mirror of https://github.com/mkerrisk/man-pages
prctl.2: Document PR_SET_MM (new in Linux 3.3)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Cyrill Gorcunov
Michael Kerrisk
parent
5ee63e782f
commit
3a620d0b7b
176
man2/prctl.2
176
man2/prctl.2
|
|
@ -43,7 +43,7 @@
|
|||
.\" FIXME: Document PR_TASK_PERF_EVENTS_DISABLE and
|
||||
.\" PR_TASK_PERF_EVENTS_ENABLE (new in 2.6.32)
|
||||
.\"
|
||||
.TH PRCTL 2 2011-09-17 "Linux" "Linux Programmer's Manual"
|
||||
.TH PRCTL 2 2012-04-14 "Linux" "Linux Programmer's Manual"
|
||||
.SH NAME
|
||||
prctl \- operations on a process
|
||||
.SH SYNOPSIS
|
||||
|
|
@ -378,6 +378,134 @@ Return the current per-process machine check kill policy.
|
|||
All unused
|
||||
.BR prctl ()
|
||||
arguments must be zero.
|
||||
.TP
|
||||
.BR PR_SET_MM " (since Linux 3.3)"
|
||||
Allows a user to modify certain kernel memory map descriptor fields
|
||||
of the calling process.
|
||||
Usually these fields are set by the kernel and dynamic loader (see
|
||||
.BR ld.so (8)
|
||||
for more information) and a regular application should not use this feature.
|
||||
Still there are cases such as self-modifying programs, where a program might
|
||||
find it useful to change its own memory map.
|
||||
The kernel must be built with
|
||||
.BR CONFIG_CHECKPOINT_RESTORE
|
||||
option turned on, otherwise this feature will not be accessible
|
||||
from a user space level.
|
||||
The calling process must have
|
||||
.BR CAP_SYS_RESOURCE
|
||||
(see
|
||||
.BR capabilities (7)
|
||||
for details) capability granted.
|
||||
The value in
|
||||
.I arg2
|
||||
is one of the options below, while
|
||||
.I arg3
|
||||
provides a new value for this option.
|
||||
|
||||
.BR PR_SET_MM_START_CODE
|
||||
to set the address above which program text can run.
|
||||
The corresponding memory area must be readable and executable,
|
||||
but not writable or shareable (see
|
||||
.BR mprotect (2)
|
||||
and
|
||||
.BR mmap (2)
|
||||
for more information).
|
||||
|
||||
.BR PR_SET_MM_END_CODE
|
||||
to set the address below which program text can run.
|
||||
The corresponding memory area must be readable and executable,
|
||||
but not writable or shareable.
|
||||
|
||||
.BR PR_SET_MM_START_DATA
|
||||
to set the address above which program data+bss is placed.
|
||||
The corresponding memory area must be readable and writable,
|
||||
but not executable or shareable.
|
||||
|
||||
.B PR_SET_MM_END_DATA
|
||||
to set the address below which program data+bss is placed.
|
||||
The corresponding memory area must be readable and writable,
|
||||
but not executable or shareable.
|
||||
|
||||
.BR PR_SET_MM_START_STACK
|
||||
to set the start address of the stack.
|
||||
The corresponding memory area must be readable and writable.
|
||||
|
||||
.BR PR_SET_MM_START_BRK
|
||||
to set the address above which program heap can be expanded with
|
||||
.BR brk (2)
|
||||
call.
|
||||
The address must not be greater than ending address of
|
||||
the current program data segment, neither it may exceed
|
||||
resource limit for data (see
|
||||
.BR setrlimit (2)
|
||||
for more information).
|
||||
|
||||
.BR PR_SET_MM_BRK
|
||||
to set the current
|
||||
.BR brk (2)
|
||||
value.
|
||||
The requirements for address are the same as for
|
||||
.BR PR_SET_MM_START_BRK
|
||||
option.
|
||||
|
||||
.BR PR_SET_MM_ARG_START
|
||||
to set the address above which program command line is placed.
|
||||
|
||||
.BR PR_SET_MM_ARG_END
|
||||
to set the address below which program command line is placed.
