capability

Documentation

Overview

Package capability provides utilities for manipulating POSIX capabilities.

Index

• Constants
• Variables
• type Cap
  • func List() []Cap
  • func (c Cap) String() string
• type CapType
  • func (c CapType) String() string
• type Capabilities
  • func NewFile(path string) (Capabilities, error)
  • func NewFile2(path string) (Capabilities, error)
  • func NewPid(pid int) (Capabilities, error)
  • func NewPid2(pid int) (Capabilities, error)

Constants

const (
	EFFECTIVE CapType = 1 << iota
	PERMITTED
	INHERITABLE
	BOUNDING
	AMBIENT

	CAPS   = EFFECTIVE | PERMITTED | INHERITABLE
	BOUNDS = BOUNDING
	AMBS   = AMBIENT
)

const (
	// In a system with the [_POSIX_CHOWN_RESTRICTED] option defined, this
	// overrides the restriction of changing file ownership and group
	// ownership.
	CAP_CHOWN = Cap(0)

	// Override all DAC access, including ACL execute access if
	// [_POSIX_ACL] is defined. Excluding DAC access covered by
	// CAP_LINUX_IMMUTABLE.
	CAP_DAC_OVERRIDE = Cap(1)

	// Overrides all DAC restrictions regarding read and search on files
	// and directories, including ACL restrictions if [_POSIX_ACL] is
	// defined. Excluding DAC access covered by CAP_LINUX_IMMUTABLE.
	CAP_DAC_READ_SEARCH = Cap(2)

	// Overrides all restrictions about allowed operations on files, where
	// file owner ID must be equal to the user ID, except where CAP_FSETID
	// is applicable. It doesn't override MAC and DAC restrictions.
	CAP_FOWNER = Cap(3)

	// Overrides the following restrictions that the effective user ID
	// shall match the file owner ID when setting the S_ISUID and S_ISGID
	// bits on that file; that the effective group ID (or one of the
	// supplementary group IDs) shall match the file owner ID when setting
	// the S_ISGID bit on that file; that the S_ISUID and S_ISGID bits are
	// cleared on successful return from chown(2) (not implemented).
	CAP_FSETID = Cap(4)

	// Overrides the restriction that the real or effective user ID of a
	// process sending a signal must match the real or effective user ID
	// of the process receiving the signal.
	CAP_KILL = Cap(5)

	// Allows setgid(2) manipulation
	// Allows setgroups(2)
	// Allows forged gids on socket credentials passing.
	CAP_SETGID = Cap(6)

	// Allows set*uid(2) manipulation (including fsuid).
	// Allows forged pids on socket credentials passing.
	CAP_SETUID = Cap(7)

	// Without VFS support for capabilities:
	//   Transfer any capability in your permitted set to any pid,
	//   remove any capability in your permitted set from any pid
	// With VFS support for capabilities (neither of above, but)
	//   Add any capability from current's capability bounding set
	//     to the current process' inheritable set
	//   Allow taking bits out of capability bounding set
	//   Allow modification of the securebits for a process
	CAP_SETPCAP = Cap(8)

	// Allow modification of S_IMMUTABLE and S_APPEND file attributes
	CAP_LINUX_IMMUTABLE = Cap(9)

	// Allows binding to TCP/UDP sockets below 1024
	// Allows binding to ATM VCIs below 32
	CAP_NET_BIND_SERVICE = Cap(10)

	// Allow broadcasting, listen to multicast
	CAP_NET_BROADCAST = Cap(11)

	// Allow interface configuration
	// Allow administration of IP firewall, masquerading and accounting
	// Allow setting debug option on sockets
	// Allow modification of routing tables
	// Allow setting arbitrary process / process group ownership on
	// sockets
	// Allow binding to any address for transparent proxying (also via NET_RAW)
	// Allow setting TOS (type of service)
	// Allow setting promiscuous mode
	// Allow clearing driver statistics
	// Allow multicasting
	// Allow read/write of device-specific registers
	// Allow activation of ATM control sockets
	CAP_NET_ADMIN = Cap(12)

	// Allow use of RAW sockets
	// Allow use of PACKET sockets
	// Allow binding to any address for transparent proxying (also via NET_ADMIN)
	CAP_NET_RAW = Cap(13)

	// Allow locking of shared memory segments
	// Allow mlock and mlockall (which doesn't really have anything to do
	// with IPC)
	CAP_IPC_LOCK = Cap(14)

	// Override IPC ownership checks
	CAP_IPC_OWNER = Cap(15)

	// Insert and remove kernel modules - modify kernel without limit
	CAP_SYS_MODULE = Cap(16)

	// Allow ioperm/iopl access
	// Allow sending USB messages to any device via /proc/bus/usb
	CAP_SYS_RAWIO = Cap(17)

	// Allow use of chroot()
	CAP_SYS_CHROOT = Cap(18)

	// Allow ptrace() of any process
	CAP_SYS_PTRACE = Cap(19)

