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Full Discussion: Timed action after fork() in parent process
Top Forums Programming Timed action after fork() in parent process Post 302510847 by disaster on Tuesday 5th of April 2011 06:45:47 AM
Old 04-05-2011
Well, looks like I learned more than I intended to... didn't know that this was possible for binaries either... Anyways: If you take away the read flag, this way won't work anymore:
Code:
[chris@myhost Test]$ ./hw
Hallo welt
[chris@myhost Test]$ ls -l hw
-rwxr-xr-x 1 chris users 5432 Apr  1 14:44 hw
[chris@myhost Test]$ chmod -x hw
[chris@myhost Test]$ ./hw
bash: ./hw: Permission denied
[chris@myhost Test]$ /lib/ld-linux.so.2 ./hw
Hallo welt
[chris@myhost Test]$ chmod -r hw
[chris@myhost Test]$ /lib/ld-linux.so.2 ./hw
./hw: error while loading shared libraries: ./hw: cannot open shared object file: Permission denied
[chris@myhost Test]$ chmod +x hw
[chris@myhost Test]$ ./hw
Hallo welt
[chris@myhost Test]$ /lib/ld-linux.so.2 ./hw
./hw: error while loading shared libraries: ./hw: cannot open shared object file: Permission denied


My intention is to make one program available only over one call within another program. So I would take away its read and exec permissions, so it cannot be executed from anywhere else (assume chmod isn't available to the user). Just with my call as above. The program is obvious: If I wait in the parent process until the child exits there is a time gap in which the permissions are not so strict as I actually want them to be...
 

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LEARN ABOUT FREEBSD

forward

FORWARD(5)						      BSD File Formats Manual							FORWARD(5)

NAME

     forward -- mail forwarding instructions

DESCRIPTION

     The .forward file contains a list of mail addresses or programs that the user's mail should be redirected to.  If the file is not present,
     then no mail forwarding will be done.  Mail may also be forwarded as the standard input to a program by prefixing the line with the normal
     shell pipe symbol (|).  If arguments are to be passed to the command, then the entire line should be enclosed in quotes.  For security rea-
     sons, the .forward file must be owned by the user the mail is being sent to, or by root, and the user's shell must be listed in /etc/shells.

     For example, if a .forward file contained the following lines:

	   nobody@FreeBSD.org
	   "|/usr/bin/vacation nobody"

     Mail would be forwarded to <nobody@FreeBSD.org> and to the program /usr/bin/vacation with the single argument nobody.

     If a local user address is prefixed with a backslash character, mail is delivered directly to the user's mail spool file, bypassing further
     redirection.

     For example, if user chris had a .forward file containing the following lines:

	   chris@otherhost
	   chris

     One copy of mail would be forwarded to chris@otherhost and another copy would be retained as mail for local user chris.

FILES

     $HOME/.forward  The user's forwarding instructions.

SEE ALSO

     aliases(5), mailaddr(7), sendmail(8)

BSD
								   July 2, 1996 							       BSD
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