.\" 2012-02-04 Michael kerrisk, document PR_{SET,GET}_CHILD_SUBREAPER
.\"
.\"
-.TH PRCTL 2 2013-05-21 "Linux" "Linux Programmer's Manual"
+.TH PRCTL 2 2014-02-22 "Linux" "Linux Programmer's Manual"
.SH NAME
prctl \- operations on a process
.SH SYNOPSIS
.IR Documentation/prctl/no_new_privs.txt .
.TP
.BR PR_GET_NO_NEW_PRIVS " (since Linux 3.5)"
-Return the value of the
+Return (as the function result) the value of the
.I no_new_privs
bit for the current process.
A value of 0 indicates the regular
.BR fork (2)
and (since Linux 2.4.36 / 2.6.23)
when executing a set-user-ID or set-group-ID binary.
+This value is preserved across
+.BR execve (2).
.TP
.BR PR_GET_PDEATHSIG " (since Linux 2.3.15)"
Return the current value of the parent process death signal,
If
.I arg2
is
-.BR PR_SET_PTRACER_ANY,
+.BR PR_SET_PTRACER_ANY ,
the ptrace restrictions introduced by Yama are effectively disabled for the
calling process.
.IR Documentation/prctl/seccomp_filter.txt .
.TP
.BR PR_GET_SECCOMP " (since Linux 2.6.23)"
-Return the secure computing mode of the calling thread.
+Return (as the function result)
+the secure computing mode of the calling thread.
If the caller is not in secure computing mode, this operation returns 0;
if the caller is in strict secure computing mode, then the
.BR prctl ()
.BR sem_timedwait (3)).
Timer slack is not applied to threads that are scheduled under
-a realtime scheduling policy (see
+a real-time scheduling policy (see
.BR sched_setscheduler (2)).
Each thread has two associated timer slack values:
.BR execve (2).
.TP
.BR PR_GET_TIMERSLACK " (since Linux 2.6.28)"
-Return the current timer slack value of the calling thread.
+Return (as the function result)
+the current timer slack value of the calling thread.
.TP
.BR PR_SET_TIMING " (since Linux 2.6.0-test4)"
Set whether to use (normal, traditional) statistical process timing or
arguments must be zero.
.TP
.BR PR_SET_MM " (since Linux 3.3)"
+.\" commit 028ee4be34a09a6d48bdf30ab991ae933a7bc036
Modify certain kernel memory map descriptor fields
of the calling process.
Usually these fields are set by the kernel and dynamic loader (see
The requirements for the address are the same as for the
.BR PR_SET_MM_START_BRK
option.
-.\" FIXME The following (until ========) is not yet in mainline kernel,
-.\" so commented out for the moment.
-.\" .TP
-.\" .BR PR_SET_MM_ARG_START
-.\" Set the address above which the program command line is placed.
-.\" .TP
-.\" .BR PR_SET_MM_ARG_END
-.\" Set the address below which the program command line is placed.
-.\" .TP
-.\" .BR PR_SET_MM_ENV_START
-.\" Set the address above which the program environment is placed.
-.\" .TP
-.\" .BR PR_SET_MM_ENV_END
-.\" Set the address below which the program environment is placed.
-.\" .IP
-.\" The address passed with
-.\" .BR PR_SET_MM_ARG_START ,
-.\" .BR PR_SET_MM_ARG_END ,
-.\" .BR PR_SET_MM_ENV_START ,
-.\" and
-.\" .BR PR_SET_MM_ENV_END
-.\" should belong to a process stack area.
-.\" Thus, the corresponding memory area must be readable, writable, and
-.\" (depending on the kernel configuration) have the
-.\" .BR MAP_GROWSDOWN
-.\" attribute set (see
-.\" .BR mmap (2)).
-.\" .TP
-.\" .BR PR_SET_MM_AUXV
-.\" Set a new auxiliary vector.
-.\" The
-.\" .I arg3
-.\" argument should provide the address of the vector.
-.\" The
-.\" .I arg4
-.\" is the size of the vector.
-.\" .TP
-.\" .BR PR_SET_MM_EXE_FILE
-.\" Supersede the
-.\" .IR /proc/pid/exe
-.\" symbolic link with a new one pointing to a new executable file
-.\" identified by the file descriptor provided in
-.\" .I arg3
-.\" argument.
-.\" The file descriptor should be obtained with a regular
-.\" .BR open (2)
-.\" call.
-.\" .IP
-.\" To change the symbolic link, one needs to unmap all existing
-.\" executable memory areas, including those created by the kernel itself
-.\" (for example the kernel usually creates at least one executable
-.\" memory area for the ELF
-.\" .IR \.text
-.\" section).
-.\" .IP
-.\" The second limitation is that such transitions can be done only once
-.\" in a process life time.
-.\" Any further attempts will be rejected.
