PRIVILEGES(7) Standards, Environments, and Macros PRIVILEGES(7)

NAME

privileges - process privilege model

DESCRIPTION

In illumos, software implements a set of privileges that provide
fine-grained control over the actions of processes. The possession of
a certain privilege allows a process to perform a specific set of
restricted operations.


The change to a primarily privilege-based security model in the
operating system gives developers an opportunity to restrict
processes to those privileged operations actually needed instead of
all (super-user) or no privileges (non-zero UIDs). Additionally, a
set of previously unrestricted operations now requires a privilege;
these privileges are dubbed the "basic" privileges and are by default
given to all processes.


Taken together, all defined privileges with the exception of the
"basic" privileges compose the set of privileges that are
traditionally associated with the root user. The "basic" privileges
are "privileges" unprivileged processes were accustomed to having.


The defined privileges are:

PRIV_CONTRACT_EVENT

Allow a process to request reliable delivery of events to an
event endpoint.

Allow a process to include events in the critical event set term
of a template which could be generated in volume by the user.


PRIV_CONTRACT_IDENTITY

Allows a process to set the service FMRI value of a process
contract template.


PRIV_CONTRACT_OBSERVER

Allow a process to observe contract events generated by contracts
created and owned by users other than the process's effective
user ID.

Allow a process to open contract event endpoints belonging to
contracts created and owned by users other than the process's
effective user ID.


PRIV_CPC_CPU

Allow a process to access per-CPU hardware performance counters.


PRIV_DTRACE_KERNEL

Allow DTrace kernel-level tracing.


PRIV_DTRACE_PROC

Allow DTrace process-level tracing. Allow process-level tracing
probes to be placed and enabled in processes to which the user
has permissions.


PRIV_DTRACE_USER

Allow DTrace user-level tracing. Allow use of the syscall and
profile DTrace providers to examine processes to which the user
has permissions.


PRIV_FILE_CHOWN

Allow a process to change a file's owner user ID. Allow a process
to change a file's group ID to one other than the process's
effective group ID or one of the process's supplemental group
IDs.


PRIV_FILE_CHOWN_SELF

Allow a process to give away its files. A process with this
privilege runs as if {_POSIX_CHOWN_RESTRICTED} is not in effect.


PRIV_FILE_DAC_EXECUTE

Allow a process to execute an executable file whose permission
bits or ACL would otherwise disallow the process execute
permission.


PRIV_FILE_DAC_READ

Allow a process to read a file or directory whose permission bits
or ACL would otherwise disallow the process read permission.


PRIV_FILE_DAC_SEARCH

Allow a process to search a directory whose permission bits or
ACL would not otherwise allow the process search permission.


PRIV_FILE_DAC_WRITE

Allow a process to write a file or directory whose permission
bits or ACL do not allow the process write permission. All
privileges are required to write files owned by UID 0 in the
absence of an effective UID of 0.


PRIV_FILE_DOWNGRADE_SL

Allow a process to set the sensitivity label of a file or
directory to a sensitivity label that does not dominate the
existing sensitivity label.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_FILE_FLAG_SET

Allows a process to set immutable, nounlink or appendonly file
attributes.


PRIV_FILE_LINK_ANY

Allow a process to create hardlinks to files owned by a UID
different from the process's effective UID.


PRIV_FILE_OWNER

Allow a process that is not the owner of a file to modify that
file's access and modification times. Allow a process that is not
the owner of a directory to modify that directory's access and
modification times. Allow a process that is not the owner of a
file or directory to remove or rename a file or directory whose
parent directory has the "save text image after execution"
(sticky) bit set. Allow a process that is not the owner of a file
to mount a namefs upon that file. Allow a process that is not the
owner of a file or directory to modify that file's or directory's
permission bits or ACL.


PRIV_FILE_READ

Allow a process to open objects in the filesystem for reading.
This privilege is not necessary to read from an already open file
which was opened before dropping the PRIV_FILE_READ privilege.


