Index: head/lib/libc/sys/procctl.2 =================================================================== --- head/lib/libc/sys/procctl.2 (revision 333520) +++ head/lib/libc/sys/procctl.2 (revision 333521) @@ -1,553 +1,553 @@ .\" Copyright (c) 2013 Hudson River Trading LLC .\" Written by: John H. Baldwin .\" All rights reserved. .\" .\" Copyright (c) 2014 The FreeBSD Foundation .\" Portions of this documentation were written by Konstantin Belousov .\" under sponsorship from the FreeBSD Foundation. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" 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 .\" SUCH DAMAGE. .\" .\" $FreeBSD$ .\" -.Dd April 20, 2018 +.Dd May 12, 2018 .Dt PROCCTL 2 .Os .Sh NAME .Nm procctl .Nd control processes .Sh LIBRARY .Lb libc .Sh SYNOPSIS .In sys/procctl.h .Ft int .Fn procctl "idtype_t idtype" "id_t id" "int cmd" "void *arg" .Sh DESCRIPTION The .Fn procctl system call provides for control over processes. The .Fa idtype and .Fa id arguments specify the set of processes to control. If multiple processes match the identifier, .Nm will make a .Dq best effort to control as many of the selected processes as possible. An error is only returned if no selected processes successfully complete the request. The following identifier types are supported: .Bl -tag -width "Dv P_PGID" .It Dv P_PID Control the process with the process ID .Fa id . .It Dv P_PGID Control processes belonging to the process group with the ID .Fa id . .El .Pp The control request to perform is specified by the .Fa cmd argument. The following commands are supported: .Bl -tag -width "Dv PROC_TRAPCAP_STATUS" .It Dv PROC_SPROTECT Set process protection state. This is used to mark a process as protected from being killed if the system exhausts the available memory and swap. The .Fa arg parameter must point to an integer containing an operation and zero or more optional flags. The following operations are supported: .Bl -tag -width "Dv PPROT_CLEAR" .It Dv PPROT_SET Mark the selected processes as protected. .It Dv PPROT_CLEAR Clear the protected state of selected processes. .El .Pp The following optional flags are supported: .Bl -tag -width "Dv PPROT_DESCEND" .It Dv PPROT_DESCEND Apply the requested operation to all child processes of each selected process in addition to each selected process. .It Dv PPROT_INHERIT When used with .Dv PPROT_SET , mark all future child processes of each selected process as protected. Future child processes will also mark all of their future child processes. .El .It Dv PROC_REAP_ACQUIRE Acquires the reaper status for the current process. Reaper status means that children orphaned by the reaper's descendants that were forked after the acquisition of reaper status are reparented to the reaper process. After system initialization, .Xr init 8 is the default reaper. .It Dv PROC_REAP_RELEASE Release the reaper state for the current process. The reaper of the current process becomes the new reaper of the current process's descendants. .It Dv PROC_REAP_STATUS Provides information about the reaper of the specified process, or the process itself when it is a reaper. The .Fa data argument must point to a .Vt procctl_reaper_status structure which is filled in by the syscall on successful return. .Bd -literal struct procctl_reaper_status { u_int rs_flags; u_int rs_children; u_int rs_descendants; pid_t rs_reaper; pid_t rs_pid; }; .Ed The .Fa rs_flags may have the following flags returned: .Bl -tag -width "Dv REAPER_STATUS_REALINIT" .It Dv REAPER_STATUS_OWNED The specified process has acquired reaper status and has not released it. When the flag is returned, the specified process .Fa id , pid, identifies the reaper, otherwise the .Fa rs_reaper field of the structure is set to the pid of the reaper for the specified process id. .It Dv REAPER_STATUS_REALINIT The specified process is the root of the reaper tree, i.e., .Xr init 8 . .El .Pp The .Fa rs_children field returns the number of children of the reaper among the descendants. It is possible to have a child whose reaper is not the specified process, since the reaper for any existing children is not reset on the .Dv PROC_REAP_ACQUIRE operation. The .Fa rs_descendants field returns the total number of descendants of the reaper(s), not counting descendants of the reaper in the subtree. The .Fa rs_reaper field returns the reaper pid. The .Fa rs_pid returns the pid of one reaper child if there are any descendants. .It Dv PROC_REAP_GETPIDS Queries the list of descendants of the reaper of the specified process. The request takes a pointer to a .Vt procctl_reaper_pids structure in the .Fa data parameter. .Bd -literal struct procctl_reaper_pids { u_int rp_count; struct procctl_reaper_pidinfo *rp_pids; }; .Ed When called, the .Fa rp_pids field must point to an array of .Vt procctl_reaper_pidinfo structures, to be filled in on return, and the .Fa rp_count field must specify the size of the array, into which no more than .Fa rp_count elements will be filled in by the kernel. .Pp The .Vt "struct procctl_reaper_pidinfo" structure provides some information about one of the reaper's descendants. Note that for a descendant that is not a child, it may be incorrectly identified because of a race in which the original child process exited and the exited process's pid was reused for an unrelated process. .Bd -literal struct procctl_reaper_pidinfo { pid_t pi_pid; pid_t pi_subtree; u_int pi_flags; }; .Ed The .Fa pi_pid field is the process id of the descendant. The .Fa pi_subtree field provides the pid of the child of the reaper, which is the (grand-)parent of the process. The .Fa pi_flags field returns the following flags, further describing the descendant: .Bl -tag -width "Dv REAPER_PIDINFO_REAPER" .It Dv REAPER_PIDINFO_VALID Set to indicate that the .Vt procctl_reaper_pidinfo structure was filled in by the kernel. Zero-filling the .Fa rp_pids array and testing the .Dv REAPER_PIDINFO_VALID flag allows the caller to detect the end of the returned array. .It Dv REAPER_PIDINFO_CHILD The .Fa pi_pid field identifies the direct child of the reaper. .It Dv REAPER_PIDINFO_REAPER The reported process is itself a reaper. The descendants of the subordinate reaper are not reported. .El .It Dv PROC_REAP_KILL Request to deliver a signal to some subset of the descendants of the reaper. The .Fa data parameter must point to a .Vt procctl_reaper_kill structure, which is used both for parameters and status return. .Bd -literal struct procctl_reaper_kill { int rk_sig; u_int rk_flags; pid_t rk_subtree; u_int rk_killed; pid_t rk_fpid; }; .Ed The .Fa rk_sig field specifies the signal to be delivered. Zero is not a valid signal number, unlike for .Xr kill 2 . The .Fa rk_flags field further directs the operation. It is or-ed from the following flags: .Bl -tag -width "Dv REAPER_KILL_CHILDREN" .It Dv REAPER_KILL_CHILDREN Deliver the specified signal only to direct children of the reaper. .It Dv REAPER_KILL_SUBTREE Deliver the specified signal only to descendants that were forked by the direct child with pid specified in the .Fa rk_subtree field. .El If neither the .Dv REAPER_KILL_CHILDREN nor the .Dv REAPER_KILL_SUBTREE flags are specified, all current descendants of the reaper are signalled. .Pp If a signal was delivered to any process, the return value from the request is zero. In this case, the .Fa rk_killed field identifies the number of processes signalled. The .Fa rk_fpid field is set to the pid of the first process for which signal delivery failed, e.g., due to permission problems. If no such process exists, the .Fa rk_fpid field is set to -1. .It Dv PROC_TRACE_CTL Enable or disable tracing of the specified process(es), according to the value of the integer argument. Tracing includes attachment to the process using the .Xr ptrace 2 and .Xr ktrace 2 , debugging sysctls, .Xr hwpmc 4 , .Xr dtrace 1 , and core dumping. Possible values for the .Fa data argument are: .Bl -tag -width "Dv PROC_TRACE_CTL_DISABLE_EXEC" .It Dv PROC_TRACE_CTL_ENABLE Enable tracing, after it was disabled by .Dv PROC_TRACE_CTL_DISABLE . Only allowed for self. .It Dv PROC_TRACE_CTL_DISABLE Disable tracing for the specified process. Tracing is re-enabled when the process changes the executing program with the .Xr execve 2 syscall. A child inherits the trace settings from the parent on .Xr fork 2 . .It Dv PROC_TRACE_CTL_DISABLE_EXEC Same as .Dv PROC_TRACE_CTL_DISABLE , but the setting persists for the process even after .Xr execve 2 . .El .It Dv PROC_TRACE_STATUS Returns the current tracing status for the specified process in the integer variable pointed to by .Fa data . If tracing is disabled, .Fa data is set to -1. If tracing is enabled, but no debugger is attached by the .Xr ptrace 2 syscall, .Fa data is set to 0. If a debugger is attached, .Fa data is set to the pid of the debugger process. .It Dv PROC_TRAPCAP_CTL Controls the capability mode sandbox actions for the specified sandboxed processes, on a return from any syscall which gives either a .Er ENOTCAPABLE or .Er ECAPMODE error. If the control is enabled, such errors from the syscalls cause delivery of the synchronous .Dv SIGTRAP signal to the thread immediately before returning from the syscalls. .Pp Possible values for the .Fa data argument are: .Bl -tag -width "Dv PROC_TRAPCAP_CTL_DISABLE" .It Dv PROC_TRAPCAP_CTL_ENABLE