linux-stable.git/kernel/kprobes.c, branch v4.18.2

kprobes: Fix random address output of blacklist file

2018-04-25T14:27:56+00:00

File /sys/kernel/debug/kprobes/blacklist displays random addresses:

[root@s8360046 linux]# cat /sys/kernel/debug/kprobes/blacklist
0x0000000047149a90-0x00000000bfcb099a	print_type_x8
....

This breaks 'perf probe' which uses the blacklist file to prohibit
probes on certain functions by checking the address range.

Fix this by printing the correct (unhashed) address.

The file mode is read all but this is not an issue as the file
hierarchy points out:
 # ls -ld /sys/ /sys/kernel/ /sys/kernel/debug/ /sys/kernel/debug/kprobes/
	/sys/kernel/debug/kprobes/blacklist
dr-xr-xr-x 12 root root 0 Apr 19 07:56 /sys/
drwxr-xr-x  8 root root 0 Apr 19 07:56 /sys/kernel/
drwx------ 16 root root 0 Apr 19 06:56 /sys/kernel/debug/
drwxr-xr-x  2 root root 0 Apr 19 06:56 /sys/kernel/debug/kprobes/
-r--r--r--  1 root root 0 Apr 19 06:56 /sys/kernel/debug/kprobes/blacklist

Everything in and below /sys/kernel/debug is rwx to root only,
no group or others have access.

Background:
Directory /sys/kernel/debug/kprobes is created by debugfs_create_dir()
which sets the mode bits to rwxr-xr-x. Maybe change that to use the
parent's directory mode bits instead?

Link: http://lkml.kernel.org/r/20180419105556.86664-1-tmricht@linux.ibm.com

Fixes: ad67b74d2469 ("printk: hash addresses printed with %p")
Cc: stable@vger.kernel.org
Cc:  # v4.15+
Cc: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Cc: David S Miller 
Cc: Masami Hiramatsu 
Cc: acme@kernel.org

Signed-off-by: Thomas Richter 
Signed-off-by: Steven Rostedt (VMware)

kprobes: Propagate error from disarm_kprobe_ftrace()

2018-02-16T08:12:58+00:00

Improve error handling when disarming ftrace-based kprobes. Like with
arm_kprobe_ftrace(), propagate any errors from disarm_kprobe_ftrace() so
that we do not disable/unregister kprobes that are still armed. In other
words, unregister_kprobe() and disable_kprobe() should not report success
if the kprobe could not be disarmed.

disarm_all_kprobes() keeps its current behavior and attempts to
disarm all kprobes. It returns the last encountered error and gives a
warning if not all probes could be disarmed.

This patch is based on Petr Mladek's original patchset (patches 2 and 3)
back in 2015, which improved kprobes error handling, found here:

   https://lkml.org/lkml/2015/2/26/452

However, further work on this had been paused since then and the patches
were not upstreamed.

Based-on-patches-by: Petr Mladek 
Signed-off-by: Jessica Yu 
Acked-by: Masami Hiramatsu 
Cc: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Cc: David S . Miller 
Cc: Jiri Kosina 
Cc: Joe Lawrence 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Miroslav Benes 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/20180109235124.30886-3-jeyu@kernel.org
Signed-off-by: Ingo Molnar

kprobes: Propagate error from arm_kprobe_ftrace()

2018-02-16T08:12:52+00:00

Improve error handling when arming ftrace-based kprobes. Specifically, if
we fail to arm a ftrace-based kprobe, register_kprobe()/enable_kprobe()
should report an error instead of success. Previously, this has lead to
confusing situations where register_kprobe() would return 0 indicating
success, but the kprobe would not be functional if ftrace registration
during the kprobe arming process had failed. We should therefore take any
errors returned by ftrace into account and propagate this error so that we
do not register/enable kprobes that cannot be armed. This can happen if,
for example, register_ftrace_function() finds an IPMODIFY conflict (since
kprobe_ftrace_ops has this flag set) and returns an error. Such a conflict
is possible since livepatches also set the IPMODIFY flag for their ftrace_ops.

arm_all_kprobes() keeps its current behavior and attempts to arm all
kprobes. It returns the last encountered error and gives a warning if
not all probes could be armed.

This patch is based on Petr Mladek's original patchset (patches 2 and 3)
back in 2015, which improved kprobes error handling, found here:

   https://lkml.org/lkml/2015/2/26/452

However, further work on this had been paused since then and the patches
were not upstreamed.

Based-on-patches-by: Petr Mladek 
Signed-off-by: Jessica Yu 
Acked-by: Masami Hiramatsu 
Cc: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Cc: David S . Miller 
Cc: Jiri Kosina 
Cc: Joe Lawrence 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Miroslav Benes 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/20180109235124.30886-2-jeyu@kernel.org
Signed-off-by: Ingo Molnar

kprobes: Disable the jprobes APIs

2017-10-20T09:02:29+00:00

Disable the jprobes APIs and comment out the jprobes API function
code. This is in preparation of removing all jprobes related
code (including kprobe's break_handler).