PRIV_FILE_SETID

Allow a process to change the ownership of a file or write to a
file without the set-user-ID and set-group-ID bits being cleared.
Allow a process to set the set-group-ID bit on a file or
directory whose group is not the process's effective group or one
of the process's supplemental groups. Allow a process to set the
set-user-ID bit on a file with different ownership in the
presence of PRIV_FILE_OWNER. Additional restrictions apply when
creating or modifying a setuid 0 file.


PRIV_FILE_UPGRADE_SL

Allow a process to set the sensitivity label of a file or
directory to a sensitivity label that dominates the existing
sensitivity label.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_FILE_WRITE

Allow a process to open objects in the filesystem for writing, or
otherwise modify them. This privilege is not necessary to write
to an already open file which was opened before dropping the
PRIV_FILE_WRITE privilege.


PRIV_GRAPHICS_ACCESS

Allow a process to make privileged ioctls to graphics devices.
Typically only an xserver process needs to have this privilege. A
process with this privilege is also allowed to perform privileged
graphics device mappings.


PRIV_GRAPHICS_MAP

Allow a process to perform privileged mappings through a graphics
device.


PRIV_IPC_DAC_READ

Allow a process to read a System V IPC Message Queue, Semaphore
Set, or Shared Memory Segment whose permission bits would not
otherwise allow the process read permission.


PRIV_IPC_DAC_WRITE

Allow a process to write a System V IPC Message Queue, Semaphore
Set, or Shared Memory Segment whose permission bits would not
otherwise allow the process write permission.


PRIV_IPC_OWNER

Allow a process that is not the owner of a System V IPC Message
Queue, Semaphore Set, or Shared Memory Segment to remove, change
ownership of, or change permission bits of the Message Queue,
Semaphore Set, or Shared Memory Segment.


PRIV_NET_ACCESS

Allow a process to open a TCP, UDP, SDP, or SCTP network
endpoint. This privilege is not necessary to communicate using an
existing endpoint already opened before dropping the
PRIV_NET_ACCESS privilege.


PRIV_NET_BINDMLP

Allow a process to bind to a port that is configured as a multi-
level port (MLP) for the process's zone. This privilege applies
to both shared address and zone-specific address MLPs. See
tnzonecfg(4) from the Trusted Extensions manual pages for
information on configuring MLP ports.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_NET_ICMPACCESS

Allow a process to send and receive ICMP packets.


PRIV_NET_MAC_AWARE

Allow a process to set the NET_MAC_AWARE process flag by using
setpflags(2). This privilege also allows a process to set the
SO_MAC_EXEMPT socket option by using setsockopt(3SOCKET). The
NET_MAC_AWARE process flag and the SO_MAC_EXEMPT socket option
both allow a local process to communicate with an unlabeled peer
if the local process's label dominates the peer's default label,
or if the local process runs in the global zone.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_NET_MAC_IMPLICIT

Allow a process to set SO_MAC_IMPLICIT option by using
setsockopt(3SOCKET). This allows a privileged process to
transmit implicitly-labeled packets to a peer.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_NET_OBSERVABILITY

Allow a process to open a device for just receiving network
traffic, sending traffic is disallowed.


PRIV_NET_PRIVADDR

Allow a process to bind to a privileged port number. The
privilege port numbers are 1-1023 (the traditional UNIX
privileged ports) as well as those ports marked as
"udp/tcp_extra_priv_ports" with the exception of the ports
reserved for use by NFS and SMB.


PRIV_NET_RAWACCESS

Allow a process to have direct access to the network layer.


PRIV_PROC_AUDIT

Allow a process to generate audit records. Allow a process to get
its own audit pre-selection information.


PRIV_PROC_CHROOT

Allow a process to change its root directory.


PRIV_PROC_CLOCK_HIGHRES

Allow a process to use high resolution timers with very small
time values.


PRIV_PROC_EXEC

Allow a process to call exec(2).


PRIV_PROC_FORK

Allow a process to call fork(2), fork1(2), or vfork(2).


PRIV_PROC_INFO

Allow a process to examine the status of processes other than
those to which it can send signals. Processes that cannot be
examined cannot be seen in /proc and appear not to exist.