|
||||
|
||||
.BR PR_SET_MM_ENV_START
|
||||
to set the address above which program environment is placed.
|
||||
|
||||
.BR PR_SET_MM_ENV_END
|
||||
to set the address below which program environment is placed.
|
||||
|
||||
The address passed with
|
||||
.BR PR_SET_MM_ARG_START ,
|
||||
.BR PR_SET_MM_ARG_END ,
|
||||
.BR PR_SET_MM_ENV_START ,
|
||||
.BR PR_SET_MM_ENV_END ,
|
||||
should belong to a process stack area, thus corresponding memory area
|
||||
must be readable, writable and (depending on the kernel
|
||||
configuration) has
|
||||
.BR MAP_GROWSDOWN
|
||||
attribute set (see
|
||||
.BR mmap (2)
|
||||
for details).
|
||||
|
||||
.BR PR_SET_MM_AUXV
|
||||
to 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.
|
||||
|
||||
.BR PR_SET_MM_EXE_FILE
|
||||
to supersede
|
||||
.IR /proc/pid/exe
|
||||
symbolic link with a new one pointing to a new executable file
|
||||
which descriptor is provided provided in the
|
||||
.I arg3
|
||||
argument.
|
||||
The file descriptor should be obtaned with a regular
|
||||
.BR open (2)
|
||||
call.
|
||||
|
||||
To change the symlink, one needs to unmap all existing
|
||||
executable memory areas being created by the kernel itself
|
||||
(for example the kernel usually creates at least one executable
|
||||
memory area for Elf file
|
||||
.IR \.text
|
||||
section).
|
||||
|
||||
The second limitation is that such transition can be done once
|
||||
in a process life time.
|
||||
Any furter attempts will be rejected.
|
||||
This should help system administrators to monitor the unusual
|
||||
symlinks transitions over all process running in a system.
|
||||
.\"
|
||||
.SH "RETURN VALUE"
|
||||
On success,
|
||||
.BR PR_GET_DUMPABLE ,
|
||||
|
|
@ -411,7 +539,9 @@ is not recognized.
|
|||
is
|
||||
.BR PR_MCE_KILL
|
||||
or
|
||||
.BR PR_MCE_KILL_GET ,
|
||||
.BR PR_MCE_KILL_GET
|
||||
or
|
||||
.BR PR_SET_MM ,
|
||||
and unused
|
||||
.BR prctl ()
|
||||
arguments were not specified as zero.
|
||||
|
|
@ -459,6 +589,48 @@ is
|
|||
and the caller does not have the
|
||||
.B CAP_SETPCAP
|
||||
capability.
|
||||
.TP
|
||||
.B EPERM
|
||||
.I option
|
||||
is
|
||||
.BR PR_SET_MM ,
|
||||
and the caller does not have the
|
||||
.B CAP_SYS_RESOURCE
|
||||
capability.
|
||||
.TP
|
||||
.B EACCES
|
||||
.I option
|
||||
is
|
||||
.BR PR_SET_MM ,
|
||||
and the
|
||||
.I arg3
|
||||
is
|
||||
.BR PR_SET_MM_EXE_FILE ,
|
||||
the file is not executable one.
|
||||
.TP
|
||||
.B EBUSY
|
||||
.I option
|
||||
is
|
||||
.BR PR_SET_MM ,
|
||||
and the
|
||||
.I arg3
|
||||
is
|
||||
.BR PR_SET_MM_EXE_FILE ,
|
||||
the second attempt to change
|
||||
.I /proc/pid/exe
|
||||
symlink is prohibited.
|
||||
.TP
|
||||
.B EBADF
|
||||
.I option
|
||||
is
|
||||
.BR PR_SET_MM ,
|
||||
and the
|
||||
.I arg3
|
||||
is
|
||||
.BR PR_SET_MM_EXE_FILE ,
|
||||
the file descriptor passed in
|
||||
.I arg4
|
||||
is not found.
|
||||
.\" The following can't actually happen, because prctl() in
|
||||
.\" seccomp mode will cause SIGKILL.
|
||||
.\" .TP
|
||||
|
|
|
|||
Loading…
Reference in New Issue