	// Allow configuration of process accounting
	CAP_SYS_PACCT = Cap(20)

	// Allow configuration of the secure attention key
	// Allow administration of the random device
	// Allow examination and configuration of disk quotas
	// Allow setting the domainname
	// Allow setting the hostname
	// Allow calling bdflush()
	// Allow mount() and umount(), setting up new smb connection
	// Allow some autofs root ioctls
	// Allow nfsservctl
	// Allow VM86_REQUEST_IRQ
	// Allow to read/write pci config on alpha
	// Allow irix_prctl on mips (setstacksize)
	// Allow flushing all cache on m68k (sys_cacheflush)
	// Allow removing semaphores
	// Used instead of CAP_CHOWN to "chown" IPC message queues, semaphores
	// and shared memory
	// Allow locking/unlocking of shared memory segment
	// Allow turning swap on/off
	// Allow forged pids on socket credentials passing
	// Allow setting readahead and flushing buffers on block devices
	// Allow setting geometry in floppy driver
	// Allow turning DMA on/off in xd driver
	// Allow administration of md devices (mostly the above, but some
	// extra ioctls)
	// Allow tuning the ide driver
	// Allow access to the nvram device
	// Allow administration of apm_bios, serial and bttv (TV) device
	// Allow manufacturer commands in isdn CAPI support driver
	// Allow reading non-standardized portions of pci configuration space
	// Allow DDI debug ioctl on sbpcd driver
	// Allow setting up serial ports
	// Allow sending raw qic-117 commands
	// Allow enabling/disabling tagged queuing on SCSI controllers and sending
	// arbitrary SCSI commands
	// Allow setting encryption key on loopback filesystem
	// Allow setting zone reclaim policy
	// Allow everything under CAP_BPF and CAP_PERFMON for backward compatibility
	CAP_SYS_ADMIN = Cap(21)

	// Allow use of reboot()
	CAP_SYS_BOOT = Cap(22)

	// Allow raising priority and setting priority on other (different
	// UID) processes
	// Allow use of FIFO and round-robin (realtime) scheduling on own
	// processes and setting the scheduling algorithm used by another
	// process.
	// Allow setting cpu affinity on other processes
	CAP_SYS_NICE = Cap(23)

	// Override resource limits. Set resource limits.
	// Override quota limits.
	// Override reserved space on ext2 filesystem
	// Modify data journaling mode on ext3 filesystem (uses journaling
	// resources)
	// NOTE: ext2 honors fsuid when checking for resource overrides, so
	// you can override using fsuid too
	// Override size restrictions on IPC message queues
	// Allow more than 64hz interrupts from the real-time clock
	// Override max number of consoles on console allocation
	// Override max number of keymaps
	// Control memory reclaim behavior
	CAP_SYS_RESOURCE = Cap(24)

	// Allow manipulation of system clock
	// Allow irix_stime on mips
	// Allow setting the real-time clock
	CAP_SYS_TIME = Cap(25)

	// Allow configuration of tty devices
	// Allow vhangup() of tty
	CAP_SYS_TTY_CONFIG = Cap(26)

	// Allow the privileged aspects of mknod()
	CAP_MKNOD = Cap(27)

	// Allow taking of leases on files
	CAP_LEASE = Cap(28)

	CAP_AUDIT_WRITE   = Cap(29)
	CAP_AUDIT_CONTROL = Cap(30)
	CAP_SETFCAP       = Cap(31)

	// Override MAC access.
	// The base kernel enforces no MAC policy.
	// An LSM may enforce a MAC policy, and if it does and it chooses
	// to implement capability based overrides of that policy, this is
	// the capability it should use to do so.
	CAP_MAC_OVERRIDE = Cap(32)

	// Allow MAC configuration or state changes.
	// The base kernel requires no MAC configuration.
	// An LSM may enforce a MAC policy, and if it does and it chooses
	// to implement capability based checks on modifications to that
	// policy or the data required to maintain it, this is the
	// capability it should use to do so.
	CAP_MAC_ADMIN = Cap(33)

	// Allow configuring the kernel's syslog (printk behaviour)
	CAP_SYSLOG = Cap(34)

	// Allow triggering something that will wake the system
	CAP_WAKE_ALARM = Cap(35)

	// Allow preventing system suspends
	CAP_BLOCK_SUSPEND = Cap(36)

	// Allow reading the audit log via multicast netlink socket
	CAP_AUDIT_READ = Cap(37)

	// Allow system performance and observability privileged operations
	// using perf_events, i915_perf and other kernel subsystems
	CAP_PERFMON = Cap(38)

