util  Check-in [193c065041]

 *  $ cc -fPIC -pie nkvd.c -Wl,-E -onkvd -ldl
 *       [-D_NO_GNU [-D_LIBC=…]] [-D_CONF_HOME=…]
 *  $ export LD_PRELOAD=nkvd.so <dissident>
 *
 *  ! NOTE:  for unknown reasons,  nkvd currently only works
 *    when  built without optimizations.  it's probably that
 *    wrecker Trotsky's fault. i'm working on it.








 *
 *  ! WARNING: test this program thoroughly before you start
 *    exporting it from your shellrcs; if things get fucked,
 *    you  may not be able to execute any binaries with  the
 *    variable set,  and will need to log in as root or boot
 *    off  a rescue disk  to fix the problem.  LD_PRELOAD is
 *    not a toy. you have been warned.
................................................................................
 *
 * TODO: exempt xdg dirs beginning with ~/. from proscription
 *       in nkvd_interdict_all=1 mode
 */

#include <stdarg.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <pwd.h>
#ifdef _NO_GNU
	/* the POSIX version of basename is a goddamn mess and
................................................................................
#	define SYMSRC hnd
#else
	/* glibc's basename() is imported from <string.h> via
	 * the following directive. i have no idea how this
	 * magic works unless they're abusing asm declarations */
#	define _GNU_SOURCE /* for basename() */
#	define __USE_GNU   /* for RTLD_NEXT  */

#	define SYMSRC RTLD_NEXT



#endif
#include <string.h>
#include <dlfcn.h>


#ifndef _LIBC
#	define _LIBC "libc.so"
#endif

#ifndef _CONF_HOME
#	define _CONF_HOME ".config"
#endif


................................................................................
#	endif
	return (mode == whitelist);
#	ifdef _NO_GNU
		}
#	endif
}




#define STAT_PARAMS  const char* volatile path, struct stat* statbuf
#define XSTAT_PARAMS int ver, const char* volatile path, struct stat* statbuf
#define decl_stat_ptr(nm)  static int (*libc_##nm) (STAT_PARAMS)
#define decl_xstat_ptr(nm) static int (*libc_##nm) (XSTAT_PARAMS)

static int (*libc_open)  (const char*,int,...);
static int (*libc_unlink)(const char*);

decl_stat_ptr(stat);
................................................................................
#ifndef _NO_GNU
	decl_xstat_ptr(xstat);
	decl_xstat_ptr(xstat64);
	decl_xstat_ptr(lxstat);
	decl_xstat_ptr(lxstat64);
#endif

int nkvd_stat(int (*fn)(STAT_PARAMS), STAT_PARAMS) {

	if (intercept) {
		size_t plen = strlen(path);
		char gulag[redir_len + plen];
		if (interrogate(path, plen, gulag)) {
			return (*fn)(gulag,statbuf);
		}
	}
	return (*fn)(path,statbuf);
}

int nkvd_xstat(int (*fn)(XSTAT_PARAMS), XSTAT_PARAMS) {

	if (intercept) {
		size_t plen = strlen(path);
		char gulag[redir_len + plen];
		if (interrogate(path, plen, gulag)) {
			return (*fn)(ver,gulag,statbuf);
		}
	}
................................................................................

#ifndef _NO_GNU
	def_xstat_fn(__xstat,xstat);
	def_xstat_fn(__xstat64,xstat64);
	def_xstat_fn(__lxstat,lxstat);
	def_xstat_fn(__lxstat64,lxstat64);
#endif



int unlink(const char* volatile path) {
	if (intercept) {
		size_t plen = strlen(path);
		char gulag[redir_len + plen];
		if (interrogate(path, plen, gulag)) {
			return (*libc_unlink)(gulag);
................................................................................
	return (*libc_open)(path, flags, m);
}

int nkvd_init(int argc, const char** argv) {
	wiretap_argc = argc;
	wiretap_argv = argv;

#	ifdef _NO_GNU
		/* RTLD_NEXT is unfortunately a glibc extension, so in
		* the _NO_GNU case we need to load open() via other
		* means. */
		void* SYMSRC = dlopen(_LIBC,RTLD_LAZY);
		if (SYMSRC == NULL)
			fail(-2,"compiled in non-glibc mode and cannot load "
				"libc from " bold(_LIBC) "; please recompile "
				" and specify your libc with -D_LIBC= on the"
				"compile command line.");
#	endif

#	define load_fn(fn,pfx) libc_##fn = dlsym(SYMSRC, #pfx #fn)
		load_fn(open,);      load_fn(unlink,);
		load_fn(stat,);      load_fn(lstat,);
		load_fn(stat64,);    load_fn(lstat64,);

