Instead of generating a struct siginfo before calling arm64_notify_die
pass the signal number, tne sicode and the fault address into
arm64_notify_die and have it call force_sig_fault instead of
force_sig_info to let the generic code generate the struct siginfo.

This keeps code passing just the needed information into
siginfo generating code, making it easier to see what
is happening and harder to get wrong.  Further by letting
the generic code handle the generation of struct siginfo
it reduces the number of sites generating struct siginfo
making it possible to review them and verify that all
of the fiddly details for a structure passed to userspace
are handled properly.
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Tested-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Call force_sig_pkuerr directly instead of rolling it by hand
in _exception_pkey.
Reviewed-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Now that _exception no longer calls _exception_pkey it is no longer
necessary to handle any signal with any si_code.  All pkey exceptions
are SIGSEGV with paired with SEGV_PKUERR.  So just handle
that case and remove the now unnecessary parameters from _exception_pkey.
Reviewed-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The callers of _exception don't need the pkey exception logic because
they are not processing a pkey exception.  So just call exception_common
directly and then call force_sig_fault to generate the appropriate siginfo
and deliver the appropriate signal.
Reviewed-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

It is brittle and wrong to populate si_pkey when there was not a pkey
exception.  The field does not exist for all si_codes and in some
cases another field exists in the same memory location.

So factor out the code that all exceptions handlers must run
into exception_common, leaving the individual exception handlers
to generate the signals themselves.
Reviewed-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Now that bad_key_fault_exception no longer calls __bad_area_nosemaphore
there is no reason for __bad_area_nosemaphore to handle pkeys.
Reviewed-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

This removes the need for other code paths to deal with pkey exceptions.
Reviewed-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

There are no callers of __bad_area that pass in a pkey parameter so it makes
no sense to take one.
Reviewed-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

In do_sigbus isolate the mceerr signaling code and call
force_sig_mceerr instead of falling through to the force_sig_info that
works for all of the other signals.
Reviewed-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Now that si_code == SEGV_PKUERR is the flag indicating that a pkey
is present there is no longer a need to pass a pointer to a local
pkey value, instead pkey can be passed more efficiently by value.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Now that the pkey handling has been removed force_sig_info_fault and
force_sig_fault perform identical work.  Just the type of the address
paramter is different.  So replace calls to force_sig_info_fault with
calls to force_sig_fault, and remove force_sig_info_fault.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

There is only one code path that can generate a pkuerr signal.  That
code path calls __bad_area_nosemaphore and can be dectected by testing
if si_code == SEGV_PKUERR.  It can be seen from inspection that all of
the other tests in fill_sig_info_pkey are unnecessary.

Therefore call force_sig_pkuerr directly from __bad_area_semaphore and
remove fill_sig_info_pkey.

At the same time move the comment above force_sig_info_pkey into
bad_area_access_error, so that the documentation about pkey generation
races is not lost.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

There is only one caller of __bad_area that passes in PKUERR and thus
will generate a siginfo with si_pkey set.  Therefore simplify the
logic and hoist reading of vma_pkey up into that caller, and just
pass *pkey into __bad_area.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

There are no more users of the computed pkey value in __do_page_fault
so stop computing the value.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

After the previous cleanups to do_sigbus and and bad_area_nosemaphore
mm_fault_error no now longer uses it's pkey parameter.  Therefore
remove the unused parameter.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The function do_sigbus never sets si_code to PKUERR so it can never
return a pkey to userspace.  Therefore remove the unusable pkey
parameter from do_sigbus.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The function bad_area_nosemaphore always sets si_code to SEGV_MAPERR
and as such can never return a pkey parameter.  Therefore remove the
unusable pkey parameter from bad_area_nosemaphore.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Update the DO_ERROR macro to take si_code and si_addr values for a siginfo,
removing the need for the fill_trap_info function.

Update do_trap to also take the sicode and si_addr values for a sigininfo
and modify the code to call force_sig when a sicode is not passed in
and to call force_sig_fault when all of the information is present.

Making this a more obvious, simpler and less error prone construction.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The function "force_sig(sig, tsk)" is equivalent to "
force_sig_info(sig, SEND_SIG_PRIV, tsk)".  Using the siginfo variants can
be error prone so use the simpler old fashioned force_sig variant,
and with luck the force_sig_info variant can go away.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Instead of generating the siginfo in x86 specific code use the new
helper function force_sig_bnderr to separate the concerns of
collecting the information and generating a proper siginfo.

