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authorBjörn Töpel <bjorn.topel@gmail.com>2020-11-18 08:16:39 +0100
committerAndrii Nakryiko <andrii@kernel.org>2020-11-18 17:45:31 -0800
commitc77b0589ca29ad1859fe7d7c1ecd63c0632379fa (patch)
tree09ca5ed441c0f0a43ef3000b7a86b2224fc49185
parent6016df8fe874e1cf36f6357d71438b384198ce06 (diff)
selftests/bpf: Avoid running unprivileged tests with alignment requirements
Some architectures have strict alignment requirements. In that case, the BPF verifier detects if a program has unaligned accesses and rejects them. A user can pass BPF_F_ANY_ALIGNMENT to a program to override this check. That, however, will only work when a privileged user loads a program. An unprivileged user loading a program with this flag will be rejected prior entering the verifier. Hence, it does not make sense to load unprivileged programs without strict alignment when testing the verifier. This patch avoids exactly that. Signed-off-by: Björn Töpel <bjorn.topel@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Luke Nelson <luke.r.nels@gmail.com> Link: https://lore.kernel.org/bpf/20201118071640.83773-3-bjorn.topel@gmail.com
-rw-r--r--tools/testing/selftests/bpf/test_verifier.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 9be395d9dc64..4bfe3aa2cfc4 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -1152,6 +1152,19 @@ static void get_unpriv_disabled()
static bool test_as_unpriv(struct bpf_test *test)
{
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+ /* Some architectures have strict alignment requirements. In
+ * that case, the BPF verifier detects if a program has
+ * unaligned accesses and rejects them. A user can pass
+ * BPF_F_ANY_ALIGNMENT to a program to override this
+ * check. That, however, will only work when a privileged user
+ * loads a program. An unprivileged user loading a program
+ * with this flag will be rejected prior entering the
+ * verifier.
+ */
+ if (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS)
+ return false;
+#endif
return !test->prog_type ||
test->prog_type == BPF_PROG_TYPE_SOCKET_FILTER ||
test->prog_type == BPF_PROG_TYPE_CGROUP_SKB;