introduce BPF_PROG_QUERY command to retrieve a set of either
attached programs to given cgroup or a set of effective programs
that will execute for events within a cgroup
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
for cgroup bits
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

introduce BPF_F_ALLOW_MULTI flag that can be used to attach multiple
bpf programs to a cgroup.

The difference between three possible flags for BPF_PROG_ATTACH command:
- NONE(default): No further bpf programs allowed in the subtree.
- BPF_F_ALLOW_OVERRIDE: If a sub-cgroup installs some bpf program,
  the program in this cgroup yields to sub-cgroup program.
- BPF_F_ALLOW_MULTI: If a sub-cgroup installs some bpf program,
  that cgroup program gets run in addition to the program in this cgroup.

NONE and BPF_F_ALLOW_OVERRIDE existed before. This patch doesn't
change their behavior. It only clarifies the semantics in relation
to new flag.

Only one program is allowed to be attached to a cgroup with
NONE or BPF_F_ALLOW_OVERRIDE flag.
Multiple programs are allowed to be attached to a cgroup with
BPF_F_ALLOW_MULTI flag. They are executed in FIFO order
(those that were attached first, run first)
The programs of sub-cgroup are executed first, then programs of
this cgroup and then programs of parent cgroup.
All eligible programs are executed regardless of return code from
earlier programs.

To allow efficient execution of multiple programs attached to a cgroup
and to avoid penalizing cgroups without any programs attached
introduce 'struct bpf_prog_array' which is RCU protected array
of pointers to bpf programs.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
for cgroup bits
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Created a new BPF program type, BPF_PROG_TYPE_SOCK_OPS, and a corresponding
struct that allows BPF programs of this type to access some of the
socket's fields (such as IP addresses, ports, etc.). It uses the
existing bpf cgroups infrastructure so the programs can be attached per
cgroup with full inheritance support. The program will be called at
appropriate times to set relevant connections parameters such as buffer
sizes, SYN and SYN-ACK RTOs, etc., based on connection information such
as IP addresses, port numbers, etc.

Alghough there are already 3 mechanisms to set parameters (sysctls,
route metrics and setsockopts), this new mechanism provides some
distinct advantages. Unlike sysctls, it can set parameters per
connection. In contrast to route metrics, it can also use port numbers
and information provided by a user level program. In addition, it could
set parameters probabilistically for evaluation purposes (i.e. do
something different on 10% of the flows and compare results with the
other 90% of the flows). Also, in cases where IPv6 addresses contain
geographic information, the rules to make changes based on the distance
(or RTT) between the hosts are much easier than route metric rules and
can be global. Finally, unlike setsockopt, it oes not require
application changes and it can be updated easily at any time.

Although the bpf cgroup framework already contains a sock related
program type (BPF_PROG_TYPE_CGROUP_SOCK), I created the new type
(BPF_PROG_TYPE_SOCK_OPS) beccause the existing type expects to be called
only once during the connections's lifetime. In contrast, the new
program type will be called multiple times from different places in the
network stack code.  For example, before sending SYN and SYN-ACKs to set
an appropriate timeout, when the connection is established to set
congestion control, etc. As a result it has "op" field to specify the
type of operation requested.

The purpose of this new program type is to simplify setting connection
parameters, such as buffer sizes, TCP's SYN RTO, etc. For example, it is
easy to use facebook's internal IPv6 addresses to determine if both hosts
of a connection are in the same datacenter. Therefore, it is easy to
write a BPF program to choose a small SYN RTO value when both hosts are
in the same datacenter.

This patch only contains the framework to support the new BPF program
type, following patches add the functionality to set various connection
parameters.

This patch defines a new BPF program type: BPF_PROG_TYPE_SOCKET_OPS
and a new bpf syscall command to load a new program of this type:
BPF_PROG_LOAD_SOCKET_OPS.

