Adjust the XDP feature flags for the bond device when no bond slave
devices are attached. After 9b0ed890ac2a ("bonding: do not report
NETDEV_XDP_ACT_XSK_ZEROCOPY"), the empty bond device must report 0
as flags instead of NETDEV_XDP_ACT_MASK.

  # ./vmtest.sh -- ./test_progs -t xdp_bond
  [...]
  [    3.983311] bond1 (unregistering): (slave veth1_1): Releasing backup interface
  [    3.995434] bond1 (unregistering): Released all slaves
  [    4.022311] bond2: (slave veth2_1): Releasing backup interface
  #507/1   xdp_bonding/xdp_bonding_attach:OK
  #507/2   xdp_bonding/xdp_bonding_nested:OK
  #507/3   xdp_bonding/xdp_bonding_features:OK
  #507/4   xdp_bonding/xdp_bonding_roundrobin:OK
  #507/5   xdp_bonding/xdp_bonding_activebackup:OK
  #507/6   xdp_bonding/xdp_bonding_xor_layer2:OK
  #507/7   xdp_bonding/xdp_bonding_xor_layer23:OK
  #507/8   xdp_bonding/xdp_bonding_xor_layer34:OK
  #507/9   xdp_bonding/xdp_bonding_redirect_multi:OK
  #507     xdp_bonding:OK
  Summary: 1/9 PASSED, 0 SKIPPED, 0 FAILED
  [    4.185255] bond2 (unregistering): Released all slaves
  [...]

Fixes: 9b0ed890ac2a ("bonding: do not report NETDEV_XDP_ACT_XSK_ZEROCOPY")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Message-ID: <20240305090829.17131-2-daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

The test case was minimized from mailing list discussion [0].
It is equivalent to the following C program:

    struct iter_limit_bug_ctx { __u64 a; __u64 b; __u64 c; };

    static __naked void iter_limit_bug_cb(void)
    {
    	switch (bpf_get_prandom_u32()) {
    	case 1:  ctx->a = 42; break;
    	case 2:  ctx->b = 42; break;
    	default: ctx->c = 42; break;
    	}
    }

    int iter_limit_bug(struct __sk_buff *skb)
    {
    	struct iter_limit_bug_ctx ctx = { 7, 7, 7 };

    	bpf_loop(2, iter_limit_bug_cb, &ctx, 0);
    	if (ctx.a == 42 && ctx.b == 42 && ctx.c == 7)
    	  asm volatile("r1 /= 0;":::"r1");
    	return 0;
    }

The main idea is that each loop iteration changes one of the state
variables in a non-deterministic manner. Hence it is premature to
prune the states that have two iterations left comparing them to
states with one iteration left.
E.g. {{7,7,7}, callback_depth=0} can reach state {42,42,7},
while {{7,7,7}, callback_depth=1} can't.

[0] https://lore.kernel.org/bpf/9b251840-7cb8-4d17-bd23-1fc8071d8eef@linux.dev/

Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240222154121.6991-3-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Incorporate a test case to assess the handling of invalid flags or
task__nullable parameters passed to bpf_iter_task_new(). Prior to the
preceding commit, this scenario could potentially trigger a kernel panic.
However, with the previous commit, this test case is expected to function
correctly.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240217114152.1623-3-laoar.shao@gmail.com

This selftest is based on a Alexei's test adopted from an internal
user to troubleshoot another bug. During this exercise, a separate
racing bug was discovered between bpf_timer_cancel_and_free
and bpf_timer_cancel. The details can be found in the previous
patch.

This patch is to add a selftest that can trigger the bug.
I can trigger the UAF everytime in my qemu setup with KASAN. The idea
is to have multiple user space threads running in a tight loop to exercise
both bpf_map_update_elem (which calls into bpf_timer_cancel_and_free)
and bpf_timer_cancel.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20240215211218.990808-2-martin.lau@linux.dev

Under x86-64, when using bpf_probe_read_kernel{_str}() or
bpf_probe_read{_str}() to read vsyscall page, the read may trigger oops,
so add one test case to ensure that the problem is fixed. Beside those
four bpf helpers mentioned above, testing the read of vsyscall page by
using bpf_probe_read_user{_str} and bpf_copy_from_user{_task}() as well.

