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84bef5b603
PPTP uses pppox sockets (struct pppox_sock). These sockets don't embed
an inet_sock structure, so it's invalid to call inet_sk() on them.
Therefore, the ip_route_output_ports() call in pptp_connect() has two
problems:
* The tos variable is set with RT_CONN_FLAGS(sk), which calls
inet_sk() on the pppox socket.
* ip_route_output_ports() tries to retrieve routing flags using
inet_sk_flowi_flags(), which is also going to call inet_sk() on the
pppox socket.
While PPTP doesn't use inet sockets, it's actually really layered on
top of IP and therefore needs a proper way to do fib lookups. So let's
define pptp_route_output() to get a struct rtable from a pptp socket.
Let's also replace the ip_route_output_ports() call of pptp_xmit() for
consistency.
In practice, this means that:
* pptp_connect() sets ->flowi4_tos and ->flowi4_flags to zero instead
of using bits of unrelated struct pppox_sock fields.
* pptp_xmit() now respects ->sk_mark and ->sk_uid.
* pptp_xmit() now calls the security_sk_classify_flow() security
hook, thus allowing to set ->flowic_secid.
* pptp_xmit() now passes the pppox socket to xfrm_lookup_route().
Found by code inspection.
Fixes: 00959ade36 ("PPTP: PPP over IPv4 (Point-to-Point Tunneling Protocol)")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.