Making the code easier to understand and maintain.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The function do_trap_no_signal embodies almost all of the work of the
function do_trap.  The exceptions are setting of thread.error_code and
thread.trap_nr in the case when the signal will be sent, and reporting
which signal will be sent with show_signal.

Filling in struct siginfo and then calling do_trap is problematic as
filling in struct siginfo is an fiddly process that can through
inattention has resulted in fields not initialized and the wrong
fields being filled in.

To avoid this error prone situation I am replacing force_sig_info with
a set of functions that take as arguments the information needed to
send a specific kind of signal.

The function do_trap is called in the context of several different
kinds of signals today.  Having a solid do_trap_no_signal that
can be reused allows call sites that send different kinds of
signals to reuse all of the code in do_trap_no_signal.

Modify do_trap_no_signal to have a single exit there signals
where be sent (aka returning -1) to allow more of the signal
sending path to be moved to from do_trap to do_trap_no_signal.

Move setting thread.trap_nr and thread.error_code into do_trap_no_signal
so the code does not need to be duplicated.

Make the type of the string that is passed into do_trap_no_signal to
const.  The only user of that str is die and it already takes a const
string, so this just makes it explicit that the string won't change.

All of this prepares the way for using do_trap_no_signal outside
of do_trap.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The code for conditionally printing unhanded signals is duplicated twice
in arch/x86/kernel/traps.c.  Factor it out into it's own subroutine
called show_signal to make the code clearer and easier to maintain.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

This separates the logic of generating the signal from the logic of
gathering the information about the bounds violation.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The value passed in to addr_referenced is of type void __user *, so update
the addr_referenced parameter in trace_mpx_bounds_register_exception to match.

Also update the addr_referenced paramater in TP_STRUCT__entry as it again
holdes the same value.

I don't know why this was missed earlier but sparse was complaining when
testing test branch so fix this now.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

This simplifies the code making it clearer what is going on.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Only the call from do_sigbus will send SIGBUS due to a memory machine
check error.  Consolidate all of the machine check signal generation
code in do_sigbus and remove the now unnecessary fault parameter from
force_sig_info_fault.

Explicitly use the now constant si_code BUS_ADRERR in the call
to force_sig_info_fault from do_sigbus.

This makes the code in arch/x86/mm/fault.c easier to follower and
simpler to maintain.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The function fill_sigtrap_info now only has one caller so remove
it and put it's contents in it's caller.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace user_single_step_siginfo with user_single_step_report
that allocates siginfo structure on the stack and sends it.

This allows tracehook_report_syscall_exit to become a simple
if statement that calls user_single_step_report or ptrace_report_syscall
depending on the value of step.

Update the default helper function now called user_single_step_report
to explicitly set si_code to SI_USER and to set si_uid and si_pid to 0.
The default helper has always been doing this (using memset) but it
was far from obvious.

The powerpc helper can now just call force_sig_fault.
The x86 helper can now just call send_sigtrap.

Unfortunately the default implementation of user_single_step_report
can not use force_sig_fault as it does not use a SIGTRAP si_code.
So it has to carefully setup the siginfo and use use force_sig_info.

The net result is code that is easier to understand and simpler
to maintain.

Ref: 85ec7fd9 ("ptrace: introduce user_single_step_siginfo() helper")
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

For readability and consistency with the other exports in
kernel/signal.c pair the exports of signal sending functions with
their functions, instead of having the exports in one big clump.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

This function is static and it only has two callers.  As
specific_send_sig_info is only called twice remembering what
specific_send_sig_info does when reading the code is difficutl and it
makes it hard to see which sending sending functions are equivalent to
which others.

So remove specific_send_sig_info to make the code easier to read.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace send_sig_info in zap_pid_ns_processes with
group_send_sig_info.  This makes more sense as the entire process
group is being killed.  More importantly this allows the kill of those
processes with PIDTYPE_MAX to indicate all of the process in the pid
namespace are being signaled.  This is needed for fork to detect when
signals are sent to a group of processes.

Admittedly fork has another case to catch SIGKILL but the principle remains
that it is desirable to know when a group of processes is being signaled.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace send_sig and force_sig in __do_SAK with group_send_sig_info
the general helper for sending a signal to a process group.  This is
wordier but it allows specifying PIDTYPE_SID so that the signal code
knows the signal went to a session.

