From: ebiederm@xmission.com (Eric W. Biederman)
To: David Drysdale <drysdale@google.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Meredydd Luff <meredydd@senatehouse.org>, linux-kernel@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
        x86@kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org
References: <1413978269-17274-1-git-send-email-drysdale@google.com>
	<1413978269-17274-4-git-send-email-drysdale@google.com>
Date: Wed, 22 Oct 2014 12:55:34 -0500
In-Reply-To: <1413978269-17274-4-git-send-email-drysdale@google.com> (David
	Drysdale's message of "Wed, 22 Oct 2014 12:44:29 +0100")
Message-ID: <87wq7sgfah.fsf@x220.int.ebiederm.org>
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Subject: Re: [PATCHv5 man-pages 3/3] execveat.2: initial man page for execveat(2)
Sender: linux-kernel-owner@vger.kernel.org

David Drysdale <drysdale@google.com> writes:

> Signed-off-by: David Drysdale <drysdale@google.com>
> ---
>  man2/execveat.2 | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 144 insertions(+)
>  create mode 100644 man2/execveat.2
>
> diff --git a/man2/execveat.2 b/man2/execveat.2
> new file mode 100644
> index 000000000000..d19571a3eb9d
> --- /dev/null
> +++ b/man2/execveat.2
> @@ -0,0 +1,144 @@
> +.\" Copyright (c) 2014 Google, Inc.
> +.\"
> +.\" %%%LICENSE_START(VERBATIM)
> +.\" Permission is granted to make and distribute verbatim copies of this
> +.\" manual provided the copyright notice and this permission notice are
> +.\" preserved on all copies.
> +.\"
> +.\" Permission is granted to copy and distribute modified versions of this
> +.\" manual under the conditions for verbatim copying, provided that the
> +.\" entire resulting derived work is distributed under the terms of a
> +.\" permission notice identical to this one.
> +.\"
> +.\" Since the Linux kernel and libraries are constantly changing, this
> +.\" manual page may be incorrect or out-of-date.  The author(s) assume no
> +.\" responsibility for errors or omissions, or for damages resulting from
> +.\" the use of the information contained herein.  The author(s) may not
> +.\" have taken the same level of care in the production of this manual,
> +.\" which is licensed free of charge, as they might when working
> +.\" professionally.
> +.\"
> +.\" Formatted or processed versions of this manual, if unaccompanied by
> +.\" the source, must acknowledge the copyright and authors of this work.
> +.\" %%%LICENSE_END
> +.\"
> +.TH EXECVEAT 2 2014-04-02 "Linux" "Linux Programmer's Manual"
> +.SH NAME
> +execveat \- execute program relative to a directory file descriptor
> +.SH SYNOPSIS
> +.B #include <unistd.h>
> +.sp
> +.BI "int execve(int " fd ", const char *" pathname ","
            ^^^^^^ That needs to be execveat
> +.br
> +.BI "           char *const " argv "[],  char *const " envp "[],"
> +.br
> +.BI "           int " flags);
> +.SH DESCRIPTION
> +The
> +.BR execveat ()
> +system call executes the program pointed to by the combination of \fIfd\fP and \fIpathname\fP.
> +The
> +.BR execveat ()
> +system call operates in exactly the same way as
> +.BR execve (2),
> +except for the differences described in this manual page.
> +
> +If the pathname given in
> +.I pathname
> +is relative, then it is interpreted relative to the directory
> +referred to by the file descriptor
> +.I fd
> +(rather than relative to the current working directory of
> +the calling process, as is done by
> +.BR execve (2)
> +for a relative pathname).
> +
> +If
> +.I pathname
> +is relative and
> +.I fd
> +is the special value
> +.BR AT_FDCWD ,
> +then
> +.I pathname
> +is interpreted relative to the current working
> +directory of the calling process (like
> +.BR execve (2)).
> +
> +If
> +.I pathname
> +is absolute, then
> +.I fd
> +is ignored.
> +
> +If
> +.I pathname
> +is an empty string and the
> +.BR AT_EMPTY_PATH
> +flag is specified, then the file descriptor
> +.I fd
> +specifies the file to be executed.
> +
> +.I flags
> +can either be 0, or include the following flags:
> +.TP
> +.BR AT_EMPTY_PATH
> +If
> +.I pathname
> +is an empty string, operate on the file referred to by
> +.IR fd
> +(which may have been obtained using the
> +.BR open (2)
> +.B O_PATH
> +flag).
> +.TP
> +.B AT_SYMLINK_NOFOLLOW
> +If the file identified by
> +.I fd
> +and a non-NULL
> +.I pathname
> +is a symbolic link, then the call fails with the error
> +.BR EINVAL .
> +.SH "RETURN VALUE"
> +On success,
> +.BR execveat ()
> +does not return. On error \-1 is returned, and
> +.I errno
> +is set appropriately.
> +.SH ERRORS
> +The same errors that occur for
> +.BR execve (2)
> +can also occur for
> +.BR execveat ().
> +The following additional errors can occur for
> +.BR execveat ():
> +.TP
> +.B EBADF
> +.I fd
> +is not a valid file descriptor.
> +.TP
> +.B EINVAL
> +Invalid flag specified in
> +.IR flags .
> +.TP
> +.B ENOTDIR
> +.I pathname
> +is relative and
> +.I fd
> +is a file descriptor referring to a file other than a directory.
> +.SH VERSIONS
> +.BR execveat ()
> +was added to Linux in kernel 3.???.
> +.SH NOTES
> +In addition to the reasons explained in
> +.BR openat (2),
> +the
> +.BR execveat ()
> +system call is also needed to allow
> +.BR fexecve (3)
> +to be implemented on systems that do not have the
> +.I /proc
> +filesystem mounted.
> +.SH SEE ALSO
> +.BR execve (2),
> +.BR fexecve (3)
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