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From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <martin.lau@kernel.org>
Subject: [PATCH bpf-next v5 11/12] selftests/bpf: Add dynptr partial slot overwrite tests
Date: Sat, 21 Jan 2023 05:52:40 +0530	[thread overview]
Message-ID: <20230121002241.2113993-12-memxor@gmail.com> (raw)
In-Reply-To: <20230121002241.2113993-1-memxor@gmail.com>

Try creating a dynptr, then overwriting second slot with first slot of
another dynptr. Then, the first slot of first dynptr should also be
invalidated, but without our fix that does not happen. As a consequence,
the unfixed case allows passing first dynptr (as the kernel check only
checks for slot_type and then first_slot == true).

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 .../testing/selftests/bpf/progs/dynptr_fail.c | 66 +++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c
index 2d899f2bebb0..1cbec5468879 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_fail.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c
@@ -834,3 +834,69 @@ int dynptr_var_off_overwrite(struct __sk_buff *ctx)
 	);
 	return 0;
 }
+
+SEC("?tc")
+__failure __msg("cannot overwrite referenced dynptr") __log_level(2)
+int dynptr_partial_slot_invalidate(struct __sk_buff *ctx)
+{
+	asm volatile (
+		"r6 = %[ringbuf] ll;			\
+		 r7 = %[array_map4] ll;			\
+		 r1 = r7;				\
+		 r2 = r10;				\
+		 r2 += -8;				\
+		 r9 = 0;				\
+		 *(u64 *)(r2 + 0) = r9;			\
+		 r3 = r2;				\
+		 r4 = 0;				\
+		 r8 = r2;				\
+		 call %[bpf_map_update_elem];		\
+		 r1 = r7;				\
+		 r2 = r8;				\
+		 call %[bpf_map_lookup_elem];		\
+		 if r0 != 0 goto sjmp1;			\
+		 exit;					\
+	sjmp1:						\
+		 r7 = r0;				\
+		 r1 = r6;				\
+		 r2 = 8;				\
+		 r3 = 0;				\
+		 r4 = r10;				\
+		 r4 += -24;				\
+		 call %[bpf_ringbuf_reserve_dynptr];	\
+		 *(u64 *)(r10 - 16) = r9;		\
+		 r1 = r7;				\
+		 r2 = 8;				\
+		 r3 = 0;				\
+		 r4 = r10;				\
+		 r4 += -16;				\
+		 call %[bpf_dynptr_from_mem];		\
+		 r1 = r10;				\
+		 r1 += -512;				\
+		 r2 = 488;				\
+		 r3 = r10;				\
+		 r3 += -24;				\
+		 r4 = 0;				\
+		 r5 = 0;				\
+		 call %[bpf_dynptr_read];		\
+		 r8 = 1;				\
+		 if r0 != 0 goto sjmp2;			\
+		 r8 = 0;				\
+	sjmp2:						\
+		 r1 = r10;				\
+		 r1 += -24;				\
+		 r2 = 0;				\
+		 call %[bpf_ringbuf_discard_dynptr];	"
+		:
+		: __imm(bpf_map_update_elem),
+		  __imm(bpf_map_lookup_elem),
+		  __imm(bpf_ringbuf_reserve_dynptr),
+		  __imm(bpf_ringbuf_discard_dynptr),
+		  __imm(bpf_dynptr_from_mem),
+		  __imm(bpf_dynptr_read),
+		  __imm_addr(ringbuf),
+		  __imm_addr(array_map4)
+		: __clobber_all
+	);
+	return 0;
+}
-- 
2.39.1


  parent reply	other threads:[~2023-01-21  0:25 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-21  0:22 [PATCH bpf-next v5 00/12] Dynptr fixes Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 01/12] bpf: Fix state pruning for STACK_DYNPTR stack slots Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 02/12] bpf: Fix missing var_off check for ARG_PTR_TO_DYNPTR Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 03/12] bpf: Fix partial dynptr stack slot reads/writes Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 04/12] bpf: Invalidate slices on destruction of dynptrs on stack Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 05/12] bpf: Allow reinitializing unreferenced dynptr stack slots Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 06/12] bpf: Combine dynptr_get_spi and is_spi_bounds_valid Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 07/12] bpf: Avoid recomputing spi in process_dynptr_func Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 08/12] selftests/bpf: convenience macro for use with 'asm volatile' blocks Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 09/12] selftests/bpf: Add dynptr pruning tests Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` [PATCH bpf-next v5 10/12] selftests/bpf: Add dynptr var_off tests Kumar Kartikeya Dwivedi
2023-01-21  0:22 ` Kumar Kartikeya Dwivedi [this message]
2023-01-21  0:22 ` [PATCH bpf-next v5 12/12] selftests/bpf: Add dynptr helper tests Kumar Kartikeya Dwivedi
2023-01-21  2:00 ` [PATCH bpf-next v5 00/12] Dynptr fixes Alexei Starovoitov
2023-01-21  2:10 ` patchwork-bot+netdevbpf

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