PRIV_PROC_LOCK_MEMORY

Allow a process to lock pages in physical memory.


PRIV_PROC_MEMINFO

Allow a process to access physical memory information.


PRIV_PROC_OWNER

Allow a process to send signals to other processes and inspect
and modify the process state in other processes, regardless of
ownership. When modifying another process, additional
restrictions apply: the effective privilege set of the attaching
process must be a superset of the target process's effective,
permitted, and inheritable sets; the limit set must be a superset
of the target's limit set; if the target process has any UID set
to 0 all privilege must be asserted unless the effective UID is
0. Allow a process to bind arbitrary processes to CPUs.


PRIV_PROC_PRIOUP

Allow a process to elevate its priority above its current level.


PRIV_PROC_PRIOCNTL

Allows all that PRIV_PROC_PRIOUP allows. Allow a process to
change its scheduling class to any scheduling class, including
the RT class.


PRIV_PROC_SECFLAGS

Allow a process to manipulate the secflags of processes (subject
to, additionally, the ability to signal that process).


PRIV_PROC_SESSION

Allow a process to send signals or trace processes outside its
session.


PRIV_PROC_SETID

Allow a process to set its UIDs at will, assuming UID 0 requires
all privileges to be asserted.


PRIV_PROC_TASKID

Allow a process to assign a new task ID to the calling process.


PRIV_PROC_ZONE

Allow a process to trace or send signals to processes in other
zones. See zones(7).


PRIV_SYS_ACCT

Allow a process to enable and disable and manage accounting
through acct(2).


PRIV_SYS_ADMIN

Allow a process to perform system administration tasks such as
setting node and domain name and managing fmd(8) and nscd(8).


PRIV_SYS_AUDIT

Allow a process to start the (kernel) audit daemon. Allow a
process to view and set audit state (audit user ID, audit
terminal ID, audit sessions ID, audit pre-selection mask). Allow
a process to turn off and on auditing. Allow a process to
configure the audit parameters (cache and queue sizes, event to
class mappings, and policy options).


PRIV_SYS_CONFIG

Allow a process to perform various system configuration tasks.
Allow filesystem-specific administrative procedures, such as
filesystem configuration ioctls, quota calls, creation and
deletion of snapshots, and manipulating the PCFS bootsector.


PRIV_SYS_DEVICES

Allow a process to create device special files. Allow a process
to successfully call a kernel module that calls the kernel
drv_priv(9F) function to check for allowed access. Allow a
process to open the real console device directly. Allow a
process to open devices that have been exclusively opened.


PRIV_SYS_DL_CONFIG

Allow a process to configure a system's datalink interfaces.


PRIV_SYS_IP_CONFIG

Allow a process to configure a system's IP interfaces and routes.
Allow a process to configure network parameters for TCP/IP using
ndd. Allow a process access to otherwise restricted TCP/IP
information using ndd. Allow a process to configure IPsec. Allow
a process to pop anchored STREAMs modules with matching zoneid.


PRIV_SYS_IPC_CONFIG

Allow a process to increase the size of a System V IPC Message
Queue buffer.


PRIV_SYS_IPTUN_CONFIG

Allow a process to configure IP tunnel links.


PRIV_SYS_LINKDIR

Allow a process to unlink and link directories.


PRIV_SYS_MOUNT

Allow a process to mount and unmount filesystems that would
otherwise be restricted (that is, most filesystems except
namefs). Allow a process to add and remove swap devices.


PRIV_SYS_NET_CONFIG

Allow a process to do all that PRIV_SYS_IP_CONFIG,
PRIV_SYS_DL_CONFIG, and PRIV_SYS_PPP_CONFIG allow, plus the
following: use the rpcmod STREAMS module and insert/remove
STREAMS modules on locations other than the top of the module
stack.


PRIV_SYS_NFS

Allow a process to provide NFS service: start NFS kernel threads,
perform NFS locking operations, bind to NFS reserved ports: ports
2049 (nfs) and port 4045 (lockd).