Enable the .Dv SIGTRAP signal delivery on capability mode access violations. The enabled mode is inherited by the children of the process, and is kept after .Xr fexecve 2 calls. .It Dv PROC_TRAPCAP_CTL_DISABLE Disable the signal delivery on capability mode access violations. Note that the global sysctl .Dv kern.trap_enotcap might still cause the signal to be delivered. See .Xr capsicum 4 . .El .Pp On signal delivery, the .Va si_errno member of the .Fa siginfo signal handler parameter is set to the syscall error value, and the .Va si_code member is set to .Dv TRAP_CAP . .Pp See .Xr capsicum 4 for more information about the capability mode. .It Dv PROC_TRAPCAP_STATUS Return the current status of signalling capability mode access violations for the specified process. The integer value pointed to by the .Fa data argument is set to the .Dv PROC_TRAPCAP_CTL_ENABLE value if the process control enables signal delivery, and to .Dv PROC_TRAPCAP_CTL_DISABLE otherwise. .Pp See the note about sysctl .Dv kern.trap_enotcap above, which gives independent global control of signal delivery. .It Dv PROC_PDEATHSIG_CTL Request the delivery of a signal when the parent of the calling process exits. .Fa idtype must be .Dv P_PID and .Fa id must be the either caller's pid or zero, with no difference in effect. The value is cleared for child processes and when executing set-user-ID or set-group-ID binaries. .Fa arg must point to a value of type .Vt int indicating the signal that should be delivered to the caller. Use zero to cancel a previously requested signal delivery. .It Dv PROC_PDEATHSIG_STATUS Query the current signal number that will be delivered when the parent of the calling process exits. .Fa idtype must be .Dv P_PID and .Fa id must be the either caller's pid or zero, with no difference in effect. .Fa arg must point to a memory location that can hold a value of type .Vt int . If signal delivery has not been requested, it will contain zero on return. .El .Sh NOTES Disabling tracing on a process should not be considered a security feature, as it is bypassable both by the kernel and privileged processes, and via other system mechanisms. As such, it should not be utilized to reliably protect cryptographic keying material or other confidential data. .Sh RETURN VALUES If an error occurs, a value of -1 is returned and .Va errno is set to indicate the error. .Sh ERRORS The .Fn procctl system call will fail if: .Bl -tag -width Er .It Bq Er EFAULT The .Fa arg parameter points outside the process's allocated address space. .It Bq Er EINVAL The .Fa cmd argument specifies an unsupported command. .Pp The .Fa idtype argument specifies an unsupported identifier type. .It Bq Er EPERM The calling process does not have permission to perform the requested operation on any of the selected processes. .It Bq Er ESRCH No processes matched the requested .Fa idtype and .Fa id . .It Bq Er EINVAL An invalid operation or flag was passed in .Fa arg for a .Dv PROC_SPROTECT command. .It Bq Er EPERM The .Fa idtype argument is not equal to .Dv P_PID , or .Fa id is not equal to the pid of the calling process, for .Dv PROC_REAP_ACQUIRE or .Dv PROC_REAP_RELEASE requests. .It Bq Er EINVAL Invalid or undefined flags were passed to a .Dv PROC_REAP_KILL request. .It Bq Er EINVAL An invalid or zero signal number was requested for a .Dv PROC_REAP_KILL request. .It Bq Er EINVAL The .Dv PROC_REAP_RELEASE request was issued by the .Xr init 8 process. .It Bq Er EBUSY The .Dv PROC_REAP_ACQUIRE request was issued by a process that had already acquired reaper status and has not yet released it. .It Bq Er EBUSY The .Dv PROC_TRACE_CTL request was issued for a process already being traced. .It Bq Er EPERM The .Dv PROC_TRACE_CTL request to re-enable tracing of the process .Po Dv PROC_TRACE_CTL_ENABLE Pc , or to disable persistence of .Dv PROC_TRACE_CTL_DISABLE on .Xr execve 2 was issued for a non-current process. .It Bq Er EINVAL The value of the integer .Fa data parameter for the .Dv PROC_TRACE_CTL or .Dv PROC_TRAPCAP_CTL request is invalid. .It Bq Er EINVAL The .Dv PROC_PDEATHSIG_CTL or .Dv PROC_PDEATHSIG_STATUS request referenced an unsupported .Fa id , .Fa idtype or invalid signal number. .El .Sh SEE ALSO .Xr dtrace 1 , .Xr cap_enter 2, .Xr kill 2 , .Xr ktrace 2 , .Xr ptrace 2 , .Xr wait 2 , .Xr capsicum 4 , .Xr hwpmc 4 , .Xr init 8 .Sh HISTORY The .Fn procctl function appeared in .Fx 10.0 . The reaper facility is based on a similar feature of Linux and DragonflyBSD, and first appeared in .Fx 10.2 . The .Dv PROC_PDEATHSIG_CTL facility is based on the prctl(PR_SET_PDEATHSIG, ...) feature of Linux, and first appeared in -.Fx 12.0 . +.Fx 11.2 .