If the kernel is compiled with CONFIG_CGROUP_BPF not enabled, it is not
possible to attach, detach or query IR BPF programs to /dev/lircN devices,
making them impossible to use. For embedded devices, it should be possible
to use IR decoding without cgroups or CONFIG_CGROUP_BPF enabled.

This change requires some refactoring, since bpf_prog_{attach,detach,query}
functions are now always compiled, but their code paths for cgroups need
moving out. Rather than a #ifdef CONFIG_CGROUP_BPF in kernel/bpf/syscall.c,
moving them to kernel/bpf/cgroup.c and kernel/bpf/sockmap.c does not
require #ifdefs since that is already conditionally compiled.

Fixes: f4364dcf ("media: rc: introduce BPF_PROG_LIRC_MODE2")
Signed-off-by: NSean Young <sean@mess.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

We currently lock any JITed image as read-only via bpf_jit_binary_lock_ro()
as well as the BPF image as read-only through bpf_prog_lock_ro(). In
the case any of these would fail we throw a WARN_ON_ONCE() in order to
yell loudly to the log. Perhaps, to some extend, this may be comparable
to an allocation where __GFP_NOWARN is explicitly not set.

Added via 65869a47 ("bpf: improve read-only handling"), this behavior
is slightly different compared to any of the other in-kernel set_memory_ro()
users who do not check the return code of set_memory_ro() and friends /at
all/ (e.g. in the case of module_enable_ro() / module_disable_ro()). Given
in BPF this is mandatory hardening step, we want to know whether there
are any issues that would leave both BPF data writable. So it happens
that syzkaller enabled fault injection and it triggered memory allocation
failure deep inside x86's change_page_attr_set_clr() which was triggered
from set_memory_ro().

Now, there are two options: i) leaving everything as is, and ii) reworking
the image locking code in order to have a final checkpoint out of the
central bpf_prog_select_runtime() which probes whether any of the calls
during prog setup weren't successful, and then bailing out with an error.
Option ii) is a better approach since this additional paranoia avoids
altogether leaving any potential W+X pages from BPF side in the system.
Therefore, lets be strict about it, and reject programs in such unlikely
occasion. While testing I noticed also that one bpf_prog_lock_ro()
call was missing on the outer dummy prog in case of calls, e.g. in the
destructor we call bpf_prog_free_deferred() on the main prog where we
try to bpf_prog_unlock_free() the program, and since we go via
bpf_prog_select_runtime() do that as well.

Reported-by: syzbot+3b889862e65a98317058@syzkaller.appspotmail.com
Reported-by: syzbot+9e762b52dd17e616a7a5@syzkaller.appspotmail.com
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

While testing I found that when hitting error path in bpf_prog_load()
where we jump to free_used_maps and prog contained BPF to BPF calls
that were JITed earlier, then we never clean up the bpf_prog_kallsyms_add()
done under jit_subprogs(). Add proper API to make BPF kallsyms deletion
more clear and fix that.

Fixes: 1c2a088a ("bpf: x64: add JIT support for multi-function programs")
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Its trivial and straight forward to expose it for scripts that can
then use it along with bpftool in order to inspect an individual
application's used maps and progs. Right now we dump some basic
information in the fdinfo file but with the help of the map/prog
id full introspection becomes possible now.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NSong Liu <songliubraving@fb.com>
Acked-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Add support for BPF_PROG_LIRC_MODE2. This type of BPF program can call
rc_keydown() to reported decoded IR scancodes, or rc_repeat() to report
that the last key should be repeated.

The bpf program can be attached to using the bpf(BPF_PROG_ATTACH) syscall;
the target_fd must be the /dev/lircN device.
Acked-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NSean Young <sean@mess.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

In addition to already existing BPF hooks for sys_bind and sys_connect,
the patch provides new hooks for sys_sendmsg.

It leverages existing BPF program type `BPF_PROG_TYPE_CGROUP_SOCK_ADDR`
that provides access to socket itlself (properties like family, type,
protocol) and user-passed `struct sockaddr *` so that BPF program can
override destination IP and port for system calls such as sendto(2) or
sendmsg(2) and/or assign source IP to the socket.

The hooks are implemented as two new attach types:
`BPF_CGROUP_UDP4_SENDMSG` and `BPF_CGROUP_UDP6_SENDMSG` for UDPv4 and
UDPv6 correspondingly.

UDPv4 and UDPv6 separate attach types for same reason as sys_bind and
sys_connect hooks, i.e. to prevent reading from / writing to e.g.
user_ip6 fields when user passes sockaddr_in since it'd be out-of-bound.

The difference with already existing hooks is sys_sendmsg are
implemented only for unconnected UDP.

For TCP it doesn't make sense to change user-provided `struct sockaddr *`
at sendto(2)/sendmsg(2) time since socket either was already connected
and has source/destination set or wasn't connected and call to
sendto(2)/sendmsg(2) would lead to ENOTCONN anyway.

Connected UDP is already handled by sys_connect hooks that can override
source/destination at connect time and use fast-path later, i.e. these
hooks don't affect UDP fast-path.

Rewriting source IP is implemented differently than that in sys_connect
hooks. When sys_sendmsg is used with unconnected UDP it doesn't work to
just bind socket to desired local IP address since source IP can be set
on per-packet basis by using ancillary data (cmsg(3)). So no matter if
socket is bound or not, source IP has to be rewritten on every call to
sys_sendmsg.

To do so two new fields are added to UAPI `struct bpf_sock_addr`;
* `msg_src_ip4` to set source IPv4 for UDPv4;
* `msg_src_ip6` to set source IPv6 for UDPv6.
Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Currently, suppose a userspace application has loaded a bpf program
and attached it to a tracepoint/kprobe/uprobe, and a bpf
introspection tool, e.g., bpftool, wants to show which bpf program
is attached to which tracepoint/kprobe/uprobe. Such attachment
information will be really useful to understand the overall bpf
deployment in the system.

There is a name field (16 bytes) for each program, which could
be used to encode the attachment point. There are some drawbacks
for this approaches. First, bpftool user (e.g., an admin) may not
really understand the association between the name and the
attachment point. Second, if one program is attached to multiple
places, encoding a proper name which can imply all these
attachments becomes difficult.

This patch introduces a new bpf subcommand BPF_TASK_FD_QUERY.
Given a pid and fd, if the <pid, fd> is associated with a
tracepoint/kprobe/uprobe perf event, BPF_TASK_FD_QUERY will return
   . prog_id
   . tracepoint name, or
   . k[ret]probe funcname + offset or kernel addr, or
   . u[ret]probe filename + offset
to the userspace.
The user can use "bpftool prog" to find more information about
bpf program itself with prog_id.
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

This adds new two new fields to struct bpf_prog_info. For
multi-function programs, these fields can be used to pass
a list of the JITed image lengths of each function for a
given program to userspace using the bpf system call with
the BPF_OBJ_GET_INFO_BY_FD command.

This can be used by userspace applications like bpftool
to split up the contiguous JITed dump, also obtained via
the system call, into more relatable chunks corresponding
to each function.
Signed-off-by: NSandipan Das <sandipan@linux.vnet.ibm.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Currently, for multi-function programs, we cannot get the JITed
instructions using the bpf system call's BPF_OBJ_GET_INFO_BY_FD
command. Because of this, userspace tools such as bpftool fail
to identify a multi-function program as being JITed or not.

With the JIT enabled and the test program running, this can be
verified as follows:

  # cat /proc/sys/net/core/bpf_jit_enable
  1

Before applying this patch:

  # bpftool prog list
  1: kprobe  name foo  tag b811aab41a39ad3d  gpl
          loaded_at 2018-05-16T11:43:38+0530  uid 0
          xlated 216B  not jited  memlock 65536B
  ...

  # bpftool prog dump jited id 1
  no instructions returned

After applying this patch:

  # bpftool prog list
  1: kprobe  name foo  tag b811aab41a39ad3d  gpl
          loaded_at 2018-05-16T12:13:01+0530  uid 0
          xlated 216B  jited 308B  memlock 65536B
  ...

  # bpftool prog dump jited id 1
     0:   nop
     4:   nop
     8:   mflr    r0
     c:   std     r0,16(r1)
    10:   stdu    r1,-112(r1)
    14:   std     r31,104(r1)
    18:   addi    r31,r1,48
    1c:   li      r3,10
  ...
Signed-off-by: NSandipan Das <sandipan@linux.vnet.ibm.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This adds new two new fields to struct bpf_prog_info. For
multi-function programs, these fields can be used to pass
a list of kernel symbol addresses for all functions in a
given program to userspace using the bpf system call with
the BPF_OBJ_GET_INFO_BY_FD command.

When bpf_jit_kallsyms is enabled, we can get the address
of the corresponding kernel symbol for a callee function
and resolve the symbol's name. The address is determined
by adding the value of the call instruction's imm field
to __bpf_call_base. This offset gets assigned to the imm
field by the verifier.

For some architectures, such as powerpc64, the imm field
is not large enough to hold this offset.

We resolve this by:

[1] Assigning the subprog id to the imm field of a call
    instruction in the verifier instead of the offset of
    the callee's symbol's address from __bpf_call_base.

[2] Determining the address of a callee's corresponding
    symbol by using the imm field as an index for the
    list of kernel symbol addresses now available from
    the program info.
Suggested-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NSandipan Das <sandipan@linux.vnet.ibm.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

In "struct bpf_map_info", the name "btf_id", "btf_key_id" and "btf_value_id"
could cause confusion because the "id" of "btf_id" means the BPF obj id
given to the BTF object while
"btf_key_id" and "btf_value_id" means the BTF type id within
that BTF object.

To make it clear, btf_key_id and btf_value_id are
renamed to btf_key_type_id and btf_value_type_id.
Suggested-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch exposes check_uarg_tail_zero() which will
be reused by a later BTF patch.  Its name is changed to
bpf_check_uarg_tail_zero().
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

During BPF_OBJ_GET_INFO_BY_FD on a btf_fd, the current bpf_attr's
info.info is directly filled with the BTF binary data.  It is
not extensible.  In this case, we want to add BTF ID.

This patch adds "struct bpf_btf_info" which has the BTF ID as
one of its member.  The BTF binary data itself is exposed through
the "btf" and "btf_size" members.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Acked-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch gives an ID to each loaded BTF.  The ID is allocated by
the idr like the existing prog-id and map-id.

The bpf_put(map->btf) is moved to __bpf_map_put() so that the
userspace can stop seeing the BTF ID ASAP when the last BTF
refcnt is gone.

It also makes BTF accessible from userspace through the
1. new BPF_BTF_GET_FD_BY_ID command.  It is limited to CAP_SYS_ADMIN
   which is inline with the BPF_BTF_LOAD cmd and the existing
   BPF_[MAP|PROG]_GET_FD_BY_ID cmd.
2. new btf_id (and btf_key_id + btf_value_id) in "struct bpf_map_info"

Once the BTF ID handler is accessible from userspace, freeing a BTF
object has to go through a rcu period.  The BPF_BTF_GET_FD_BY_ID cmd
can then be done under a rcu_read_lock() instead of taking
spin_lock.
[Note: A similar rcu usage can be done to the existing
       bpf_prog_get_fd_by_id() in a follow up patch]

When processing the BPF_BTF_GET_FD_BY_ID cmd,
refcount_inc_not_zero() is needed because the BTF object
could be already in the rcu dead row .  btf_get() is
removed since its usage is currently limited to btf.c
alone.  refcount_inc() is used directly instead.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Acked-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

For asynchronous events originating from the device, like perf event
output, we need to be able to make sure that objects being referred
to by the FW message are valid on the host.  FW events can get queued
and reordered.  Even if we had a FW message "barrier" we should still
protect ourselves from bogus FW output.

Add a reverse-mapping hash table and record in it all raw map pointers
FW may refer to.  Only record neutral maps, i.e. perf event arrays.
These are currently the only objects FW can refer to.  Use RCU protection
on the read side, update side is under RTNL.

Since program vs map destruction order is slightly painful for offload
simply take an extra reference on all the recorded maps to make sure
they don't disappear.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Commit 9ef09e35 ("bpf: fix possible spectre-v1 in find_and_alloc_map()")
converted find_and_alloc_map() over to use array_index_nospec() to sanitize
map type that user space passes on map creation, and this patch does an
analogous conversion for progs in find_prog_type() as it's also passed from
user space when loading progs as attr->prog_type.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

It's possible for userspace to control attr->map_type. Sanitize it when
using it as an array index to prevent an out-of-bounds value being used
under speculation.

Found by smatch.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: netdev@vger.kernel.org
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

tracepoints to bpf core were added as a way to provide introspection
to bpf programs and maps, but after some time it became clear that
this approach is inadequate, so prog_id, map_id and corresponding
get_next_id, get_fd_by_id, get_info_by_fd, prog_query APIs were
introduced and fully adopted by bpftool and other applications.
The tracepoints in bpf core started to rot and causing syzbot warnings:
WARNING: CPU: 0 PID: 3008 at kernel/trace/trace_event_perf.c:274
Kernel panic - not syncing: panic_on_warn set ...
perf_trace_bpf_map_keyval+0x260/0xbd0 include/trace/events/bpf.h:228
trace_bpf_map_update_elem include/trace/events/bpf.h:274 [inline]
map_update_elem kernel/bpf/syscall.c:597 [inline]
SYSC_bpf kernel/bpf/syscall.c:1478 [inline]
Hence this patch deletes tracepoints in bpf core.
Reported-by: NEric Biggers <ebiggers3@gmail.com>
Reported-by: Nsyzbot <bot+a9dbb3c3e64b62536a4bc5ee7bbd4ca627566188@syzkaller.appspotmail.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Adding gpl_compatible flag to struct bpf_prog_info
so it can be dumped via bpf_prog_get_info_by_fd and
displayed via bpftool progs dump.

Alexei noticed 4-byte hole in struct bpf_prog_info,
so we put the u32 flags field in there, and we can
keep adding bit fields in there without breaking
user space.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Relying on map_release hook to decrement the reference counts when a
map is removed only works if the map is not being pinned. In the
pinned case the ref is decremented immediately and the BPF programs
released. After this BPF programs may not be in-use which is not
what the user would expect.

This patch moves the release logic into bpf_map_put_uref() and brings
sockmap in-line with how a similar case is handled in prog array maps.

Fixes: 3d9e9526 ("bpf: sockmap, fix leaking maps with attached but not detached progs")
Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch adds pretty print support to the basic arraymap.
Support for other bpf maps can be added later.

This patch adds new attrs to the BPF_MAP_CREATE command to allow
specifying the btf_fd, btf_key_id and btf_value_id.  The
BPF_MAP_CREATE can then associate the btf to the map if
the creating map supports BTF.

A BTF supported map needs to implement two new map ops,
map_seq_show_elem() and map_check_btf().  This patch has
implemented these new map ops for the basic arraymap.

It also adds file_operations, bpffs_map_fops, to the pinned
map such that the pinned map can be opened and read.
After that, the user has an intuitive way to do
"cat bpffs/pathto/a-pinned-map" instead of getting
an error.

bpffs_map_fops should not be extended further to support
other operations.  Other operations (e.g. write/key-lookup...)
should be realized by the userspace tools (e.g. bpftool) through
the BPF_OBJ_GET_INFO_BY_FD, map's lookup/update interface...etc.
Follow up patches will allow the userspace to obtain
the BTF from a map-fd.

Here is a sample output when reading a pinned arraymap
with the following map's value:

struct map_value {
	int count_a;
	int count_b;
};

cat /sys/fs/bpf/pinned_array_map:

0: {1,2}
1: {3,4}
2: {5,6}
...
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch adds BPF_OBJ_GET_INFO_BY_FD support to BTF fd.
The original BTF data, which was used to create the BTF fd during
the earlier BPF_BTF_LOAD call, will be returned.

The userspace is expected to allocate buffer
to info.info and the buffer size is set to info.info_len before
calling BPF_OBJ_GET_INFO_BY_FD.

The original BTF data is copied to the userspace buffer (info.info).
Only upto the user's specified info.info_len will be copied.

The original BTF data size is set to info.info_len.  The userspace
needs to check if it is bigger than its allocated buffer size.
If it is, the userspace should realloc with the kernel-returned
info.info_len and call the BPF_OBJ_GET_INFO_BY_FD again.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch adds a BPF_BTF_LOAD command which
1) loads and verifies the BTF (implemented in earlier patches)
2) returns a BTF fd to userspace.  In the next patch, the
   BTF fd can be specified during BPF_MAP_CREATE.

It currently limits to CAP_SYS_ADMIN.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

There will be a build warning -Wunused-function if CONFIG_CGROUP_BPF
isn't defined, since the only user is inside #ifdef CONFIG_CGROUP_BPF:
kernel/bpf/syscall.c:1229:12: warning: ‘bpf_prog_attach_check_attach_type’
    defined but not used [-Wunused-function]
 static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Current code moves function bpf_prog_attach_check_attach_type inside
ifdef CONFIG_CGROUP_BPF.

Fixes: 5e43f899 ("bpf: Check attach type at prog load time")
Signed-off-by: NAnders Roxell <anders.roxell@linaro.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

"Post-hooks" are hooks that are called right before returning from
sys_bind. At this time IP and port are already allocated and no further
changes to `struct sock` can happen before returning from sys_bind but
BPF program has a chance to inspect the socket and change sys_bind
result.

Specifically it can e.g. inspect what port was allocated and if it
doesn't satisfy some policy, BPF program can force sys_bind to fail and
return EPERM to user.

Another example of usage is recording the IP:port pair to some map to
use it in later calls to sys_connect. E.g. if some TCP server inside
cgroup was bound to some IP:port_n, it can be recorded to a map. And
later when some TCP client inside same cgroup is trying to connect to
127.0.0.1:port_n, BPF hook for sys_connect can override the destination
and connect application to IP:port_n instead of 127.0.0.1:port_n. That
helps forcing all applications inside a cgroup to use desired IP and not
break those applications if they e.g. use localhost to communicate
between each other.

