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.\"
.\" This file and its contents are supplied under the terms of the
.\" Common Development and Distribution License ("CDDL"), version 1.0.
.\" You may only use this file in accordance with the terms of version
.\" 1.0 of the CDDL.
.\"
.\" A full copy of the text of the CDDL should have accompanied this
.\" source. A copy of the CDDL is also available via the Internet at
.\" http://www.illumos.org/license/CDDL.
.\"
.\" Copyright 2015, Richard Lowe.
.\"
.TH "SECURITY-FLAGS" "5" "June 6, 2016"
.SH "NAME"
\fBsecurity-flags\fR - process security flags
.SH "DESCRIPTION"
Each process on an illumos system has an associated set of security-flags
which describe additional per-process security and exploit mitigation
features which are enabled for that process.
.P
There are four sets of these flags for each process, the effective set
(abbreviated \fIE\fR) are the set which currently apply to the process and are
immutable. The inheritable set (abbreviated \fII\fR) are the flags which will
become effective the next time the process calls one of the \fBexec(2)\fR
family of functions, and will be inherited as both the effective and
inheritable sets by any child processes. The upper set (abbreviated \fIU\fR)
specify the maximal flags that a process can have in its inheritable set. The
lower set (abbreviated \fIL\fR) specify the minimal amount of flags that a
process must have in its inheritable set. The inheritable set may be changed
at any time, subject to permissions and the lower and upper sets.
.P
To change the security-flags of a process one must have both permissions
equivalent to those required to send a signal to the process and have the
\fBPRIV_PROC_SECFLAGS\fR privilege.
.P
Currently available features are:
.sp
.ne 2
.na
Address Space Layout Randomisation (\fBASLR\fR)
.ad
.RS 11n
The base addresses of the stack, heap and shared library (including
\fBld.so\fR) mappings are randomised, the bases of mapped regions other than
those using \fBMAP_FIXED\fR are randomised.
.P
Currently, executable base addresses are \fInot\fR randomised, due to which
the mitigation provided by this feature is currently limited.
.P
This flag may also be enabled by the presence of the \fBDT_SUNW_ASLR\fR
dynamic tag in the \fB.dynamic\fR section of the executable file. If this
tag has a value of 1, ASLR will be enabled. If the flag has a value of
\fB0\fR ASLR will be disabled. If the tag is not present, the value of the
ASLR flag will be inherited as normal.
.RE
.sp
.ne 2
.na
Forbid mappings at NULL (\fBFORBIDNULLMAP\fR)
.ad
.RS 11n
Mappings with an address of 0 are forbidden, and return EINVAL rather than
being honored.
.RE
.sp
.ne 2
.na
Make the userspace stack non-executable (\fBNOEXECSTACK\fR)
.ad
.RS 11n
The stack will be mapped without executable permission, and attempts to
execute it will fault.
.RE
System default security-flags are configured via properties on the
\fBsvc:/system/process-security\fR service, which contains a boolean property
per-flag in the \fBdefault\fR, \fBlower\fR and \fBupper\fR, property groups.
The value indicates the setting of the flag, flags with no value take their
defaults. For example, to enable ASLR by default you would execute the
following commands:
.sp
.in +2
.nf
# svccfg -s svc:/system/process-security setprop default/aslr = true
.fi
.in -2
.sp
.P
To restore the setting to the defaults you would execute:
.sp
.in +2
.nf
# svccfg -s svc:/system/process-security delpropvalue default/aslr true
.fi
.in -2
.sp
.P
This can be done by any user with the \fBsolaris.smf.value.process-security\fR
authorization.
.P
Since security-flags are strictly inherited, this will not take effect until
the system or zone is next booted.
.SH "SEE ALSO"
.BR psecflags (1),
.BR svccfg (1M),
.BR brk (2),
.BR exec (2),
.BR mmap (2),
.BR mmapobj (2),
.BR privileges (5),
.BR rbac (5)
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