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   5 .\" 1.0 of the CDDL.
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  11 .\" Copyright 2015, Richard Lowe.
  12 .\"
  13 .TH "SECURITY-FLAGS" "5" "May 5, 2014"
  14 .SH "NAME"
  15 \fBsecurity-flags\fR - process security flags
  16 .SH "DESCRIPTION"
  17 Each process on an illumos system has an associated set of security-flags
  18 which describe additional per-process security and exploit mitigation
  19 features which are enabled for that process.
  20 .P
  21 There are four sets of these flags for each process, the effective set
  22 (abbreviated \fIE\fR) are the set which currently apply to the process and are
  23 immutable. The inheritable set (abbreviated \fII\fR) are the flags which will
  24 become effective the next time the process calls one of the \fBexec(2)\fR
  25 family of functions, and will be inherited as both the effective and
  26 inheritable sets by any child processes. The upper set (abbreviated \fIU\fR)
  27 specify the maximal flags that a process can have in its inheritable set.  The
  28 lower set (abbreviated \fIL\fR) specify the minimal amount of flags that a
  29 process must have in its inheritable set.  The inheritable set may be changed
  30 at any time, subject to permissions and the lower and upper sets.
  31 .P
  32 To change the security-flags of a process one must have both permissions
  33 equivalent to those required to send a signal to the process and have the
  34 \fBPRIV_PROC_SECFLAGS\fR privilege.
  35 .P
  36 Currently available features are:
  37 
  38 .sp
  39 .ne 2
  40 .na
  41 Address Space Layout Randomisation (\fBASLR\fR)
  42 .ad
  43 .RS 11n
  44 The base addresses of the stack, heap and shared library (including
  45 \fBld.so\fR) mappings are randomised, the bases of mapped regions other than
  46 those using \fBMAP_FIXED\fR are randomised.
  47 .P
  48 Currently, executable base addresses are \fInot\fR randomised, due to which
  49 the mitigation provided by this feature is currently limited.
  50 .P
  51 This flag may also be enabled by the presence of the \fBDT_SUNW_ASLR\fR
  52 dynamic tag in the \fB.dynamic\fR section of the executable file. If this
  53 tag has a value of 1, ASLR will be enabled. If the flag has a value of
  54 \fB0\fR ASLR will be disabled. If the tag is not present, the value of the
  55 ASLR flag will be inherited as normal.
  56 .RE
  57 
  58 .sp
  59 .ne 2
  60 .na
  61 Forbid mappings at NULL (\fBFORBIDNULLMAP\fR)
  62 .ad
  63 .RS 11n
  64 Mappings with an address of 0 are forbidden, and return EINVAL rather than
  65 being honored.
  66 .RE
  67 
  68 .sp
  69 .ne 2
  70 .na
  71 Make the userspace stack non-executable (\fBNOEXECSTACK\fR)
  72 .ad
  73 .RS 11n
  74 The stack will be mapped without executable permission, and attempts to
  75 execute it will fault.
  76 .RE
  77 
  78 System default security-flags are configured via properties on the
  79 \fBsvc:/system/process-security\fR service, which contains a boolean property
  80 per-flag in the \fBdefault\fR, \fBlower\fR and \fBupper\fR, property groups.
  81 For example, to enable ASLR by default you would execute the following
  82 commands:
  83 .sp
  84 .in +2
  85 .nf
  86 # svccfg -s svc:/system/process-security setprop default/aslr = true
  87 .fi
  88 .in -2
  89 .sp
  90 .P
  91 This can be done by any user with the \fBsolaris.smf.value.process-security\fR
  92 authorization.
  93 .P
  94 Since security-flags are strictly inherited, this will not take effect until
  95 the system or zone is next booted.
  96 
  97 .SH "SEE ALSO"
  98 .BR psecflags (1),
  99 .BR svccfg (1M),
 100 .BR brk (2),
 101 .BR exec (2),
 102 .BR mmap (2),
 103 .BR mmapobj (2),
 104 .BR privileges (5),
 105 .BR rbac (5)