1 SECURITY-FLAGS(5)     Standards, Environments, and Macros    SECURITY-FLAGS(5)
   2 
   3 
   4 
   5 NAME
   6        security-flags - process security flags
   7 
   8 DESCRIPTION
   9        Each process on an illumos system has an associated set of security-
  10        flags which describe additional per-process security and exploit
  11        mitigation features which are enabled for that process.
  12 
  13        There are four sets of these flags for each process, the effective set
  14        (abbreviated E) are the set which currently apply to the process and
  15        are immutable. The inheritable set (abbreviated I) are the flags which
  16        will become effective the next time the process calls one of the
  17        exec(2) family of functions, and will be inherited as both the
  18        effective and inheritable sets by any child processes. The upper set
  19        (abbreviated U) specify the maximal flags that a process can have in
  20        its inheritable set.  The lower set (abbreviated L) specify the minimal
  21        amount of flags that a process must have in its inheritable set.  The
  22        inheritable set may be changed at any time, subject to permissions and
  23        the lower and upper sets.
  24 
  25        To change the security-flags of a process one must have both
  26        permissions equivalent to those required to send a signal to the
  27        process and have the PRIV_PROC_SECFLAGS privilege.
  28 
  29        Currently available features are:
  30 
  31 
  32        Address Space Layout Randomisation (ASLR)
  33                   The base addresses of the stack, heap and shared library
  34                   (including ld.so) mappings are randomised, the bases of
  35                   mapped regions other than those using MAP_FIXED are
  36                   randomised.
  37 
  38                   Currently, executable base addresses are not randomised, due
  39                   to which the mitigation provided by this feature is
  40                   currently limited.
  41 
  42                   This flag may also be enabled by the presence of the
  43                   DT_SUNW_ASLR dynamic tag in the .dynamic section of the
  44                   executable file. If this tag has a value of 1, ASLR will be
  45                   enabled. If the flag has a value of 0 ASLR will be disabled.
  46                   If the tag is not present, the value of the ASLR flag will
  47                   be inherited as normal.
  48 
  49 
  50        Forbid mappings at NULL (FORBIDNULLMAP)
  51                   Mappings with an address of 0 are forbidden, and return
  52                   EINVAL rather than being honored.
  53 
  54 
  55        Make the userspace stack non-executable (NOEXECSTACK)
  56                   The stack will be mapped without executable permission, and
  57                   attempts to execute it will fault.
  58 
  59        System default security-flags are configured via properties on the
  60        svc:/system/process-security service, which contains a boolean property
  61        per-flag in the default, lower and upper, property groups.  For
  62        example, to enable ASLR by default you would execute the following
  63        commands:
  64 
  65          # svccfg -s svc:/system/process-security setprop default/aslr = true
  66 
  67 
  68        This can be done by any user with the solaris.smf.value.process-
  69        security authorization.
  70 
  71        Since security-flags are strictly inherited, this will not take effect
  72        until the system or zone is next booted.
  73 
  74 
  75 SEE ALSO
  76        psecflags(1), svccfg(1M), brk(2), exec(2), mmap(2), mmapobj(2),
  77        privileges(5), rbac(5)
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  81                                   May 5, 2014                SECURITY-FLAGS(5)