p_candebug(9) on freebsd

NAME

p_candebug – determine debuggability of a process

#include <sys/param.h>

#include <sys/proc.h>

int

p_candebug(struct thread *td, struct proc *p);

This function determines if a given process p is debuggable by some thread td.

The following sysctl(8) variables directly influence the behaviour of p_candebug():

security.bsd.unprivileged_proc_debug: Must be set to a non-zero value to allow unprivileged processes access to the kernel's debug facilities.
kern.securelevel: Debugging of the init process is not allowed if this variable is 1 or greater.

Other such variables indirectly influence it; see cr_bsd_visible(9).

The p_candebug() function returns 0 if the process denoted by p is debuggable by thread td, or a non-zero error return value otherwise.

[EPERM]: An unprivileged process attempted to debug another process but the system is configured to deny it( see sysctl(8) variable security.bsd.unprivileged_proc_debug above).
[ESRCH]: Thread td has been jailed and the process to debug does not belong to the same jail or one of its sub-jails, as determined by prison_check(9).
[ESRCH]: cr_bsd_visible(9) denied visibility according to the BSD security policies in force.
[EPERM]: Thread td lacks superuser credentials and its (effective) group set is not a superset of process p's whole group set (including real, effective and saved group IDs).
[EPERM]: Thread td lacks superuser credentials and its (effective) user ID does not match all user IDs of process p.
[EPERM]: Thread td lacks superuser credentials and process p is executing a set-user-ID or set-group-ID executable.
[EPERM]: Process p denotes the initial process initproc() and the sysctl(8) variable kern.securelevel is greater than zero.
[EBUSY]: Process p is in the process of being exec(Ns, 'ed.)
[EPERM]: Process p denied debuggability( see procctl(2), command PROC_TRACE_CTL).