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  1. 03 Feb, 2013 3 commits
  3. 23 Nov, 2012 1 commit
    • Martin Schwidefsky's avatar
      s390/ptrace: race of single stepping vs signal delivery · 39efd4ec
      Martin Schwidefsky authored 
      The current single step code is racy in regard to concurrent delivery
of signals. If a signal is delivered after a PER program check occurred
but before the TIF_PER_TRAP bit has been checked in entry[64].S the code
clears TIF_PER_TRAP and then calls do_signal. This is wrong, if the
instruction completed (or has been suppressed) a SIGTRAP should be
delivered to the debugger in any case. Only if the instruction has been
nullified the SIGTRAP may not be send.

The new logic always sets TIF_PER_TRAP if the program check indicates PER
tracing but removes it again for all program checks that are nullifying.
The effect is that for each change in the PSW address we now get a
single SIGTRAP.
Reported-by: default avatarAndreas Arnez <arnez@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      39efd4ec
  5. 12 Nov, 2012 1 commit
    • Martin Schwidefsky's avatar
      s390/signal: set correct address space control · fa968ee2
      Martin Schwidefsky authored 
      If user space is running in primary mode it can switch to secondary
or access register mode, this is used e.g. in the clock_gettime code
of the vdso. If a signal is delivered to the user space process while
it has been running in access register mode the signal handler is
executed in access register mode as well which will result in a crash
most of the time.

Set the address space control bits in the PSW to the default for the
execution of the signal handler and make sure that the previous
address space control is restored on signal return. Take care
that user space can not switch to the kernel address space by
modifying the registers in the signal frame.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      fa968ee2
  7. 20 Jul, 2012 1 commit
    • Heiko Carstens's avatar
      s390/comments: unify copyright messages and remove file names · a53c8fab
      Heiko Carstens authored 
      Remove the file name from the comment at top of many files. In most
cases the file name was wrong anyway, so it's rather pointless.

Also unify the IBM copyright statement. We did have a lot of sightly
different statements and wanted to change them one after another
whenever a file gets touched. However that never happened. Instead
people start to take the old/"wrong" statements to use as a template
for new files.
So unify all of them in one go.
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      a53c8fab
  9. 01 Jun, 2012 5 commits
  11. 24 May, 2012 1 commit
  13. 22 May, 2012 1 commit
  15. 16 May, 2012 1 commit
  17. 28 Mar, 2012 1 commit
  19. 11 Mar, 2012 1 commit
  21. 27 Feb, 2012 1 commit
  23. 27 Dec, 2011 1 commit
    • Martin Schwidefsky's avatar
      [S390] cleanup trap handling · aa33c8cb
      Martin Schwidefsky authored 
      Move the program interruption code and the translation exception identifier
to the pt_regs structure as 'int_code' and 'int_parm_long' and make the
first level interrupt handler in entry[64].S store the two values. That
makes it possible to drop 'prot_addr' and 'trap_no' from the thread_struct
and to reduce the number of arguments to a lot of functions. Finally
un-inline do_trap. Overall this saves 5812 bytes in the .text section of
the 64 bit kernel.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      aa33c8cb
  25. 01 Dec, 2011 1 commit
  27. 30 Oct, 2011 5 commits
    • Martin Schwidefsky's avatar
      [S390] allow all addressing modes · d4e81b35
      Martin Schwidefsky authored 
      The user space program can change its addressing mode between the
24-bit, 31-bit and the 64-bit mode if the kernel is 64 bit. Currently
the kernel always forces the standard amode on signal delivery and
signal return and on ptrace: 64-bit for a 64-bit process, 31-bit for
a compat process and 31-bit kernels. Change the signal and ptrace code
to allow the full range of addressing modes. Signal handlers are
run in the standard addressing mode for the process.

One caveat is that even an 31-bit compat process can switch to the
64-bit mode. The next signal will switch back into the 31-bit mode
and there is no room in the 31-bit compat signal frame to store the
information that the program came from the 64-bit mode.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      d4e81b35
    • Martin Schwidefsky's avatar
      [S390] cleanup psw related bits and pieces · b50511e4
      Martin Schwidefsky authored 
      Split out addressing mode bits from PSW_BASE_BITS, rename PSW_BASE_BITS
to PSW_MASK_BASE, get rid of psw_user32_bits, remove unused function
enabled_wait(), introduce PSW_MASK_USER, and drop PSW_MASK_MERGE macros.
Change psw_kernel_bits / psw_user_bits to contain only the bits that
are always set in the respective mode.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      b50511e4
    • Martin Schwidefsky's avatar
      [S390] add TIF_SYSCALL thread flag · b6ef5bb3
      Martin Schwidefsky authored 
      Add an explicit TIF_SYSCALL bit that indicates if a task is inside
a system call. The svc_code in the pt_regs structure is now only
valid if TIF_SYSCALL is set. With this definition TIF_RESTART_SVC
can be replaced with TIF_SYSCALL. Overall do_signal is a bit more
readable and it saves a few lines of code.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      b6ef5bb3
    • Martin Schwidefsky's avatar
      [S390] addressing mode limits and psw address wrapping · ccf45caf
      Martin Schwidefsky authored 
      An instruction with an address right below the adress limit for the
current addressing mode will wrap. The instruction restart logic in
the protection fault handler and the signal code need to follow the
wrapping rules to find the correct instruction address.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      ccf45caf
    • Martin Schwidefsky's avatar
      [S390] signal race with restarting system calls · 20b40a79
      Martin Schwidefsky authored 
      For a ERESTARTNOHAND/ERESTARTSYS/ERESTARTNOINTR restarting system call
do_signal will prepare the restart of the system call with a rewind of
the PSW before calling get_signal_to_deliver (where the debugger might
take control). For A ERESTART_RESTARTBLOCK restarting system call
do_signal will set -EINTR as return code.
There are two issues with this approach:
1) strace never sees ERESTARTNOHAND, ERESTARTSYS, ERESTARTNOINTR or
   ERESTART_RESTARTBLOCK as the rewinding already took place or the
   return code has been changed to -EINTR
2) if get_signal_to_deliver does not return with a signal to deliver
   the restart via the repeat of the svc instruction is left in place.
   This opens a race if another signal is made pending before the
   system call instruction can be reexecuted. The original system call
   will be restarted even if the second signal would have ended the
   system call with -EINTR.