PRIV_SYS_PPP_CONFIG

Allow a process to create, configure, and destroy PPP instances
with pppd(8) pppd(8) and control PPPoE plumbing with sppptun(8).
This privilege is granted by default to exclusive IP stack
instance zones.


PRIV_SYS_RES_BIND

Allows a process to bind processes to processor sets.


PRIV_SYS_RES_CONFIG

Allows all that PRIV_SYS_RES_BIND allows. Allow a process to
create and delete processor sets, assign CPUs to processor sets
and override the PSET_NOESCAPE property. Allow a process to
change the operational status of CPUs in the system using
p_online(2). Allow a process to configure filesystem quotas.
Allow a process to configure resource pools and bind processes to
pools.


PRIV_SYS_RESOURCE

Allow a process to exceed the resource limits imposed on it by
setrlimit(2) and setrctl(2).


PRIV_SYS_SMB

Allow a process to provide NetBIOS or SMB services: start SMB
kernel threads or bind to NetBIOS or SMB reserved ports: ports
137, 138, 139 (NetBIOS) and 445 (SMB).


PRIV_SYS_SUSER_COMPAT

Allow a process to successfully call a third party loadable
module that calls the kernel suser() function to check for
allowed access. This privilege exists only for third party
loadable module compatibility and is not used by illumos.


PRIV_SYS_TIME

Allow a process to manipulate system time using any of the
appropriate system calls: stime(2), adjtime(2), and
ntp_adjtime(2).


PRIV_SYS_TRANS_LABEL

Allow a process to translate labels that are not dominated by the
process's sensitivity label to and from an external string form.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_VIRT_MANAGE

Allows a process to manage virtualized environments such as
xVM(7).


PRIV_WIN_COLORMAP

Allow a process to override colormap restrictions.

Allow a process to install or remove colormaps.

Allow a process to retrieve colormap cell entries allocated by
other processes.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_CONFIG

Allow a process to configure or destroy resources that are
permanently retained by the X server.

Allow a process to use SetScreenSaver to set the screen saver
timeout value

Allow a process to use ChangeHosts to modify the display access
control list.

Allow a process to use GrabServer.

Allow a process to use the SetCloseDownMode request that can
retain window, pixmap, colormap, property, cursor, font, or
graphic context resources.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_DAC_READ

Allow a process to read from a window resource that it does not
own (has a different user ID).

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_DAC_WRITE

Allow a process to write to or create a window resource that it
does not own (has a different user ID). A newly created window
property is created with the window's user ID.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_DEVICES

Allow a process to perform operations on window input devices.

Allow a process to get and set keyboard and pointer controls.

Allow a process to modify pointer button and key mappings.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_DGA

Allow a process to use the direct graphics access (DGA) X
protocol extensions. Direct process access to the frame buffer
is still required. Thus the process must have MAC and DAC
privileges that allow access to the frame buffer, or the frame
buffer must be allocated to the process.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_DOWNGRADE_SL

Allow a process to set the sensitivity label of a window resource
to a sensitivity label that does not dominate the existing
sensitivity label.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_FONTPATH

Allow a process to set a font path.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_MAC_READ

Allow a process to read from a window resource whose sensitivity
label is not equal to the process sensitivity label.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_MAC_WRITE

Allow a process to create a window resource whose sensitivity
label is not equal to the process sensitivity label. A newly
created window property is created with the window's sensitivity
label.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_SELECTION

Allow a process to request inter-window data moves without the
intervention of the selection confirmer.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_WIN_UPGRADE_SL

Allow a process to set the sensitivity label of a window resource
to a sensitivity label that dominates the existing sensitivity
label.

This privilege is interpreted only if the system is configured
with Trusted Extensions.


PRIV_XVM_CONTROL

Allows a process access to the xVM(7) control devices for
managing guest domains and the hypervisor. This privilege is used
only if booted into xVM on x86 platforms.


Of the privileges listed above, the privileges PRIV_FILE_LINK_ANY,
PRIV_PROC_INFO, PRIV_PROC_SESSION, PRIV_PROC_FORK, PRIV_FILE_READ,
PRIV_FILE_WRITE, PRIV_NET_ACCESS and PRIV_PROC_EXEC are considered
"basic" privileges. These are privileges that used to be always
available to unprivileged processes. By default, processes still have
the basic privileges.