Nowadays ftrace and other tracing features are mature enough
to replace jprobes use-cases. Users can safely use ftrace and
perf probe etc. for their use cases.

Signed-off-by: Masami Hiramatsu 
Cc: Alexei Starovoitov 
Cc: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Cc: David S . Miller 
Cc: Ian McDonald 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Paul E . McKenney 
Cc: Peter Zijlstra 
Cc: Stephen Hemminger 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Vlad Yasevich 
Link: http://lkml.kernel.org/r/150724527741.5014.15465541485637899227.stgit@devbox
Signed-off-by: Ingo Molnar

kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT=y

2017-10-20T07:45:15+00:00

We want to wait for all potentially preempted kprobes trampoline
execution to have completed. This guarantees that any freed
trampoline memory is not in use by any task in the system anymore.
synchronize_rcu_tasks() gives such a guarantee, so use it.

Also, this guarantees to wait for all potentially preempted tasks
on the instructions which will be replaced with a jump.

Since this becomes a problem only when CONFIG_PREEMPT=y, enable
CONFIG_TASKS_RCU=y for synchronize_rcu_tasks() in that case.

Signed-off-by: Masami Hiramatsu 
Acked-by: Paul E. McKenney 
Cc: Ananth N Mavinakayanahalli 
Cc: Linus Torvalds 
Cc: Naveen N . Rao 
Cc: Paul E . McKenney 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/150845661962.5443.17724352636247312231.stgit@devbox
Signed-off-by: Ingo Molnar

Revert "kprobes: Warn if optprobe handler tries to change execution path"

2017-10-18T13:21:35+00:00

This reverts commit:

  e863d539614641 ("kprobes: Warn if optprobe handler tries to change execution path")

On PowerPC, we place a probe at kretprobe_trampoline to catch function
returns and with CONFIG_OPTPROBES=y, this probe gets optimized. This
works for us due to the way we handle the optprobe as described in
commit:

  762df10bad6954 ("powerpc/kprobes: Optimize kprobe in kretprobe_trampoline()")

With the above commit, we end up with a warning. As such, revert this change.

Reported-by: Michael Ellerman 
Signed-off-by: Naveen N. Rao 
Cc: Ananth N Mavinakayanahalli 
Cc: Linus Torvalds 
Cc: Masami Hiramatsu 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20171017081834.3629-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

kprobes: Warn if optprobe handler tries to change execution path

2017-09-28T07:23:04+00:00

Warn if optprobe handler tries to change execution path.
As described in Documentation/kprobes.txt, with optprobe
user handler can not change instruction pointer. In that
case user must avoid optimizing the kprobes by setting
post_handler or break_handler.

Signed-off-by: Masami Hiramatsu 
Cc: Alexei Starovoitov 
Cc: Alexei Starovoitov 
Cc: Ananth N Mavinakayanahalli 
Cc: Linus Torvalds 
Cc: Paul E . McKenney 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/150581521955.32348.3615624715034787365.stgit@devbox
Signed-off-by: Ingo Molnar

kprobes/x86: Make insn buffer always ROX and use text_poke()

2017-09-28T07:23:03+00:00

Make insn buffer always ROX and use text_poke() to write
the copied instructions instead of set_memory_*().
This makes instruction buffer stronger against other
kernel subsystems because there is no window time
to modify the buffer.

Suggested-by: Ingo Molnar 
Signed-off-by: Masami Hiramatsu 
Cc: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Cc: David S . Miller 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/150304463032.17009.14195368040691676813.stgit@devbox
Signed-off-by: Ingo Molnar

kprobes: Ensure that jprobe probepoints are at function entry

2017-07-08T09:05:35+00:00

Similar to commit 90ec5e89e393c ("kretprobes: Ensure probe location is
at function entry"), ensure that the jprobe probepoint is at function
entry.

Signed-off-by: Naveen N. Rao 
Cc: Ananth N Mavinakayanahalli 
Cc: Linus Torvalds 
Cc: Masami Hiramatsu 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/a4525af6c5a42df385efa31251246cf7cca73598.1499443367.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

kprobes: Simplify register_jprobes()

2017-07-08T09:05:34+00:00

Re-factor jprobe registration functions as the current version is
getting too unwieldy. Move the actual jprobe registration to
register_jprobe() and re-organize code accordingly.

Suggested-by: Ingo Molnar 
Signed-off-by: Naveen N. Rao 
Cc: Ananth N Mavinakayanahalli 
Cc: Linus Torvalds 
Cc: Masami Hiramatsu 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/089cae4bfe73767f765291ee0e6fb0c3d240e5f1.1499443367.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar