Hello. James Morris wrote: > From memory, one approach under discussion was to add netfilter hooks to > the transport layer, which could be invoked correctly by each type of > protocol when the target process is selected. > > If this is done for netfilter, then an LSM hook is probably not needed at > all, as security modules can utilize netfilter hooks directly.
Patrick McHardy says (at http://marc.info/?l=linux-netdev&m=118495005800410&w=2 ) "Even with socket filters netfilter doesn't know the final receipient process, that is not known until it calls recvmsg and the data is read, which is too late for netfilter." > > Precautions: This approach has a side effect which unlikely occurs. > > > > If a socket is shared by multiple processes with different policy, > > the process who should be able to accept this connection > > will not be able to accept this connection > > because socket_post_accept() aborts this connection. > > But if socket_post_accept() doesn't abort this connection, > > the process who must not be able to accept this connection > > will repeat accept() forever, which is a worse side effect. I think this change is needed regardless of whether to use connection filtering or not. Currently, SELinux doesn't use socket_post_accept(). | * @socket_post_accept: | * This hook allows a security module to copy security | * information into the newly created socket's inode. But if one wants to *copy* security information to accept()ed socket, the location after fd_install() is too late to copy because the userland process can access accept()ed socket's fd whose security information is not copied yet. Also, if one wants to *assign* security information to accept()ed socket, it might attend memory allocation which can fail. So, use of void for socket_post_accept() deprives a security module of a chance to abort this connection if the security module failed to *assign* security information. Regards. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
