Differential D21352 Diff 61615 head/lib/libc/sys/procctl.2

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head/lib/libc/sys/procctl.2

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	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)			.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT			.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY			.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF			.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	.\" SUCH DAMAGE.			.\" SUCH DAMAGE.
	.\"			.\"
	.\" $FreeBSD$			.\" $FreeBSD$
	.\"			.\"
	.Dd April 9, 2019			.Dd August 31, 2019
	.Dt PROCCTL 2			.Dt PROCCTL 2
	.Os			.Os
	.Sh NAME			.Sh NAME
	.Nm procctl			.Nm procctl
	.Nd control processes			.Nd control processes
	.Sh LIBRARY			.Sh LIBRARY
	.Lb libc			.Lb libc
	.Sh SYNOPSIS			.Sh SYNOPSIS
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	and			and
	.Fa id			.Fa id
	must be the either caller's pid or zero, with no difference in effect.			must be the either caller's pid or zero, with no difference in effect.
	.Fa arg			.Fa arg
	must point to a memory location that can hold a value of type			must point to a memory location that can hold a value of type
	.Vt int .			.Vt int .
	If signal delivery has not been requested, it will contain zero			If signal delivery has not been requested, it will contain zero
	on return.			on return.
				.It Dv PROC_STACKGAP_CTL
				Controls the stack gaps in the specified process.
				A stack gap is the part of the growth area for a
				.Dv MAP_STACK
				mapped region that is reserved and never filled by memory.
				Instead, the process is guaranteed to receive a
				.Dv SIGSEGV
				signal on accessing pages in the gap.
				Gaps protect against stack overflow corrupting memory adjacent
				to the stack.
				.Pp
				The
				.Fa data
				argument must point to an integer variable containing flags.
				The following flags are allowed:
				.Bl -tag -width PROC_STACKGAP_DISABLE_EXEC
				.It Dv PROC_STACKGAP_ENABLE
				This flag is only accepted for consistency with
				.Dv PROC_STACKGAP_STATUS .
				If stack gaps are enabled, the flag is ignored.
				If disabled, the flag causes an
				.Ev EINVAL
				error to be returned.
				After gaps are disabled in a process, they can only be re-enabled when an
				.Xr execve 2
				is performed.
				.It Dv PROC_STACKGAP_DISABLE
				Disable stack gaps for the process.
				For existing stacks, the gap is no longer a reserved part of the growth
				area and can be filled by memory on access.
				.It Dv PROC_STACKGAP_ENABLE_EXEC
				Enable stack gaps for programs started after an
				.Xr execve 2
				by the specified process.
				.It Dv PROC_STACKGAP_DISABLE_EXEC
				Inherit disabled stack gaps state after
				.Xr execve 2 .
				In other words, if the currently executing program has stack gaps disabled,
				they are kept disabled on exec.
				If gaps were enabled, they are kept enabled after exec.
				.El
				.Pp
				The stack gap state is inherited from the parent on
				.Xr fork 2 .
				.It Dv PROC_STACKGAP_STATUS
				Returns the current stack gap state for the specified process.
				.Fa data
				must point to an integer variable, which is used to return a bitmask
				consisting of the following flags:
				.Bl -tag -width PROC_STACKGAP_DISABLE_EXEC
				.It Dv PROC_STACKGAP_ENABLE
				Stack gaps are enabled.
				.It Dv PROC_STACKGAP_DISABLE
				Stack gaps are disabled.
				.It Dv PROC_STACKGAP_ENABLE_EXEC
				Stack gaps are enabled in the process after
				.Xr execve 2 .
				.It Dv PROC_STACKGAP_DISABLE_EXEC
				Stack gaps are disabled in the process after
				.Xr execve 2 .
				.El
	.El			.El
	.Sh NOTES			.Sh NOTES
	Disabling tracing on a process should not be considered a security			Disabling tracing on a process should not be considered a security
	feature, as it is bypassable both by the kernel and privileged processes,			feature, as it is bypassable both by the kernel and privileged processes,
	and via other system mechanisms.			and via other system mechanisms.
	As such, it should not be utilized to reliably protect cryptographic			As such, it should not be utilized to reliably protect cryptographic
	keying material or other confidential data.			keying material or other confidential data.
	.Sh RETURN VALUES			.Sh RETURN VALUES
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