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prctl.2: Document (uncomment) PR_SET_MM options in Linux 3.5 

Some of the PR_SET_MM options were merged to vanilla kernel
later, and appeared in Linux 3.5. Those are:

   - PR_SET_MM_ARG_START
   - PR_SET_MM_ARG_END
   - PR_SET_MM_ENV_START
   - PR_SET_MM_ENV_END
   - PR_SET_MM_AUXV
   - PR_SET_MM_EXE_FILE

This patch merely uncomments description and error codes
for these options, which were present but commented out,
and removes the appropriate FIXME marks.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Kir Kolyshkin 2014-02-12 16:49:13 -08:00 committed by Michael Kerrisk
parent b40dd7e45d
commit 77649527ec
1 changed files with 90 additions and 96 deletions
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186
man2/prctl.2
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@ -713,67 +713,64 @@ value.
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
.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.
.RE
.\"
.SH RETURN VALUE
@ -919,41 +916,38 @@ is
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