Both force_sig() and send_sig(..., 1) specify SEND_SIG_PRIV and the
new call of group_send_sig_info does that explicitly.  This is enough
to ensure even a pid namespace init is killed.

The global init remains unkillable.  The guarantee that __do_SAK tries
to provide is a clean path to login to a machine.  As the global init is
unkillable, if it chooses to hold open a tty it can violate this
guarantee.  A technique other than killing processes would be needed
to provide this guarantee to userspace.

The only difference between force_sig and send_sig when sending
SIGKILL is that SIGNAL_UNKILLABLE is cleared.  This has no affect on
the processing of a signal sent with SEND_SIG_PRIV by any process, making
it unnecessary, and not behavior that needs to be preserved.

force_sig was used originally because it did not take as many locks as
send_sig.  Today send_sig, force_sig and group_send_sig_info take the
same locks when delivering a signal.

group_send_sig_info also contains a permission check that force_sig
and send_sig do not.  However the presence of SEND_SIG_PRIV makes the
permission check a noop.  So the permission check does not result
in any behavioral differences.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The genweq_add_file and genwqe_del_file by caching current without
using reference counting embed the assumption that a file descriptor
will never be passed from one process to another.  It even embeds the
assumption that the the thread that opened the file will be in
existence when the process terminates.   Neither of which are
guaranteed to be true.

Therefore replace caching the task_struct of the opener with
pid of the openers thread group id.  All the knowledge of the
opener is used for is as the target of SIGKILL and a SIGKILL
will kill the entire process group.

Rename genwqe_force_sig to genwqe_terminate, remove it's unncessary
signal argument, update it's ownly caller, and use kill_pid
instead of force_sig.

The work force_sig does in changing signal handling state is not
relevant to SIGKILL sent as SEND_SIG_PRIV.  The exact same processess
will be killed just with less work, and less confusion.  The work done
by force_sig is really only needed for handling syncrhonous
exceptions.

It will still be possible to cause genwqe_device_remove to wait
8 seconds by passing a file descriptor to another process but
the possible user after free is fixed.

Fixes: eaf4722d ("GenWQE Character device and DDCB queue")
Cc: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Frank Haverkamp <haver@linux.vnet.ibm.com>
Cc: Joerg-Stephan Vogt <jsvogt@de.ibm.com>
Cc: Michael Jung <mijung@gmx.net>
Cc: Michael Ruettger <michael@ibmra.de>
Cc: Kleber Sacilotto de Souza <klebers@linux.vnet.ibm.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Eberhard S. Amann <esa@linux.vnet.ibm.com>
Cc: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Cc: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

There are no more users of SEND_SIG_FORCED so it may be safely removed.

Remove the definition of SEND_SIG_FORCED, it's use in is_si_special,
it's use in TP_STORE_SIGINFO, and it's use in __send_signal as without
any users the uses of SEND_SIG_FORCED are now unncessary.

This makes the code simpler, easier to understand and use.  Users of
signal sending functions now no longer need to ask themselves do I
need to use SEND_SIG_FORCED.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Now that siginfo is never allocated for SIGKILL and SIGSTOP there is
no difference between SEND_SIG_PRIV and SEND_SIG_FORCED for SIGKILL
and SIGSTOP.  This makes SEND_SIG_FORCED unnecessary and redundant in
the presence of SIGKILL and SIGSTOP.  Therefore change users of
SEND_SIG_FORCED that are sending SIGKILL or SIGSTOP to use
SEND_SIG_PRIV instead.

This removes the last users of SEND_SIG_FORCED.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The SIGKILL and SIGSTOP signals are never delivered to userspace so
queued siginfo for these signals can never be observed.  Therefore
remove the chance of failure by never even attempting to allocate
siginfo in those cases.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Today kernel threads never dequeue siginfo so it is pointless to
enqueue siginfo for them.  The usb gadget mass storage driver goes
one farther and uses SEND_SIG_FORCED to guarantee that no siginfo is
even enqueued.

Generalize the optimization of the usb mass storage driver and never
perform an unnecessary allocation when delivering signals to kthreads.

Switch the mass storage driver from sending signals with
SEND_SIG_FORCED to SEND_SIG_PRIV.  As using SEND_SIG_FORCED is now
unnecessary.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

None of the callers use the it so remove it.
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>