== Implementation details ==

Post-hooks are implemented as two new attach types
`BPF_CGROUP_INET4_POST_BIND` and `BPF_CGROUP_INET6_POST_BIND` for
existing prog type `BPF_PROG_TYPE_CGROUP_SOCK`.

Separate attach types for IPv4 and IPv6 are introduced to avoid access
to IPv6 field in `struct sock` from `inet_bind()` and to IPv4 field from
`inet6_bind()` since those fields might not make sense in such cases.
Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

== The problem ==

See description of the problem in the initial patch of this patch set.

== The solution ==

The patch provides much more reliable in-kernel solution for the 2nd
part of the problem: making outgoing connecttion from desired IP.

It adds new attach types `BPF_CGROUP_INET4_CONNECT` and
`BPF_CGROUP_INET6_CONNECT` for program type
`BPF_PROG_TYPE_CGROUP_SOCK_ADDR` that can be used to override both
source and destination of a connection at connect(2) time.

Local end of connection can be bound to desired IP using newly
introduced BPF-helper `bpf_bind()`. It allows to bind to only IP though,
and doesn't support binding to port, i.e. leverages
`IP_BIND_ADDRESS_NO_PORT` socket option. There are two reasons for this:
* looking for a free port is expensive and can affect performance
  significantly;
* there is no use-case for port.

As for remote end (`struct sockaddr *` passed by user), both parts of it
can be overridden, remote IP and remote port. It's useful if an
application inside cgroup wants to connect to another application inside
same cgroup or to itself, but knows nothing about IP assigned to the
cgroup.

Support is added for IPv4 and IPv6, for TCP and UDP.

IPv4 and IPv6 have separate attach types for same reason as sys_bind
hooks, i.e. to prevent reading from / writing to e.g. user_ip6 fields
when user passes sockaddr_in since it'd be out-of-bound.

== Implementation notes ==

The patch introduces new field in `struct proto`: `pre_connect` that is
a pointer to a function with same signature as `connect` but is called
before it. The reason is in some cases BPF hooks should be called way
before control is passed to `sk->sk_prot->connect`. Specifically
`inet_dgram_connect` autobinds socket before calling
`sk->sk_prot->connect` and there is no way to call `bpf_bind()` from
hooks from e.g. `ip4_datagram_connect` or `ip6_datagram_connect` since
it'd cause double-bind. On the other hand `proto.pre_connect` provides a
flexible way to add BPF hooks for connect only for necessary `proto` and
call them at desired time before `connect`. Since `bpf_bind()` is
allowed to bind only to IP and autobind in `inet_dgram_connect` binds
only port there is no chance of double-bind.

bpf_bind() sets `force_bind_address_no_port` to bind to only IP despite
of value of `bind_address_no_port` socket field.

bpf_bind() sets `with_lock` to `false` when calling to __inet_bind()
and __inet6_bind() since all call-sites, where bpf_bind() is called,
already hold socket lock.
Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

== The problem ==

There is a use-case when all processes inside a cgroup should use one
single IP address on a host that has multiple IP configured.  Those
processes should use the IP for both ingress and egress, for TCP and UDP
traffic. So TCP/UDP servers should be bound to that IP to accept
incoming connections on it, and TCP/UDP clients should make outgoing
connections from that IP. It should not require changing application
code since it's often not possible.

Currently it's solved by intercepting glibc wrappers around syscalls
such as `bind(2)` and `connect(2)`. It's done by a shared library that
is preloaded for every process in a cgroup so that whenever TCP/UDP
server calls `bind(2)`, the library replaces IP in sockaddr before
passing arguments to syscall. When application calls `connect(2)` the
library transparently binds the local end of connection to that IP
(`bind(2)` with `IP_BIND_ADDRESS_NO_PORT` to avoid performance penalty).

Shared library approach is fragile though, e.g.:
* some applications clear env vars (incl. `LD_PRELOAD`);
* `/etc/ld.so.preload` doesn't help since some applications are linked
  with option `-z nodefaultlib`;
* other applications don't use glibc and there is nothing to intercept.

== The solution ==

The patch provides much more reliable in-kernel solution for the 1st
part of the problem: binding TCP/UDP servers on desired IP. It does not
depend on application environment and implementation details (whether
glibc is used or not).

It adds new eBPF program type `BPF_PROG_TYPE_CGROUP_SOCK_ADDR` and
attach types `BPF_CGROUP_INET4_BIND` and `BPF_CGROUP_INET6_BIND`
(similar to already existing `BPF_CGROUP_INET_SOCK_CREATE`).

