr(line, "[<")) == (char *) 0 )
{
strcpy(el, line);
return(el);
}
/* Loop through and expand all kernel messages. */
do
{
while ( sl < kp+1 )
*elp++ = *sl++;
/* Now poised at a kernel delimiter. */
if ( (kp = strstr(sl, ">]")) == (char *) 0 )
{
strcpy(el, sl);
return(el);
}
dlm = *kp;
strncpy(num,sl+1,kp-sl-1);
num[kp-sl-1] = '\0';
value = strtoul(num, (char **) 0, 16);
if ( (symbol = LookupSymbol(value, &sym)) == (char *) 0 )
symbol = sl;
strcat(elp, symbol);
elp += strlen(symbol);
if ( debugging )
fprintf(stderr, "Symbol: %s = %lx = %s, %x/%d\n", \
sl+1, value, \
(sym.size==0) ? symbol+1 : symbol, \
sym.offset, sym.size);
value = 2;
if ( sym.size != 0 )
{
--value;
++kp;
elp += sprintf(elp, "+%x/%d", sym.offset, sym.size);
}
strncat(elp, kp, value);
elp += value;
sl = kp + value;
if ( (kp = strstr(sl, "[<")) == (char *) 0 )
strcat(elp, sl);
}
while ( kp != (char *) 0);
if ( debugging )
fprintf(stderr, "Expanded line: %s\n", el);
return(el);
}
/**************************************************************************
* Function: SetParanoiaLevel
*
* Purpose: This function is an interface function for setting the
* mode of loadable module symbol lookups. Probably overkill
* but it does slay another global variable.
*
* Arguements: (int) level
*
* level:-> The amount of paranoia which is to be
* present when resolving kernel exceptions.
* Return: void
**************************************************************************/
extern void SetParanoiaLevel(level)
int level;
{
i_am_paranoid = level;
return;
}
/*
* Setting the -DTEST define enables the following code fragment to
* be compiled. This produces a small standalone program which will
* echo the standard input of the process to stdout while translating
* all numeric kernel addresses into their symbolic equivalent.
*/
#if defined(TEST)
#include <stdarg.h>
extern int main(int, char **);
extern int main(int argc, char *argv[])
{
auto char line[1024], eline[2048];
debugging = 1;
if ( !InitKsyms((char *) 0) )
{
fputs("ksym: Error loading system map.\n", stderr);
return(1);
}
while ( !feof(stdin) )
{
fgets(line, sizeof(line), stdin);
if (line[strlen(line)-1] == '\n') line[strlen(line)-1] = '\0'; /* Trash NL char */
memset(eline, '\0', sizeof(eline));
ExpandKadds(line, eline);
fprintf(stdout, "%s\n", eline);
}
return(0);
}
extern void Syslog(int priority, char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
fprintf(stdout, "Pr: %d, ", priority);
vfprintf(stdout, fmt, ap);
va_end(ap);
fputc('\n', stdout);
return;
}
#endif
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* tab-width: 8
* End:
*/
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