Commit Graph

11 Commits

Author SHA1 Message Date
Konstantin Belousov
c22994e3ad Add stackgap control mode to proccontrol(1).
PR:	239894
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D21352
2019-09-03 18:58:48 +00:00
Konstantin Belousov
469220742e Add implicit PROT_MAX() knob to proccontrol(1).
Reviewed by:	emaste, markj (previous version)
Discussed with:	brooks
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D20795
2019-07-02 19:12:02 +00:00
Konstantin Belousov
fab66680b3 Mention proccontrol(1) -m kpti.
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
2019-06-28 18:03:13 +00:00
Konstantin Belousov
bab3f1d04a proccontrol(1): Add kpti control mode.
Requested by:	jhb
Reviewed by:	jhb, markj (previous version)
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D19514
2019-03-16 11:46:48 +00:00
Konstantin Belousov
504748bc88 Some fixes for proccontrol(1) man page.
- Fix markup.
- Mention that process can only allow tracing for itself.  This is already
  stated in procctl(2), but requiring knowledge of the syscall description
  is too much for the tool user.
- Clearly state that query mode only works for existing process.

Noted and reviewed by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
2019-03-13 17:30:03 +00:00
Konstantin Belousov
146537449b proccontrol(1) man page.
Reviewed by:	0mp
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D19308
2019-02-26 17:46:19 +00:00
Konstantin Belousov
fa50a3552d Implement Address Space Layout Randomization (ASLR)
With this change, randomization can be enabled for all non-fixed
mappings.  It means that the base address for the mapping is selected
with a guaranteed amount of entropy (bits). If the mapping was
requested to be superpage aligned, the randomization honours the
superpage attributes.

Although the value of ASLR is diminshing over time as exploit authors
work out simple ASLR bypass techniques, it elimintates the trivial
exploitation of certain vulnerabilities, at least in theory.  This
implementation is relatively small and happens at the correct
architectural level.  Also, it is not expected to introduce
regressions in existing cases when turned off (default for now), or
cause any significant maintaince burden.

The randomization is done on a best-effort basis - that is, the
allocator falls back to a first fit strategy if fragmentation prevents
entropy injection.  It is trivial to implement a strong mode where
failure to guarantee the requested amount of entropy results in
mapping request failure, but I do not consider that to be usable.

I have not fine-tuned the amount of entropy injected right now. It is
only a quantitive change that will not change the implementation.  The
current amount is controlled by aslr_pages_rnd.

To not spoil coalescing optimizations, to reduce the page table
fragmentation inherent to ASLR, and to keep the transient superpage
promotion for the malloced memory, locality clustering is implemented
for anonymous private mappings, which are automatically grouped until
fragmentation kicks in.  The initial location for the anon group range
is, of course, randomized.  This is controlled by vm.cluster_anon,
enabled by default.

The default mode keeps the sbrk area unpopulated by other mappings,
but this can be turned off, which gives much more breathing bits on
architectures with small address space, such as i386.  This is tied
with the question of following an application's hint about the mmap(2)
base address. Testing shows that ignoring the hint does not affect the
function of common applications, but I would expect more demanding
code could break. By default sbrk is preserved and mmap hints are
satisfied, which can be changed by using the
kern.elf{32,64}.aslr.honor_sbrk sysctl.

ASLR is enabled on per-ABI basis, and currently it is only allowed on
FreeBSD native i386 and amd64 (including compat 32bit) ABIs.  Support
for additional architectures will be added after further testing.

Both per-process and per-image controls are implemented:
- procctl(2) adds PROC_ASLR_CTL/PROC_ASLR_STATUS;
- NT_FREEBSD_FCTL_ASLR_DISABLE feature control note bit makes it possible
  to force ASLR off for the given binary.  (A tool to edit the feature
  control note is in development.)
Global controls are:
- kern.elf{32,64}.aslr.enable - for non-fixed mappings done by mmap(2);
- kern.elf{32,64}.aslr.pie_enable - for PIE image activation mappings;
- kern.elf{32,64}.aslr.honor_sbrk - allow to use sbrk area for mmap(2);
- vm.cluster_anon - enables anon mapping clustering.

PR:	208580 (exp runs)
Exp-runs done by:	antoine
Reviewed by:	markj (previous version)
Discussed with:	emaste
Tested by:	pho
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D5603
2019-02-10 17:19:45 +00:00
Bryan Drewery
ea825d0274 DIRDEPS_BUILD: Update dependencies.
Sponsored by:	Dell EMC Isilon
2017-10-31 00:07:04 +00:00
Brooks Davis
517b671957 Use MAN=<empty> rather than MK_MAN=no to not install a manpage.
MFC after:	1 week
2017-05-02 21:09:07 +00:00
Bryan Drewery
304336144c DIRDEPS_BUILD: Connect new directories.
Sponsored by:	Dell EMC Isilon
2016-09-23 22:46:19 +00:00
Konstantin Belousov
7402f93ef2 Provide proccontrol(1), an utility to control processes behaviour, related
to procctl(2).

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2016-09-23 12:34:54 +00:00