Commit Graph

64 Commits

Author SHA1 Message Date
Andy Lutomirski
f56141e3e2 all arches, signal: move restart_block to struct task_struct
If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target.  This is because the
restart_block is held in the same memory allocation as the kernel stack.

Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.

Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.

It's also a decent simplification, since the restart code is more or less
identical on all architectures.

[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:12 -08:00
Martin Schwidefsky
37d2cd9d84 s390/signal: add sparse annotations
Fix the following warnings from the sparse code checker:

arch/s390/kernel/signal.c:374:38: warning: cast removes address space of expression
arch/s390/kernel/signal.c:374:65: warning: incorrect type in initializer (different address spaces)
arch/s390/kernel/signal.c:374:65:    expected unsigned short [noderef] [usertype] <asn:1>*svc
arch/s390/kernel/signal.c:374:65:    got void *

arch/s390/kernel/compat_signal.c:437:38: warning: cast removes address space of expression
arch/s390/kernel/compat_signal.c:437:65: warning: incorrect type in initializer (different address spaces)
arch/s390/kernel/compat_signal.c:437:65:    expected unsigned short [noderef] [usertype] <asn:1>*svc
arch/s390/kernel/compat_signal.c:437:65:    got void *

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-11-03 13:30:36 +01:00
Martin Schwidefsky
8070361799 s390: add support for vector extension
The vector extension introduces 32 128-bit vector registers and a set of
instruction to operate on the vector registers.

The kernel can control the use of vector registers for the problem state
program with a bit in control register 0. Once enabled for a process the
kernel needs to retain the content of the vector registers on context
switch. The signal frame is extended to include the vector registers.
Two new register sets NT_S390_VXRS_LOW and NT_S390_VXRS_HIGH are added
to the regset interface for the debugger and core dumps.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-10-09 09:14:13 +02:00
Richard Weinberger
067bf2d4d3 s390: Use get_signal() signal_setup_done()
Use the more generic functions get_signal() signal_setup_done()
for signal delivery.

Signed-off-by: Richard Weinberger <richard@nod.at>
2014-08-06 13:03:10 +02:00
Martin Schwidefsky
d3a73acbc2 s390: split TIF bits into CIF, PIF and TIF bits
The oi and ni instructions used in entry[64].S to set and clear bits
in the thread-flags are not guaranteed to be atomic in regard to other
CPUs. Split the TIF bits into CPU, pt_regs and thread-info specific
bits. Updates on the TIF bits are done with atomic instructions,
updates on CPU and pt_regs bits are done with non-atomic instructions.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-05-20 08:58:47 +02:00
Hendrik Brueckner
aa7e04b380 s390/signal: always restore saved runtime instrumentation psw bit
Commit "s390: fix handling of runtime instrumentation psw bit" (5ebf250dab)
changed the behavior of setting the runtime instrumentation psw bit.  This
commit restores the original logic:

1. When returning from the signal handler, the runtime instrumentation psw bit
   is restored to its saved state.
2. If the runtime instrumentation psw bit is enabled during the signal handler,
   it is always turned off when leaving the signal handler.  The saved state
   is restored as described in 1.  That also implies that turning on runtime
   instrumentation in the signal handler is only effective while running in the
   signal context.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
2013-11-20 09:04:53 +01:00
Heiko Carstens
5ebf250dab s390: fix handling of runtime instrumentation psw bit
Fix the following bugs:
- When returning from a signal the signal handler copies the saved psw mask
  from user space and uses parts of it. Especially it restores the RI bit
  unconditionally. If however the machine doesn't support RI, or RI is
  disabled for the task, the last lpswe instruction which returns to user
  space will generate a specification exception.
  To fix this check if the RI bit is allowed to be set and kill the task
  if not.
- In the compat mode signal handler code the RI bit of the psw mask gets
  propagated to the mask of the return psw: if user space enables RI in the
  signal handler, RI will also be enabled after the signal handler is
  finished.
  This is a different behaviour than with 64 bit tasks. So change this to
  match the 64 bit semantics, which restores the original RI bit value.
- Fix similar oddities within the ptrace code as well.

Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-10-24 17:17:11 +02:00
Martin Schwidefsky
4725c86055 s390: fix save and restore of the floating-point-control register
The FPC_VALID_MASK has been used to check the validity of the value
to be loaded into the floating-point-control register. With the
introduction of the floating-point extension facility and the
decimal-floating-point additional bits have been defined which need
to be checked in a non straight forward way. So far these bits have
been ignored which can cause an incorrect results for decimal-
floating-point operations, e.g. an incorrect rounding mode to be
set after signal return.

The static check with the FPC_VALID_MASK is replaced with a trial
load of the floating-point-control value, see test_fp_ctl.

In addition an information leak with the padding word between the
floating-point-control word and the floating-point registers in
the s390_fp_regs is fixed.

Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-10-24 17:17:11 +02:00
Heiko Carstens
f8544ec4f4 s390/compat,signal: change return values to -EFAULT
Instead of returnin the number of bytes not copied and/or -EFAULT let the
signal handler helper functions always return -EFAULT if a user space
access failed.
This doesn't fix a bug in the current code, but makes is harder to get it
wrong in the future.
Also "smatch" won't complain anymore about the fact that the number of
remaining bytes gets returned instead of -EFAULT.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-10-24 17:17:06 +02:00
Martin Schwidefsky
e258d719ff s390/uaccess: always run the kernel in home space
Simplify the uaccess code by removing the user_mode=home option.
The kernel will now always run in the home space mode.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-10-24 17:16:57 +02:00
Heiko Carstens
d12a297038 s390/uaccess: remove pointless access_ok() checks
access_ok() always returns 'true' on s390. Therefore all calls
are quite pointless and can be removed.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-02-28 09:37:09 +01:00
Al Viro
7eddd99c28 s390: switch to generic old sigaction()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-03 18:16:14 -05:00
Al Viro
e181ee4cd7 s390: switch to generic old sigsuspend
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-03 18:16:13 -05:00
Al Viro
e214125aa8 s390: switch to generic sigaltstack
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-03 18:16:11 -05:00
Martin Schwidefsky
39efd4ec9a s390/ptrace: race of single stepping vs signal delivery
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: Andreas Arnez <arnez@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-23 11:14:33 +01:00
Martin Schwidefsky
fa968ee215 s390/signal: set correct address space control
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-12 16:24:38 +01:00
Heiko Carstens
a53c8fab3f s390/comments: unify copyright messages and remove file names
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: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-07-20 11:15:04 +02:00
Al Viro
efee984c27 new helper: signal_delivered()
Does block_sigmask() + tracehook_signal_handler();  called when
sigframe has been successfully built.  All architectures converted
to it; block_sigmask() itself is gone now (merged into this one).

I'm still not too happy with the signature, but that's a separate
story (IMO we need a structure that would contain signal number +
siginfo + k_sigaction, so that get_signal_to_deliver() would fill one,
signal_delivered(), handle_signal() and probably setup...frame() -
take one).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-06-01 12:58:52 -04:00
Al Viro
77097ae503 most of set_current_blocked() callers want SIGKILL/SIGSTOP removed from set
Only 3 out of 63 do not.  Renamed the current variant to __set_current_blocked(),
added set_current_blocked() that will exclude unblockable signals, switched
open-coded instances to it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-06-01 12:58:51 -04:00
Al Viro
a610d6e672 pull clearing RESTORE_SIGMASK into block_sigmask()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-06-01 12:58:49 -04:00
Al Viro
b7f9a11a6c new helper: sigmask_to_save()
replace boilerplate "should we use ->saved_sigmask or ->blocked?"
with calls of obvious inlined helper...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-06-01 12:58:48 -04:00
Al Viro
51a7b448d4 new helper: restore_saved_sigmask()
first fruits of ..._restore_sigmask() helpers: now we can take
boilerplate "signal didn't have a handler, clear RESTORE_SIGMASK
and restore the blocked mask from ->saved_mask" into a common
helper.  Open-coded instances switched...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-06-01 12:58:47 -04:00
Al Viro
a42c6ded82 move key_repace_session_keyring() into tracehook_notify_resume()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-05-23 22:09:20 -04:00
Al Viro
68f3f16d9a new helper: sigsuspend()
guts of saved_sigmask-based sigsuspend/rt_sigsuspend.  Takes
kernel sigset_t *.

Open-coded instances replaced with calling it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-05-21 23:52:30 -04:00
Martin Schwidefsky
c15787a7c3 s390: remove dead code from signal handler
The code in entry[64].S calls do_signal only on return to user space.
user_mode(regs) is true for every calls to do_signal, it is unnecessary
to recheck user_mode at the start of do_signal and the legacy signal
stack switching path in get_sigframe is never reached.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-05-16 14:42:40 +02:00
David Howells
a0616cdebc Disintegrate asm/system.h for S390
Disintegrate asm/system.h for S390.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-s390@vger.kernel.org
2012-03-28 18:30:02 +01:00
Matt Fleming
ad252ffa2a [S390] Use block_sigmask()
Use the new helper function introduced in commit 5e6292c0f2
("signal: add block_sigmask() for adding sigmask to current->blocked")
which centralises the code for updating current->blocked after
successfully delivering a signal and reduces the amount of duplicate
code across architectures.

In the past some architectures got this code wrong, so using this
helper function should stop that from happening again.

Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-03-11 11:59:29 -04:00
Heiko Carstens
048cd4e51d compat: fix compile breakage on s390
The new is_compat_task() define for the !COMPAT case in
include/linux/compat.h conflicts with a similar define in
arch/s390/include/asm/compat.h.

