From: Frank van der Linden <fllinden@amazon.com>
To: <stable@vger.kernel.org>
Cc: <bpf@vger.kernel.org>, <daniel@iogearbox.net>
Subject: [PATCH v2 4.14 06/17] bpf: Refactor and streamline bounds check into helper
Date: Mon, 31 May 2021 18:25:45 +0000 [thread overview]
Message-ID: <20210531182556.25277-7-fllinden@amazon.com> (raw)
In-Reply-To: <20210531182556.25277-1-fllinden@amazon.com>
From: Daniel Borkmann <daniel@iogearbox.net>
commit 073815b756c51ba9d8384d924c5d1c03ca3d1ae4 upstream.
Move the bounds check in adjust_ptr_min_max_vals() into a small helper named
sanitize_check_bounds() in order to simplify the former a bit.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
[fllinden@amazon.com: backport to 4.14]
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
---
kernel/bpf/verifier.c | 54 +++++++++++++++++++++++++++++--------------
1 file changed, 37 insertions(+), 17 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b44a4efeb1be..d178098f2298 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2206,6 +2206,41 @@ static int sanitize_err(struct bpf_verifier_env *env,
return -EACCES;
}
+static int sanitize_check_bounds(struct bpf_verifier_env *env,
+ const struct bpf_insn *insn,
+ const struct bpf_reg_state *dst_reg)
+{
+ u32 dst = insn->dst_reg;
+
+ /* For unprivileged we require that resulting offset must be in bounds
+ * in order to be able to sanitize access later on.
+ */
+ if (env->allow_ptr_leaks)
+ return 0;
+
+ switch (dst_reg->type) {
+ case PTR_TO_STACK:
+ if (check_stack_access(env, dst_reg, dst_reg->off +
+ dst_reg->var_off.value, 1)) {
+ verbose("R%d stack pointer arithmetic goes out of range, "
+ "prohibited for !root\n", dst);
+ return -EACCES;
+ }
+ break;
+ case PTR_TO_MAP_VALUE:
+ if (check_map_access(env, dst, dst_reg->off, 1)) {
+ verbose("R%d pointer arithmetic of map value goes out of range, "
+ "prohibited for !root\n", dst);
+ return -EACCES;
+ }
+ break;
+ default:
+ break;
+ }
+
+ return 0;
+}
+
/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
* Caller should also handle BPF_MOV case separately.
* If we return -EACCES, caller may want to try again treating pointer as a
@@ -2421,23 +2456,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
__reg_deduce_bounds(dst_reg);
__reg_bound_offset(dst_reg);
- /* For unprivileged we require that resulting offset must be in bounds
- * in order to be able to sanitize access later on.
- */
- if (!env->allow_ptr_leaks) {
- if (dst_reg->type == PTR_TO_MAP_VALUE &&
- check_map_access(env, dst, dst_reg->off, 1)) {
- verbose("R%d pointer arithmetic of map value goes out of range, "
- "prohibited for !root\n", dst);
- return -EACCES;
- } else if (dst_reg->type == PTR_TO_STACK &&
- check_stack_access(env, dst_reg, dst_reg->off +
- dst_reg->var_off.value, 1)) {
- verbose("R%d stack pointer arithmetic goes out of range, "
- "prohibited for !root\n", dst);
- return -EACCES;
- }
- }
+ if (sanitize_check_bounds(env, insn, dst_reg) < 0)
+ return -EACCES;
return 0;
}
--
2.23.4
next prev parent reply other threads:[~2021-05-31 18:26 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-31 18:25 [PATCH v2 4.14 00/16] CVE fixes and selftests cleanup Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 01/17] bpf, selftests: Fix up some test_verifier cases for unprivileged Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 02/17] bpf: Move off_reg into sanitize_ptr_alu Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 03/17] bpf: Ensure off_reg has no mixed signed bounds for all types Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 04/17] bpf: Rework ptr_limit into alu_limit and add common error path Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 05/17] bpf: Improve verifier error messages for users Frank van der Linden
2021-05-31 18:25 ` Frank van der Linden [this message]
2021-05-31 18:25 ` [PATCH v2 4.14 07/17] bpf: Move sanitize_val_alu out of op switch Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 08/17] bpf: Tighten speculative pointer arithmetic mask Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 09/17] bpf: Update selftests to reflect new error states Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 10/17] bpf: do not allow root to mangle valid pointers Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 11/17] bpf/verifier: disallow pointer subtraction Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 12/17] selftests/bpf: fix test_align Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 13/17] selftests/bpf: make 'dubious pointer arithmetic' test useful Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 14/17] bpf: Fix leakage of uninitialized bpf stack under speculation Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 15/17] bpf: Wrap aux data inside bpf_sanitize_info container Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 16/17] bpf: Fix mask direction swap upon off reg sign change Frank van der Linden
2021-05-31 18:25 ` [PATCH v2 4.14 17/17] bpf: No need to simulate speculative domain for immediates Frank van der Linden
2021-06-08 14:48 ` [PATCH v2 4.14 00/16] CVE fixes and selftests cleanup Greg KH
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