The new program type is intended to be used with sockets (`struct sock`)
in a cgroup and provided by user `struct sockaddr`. Pointers to both of
them are parts of the context passed to programs of newly added types.

The new attach types provides hooks in `bind(2)` system call for both
IPv4 and IPv6 so that one can write a program to override IP addresses
and ports user program tries to bind to and apply such a program for
whole cgroup.

== Implementation notes ==

[1]
Separate attach types for `AF_INET` and `AF_INET6` are added
intentionally to prevent reading/writing to offsets that don't make
sense for corresponding socket family. E.g. if user passes `sockaddr_in`
it doesn't make sense to read from / write to `user_ip6[]` context
fields.

[2]
The write access to `struct bpf_sock_addr_kern` is implemented using
special field as an additional "register".

There are just two registers in `sock_addr_convert_ctx_access`: `src`
with value to write and `dst` with pointer to context that can't be
changed not to break later instructions. But the fields, allowed to
write to, are not available directly and to access them address of
corresponding pointer has to be loaded first. To get additional register
the 1st not used by `src` and `dst` one is taken, its content is saved
to `bpf_sock_addr_kern.tmp_reg`, then the register is used to load
address of pointer field, and finally the register's content is restored
from the temporary field after writing `src` value.
Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

== The problem ==

There are use-cases when a program of some type can be attached to
multiple attach points and those attach points must have different
permissions to access context or to call helpers.

E.g. context structure may have fields for both IPv4 and IPv6 but it
doesn't make sense to read from / write to IPv6 field when attach point
is somewhere in IPv4 stack.

Same applies to BPF-helpers: it may make sense to call some helper from
some attach point, but not from other for same prog type.

== The solution ==

Introduce `expected_attach_type` field in in `struct bpf_attr` for
`BPF_PROG_LOAD` command. If scenario described in "The problem" section
is the case for some prog type, the field will be checked twice:

1) At load time prog type is checked to see if attach type for it must
   be known to validate program permissions correctly. Prog will be
   rejected with EINVAL if it's the case and `expected_attach_type` is
   not specified or has invalid value.

2) At attach time `attach_type` is compared with `expected_attach_type`,
   if prog type requires to have one, and, if they differ, attach will
   be rejected with EINVAL.

The `expected_attach_type` is now available as part of `struct bpf_prog`
in both `bpf_verifier_ops->is_valid_access()` and
`bpf_verifier_ops->get_func_proto()` () and can be used to check context
accesses and calls to helpers correspondingly.

Initially the idea was discussed by Alexei Starovoitov <ast@fb.com> and
Daniel Borkmann <daniel@iogearbox.net> here:
https://marc.info/?l=linux-netdev&m=152107378717201&w=2Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access
kernel internal arguments of the tracepoints in their raw form.

>From bpf program point of view the access to the arguments look like:
struct bpf_raw_tracepoint_args {
       __u64 args[0];
};

int bpf_prog(struct bpf_raw_tracepoint_args *ctx)
{
  // program can read args[N] where N depends on tracepoint
  // and statically verified at program load+attach time
}

kprobe+bpf infrastructure allows programs access function arguments.
This feature allows programs access raw tracepoint arguments.

Similar to proposed 'dynamic ftrace events' there are no abi guarantees
to what the tracepoints arguments are and what their meaning is.
The program needs to type cast args properly and use bpf_probe_read()
helper to access struct fields when argument is a pointer.

For every tracepoint __bpf_trace_##call function is prepared.
In assembler it looks like:
(gdb) disassemble __bpf_trace_xdp_exception
Dump of assembler code for function __bpf_trace_xdp_exception:
   0xffffffff81132080 <+0>:     mov    %ecx,%ecx
   0xffffffff81132082 <+2>:     jmpq   0xffffffff811231f0 <bpf_trace_run3>

where

TRACE_EVENT(xdp_exception,
        TP_PROTO(const struct net_device *dev,
                 const struct bpf_prog *xdp, u32 act),

The above assembler snippet is casting 32-bit 'act' field into 'u64'
to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is.
All of ~500 of __bpf_trace_*() functions are only 5-10 byte long
and in total this approach adds 7k bytes to .text.

This approach gives the lowest possible overhead
while calling trace_xdp_exception() from kernel C code and
transitioning into bpf land.
Since tracepoint+bpf are used at speeds of 1M+ events per second
this is valuable optimization.

The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced
that returns anon_inode FD of 'bpf-raw-tracepoint' object.