This is the minimal patch which fixes the build issues.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-02-27 07:54:27 -08:00
Martin Schwidefsky
aa33c8cbba [S390] cleanup trap handling
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-12-27 11:27:12 +01:00
Martin Schwidefsky
d9ae6772d3 [S390] ptrace inferior call interactions with TIF_SYSCALL
The TIF_SYSCALL bit needs to be cleared if the debugger changes the state
of the ptraced process in regard to the presence of a system call.
Otherwise the system call will be restarted although the debugger set up
an inferior call.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-12-01 13:32:17 +01:00
Martin Schwidefsky
d4e81b35b8 [S390] allow all addressing modes
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-10-30 15:16:43 +01:00
Martin Schwidefsky
b50511e41a [S390] cleanup psw related bits and pieces
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-10-30 15:16:43 +01:00
Martin Schwidefsky
b6ef5bb3d9 [S390] add TIF_SYSCALL thread flag
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-10-30 15:16:43 +01:00
Martin Schwidefsky
ccf45cafb0 [S390] addressing mode limits and psw address wrapping
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-10-30 15:16:43 +01:00
Martin Schwidefsky
20b40a794b [S390] signal race with restarting system calls
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-10-30 15:16:43 +01:00
Heiko Carstens
9e8ed3ae92 [S390] signal: use set_restore_sigmask() helper
We should call set_restore_sigmask() instead of directly setting
TIF_RESTORE_SIGMASK. This change should have been done three years
earlier... see 4e4c22 "signals: add set_restore_sigmask".

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2011-08-03 16:44:21 +02:00
Heiko Carstens
391c62feb1 [S390] signal: convert to use set_current_blocked()
Convert to use set_current_blocked() like x86.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2011-08-03 16:44:20 +02:00
Martin Schwidefsky
5e9a26928f [S390] ptrace cleanup
Overhaul program event recording and the code dealing with the ptrace
user space interface.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-01-05 12:47:31 +01:00
Martin Schwidefsky
86f2552bbd [S390] add breaking event address for user space
Copy the last breaking event address from the lowcore to a new
field in the thread_struct on each system entry. Add a new
ptrace request PTRACE_GET_LAST_BREAK and a new utrace regset
REGSET_LAST_BREAK to query the last breaking event.

This is useful for debugging wild branches in user space code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-05-17 10:00:15 +02:00
Martin Schwidefsky
0b4d78903b [S390] use set_current_state in sigsuspend
Use set_current_state instead of a direct assignment to set the
task state of the current process.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-01-27 10:12:49 +01:00
Martin Schwidefsky
6f50248ef0 [S390] duplicate SIGTRAP on signal delivery.
The code in do_signal sets the TIF_SINGLE_STEP bit and calls
tracehook_signal_handler after the signal frame has been set up.
This causes two SIGTRAP signals to be delivered to the tracer.
Stop setting the TIF_SINGLE_STEP bit in do_signal to get the
correct number of SIGTRAPs.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-01-13 20:44:44 +01:00
David Howells
ee18d64c1f KEYS: Add a keyctl to install a process's session keyring on its parent [try #6]
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: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-09-02 21:29:22 +10:00
Heiko Carstens
7757591ab4 [S390] implement is_compat_task
Implement is_compat_task and use it all over the place.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-06-12 10:27:30 +02:00
Heiko Carstens
26689452f5 [CVE-2009-0029] s390 specific system call wrappers
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2009-01-14 14:15:32 +01:00
Martin Schwidefsky
59da21398e [S390] fix system call parameter functions.
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-11-27 11:06:56 +01:00
Martin Schwidefsky
753c4dd6a2 [S390] ptrace changes
* System call parameter and result access functions
* Add tracehook calls
* Split syscall_trace into two functions do_syscall_trace_enter and
  do_syscall_trace_exit

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-10-10 21:33:57 +02:00
Heiko Carstens
a806170e29 [S390] Fix a lot of sparse warnings.
Most noteable part of this commit is the new local header file entry.h
which contains all the function declarations of functions that get only
called from asm code or are arch internal. That way we can avoid extern
declarations in C files.
This is more or less the same that was done for sparc64.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2008-04-17 07:47:06 +02:00
Heiko Carstens
de553438eb [S390] Protect against sigaltstack wraparound.
This is just a port of 83bd01024b
"x86: protect against sigaltstack wraparound".

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2008-04-17 07:46:56 +02:00
Roland McGrath
0ac30be461 [S390] single-step cleanup
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-01-26 14:11:27 +01:00
Randy Dunlap
e63340ae6b header cleaning: don't include smp_lock.h when not used
Remove includes of <linux/smp_lock.h> where it is not used/needed.
Suggested by Al Viro.

Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:07 -07:00