These two issues can be solved by dropping the early rewind of the
system call before get_signal_to_deliver has been called and by using
the TIF_RESTART_SVC magic to do the restart if no signal has to be
delivered. The only situation where the system call restart via the
repeat of the svc instruction is appropriate is when a SA_RESTART
signal is delivered to user space.

Unfortunately this breaks inferior calls by the debugger again. The
system call number and the length of the system call instruction is
lost over the inferior call and user space will see ERESTARTNOHAND/
ERESTARTSYS/ERESTARTNOINTR/ERESTART_RESTARTBLOCK. To correct this a
new ptrace interface is added to save/restore the system call number
and system call instruction length.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      20b40a79
  29. 03 Aug, 2011 2 commits
  31. 05 Jan, 2011 1 commit
  33. 17 May, 2010 1 commit
  35. 27 Jan, 2010 1 commit
  37. 13 Jan, 2010 1 commit
  39. 02 Sep, 2009 1 commit
    • David Howells's avatar
      KEYS: Add a keyctl to install a process's session keyring on its parent [try #6] · ee18d64c
      David Howells authored 
      Add a keyctl to install a process's session keyring onto its parent.  This
replaces the parent's session keyring.  Because the COW credential code does
not permit one process to change another process's credentials directly, the
change is deferred until userspace next starts executing again.  Normally this
will be after a wait*() syscall.

To support this, three new security hooks have been provided:
cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in
the blank security creds and key_session_to_parent() - which asks the LSM if
the process may replace its parent's session keyring.

The replacement may only happen if the process has the same ownership details
as its parent, and the process has LINK permission on the session keyring, and
the session keyring is owned by the process, and the LSM permits it.

Note that this requires alteration to each architecture's notify_resume path.
This has been done for all arches barring blackfin, m68k* and xtensa, all of
which need assembly alteration to support TIF_NOTIFY_RESUME.  This allows the
replacement to be performed at the point the parent process resumes userspace
execution.

This allows the userspace AFS pioctl emulation to fully emulate newpag() and
the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to
alter the parent process's PAG membership.  However, since kAFS doesn't use
PAGs per se, but rather dumps the keys into the session keyring, the session
keyring of the parent must be replaced if, for example, VIOCSETTOK is passed
the newpag flag.

This can be tested with the following program:

	#include <stdio.h>
	#include <stdlib.h>
	#include <keyutils.h>

	#define KEYCTL_SESSION_TO_PARENT	18

	#define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0)

	int main(int argc, char **argv)
	{
		key_serial_t keyring, key;
		long ret;

		keyring = keyctl_join_session_keyring(argv[1]);
		OSERROR(keyring, "keyctl_join_session_keyring");

		key = add_key("user", "a", "b", 1, keyring);
		OSERROR(key, "add_key");

		ret = keyctl(KEYCTL_SESSION_TO_PARENT);
		OSERROR(ret, "KEYCTL_SESSION_TO_PARENT");

		return 0;
	}

Compiled and linked with -lkeyutils, you should see something like:

	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	355907932 --alswrv   4043    -1   \_ keyring: _uid.4043
	[dhowells@andromeda ~]$ /tmp/newpag
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	1055658746 --alswrv   4043  4043   \_ user: a
	[dhowells@andromeda ~]$ /tmp/newpag hello
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: hello
	340417692 --alswrv   4043  4043   \_ user: a

Where the test program creates a new session keyring, sticks a user key named
'a' into it and then installs it on its parent.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
      ee18d64c
  41. 12 Jun, 2009 1 commit
  43. 14 Jan, 2009 1 commit
  45. 27 Nov, 2008 1 commit
    • Martin Schwidefsky's avatar
      [S390] fix system call parameter functions. · 59da2139
      Martin Schwidefsky authored 
      syscall_get_nr() currently returns a valid result only if the call
chain of the traced process includes do_syscall_trace_enter(). But
collect_syscall() can be called for any sleeping task, the result of
syscall_get_nr() in general is completely bogus.

To make syscall_get_nr() work for any sleeping task the traps field
in pt_regs is replace with svcnr - the system call number the process
is executing. If svcnr == 0 the process is not on a system call path.

The syscall_get_arguments and syscall_set_arguments use regs->gprs[2]
for the first system call parameter. This is incorrect since gprs[2]
may have been overwritten with the system call number if the call
chain includes do_syscall_trace_enter. Use regs->orig_gprs2 instead.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      59da2139
  47. 10 Oct, 2008 1 commit
  49. 17 Apr, 2008 2 commits
  51. 26 Jan, 2008 1 commit
  53. 08 May, 2007 1 commit
  55. 27 Apr, 2007 1 commit