 *  $ cc -fPIC -pie nkvd.c -Wl,-E -onkvd -ldl
 *       [-D_NO_GNU [-D_LIBC=…]] [-D_CONF_HOME=…]
 *  $ export LD_PRELOAD=nkvd.so <dissident>
 *
 *  ! NOTE:  for unknown reasons,  nkvd currently only works
 *    when  built without optimizations.  it's probably that
 *    wrecker Trotsky's fault. i'm working on it.
 *    - partial solution on GCC: using #pragma to disable
 *      optimization around the sensitive code. unclear if
 *      this bug affects other compilers.
 *    - bizarre complication: the bug can only be reproduced
 *      if  the -O flag  itself is present;  turning on  the 
 *      same  individual  optimization flags that  -O<x>  is 
 *      supposed to represent does not trigger the problem.
 *    - conclusion: compiler devils.
 *
 *  ! WARNING: test this program thoroughly before you start
 *    exporting it from your shellrcs; if things get fucked,
 *    you  may not be able to execute any binaries with  the
 *    variable set,  and will need to log in as root or boot
 *    off  a rescue disk  to fix the problem.  LD_PRELOAD is
 *    not a toy. you have been warned.
................................................................................
 *
 * TODO: exempt xdg dirs beginning with ~/. from proscription
 *       in nkvd_interdict_all=1 mode
 */

#include <stdarg.h>
#include <unistd.h>

#include <sys/types.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <pwd.h>
#ifdef _NO_GNU
	/* the POSIX version of basename is a goddamn mess and
................................................................................
#	define SYMSRC hnd
#else
	/* glibc's basename() is imported from <string.h> via
	 * the following directive. i have no idea how this
	 * magic works unless they're abusing asm declarations */
#	define _GNU_SOURCE /* for basename() */
#	define __USE_GNU   /* for RTLD_NEXT  */
#	ifdef _USE_RTLD_NEXT
#		define SYMSRC RTLD_NEXT
#	else
#		define SYMSRC hnd
#	endif
#endif
#include <string.h>
#include <dlfcn.h>
#include <stdio.h>

#ifndef _LIBC
#	define _LIBC "libc.so.6"
#endif

#ifndef _CONF_HOME
#	define _CONF_HOME ".config"
#endif


................................................................................
#	endif
	return (mode == whitelist);
#	ifdef _NO_GNU
		}
#	endif
}

#pragma GCC push_options
#pragma GCC optimize ("O0")

#define STAT_PARAMS  const char* volatile path, struct stat* volatile statbuf
#define XSTAT_PARAMS int volatile ver, const char* volatile path, struct stat* volatile statbuf
#define decl_stat_ptr(nm)  static int (*libc_##nm) (STAT_PARAMS)
#define decl_xstat_ptr(nm) static int (*libc_##nm) (XSTAT_PARAMS)

static int (*libc_open)  (const char*,int,...);
static int (*libc_unlink)(const char*);

decl_stat_ptr(stat);
................................................................................
#ifndef _NO_GNU
	decl_xstat_ptr(xstat);
	decl_xstat_ptr(xstat64);
	decl_xstat_ptr(lxstat);
	decl_xstat_ptr(lxstat64);
#endif

int nkvd_stat(int (*volatile fn)(STAT_PARAMS), STAT_PARAMS) {
	printf(bold("nkvd") " stat: %p\n", fn);
	if (intercept) {
		size_t plen = strlen(path);
		char gulag[redir_len + plen];
		if (interrogate(path, plen, gulag)) {
			return (*fn)(gulag,statbuf);
		}
	}
	return (*fn)(path,statbuf);
}

int nkvd_xstat(int (*volatile fn)(XSTAT_PARAMS), XSTAT_PARAMS) {
	printf(bold("nkvd") " xstat: %p\n", fn);
	if (intercept) {
		size_t plen = strlen(path);
		char gulag[redir_len + plen];
		if (interrogate(path, plen, gulag)) {
			return (*fn)(ver,gulag,statbuf);
		}
	}
................................................................................

#ifndef _NO_GNU
	def_xstat_fn(__xstat,xstat);
	def_xstat_fn(__xstat64,xstat64);
	def_xstat_fn(__lxstat,lxstat);
	def_xstat_fn(__lxstat64,lxstat64);
#endif

#pragma GCC pop_options

int unlink(const char* volatile path) {
	if (intercept) {
		size_t plen = strlen(path);
		char gulag[redir_len + plen];
		if (interrogate(path, plen, gulag)) {
			return (*libc_unlink)(gulag);
................................................................................
	return (*libc_open)(path, flags, m);
}

int nkvd_init(int argc, const char** argv) {
	wiretap_argc = argc;
	wiretap_argv = argv;

#	ifndef _USE_RTLD_NEXT
		/* RTLD_NEXT is buggy as hell so we avoid it by default */


		void* SYMSRC = dlopen(_LIBC,RTLD_LAZY);
		if (SYMSRC == NULL)
			fail(-2,"compiled in non-RTLD_NEXT mode and cannot load "
				"libc from " bold(_LIBC) "; please recompile "
				" and specify your libc with -D_LIBC= on the "
				"compile command line.");
#	endif

#	define load_fn(fn,pfx) libc_##fn = dlsym(SYMSRC, #pfx #fn)
		load_fn(open,);      load_fn(unlink,);
		load_fn(stat,);      load_fn(lstat,);
		load_fn(stat64,);    load_fn(lstat64,);