Two new corresponding structs (one for the kernel one for the user/BPF
program):

/* kernel version */
struct bpf_sock_ops_kern {
        struct sock *sk;
        __u32  op;
        union {
                __u32 reply;
                __u32 replylong[4];
        };
};

/* user version
 * Some fields are in network byte order reflecting the sock struct
 * Use the bpf_ntohl helper macro in samples/bpf/bpf_endian.h to
 * convert them to host byte order.
 */
struct bpf_sock_ops {
        __u32 op;
        union {
                __u32 reply;
                __u32 replylong[4];
        };
        __u32 family;
        __u32 remote_ip4;     /* In network byte order */
        __u32 local_ip4;      /* In network byte order */
        __u32 remote_ip6[4];  /* In network byte order */
        __u32 local_ip6[4];   /* In network byte order */
        __u32 remote_port;    /* In network byte order */
        __u32 local_port;     /* In host byte horder */
};

Currently there are two types of ops. The first type expects the BPF
program to return a value which is then used by the caller (or a
negative value to indicate the operation is not supported). The second
type expects state changes to be done by the BPF program, for example
through a setsockopt BPF helper function, and they ignore the return
value.

The reply fields of the bpf_sockt_ops struct are there in case a bpf
program needs to return a value larger than an integer.
Signed-off-by: NLawrence Brakmo <brakmo@fb.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

BPF helper functions access socket fields through skb->sk. This is not
set in ingress cgroup and socket filters. The association is only made
in skb_set_owner_r once the filter has accepted the packet. Sk is
available as socket lookup has taken place.

Temporarily set skb->sk to sk in these cases.
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If BPF_F_ALLOW_OVERRIDE flag is used in BPF_PROG_ATTACH command
to the given cgroup the descendent cgroup will be able to override
effective bpf program that was inherited from this cgroup.
By default it's not passed, therefore override is disallowed.

Examples:
1.
prog X attached to /A with default
prog Y fails to attach to /A/B and /A/B/C
Everything under /A runs prog X

2.
prog X attached to /A with allow_override.
prog Y fails to attach to /A/B with default (non-override)
prog M attached to /A/B with allow_override.
Everything under /A/B runs prog M only.

3.
prog X attached to /A with allow_override.
prog Y fails to attach to /A with default.
The user has to detach first to switch the mode.

In the future this behavior may be extended with a chain of
non-overridable programs.

Also fix the bug where detach from cgroup where nothing is attached
was not throwing error. Return ENOENT in such case.

Add several testcases and adjust libbpf.

Fixes: 30070984 ("cgroup: add support for eBPF programs")
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NTejun Heo <tj@kernel.org>
Acked-by: NDaniel Mack <daniel@zonque.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add new cgroup based program type, BPF_PROG_TYPE_CGROUP_SOCK. Similar to
BPF_PROG_TYPE_CGROUP_SKB programs can be attached to a cgroup and run
any time a process in the cgroup opens an AF_INET or AF_INET6 socket.
Currently only sk_bound_dev_if is exported to userspace for modification
by a bpf program.

This allows a cgroup to be configured such that AF_INET{6} sockets opened
by processes are automatically bound to a specific device. In turn, this
enables the running of programs that do not support SO_BINDTODEVICE in a
specific VRF context / L3 domain.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Code move and rename only; no functional change intended.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There's a 'not' missing in one paragraph. Add it.

Fixes: 30070984 ("cgroup: add support for eBPF programs")
Signed-off-by: NDaniel Mack <daniel@zonque.org>
Reported-by: NRami Rosen <roszenrami@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds two sets of eBPF program pointers to struct cgroup.
One for such that are directly pinned to a cgroup, and one for such
that are effective for it.

To illustrate the logic behind that, assume the following example
cgroup hierarchy.

  A - B - C
        \ D - E

If only B has a program attached, it will be effective for B, C, D
and E. If D then attaches a program itself, that will be effective for
both D and E, and the program in B will only affect B and C. Only one
program of a given type is effective for a cgroup.

Attaching and detaching programs will be done through the bpf(2)
syscall. For now, ingress and egress inet socket filtering are the
only supported use-cases.
Signed-off-by: NDaniel Mack <daniel@zonque.org>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>