The user space looks like:
// load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type
prog_fd = bpf_prog_load(...);
// receive anon_inode fd for given bpf_raw_tracepoint with prog attached
raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd);

Ctrl-C of tracing daemon or cmdline tool that uses this feature
will automatically detach bpf program, unload it and
unregister tracepoint probe.

On the kernel side the __bpf_raw_tp_map section of pointers to
tracepoint definition and to __bpf_trace_*() probe function is used
to find a tracepoint with "xdp_exception" name and
corresponding __bpf_trace_xdp_exception() probe function
which are passed to tracepoint_probe_register() to connect probe
with tracepoint.

Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf
tracepoint mechanisms. perf_event_open() can be used in parallel
on the same tracepoint.
Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted.
Each with its own bpf program. The kernel will execute
all tracepoint probes and all attached bpf programs.

In the future bpf_raw_tracepoints can be extended with
query/introspection logic.

__bpf_raw_tp_map section logic was contributed by Steven Rostedt
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Generally we do a preload before doing idr allocation. This also help
improve the allocation success rate in memory pressure.

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: NShaohua Li <shli@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

The current check statement in BPF syscall will do a capability check
for CAP_SYS_ADMIN before checking sysctl_unprivileged_bpf_disabled. This
code path will trigger unnecessary security hooks on capability checking
and cause false alarms on unprivileged process trying to get CAP_SYS_ADMIN
access. This can be resolved by simply switch the order of the statement
and CAP_SYS_ADMIN is not required anyway if unprivileged bpf syscall is
allowed.
Signed-off-by: NChenbo Feng <fengc@google.com>
Acked-by: NLorenzo Colitti <lorenzo@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This implements a BPF ULP layer to allow policy enforcement and
monitoring at the socket layer. In order to support this a new
program type BPF_PROG_TYPE_SK_MSG is used to run the policy at
the sendmsg/sendpage hook. To attach the policy to sockets a
sockmap is used with a new program attach type BPF_SK_MSG_VERDICT.

Similar to previous sockmap usages when a sock is added to a
sockmap, via a map update, if the map contains a BPF_SK_MSG_VERDICT
program type attached then the BPF ULP layer is created on the
socket and the attached BPF_PROG_TYPE_SK_MSG program is run for
every msg in sendmsg case and page/offset in sendpage case.

BPF_PROG_TYPE_SK_MSG Semantics/API:

BPF_PROG_TYPE_SK_MSG supports only two return codes SK_PASS and
SK_DROP. Returning SK_DROP free's the copied data in the sendmsg
case and in the sendpage case leaves the data untouched. Both cases
return -EACESS to the user. Returning SK_PASS will allow the msg to
be sent.

In the sendmsg case data is copied into kernel space buffers before
running the BPF program. The kernel space buffers are stored in a
scatterlist object where each element is a kernel memory buffer.
Some effort is made to coalesce data from the sendmsg call here.
For example a sendmsg call with many one byte iov entries will
likely be pushed into a single entry. The BPF program is run with
data pointers (start/end) pointing to the first sg element.

In the sendpage case data is not copied. We opt not to copy the
data by default here, because the BPF infrastructure does not
know what bytes will be needed nor when they will be needed. So
copying all bytes may be wasteful. Because of this the initial
start/end data pointers are (0,0). Meaning no data can be read or
written. This avoids reading data that may be modified by the
user. A new helper is added later in this series if reading and
writing the data is needed. The helper call will do a copy by
default so that the page is exclusively owned by the BPF call.

The verdict from the BPF_PROG_TYPE_SK_MSG applies to the entire msg
in the sendmsg() case and the entire page/offset in the sendpage case.
This avoids ambiguity on how to handle mixed return codes in the
sendmsg case. Again a helper is added later in the series if
a verdict needs to apply to multiple system calls and/or only
a subpart of the currently being processed message.

The helper msg_redirect_map() can be used to select the socket to
send the data on. This is used similar to existing redirect use
cases. This allows policy to redirect msgs.

Pseudo code simple example:

The basic logic to attach a program to a socket is as follows,

  // load the programs
  bpf_prog_load(SOCKMAP_TCP_MSG_PROG, BPF_PROG_TYPE_SK_MSG,
		&obj, &msg_prog);

  // lookup the sockmap
  bpf_map_msg = bpf_object__find_map_by_name(obj, "my_sock_map");

  // get fd for sockmap
  map_fd_msg = bpf_map__fd(bpf_map_msg);

  // attach program to sockmap
  bpf_prog_attach(msg_prog, map_fd_msg, BPF_SK_MSG_VERDICT, 0);

Adding sockets to the map is done in the normal way,

  // Add a socket 'fd' to sockmap at location 'i'
  bpf_map_update_elem(map_fd_msg, &i, fd, BPF_ANY);

After the above any socket attached to "my_sock_map", in this case
'fd', will run the BPF msg verdict program (msg_prog) on every
sendmsg and sendpage system call.