The privileges PRIV_PROC_SETID and PRIV_PROC_AUDIT must be present in
the Limit set (see below) of a process in order for set-uid root
execs to be successful, that is, get an effective UID of 0 and
additional privileges.


The privilege implementation in illumos extends the process
credential with four privilege sets:

I, the inheritable set
The privileges inherited on exec.


P, the permitted set
The maximum set of privileges for the
process.


E, the effective set
The privileges currently in effect.


L, the limit set
The upper bound of the privileges a process
and its offspring can obtain. Changes to L
take effect on the next exec.


The sets I, P and E are typically identical to the basic set of
privileges for unprivileged processes. The limit set is typically the
full set of privileges.


Each process has a Privilege Awareness State (PAS) that can take the
value PA (privilege-aware) and NPA (not-PA). PAS is a transitional
mechanism that allows a choice between full compatibility with the
old superuser model and completely ignoring the effective UID.


To facilitate the discussion, we introduce the notion of "observed
effective set" (oE) and "observed permitted set" (oP) and the
implementation sets iE and iP.


A process becomes privilege-aware either by manipulating the
effective, permitted, or limit privilege sets through setppriv(2) or
by using setpflags(2). In all cases, oE and oP are invariant in the
process of becoming privilege-aware. In the process of becoming
privilege-aware, the following assignments take place:

iE = oE
iP = oP


When a process is privilege-aware, oE and oP are invariant under UID
changes. When a process is not privilege-aware, oE and oP are
observed as follows:

oE = euid == 0 ? L : iE
oP = (euid == 0 || ruid == 0 || suid == 0) ? L : iP


When a non-privilege-aware process has an effective UID of 0, it can
exercise the privileges contained in its limit set, the upper bound
of its privileges. If a non-privilege-aware process has any of the
UIDs 0, it appears to be capable of potentially exercising all
privileges in L.


It is possible for a process to return to the non-privilege aware
state using setpflags(). The kernel always attempts this on exec(2).
This operation is permitted only if the following conditions are met:

o If any of the UIDs is equal to 0, P must be equal to L.

o If the effective UID is equal to 0, E must be equal to L.


When a process gives up privilege awareness, the following
assignments take place:

if (euid == 0) iE = L & I
if (any uid == 0) iP = L & I


The privileges obtained when not having a UID of 0 are the
inheritable set of the process restricted by the limit set.


Only privileges in the process's (observed) effective privilege set
allow the process to perform restricted operations. A process can use
any of the privilege manipulation functions to add or remove
privileges from the privilege sets. Privileges can be removed always.
Only privileges found in the permitted set can be added to the
effective and inheritable set. The limit set cannot grow. The
inheritable set can be larger than the permitted set.


When a process performs an exec(2), the kernel first tries to
relinquish privilege awareness before making the following privilege
set modifications:

E' = P' = I' = L & I
L is unchanged


If a process has not manipulated its privileges, the privilege sets
effectively remain the same, as E, P and I are already identical.


The limit set is enforced at exec time.


To run a non-privilege-aware application in a backward-compatible
manner, a privilege-aware application should start the non-privilege-
aware application with I=basic.


For most privileges, absence of the privilege simply results in a
failure. In some instances, the absence of a privilege can cause
system calls to behave differently. In other instances, the removal
of a privilege can force a set-uid application to seriously
malfunction. Privileges of this type are considered "unsafe". When a
process is lacking any of the unsafe privileges from its limit set,
the system does not honor the set-uid bit of set-uid root
applications. The following unsafe privileges have been identified:
proc_setid, sys_resource and proc_audit.

Privilege Escalation

In certain circumstances, a single privilege could lead to a process
gaining one or more additional privileges that were not explicitly
granted to that process. To prevent such an escalation of privileges,
the security policy requires explicit permission for those additional
privileges.