The test case passes the address of vsyscall page to these six helpers
and checks whether the returned values are expected:

1) For bpf_probe_read_kernel{_str}()/bpf_probe_read{_str}(), the
   expected return value is -ERANGE as shown below:

bpf_probe_read_kernel_common
  copy_from_kernel_nofault
    // false, return -ERANGE
    copy_from_kernel_nofault_allowed

2) For bpf_probe_read_user{_str}(), the expected return value is -EFAULT
   as show below:

bpf_probe_read_user_common
  copy_from_user_nofault
    // false, return -EFAULT
    __access_ok

3) For bpf_copy_from_user(), the expected return value is -EFAULT:

// return -EFAULT
bpf_copy_from_user
  copy_from_user
    _copy_from_user
      // return false
      access_ok

4) For bpf_copy_from_user_task(), the expected return value is -EFAULT:

// return -EFAULT
bpf_copy_from_user_task
  access_process_vm
    // return 0
    vma_lookup()
    // return 0
    expand_stack()

The occurrence of oops depends on the availability of CPU SMAP [1]
feature and there are three possible configurations of vsyscall page in
the boot cmd-line: vsyscall={xonly|none|emulate}, so there are a total
of six possible combinations. Under all these combinations, the test
case runs successfully.

[1]: https://en.wikipedia.org/wiki/Supervisor_Mode_Access_Prevention

Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20240202103935.3154011-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Add a bunch of global subprogs across variety of program types to
validate expected kernel type enforcement logic for __arg_ctx arguments.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240118033143.3384355-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Add feature detector of kernel-side arg:ctx (__arg_ctx) tag support. If
this is detected, libbpf will avoid doing any __arg_ctx-related BTF
rewriting and checks in favor of letting kernel handle this completely.

test_global_funcs/ctx_arg_rewrite subtest is adjusted to do the same
feature detection (albeit in much simpler, though round-about and
inefficient, way), and skip the tests. This is done to still be able to
execute this test on older kernels (like in libbpf CI).

Note, BPF token series ([0]) does a major refactor and code moving of
libbpf-internal feature detection "framework", so to avoid unnecessary
conflicts we keep newly added feature detection stand-alone with ad-hoc
result caching. Once things settle, there will be a small follow up to
re-integrate everything back and move code into its final place in
newly-added (by BPF token series) features.c file.

  [0] https://patchwork.kernel.org/project/netdevbpf/list/?series=814209&state=*

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240118033143.3384355-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Add a test case for PTR_TO_FLOW_KEYS alu. Testing if alu with variable
offset on flow_keys is rejected. For the fixed offset success case, we
already have C code coverage to verify (e.g. via bpf_flow.c).

Signed-off-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240115082028.9992-2-sunhao.th@gmail.com

The patch adds a test to exercise the bpf_iter_udp batching
logic. It specifically tests the case that there are multiple
so_reuseport udp_sk in a bucket of the udp_table.

The test creates two sets of so_reuseport sockets and
each set on a different port. Meaning there will be
two buckets in the udp_table.

The test does the following:
1. read() 3 out of 4 sockets in the first bucket.
2. close() all sockets in the first bucket. This
   will ensure the current bucket's offset in
   the kernel does not affect the read() of the
   following bucket.
3. read() all 4 sockets in the second bucket.

The test also reads one udp_sk at a time from
the bpf_iter_udp prog. The true case in
"do_test(..., bool onebyone)". This is the buggy case
that the previous patch fixed.

It also tests the "false" case in "do_test(..., bool onebyone)",
meaning the userspace reads the whole bucket. There is
no bug in this case but adding this test also while
at it.

Considering the way to have multiple tcp_sk in the same
bucket is similar (by using so_reuseport),
this patch also tests the bpf_iter_tcp even though the
bpf_iter_tcp batching logic works correctly.

Both IP v4 and v6 are exercising the same bpf_iter batching
code path, so only v6 is tested.

Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240112190530.3751661-4-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Add a test case to verify the fix for "prog->aux->dst_trampoline and
tgt_prog is NULL" branch in bpf_tracing_prog_attach. The sequence of
events:

1. load rawtp program
2. load fentry program with rawtp as target_fd
3. create tracing link for fentry program with target_fd = 0
4. repeat 3

Acked-by: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com>
Link: https://lore.kernel.org/r/20240103190559.14750-5-9erthalion6@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>