For a complete example see BPF selftests or sockmap samples.

Implementation notes:

It seemed the simplest, to me at least, to use a refcnt to ensure
psock is not lost across the sendmsg copy into the sg, the bpf program
running on the data in sg_data, and the final pass to the TCP stack.
Some performance testing may show a better method to do this and avoid
the refcnt cost, but for now use the simpler method.

Another item that will come after basic support is in place is
supporting MSG_MORE flag. At the moment we call sendpages even if
the MSG_MORE flag is set. An enhancement would be to collect the
pages into a larger scatterlist and pass down the stack. Notice that
bpf_tcp_sendmsg() could support this with some additional state saved
across sendmsg calls. I built the code to support this without having
to do refactoring work. Other features TBD include ZEROCOPY and the
TCP_RECV_QUEUE/TCP_NO_QUEUE support. This will follow initial series
shortly.

Future work could improve size limits on the scatterlist rings used
here. Currently, we use MAX_SKB_FRAGS simply because this was being
used already in the TLS case. Future work could extend the kernel sk
APIs to tune this depending on workload. This is a trade-off
between memory usage and throughput performance.
Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Make the code more readable.
Signed-off-by: NMickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Tell user space about device on which the map was created.
Unfortunate reality of user ABI makes sharing this code
with program offload difficult but the information is the
same.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

in order to improve test coverage allow socket_filter program type
to be run via bpf_prog_test_run command.
Since such programs can be loaded by non-root tighten
permissions for bpf_prog_test_run to be root only
to avoid surprises.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

For host JIT, there are "jited_len"/"bpf_func" fields in struct bpf_prog
used by all host JIT targets to get jited image and it's length. While for
offload, targets are likely to have different offload mechanisms that these
info are kept in device private data fields.

Therefore, BPF_OBJ_GET_INFO_BY_FD syscall needs an unified way to get JIT
length and contents info for offload targets.

One way is to introduce new callback to parse device private data then fill
those fields in bpf_prog_info. This might be a little heavy, the other way
is to add generic fields which will be initialized by all offload targets.

This patch follow the second approach to introduce two new fields in
struct bpf_dev_offload and teach bpf_prog_get_info_by_fd about them to fill
correct jited_prog_len and jited_prog_insns in bpf_prog_info.
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NJiong Wang <jiong.wang@netronome.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

BPF map offload follow similar path to program offload.  At creation
time users may specify ifindex of the device on which they want to
create the map.  Map will be validated by the kernel's
.map_alloc_check callback and device driver will be called for the
actual allocation.  Map will have an empty set of operations
associated with it (save for alloc and free callbacks).  The real
device callbacks are kept in map->offload->dev_ops because they
have slightly different signatures.  Map operations are called in
process context so the driver may communicate with HW freely,
msleep(), wait() etc.

Map alloc and free callbacks are muxed via existing .ndo_bpf, and
are always called with rtnl lock held.  Maps and programs are
guaranteed to be destroyed before .ndo_uninit (i.e. before
unregister_netdev() returns).  Map callbacks are invoked with
bpf_devs_lock *read* locked, drivers must take care of exclusive
locking if necessary.

All offload-specific branches are marked with unlikely() (through
bpf_map_is_dev_bound()), given that branch penalty will be
negligible compared to IO anyway, and we don't want to penalize
SW path unnecessarily.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

All map types reimplement the field-by-field copy of union bpf_attr
members into struct bpf_map.  Add a helper to perform this operation.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NQuentin Monnet <quentin.monnet@netronome.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

.map_alloc callbacks contain a number of checks validating user-
-provided map attributes against constraints of a particular map
type.  For offloaded maps we will need to check map attributes
without actually allocating any memory on the host.  Add a new
callback for validating attributes before any memory is allocated.
This callback can be selectively implemented by map types for
sharing code with offloads, or simply to separate the logical
steps of validation and allocation.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Descriptor table is a shared object; it's not a place where you can
stick temporary references to files, especially when we don't need
an opened file at all.

Cc: stable@vger.kernel.org # v4.14
Fixes: 98589a09 ("netfilter: xt_bpf: Fix XT_BPF_MODE_FD_PINNED mode of 'xt_bpf_info_v1'")
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>