Common examples of escalation are those mechanisms that allow
modification of system resources through "raw" interfaces; for
example, changing kernel data structures through /dev/kmem or
changing files through /dev/dsk/*. Escalation also occurs when a
process controls processes with more privileges than the controlling
process. A special case of this is manipulating or creating objects
owned by UID 0 or trying to obtain UID 0 using setuid(2). The special
treatment of UID 0 is needed because the UID 0 owns all system
configuration files and ordinary file protection mechanisms allow
processes with UID 0 to modify the system configuration. With
appropriate file modifications, a given process running with an
effective UID of 0 can gain all privileges.


In situations where a process might obtain UID 0, the security policy
requires additional privileges, up to the full set of privileges.
Such restrictions could be relaxed or removed at such time as
additional mechanisms for protection of system files became
available. There are no such mechanisms in the current release.


The use of UID 0 processes should be limited as much as possible.
They should be replaced with programs running under a different UID
but with exactly the privileges they need.


Daemons that never need to exec subprocesses should remove the
PRIV_PROC_EXEC privilege from their permitted and limit sets.

Assigned Privileges and Safeguards

When privileges are assigned to a user, the system administrator
could give that user more powers than intended. The administrator
should consider whether safeguards are needed. For example, if the
PRIV_PROC_LOCK_MEMORY privilege is given to a user, the administrator
should consider setting the project.max-locked-memory resource
control as well, to prevent that user from locking all memory.

Privilege Debugging

When a system call fails with a permission error, it is not always
immediately obvious what caused the problem. To debug such a problem,
you can use a tool called privilege debugging. When privilege
debugging is enabled for a process, the kernel reports missing
privileges on the controlling terminal of the process. (Enable
debugging for a process with the -D option of ppriv(1).)
Additionally, the administrator can enable system-wide privilege
debugging by setting the system(5) variable priv_debug using:

set priv_debug = 1


On a running system, you can use mdb(1) to change this variable.

Privilege Administration

Use usermod(8) or rolemod(8) to assign privileges to or modify
privileges for, respectively, a user or a role. Use ppriv(1) to
enumerate the privileges supported on a system and truss(1) to
determine which privileges a program requires.

SEE ALSO

mdb(1), ppriv(1), Intro(2), access(2), acct(2), acl(2), adjtime(2),
audit(2), auditon(2), chmod(2), chown(2), chroot(2), creat(2),
exec(2), fcntl(2), fork(2), fpathconf(2), getacct(2), getpflags(2),
getppriv(2), getsid(2), kill(2), link(2), memcntl(2), mknod(2),
mount(2), msgctl(2), nice(2), ntp_adjtime(2), open(2), p_online(2),
priocntl(2), priocntlset(2), processor_bind(2), pset_bind(2),
pset_create(2), readlink(2), resolvepath(2), rmdir(2), semctl(2),
setauid(2), setegid(2), seteuid(2), setgid(2), setgroups(2),
setpflags(2), setppriv(2), setrctl(2), setregid(2), setreuid(2),
setrlimit(2), settaskid(2), setuid(2), shmctl(2), shmget(2),
shmop(2), sigsend(2), stat(2), statvfs(2), stime(2), swapctl(2),
sysinfo(2), uadmin(2), ulimit(2), umount(2), unlink(2), utime(2),
utimes(2), door_ucred(3C), priv_addset(3C), priv_getbyname(3C),
priv_getbynum(3C), priv_set(3C), priv_set_to_str(3C),
priv_str_to_set(3C), timer_create(3C), ucred_get(3C), t_bind(3NSL),
bind(3SOCKET), socket(3SOCKET), exec_attr(5), proc(5), system(5),
user_attr(5), xVM(7), add_drv(8), ifconfig(8), lockd(8), nfsd(8),
pppd(8), rem_drv(8), smbd(8), sppptun(8), update_drv(8),
ddi_cred(9F), drv_priv(9F), priv_getbyname(9F), priv_policy(9F),
priv_policy_choice(9F), priv_policy_only(9F)


System Administration Guide: Security Services

August 26, 2019 PRIVILEGES(7)