stddef: make __struct_group() UAPI C++-friendly

[ Upstream commit 724c6ce38bbaeb4b3f109b0e066d6c0ecd15446c ]

For the most part of the C++ history, it couldn't have type
declarations inside anonymou

stddef: make __struct_group() UAPI C++-friendly

[ Upstream commit 724c6ce38bbaeb4b3f109b0e066d6c0ecd15446c ]

For the most part of the C++ history, it couldn't have type
declarations inside anonymous unions for different reasons. At the
same time, __struct_group() relies on the latters, so when the @TAG
argument is not empty, C++ code doesn't want to build (even under
`extern "C"`):

../linux/include/uapi/linux/pkt_cls.h:25:24: error:
'struct tc_u32_sel::<unnamed union>::tc_u32_sel_hdr,' invalid;
an anonymous union may only have public non-static data members
[-fpermissive]

The safest way to fix this without trying to switch standards (which
is impossible in UAPI anyway) etc., is to disable tag declaration
for that language. This won't break anything since for now it's not
buildable at all.
Use a separate definition for __struct_group() when __cplusplus is
defined to mitigate the error, including the version from tools/.

Fixes: 50d7bd38c3aa ("stddef: Introduce struct_group() helper macro")
Reported-by: Christopher Ferris <cferris@google.com>
Closes: https://lore.kernel.org/linux-hardening/Z1HZpe3WE5As8UAz@google.com
Suggested-by: Kees Cook <kees@kernel.org> # __struct_group_tag()
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20241219135734.2130002-1-aleksander.lobakin@intel.com
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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bpf: Add cookie to perf_event bpf_link_info records

[ Upstream commit d5c16492c66fbfca85f36e42363d32212df5927b ]

At the moment we don't store cookie for perf_event probes,
while we do that for the

bpf: Add cookie to perf_event bpf_link_info records

[ Upstream commit d5c16492c66fbfca85f36e42363d32212df5927b ]

At the moment we don't store cookie for perf_event probes,
while we do that for the rest of the probes.

Adding cookie fields to struct bpf_link_info perf event
probe records:

perf_event.uprobe
perf_event.kprobe
perf_event.tracepoint
perf_event.perf_event

And the code to store that in bpf_link_info struct.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20240119110505.400573-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 4deecdd29cf2 ("bpf: fix unpopulated name_len field in perf_event link info")
Signed-off-by: Sasha Levin <sashal@kernel.org>

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bpf: Add missed value to kprobe perf link info

[ Upstream commit 3acf8ace68230e9558cf916847f1cc9f208abdf1 ]

Add missed value to kprobe attached through perf link info to
hold the stats of missed kp

bpf: Add missed value to kprobe perf link info

[ Upstream commit 3acf8ace68230e9558cf916847f1cc9f208abdf1 ]

Add missed value to kprobe attached through perf link info to
hold the stats of missed kprobe handler execution.

The kprobe's missed counter gets incremented when kprobe handler
is not executed due to another kprobe running on the same cpu.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230920213145.1941596-4-jolsa@kernel.org
Stable-dep-of: 4deecdd29cf2 ("bpf: fix unpopulated name_len field in perf_event link info")
Signed-off-by: Sasha Levin <sashal@kernel.org>

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bpf: Replace bpf_lpm_trie_key 0-length array with flexible array

[ Upstream commit 896880ff30866f386ebed14ab81ce1ad3710cfc4 ]

Replace deprecated 0-length array in struct bpf_lpm_trie_key with
flexi

bpf: Replace bpf_lpm_trie_key 0-length array with flexible array

[ Upstream commit 896880ff30866f386ebed14ab81ce1ad3710cfc4 ]

Replace deprecated 0-length array in struct bpf_lpm_trie_key with
flexible array. Found with GCC 13:

../kernel/bpf/lpm_trie.c:207:51: warning: array subscript i is outside array bounds of 'const __u8[0]' {aka 'const unsigned char[]'} [-Warray-bounds=]
207 | *(__be16 *)&key->data[i]);
| ^~~~~~~~~~~~~
../include/uapi/linux/swab.h:102:54: note: in definition of macro '__swab16'
102 | #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
| ^
../include/linux/byteorder/generic.h:97:21: note: in expansion of macro '__be16_to_cpu'
97 | #define be16_to_cpu __be16_to_cpu
| ^~~~~~~~~~~~~
../kernel/bpf/lpm_trie.c:206:28: note: in expansion of macro 'be16_to_cpu'
206 | u16 diff = be16_to_cpu(*(__be16 *)&node->data[i]
^
| ^~~~~~~~~~~
In file included from ../include/linux/bpf.h:7:
../include/uapi/linux/bpf.h:82:17: note: while referencing 'data'
82 | __u8 data[0]; /* Arbitrary size */
| ^~~~

And found at run-time under CONFIG_FORTIFY_SOURCE:

UBSAN: array-index-out-of-bounds in kernel/bpf/lpm_trie.c:218:49
index 0 is out of range for type '__u8 [*]'

Changing struct bpf_lpm_trie_key is difficult since has been used by
userspace. For example, in Cilium:

struct egress_gw_policy_key {
struct bpf_lpm_trie_key lpm_key;
__u32 saddr;
__u32 daddr;
};

While direct references to the "data" member haven't been found, there
are static initializers what include the final member. For example,
the "{}" here:

struct egress_gw_policy_key in_key = {
.lpm_key = { 32 + 24, {} },
.saddr = CLIENT_IP,
.daddr = EXTERNAL_SVC_IP & 0Xffffff,
};

To avoid the build time and run time warnings seen with a 0-sized
trailing array for struct bpf_lpm_trie_key, introduce a new struct
that correctly uses a flexible array for the trailing bytes,
struct bpf_lpm_trie_key_u8. As part of this, include the "header"
portion (which is just the "prefixlen" member), so it can be used
by anything building a bpf_lpr_trie_key that has trailing members that
aren't a u8 flexible array (like the self-test[1]), which is named
struct bpf_lpm_trie_key_hdr.

Unfortunately, C++ refuses to parse the __struct_group() helper, so
it is not possible to define struct bpf_lpm_trie_key_hdr directly in
struct bpf_lpm_trie_key_u8, so we must open-code the union directly.

Adjust the kernel code to use struct bpf_lpm_trie_key_u8 through-out,
and for the selftest to use struct bpf_lpm_trie_key_hdr. Add a comment
to the UAPI header directing folks to the two new options.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Closes: https://paste.debian.net/hidden/ca500597/
Link: https://lore.kernel.org/all/202206281009.4332AA33@keescook/ [1]
Link: https://lore.kernel.org/bpf/20240222155612.it.533-kees@kernel.org
Stable-dep-of: 59f2f841179a ("bpf: Avoid kfree_rcu() under lock in bpf_lpm_trie.")
Signed-off-by: Sasha Levin <sashal@kernel.org>

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