	// CAP_BPF allows the following BPF operations:
	// - Creating all types of BPF maps
	// - Advanced verifier features
	//   - Indirect variable access
	//   - Bounded loops
	//   - BPF to BPF function calls
	//   - Scalar precision tracking
	//   - Larger complexity limits
	//   - Dead code elimination
	//   - And potentially other features
	// - Loading BPF Type Format (BTF) data
	// - Retrieve xlated and JITed code of BPF programs
	// - Use bpf_spin_lock() helper
	//
	// CAP_PERFMON relaxes the verifier checks further:
	// - BPF progs can use of pointer-to-integer conversions
	// - speculation attack hardening measures are bypassed
	// - bpf_probe_read to read arbitrary kernel memory is allowed
	// - bpf_trace_printk to print kernel memory is allowed
	//
	// CAP_SYS_ADMIN is required to use bpf_probe_write_user.
	//
	// CAP_SYS_ADMIN is required to iterate system wide loaded
	// programs, maps, links, BTFs and convert their IDs to file descriptors.
	//
	// CAP_PERFMON and CAP_BPF are required to load tracing programs.
	// CAP_NET_ADMIN and CAP_BPF are required to load networking programs.
	CAP_BPF = Cap(39)

	// Allow checkpoint/restore related operations.
	// Introduced in kernel 5.9
	CAP_CHECKPOINT_RESTORE = Cap(40)
)

POSIX-draft defined capabilities and Linux extensions.

Defined in https://github.com/torvalds/linux/blob/master/include/uapi/linux/capability.h

Variables

var (
	// Highest valid capability of the running kernel.
	CAP_LAST_CAP = Cap(63)
)

Types

type Cap

type Cap int

func List

func List() []Cap

List returns list of all supported capabilities

func (Cap) String

func (c Cap) String() string

type CapType

type CapType uint

func (CapType) String

func (c CapType) String() string

type Capabilities

type Capabilities interface {
	// Get check whether a capability present in the given
	// capabilities set. The 'which' value should be one of EFFECTIVE,
	// PERMITTED, INHERITABLE, BOUNDING or AMBIENT.
	Get(which CapType, what Cap) bool

	// Empty check whether all capability bits of the given capabilities
	// set are zero. The 'which' value should be one of EFFECTIVE,
	// PERMITTED, INHERITABLE, BOUNDING or AMBIENT.
	Empty(which CapType) bool

	// Full check whether all capability bits of the given capabilities
	// set are one. The 'which' value should be one of EFFECTIVE,
	// PERMITTED, INHERITABLE, BOUNDING or AMBIENT.
	Full(which CapType) bool

	// Set sets capabilities of the given capabilities sets. The
	// 'which' value should be one or combination (OR'ed) of EFFECTIVE,
	// PERMITTED, INHERITABLE, BOUNDING or AMBIENT.
	Set(which CapType, caps ...Cap)

	// Unset unsets capabilities of the given capabilities sets. The
	// 'which' value should be one or combination (OR'ed) of EFFECTIVE,
	// PERMITTED, INHERITABLE, BOUNDING or AMBIENT.
	Unset(which CapType, caps ...Cap)

	// Fill sets all bits of the given capabilities kind to one. The
	// 'kind' value should be one or combination (OR'ed) of CAPS,
	// BOUNDS or AMBS.
	Fill(kind CapType)

	// Clear sets all bits of the given capabilities kind to zero. The
	// 'kind' value should be one or combination (OR'ed) of CAPS,
	// BOUNDS or AMBS.
	Clear(kind CapType)

	// String return current capabilities state of the given capabilities
	// set as string. The 'which' value should be one of EFFECTIVE,
	// PERMITTED, INHERITABLE BOUNDING or AMBIENT
	StringCap(which CapType) string

	// String return current capabilities state as string.
	String() string

	// Load load actual capabilities value. This will overwrite all
	// outstanding changes.
	Load() error

	// Apply apply the capabilities settings, so all changes will take
	// effect.
	Apply(kind CapType) error
}

func NewFile

func NewFile(path string) (Capabilities, error)

NewFile initializes a new Capabilities object for given file path.

Deprecated: Replace with NewFile2. For example, replace:

c, err := NewFile(path)
if err != nil {
  return err
}

with:

c, err := NewFile2(path)
if err != nil {
  return err
}
err = c.Load()
if err != nil {
  return err
}

func NewFile2

func NewFile2(path string) (Capabilities, error)

NewFile2 creates a new initialized Capabilities object for given file path. This does not load the process's current capabilities; to do that you must call Load explicitly.

func NewPid

func NewPid(pid int) (Capabilities, error)

NewPid initializes a new Capabilities object for given pid when it is nonzero, or for the current process if pid is 0.

Deprecated: Replace with NewPid2. For example, replace:

c, err := NewPid(0)
if err != nil {
  return err
}

with:

c, err := NewPid2(0)
if err != nil {
  return err
}
err = c.Load()
if err != nil {
  return err
}

func NewPid2

func NewPid2(pid int) (Capabilities, error)

NewPid2 initializes a new Capabilities object for given pid when it is nonzero, or for the current process if pid is 0. This does not load the process's current capabilities; to do that you must call Load explicitly.