/* ksym.c - functions for kernel address->symbol translation Copyright (c) 1995, 1996 Dr. G.W. Wettstein Copyright (c) 1996 Enjellic Systems Development Copyright (c) 1997-2007 Martin Schulze 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 * 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 * Switched to fgets() as gets() is not buffer overrun secure. * * Mon Apr 13 18:18:45 CEST 1998: Martin Schulze * 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 * 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 * Fixed bug that caused klogd to die if there is no sym_array available. * * Tue Sep 12 23:48:12 CEST 2000: Martin Schulze * Close symbol file in InitKsyms() when an error occurred. * * Thu Apr 29 18:07:16 CEST 2004: Dmitry Levin * Close file descriptor in FindSymbolFile() in order not to leak * file descriptors. * * Fri Jul 16 08:32:49 CEST 2004: Ulf Härnhammar * 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 * Added back /usr/src/linux/System.map as fall-back location. * * Thu May 31 16:56:26 CEST 2007: Martin Schulze * Improved symbol lookup, since symbols are spread over the entire * address space. Return the symbol that fits best instead of * the first hit. */ /* Includes. */ #include #include #include #include "klogd.h" #include "ksyms.h" #include "module.h" #define VERBOSE_DEBUGGING 0 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. * * Arguments: (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. * * Arguments: 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... :-) * * Arguments: (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. * * Arguments: (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. * * Arguments: (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. * * Arguments: (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; auto char *name; struct symbol ksym, msym; if (!sym_array) return((char *) 0); last = sym_array[0].name; ksym.offset = 0; ksym.size = 0; if ( value < sym_array[0].value ) return((char *) 0); for(lp = 0; lp <= num_syms; ++lp) { if ( sym_array[lp].value > value ) { ksym.offset = value - sym_array[lp-1].value; ksym.size = sym_array[lp].value - \ sym_array[lp-1].value; break; } last = sym_array[lp].name; } name = LookupModuleSymbol(value, &msym); if ( ksym.offset == 0 && msym.offset == 0 ) { return((char *) 0); } if ( ksym.size < msym.size ) { sym->offset = ksym.offset; sym->size = ksym.size; return(last); } else { sym->offset = msym.offset; sym->size = msym.size; return(name); } 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. * * Arguments: 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. * * Arguments: (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; sym.offset = 0; sym.size = 0; /* * 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. * * Arguments: (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 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: */