-.\" This should help system administrators to monitor unusual
-.\" symbolic-link transitions over all process running in a system.
-.\" ========== END FIXME
+.P
+The following options are available since Linux 3.5.
+.\" commit fe8c7f5cbf91124987106faa3bdf0c8b955c4cf7
+.TP
+.BR PR_SET_MM_ARG_START
+Set the address above which the program command line is placed.
+.TP
+.BR PR_SET_MM_ARG_END
+Set the address below which the program command line is placed.
+.TP
+.BR PR_SET_MM_ENV_START
+Set the address above which the program environment is placed.
+.TP
+.BR PR_SET_MM_ENV_END
+Set the address below which the program environment is placed.
+.IP
+The address passed with
+.BR PR_SET_MM_ARG_START ,
+.BR PR_SET_MM_ARG_END ,
+.BR PR_SET_MM_ENV_START ,
+and
+.BR PR_SET_MM_ENV_END
+should belong to a process stack area.
+Thus, the corresponding memory area must be readable, writable, and
+(depending on the kernel configuration) have the
+.BR MAP_GROWSDOWN
+attribute set (see
+.BR mmap (2)).
+.TP
+.BR PR_SET_MM_AUXV
+Set a new auxiliary vector.
+The
+.I arg3
+argument should provide the address of the vector.
+The
+.I arg4
+is the size of the vector.
+.TP
+.BR PR_SET_MM_EXE_FILE
+.\" commit b32dfe377102ce668775f8b6b1461f7ad428f8b6
+Supersede the
+.IR /proc/pid/exe
+symbolic link with a new one pointing to a new executable file
+identified by the file descriptor provided in
+.I arg3
+argument.
+The file descriptor should be obtained with a regular
+.BR open (2)
+call.
+.IP
+To change the symbolic link, one needs to unmap all existing
+executable memory areas, including those created by the kernel itself
+(for example the kernel usually creates at least one executable
+memory area for the ELF
+.IR \.text
+section).
+.IP
+The second limitation is that such transitions can be done only once
+in a process life time.
+Any further attempts will be rejected.
+This should help system administrators monitor unusual
+symbolic-link transitions over all processes running on a system.
.RE
.\"
.SH RETURN VALUE
.BR PR_GET_NO_NEW_PRIVS ,
.BR PR_CAPBSET_READ ,
.BR PR_GET_TIMING ,
+.BR PR_GET_TIMERSLACK ,
.BR PR_GET_SECUREBITS ,
.BR PR_MCE_KILL_GET ,
and (if it returns)
.BR PR_SET_MM_START_DATA ,
.BR PR_SET_MM_END_DATA ,
or
-.BR PR_SET_MM_START_STACK,
+.BR PR_SET_MM_START_STACK ,
and the permissions of the corresponding memory area are not as required;
.IP *
.I arg2
and the caller does not have the
.B CAP_SYS_RESOURCE
capability.
-.\" FIXME The following (until ========) is not yet in mainline kernel,
-.\" so commented out for the moment.
-.\" .TP
-.\" .B EACCES
-.\" .I option
-.\" is
-.\" .BR PR_SET_MM ,
-.\" and
-.\" .I arg3
-.\" is
-.\" .BR PR_SET_MM_EXE_FILE ,
-.\" the file is not executable.
-.\" .TP
-.\" .B EBUSY
-.\" .I option
-.\" is
-.\" .BR PR_SET_MM ,
-.\" .I arg3
-.\" is
-.\" .BR PR_SET_MM_EXE_FILE ,
-.\" and this the second attempt to change the
-.\" .I /proc/pid/exe
-.\" symbolic link, which is prohibited.
-.\" .TP
-.\" .B EBADF
-.\" .I option
-.\" is
-.\" .BR PR_SET_MM ,
-.\" .I arg3
-.\" is
-.\" .BR PR_SET_MM_EXE_FILE ,
-.\" and the file descriptor passed in
-.\" .I arg4
-.\" is not valid.
-.\" ========== END FIXME
+.TP
+.B EACCES
+.I option
+is
+.BR PR_SET_MM ,
+and
+.I arg3
+is
+.BR PR_SET_MM_EXE_FILE ,
+the file is not executable.
+.TP
+.B EBUSY
+.I option
+is
+.BR PR_SET_MM ,
+.I arg3
+is
+.BR PR_SET_MM_EXE_FILE ,
+and this the second attempt to change the
+.I /proc/pid/exe
+symbolic link, which is prohibited.
+.TP
+.B EBADF
+.I option
+is
+.BR PR_SET_MM ,
+.I arg3
+is
+.BR PR_SET_MM_EXE_FILE ,
+and the file descriptor passed in
+.I arg4
+is not valid.
.\" The following can't actually happen, because prctl() in
.\" seccomp mode will cause SIGKILL.
.\" .TP
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