Stack Smashing Protection (SSP) is a software vulnerability mitigation,
and fits with this page. Add a note to the beginning of security.7
providing a more explicit cross reference to mitigations.7.
Reviewed by: kevans
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D45435
In the future, we will Default to _FORTIFY_SOURCE=2 if SSP is enabled,
otherwise default to _FORTIFY_SOURCE=0. For now we default it to 0
unconditionally to ease bisect across older versions without the new
symbols, and we'll put out a call for testing.
include/*.h include their ssp/*.h equivalents as needed based on the
knob. Programs and users are allowed to override FORTIFY_SOURCE in their
Makefiles or src.conf/make.conf to force it off.
Reviewed by: des, markj
Relnotes: yes
Sponsored by: Stormshield
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D32308
In an earlier implementation the stack (gap) was randomized when the
enable sysctl was set and ASLR was also enabled (in general) for the
binary. In the current implementation the sysctl operates
independently.
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D42357
Currently, sysctls which enable KDB in some way are flagged with
CTLFLAG_SECURE, meaning that you can't modify them if securelevel > 0.
This is so that KDB cannot be used to lower a running system's
securelevel, see commit 3d7618d8bf. However, the newer mac_ddb(4)
restricts DDB operations which could be abused to lower securelevel
while retaining some ability to gather useful debugging information.
To enable the use of KDB (specifically, DDB) on systems with a raised
securelevel, change the KDB sysctl policy: rather than relying on
CTLFLAG_SECURE, add a check of the current securelevel to kdb_trap().
If the securelevel is raised, only pass control to the backend if MAC
specifically grants access; otherwise simply check to see if mac_ddb
vetoes the request, as before.
Add a new secure sysctl, debug.kdb.enter_securelevel, to override this
behaviour. That is, the sysctl lets one enter a KDB backend even with a
raised securelevel, so long as it is set before the securelevel is
raised.
Reviewed by: mhorne, stevek
MFC after: 1 month
Sponsored by: Juniper Networks
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D37122
Mostly remove from the SEE ALSO section, adding a mention of the port
where not removed. Elsewhere, remove as appropriate and change from .Xr
to .Nm where a mention of telnetd continues to make sense (or removing
it would require significant reworking of the surrounding text).
Reviewed by: imp, delphij, emaste
Differential Revision: https://reviews.freebsd.org/D36785
The approach taken by the stack gap implementation was to insert a
random gap between the top of the fixed stack mapping and the true top
of the main process stack. This approach was chosen so as to avoid
randomizing the previously fixed address of certain process metadata
stored at the top of the stack, but had some shortcomings. In
particular, mlockall(2) calls would wire the gap, bloating the process'
memory usage, and RLIMIT_STACK included the size of the gap so small
(< several MB) limits could not be used.
There is little value in storing each process' ps_strings at a fixed
location, as only very old programs hard-code this address; consumers
were converted decades ago to use a sysctl-based interface for this
purpose. Thus, this change re-implements stack address randomization by
simply breaking the convention of storing ps_strings at a fixed
location, and randomizing the location of the entire stack mapping.
This implementation is simpler and avoids the problems mentioned above,
while being unlikely to break compatibility anywhere the default ASLR
settings are used.
The kern.elfN.aslr.stack_gap sysctl is renamed to kern.elfN.aslr.stack,
and is re-enabled by default.
PR: 260303
Reviewed by: kib
Discussed with: emaste, mw
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33704
This is just like debug.kdb.panic, except the string that's passed in
is reported in the panic message. This allows people with automated
systems to collect kernel panics over a large fleet of machines to
flag panics better. Strings like "Warner look at this hang" or "see
JIRA ABC-1234 for details" allow these automated systems to route the
forced panic to the appropriate engineers like you can with other
types of panics. Other users are likely possible.
Relnotes: Yes
Sponsored by: Netflix
Reviewed by: allanjude (earlier version)
Suggestions from review folded in by: 0mp, emaste, lwhsu
Differential Revision: https://reviews.freebsd.org/D28041
The flush is needed to prevent cross-process ret2spec, which is not handled
on kernel entry if IBPB is enabled but SMEP is present.
While there, add i386 RSB flush.
Reported by: Anthony Steinhauser <asteinhauser@google.com>
Reviewed by: markj, Anthony Steinhauser
Discussed with: philip
admbugs: 961
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
"*-out" is a complex way of phrasing the fact, and it causes
confusion for people.
Submitted by: debdrup
Approved by: bcr (mentor)
Differential Revision: https://reviews.freebsd.org/D23482
r355436 moved mitigation sysctls to machdep.mitigations but did not
rationalize the sense of the invidual knobs. Clarify that the old
names remain the canonical way to set these mitigations.
Backwards compatibility will be maintained for the original names
(e.g. hw.ibrs_disable), but not from the interim names
(e.g. machdep.mitigations.ibrs.disable).
Sponsored by: The FreeBSD Foundation
Disable the use of executable 2M page mappings in EPT-format page
tables on affected CPUs. For bhyve virtual machines, this effectively
disables all use of superpage mappings on affected CPUs. The
vm.pmap.allow_2m_x_ept sysctl can be set to override the default and
enable mappings on affected CPUs.
Alternate approaches have been suggested, but at present we do not
believe the complexity is warranted for typical bhyve's use cases.
Reviewed by: alc, emaste, markj, scottl
Security: CVE-2018-12207
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D21884
More extensive changes to this page are certainly needed, but at least
remove references to binaries that no longer exist.
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Initially in_matrote() in_clsroute() in their current state was introduced by
r4105 20 years ago. Instead of deleting inactive routes immediately, we kept them
in route table, setting RTPRF_OURS flag and some expire time. After that, either
GC came or RTPRF_OURS got removed on first-packet. It was a good solution
in that days (and probably another decade after that) to keep TCP metrics.
However, after moving metrics to TCP hostcache in r122922, most of in_rmx
functionality became unused. It might had been used for flushing icmp-originated
routes before rte mutexes/refcounting, but I'm not sure about that.
So it looks like this is nearly impossible to make GC do its work nowadays:
in_rtkill() ignores non-RTPRF_OURS routes.
route can only become RTPRF_OURS after dropping last reference via rtfree()
which calls in_clsroute(), which, it turn, ignores UP and non-RTF_DYNAMIC routes.
Dynamic routes can still be installed via received redirect, but they
have default lifetime (no specific rt_expire) and no one has another trie walker
to call RTFREE() on them.
So, the changelist:
* remove custom rnh_match / rnh_close matching function.
* remove all GC functions
* partially revert r256695 (proto3 is no more used inside kernel,
it is not possible to use rt_expire from user point of view, proto3 support
is not complete)
* Finish r241884 (similar to this commit) and remove remaining IPv6 parts
MFC after: 1 month
text and, as a result, 'FreeBSD' is not visible in apropos output
when security(7) is displayed. Fix this buglet by using a
literal 'FreeBSD' string in .Nd
PR: docs/85986
Submitted by: Matthias Schmidt <schmidtm@mathematik.uni-marburg.de>
MFC after: 1 week
Files used both "securelevel" and either "secure level" or
"security level"; all are now "security level".
PR: docs/84266
Submitted by: garys
Approved by: keramida
MFC after: 3 days
Use em dashes instead of " - ".
Use .Em instead of *emphasis*.
Note that securing root indirectly (by securing staff accounts) works
only if direct root access has been limited. [1]
s/hacker/attacker, as done in the handbook. (inspired by [1])
PR: 52878 [1]
Submitted by: Brian Minard <bminard@flatfoot.ca> [1]
