Merge branch 'Dynptr Verifier Adjustments'

Daniel Rosenberg says:

====================
These patches relax a few verifier requirements around dynptrs.
Patches 1-3 are unchanged from v2, apart from rebasing
Patch 4 is the same as in v1, see
https://lore.kernel.org/bpf/CA+PiJmST4WUH061KaxJ4kRL=fqy3X6+Wgb2E2rrLT5OYjUzxfQ@mail.gmail.com/
Patch 5 adds a test for the change in Patch 4
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

3 files changed, 60 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c
index 0478916aff37..7cfac53c0d58 100644
--- a/tools/testing/selftests/bpf/prog_tests/dynptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c
@@ -26,6 +26,8 @@ static struct {
 	{"test_dynptr_is_null", SETUP_SYSCALL_SLEEP},
 	{"test_dynptr_is_rdonly", SETUP_SKB_PROG},
 	{"test_dynptr_clone", SETUP_SKB_PROG},
+	{"test_dynptr_skb_no_buff", SETUP_SKB_PROG},
+	{"test_dynptr_skb_strcmp", SETUP_SKB_PROG},
 };
 
 static void verify_success(const char *prog_name, enum test_setup_type setup_type)
diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c
index efe4ce72d00e..c2f0e18af951 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_fail.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c
@@ -1665,3 +1665,23 @@ int clone_xdp_packet_data(struct xdp_md *xdp)
 
 	return 0;
 }
+
+/* Buffers that are provided must be sufficiently long */
+SEC("?cgroup_skb/egress")
+__failure __msg("memory, len pair leads to invalid memory access")
+int test_dynptr_skb_small_buff(struct __sk_buff *skb)
+{
+	struct bpf_dynptr ptr;
+	char buffer[8] = {};
+	__u64 *data;
+
+	if (bpf_dynptr_from_skb(skb, 0, &ptr)) {
+		err = 1;
+		return 1;
+	}
+
+	/* This may return NULL. SKB may require a buffer */
+	data = bpf_dynptr_slice(&ptr, 0, buffer, 9);
+
+	return !!data;
+}
diff --git a/tools/testing/selftests/bpf/progs/dynptr_success.c b/tools/testing/selftests/bpf/progs/dynptr_success.c
index be7de62de045..0c053976f8f9 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_success.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_success.c
@@ -505,3 +505,41 @@ int test_dynptr_clone(struct __sk_buff *skb)
 
 	return 0;
 }
+
+SEC("?cgroup_skb/egress")
+int test_dynptr_skb_no_buff(struct __sk_buff *skb)
+{
+	struct bpf_dynptr ptr;
+	__u64 *data;
+
+	if (bpf_dynptr_from_skb(skb, 0, &ptr)) {
+		err = 1;
+		return 1;
+	}
+
+	/* This may return NULL. SKB may require a buffer */
+	data = bpf_dynptr_slice(&ptr, 0, NULL, 1);
+
+	return !!data;
+}
+
+SEC("?cgroup_skb/egress")
+int test_dynptr_skb_strcmp(struct __sk_buff *skb)
+{
+	struct bpf_dynptr ptr;
+	char *data;
+
+	if (bpf_dynptr_from_skb(skb, 0, &ptr)) {
+		err = 1;
+		return 1;
+	}
+
+	/* This may return NULL. SKB may require a buffer */
+	data = bpf_dynptr_slice(&ptr, 0, NULL, 10);
+	if (data) {
+		bpf_strncmp(data, 10, "foo");
+		return 1;
+	}
+
+	return 1;
+}