selftests/bpf: Test packet range of pointers sharing an idgrafted

Add tests where two packet pointers share an id and tightening one
pointer's umax from its var_off would put it less than their constant
distance from the other's umax: with an index & 0x38 capped at 50, the
base pointer keeps umax 50, so the pointer 8 bytes further on must keep
umax 58, even though its known bits allow at most 56.

These refused a valid program or accepted an out-of-bounds access before
the fix:

- check the advanced copy, load through the base: valid, was refused;
- check the base, load the byte at base + 1 through a copy advanced by
  8: was accepted;
- check base + 4, load 4 bytes at base + 2 through base + 8: reads two
  bytes past the checked range, was accepted;
- the same as the second with data_meta pointers checked against data:
  was accepted.

These pass with and without the fix and cover nearby paths:

- subtract an unknown scalar from a checked pointer and load below it
  (the range is kept across a new id);
- reach a load through two paths whose checks cover 8 and 7 bytes after
  the loaded pointer; the second path must not be pruned by the first;
- spill a copy of a pointer, check the pointer, fill the copy and load
  one byte past the checked range: the load is refused, and the copy
  has the range of the check.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 77 insertions, 0 deletions

diff --git a/include/net/calipso.h b/include/net/calipso.h
new file mode 100644
index 000000000..76b9e08c1
--- /dev/null
+++ b/include/net/calipso.h
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * CALIPSO - Common Architecture Label IPv6 Security Option
+ *
+ * This is an implementation of the CALIPSO protocol as specified in
+ * RFC 5570.
+ *
+ * Authors: Paul Moore <paul@paul-moore.com>
+ *          Huw Davies <huw@codeweavers.com>
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
+ * (c) Copyright Huw Davies <huw@codeweavers.com>, 2015
+ */
+
+#ifndef _CALIPSO_H
+#define _CALIPSO_H
+
+#include <linux/types.h>
+#include <linux/rcupdate.h>
+#include <linux/list.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <net/netlabel.h>
+#include <net/request_sock.h>
+#include <linux/refcount.h>
+#include <linux/unaligned.h>
+
+/* known doi values */
+#define CALIPSO_DOI_UNKNOWN          0x00000000
+
+/* doi mapping types */
+#define CALIPSO_MAP_UNKNOWN          0
+#define CALIPSO_MAP_PASS             2
+
+/*
+ * CALIPSO DOI definitions
+ */
+
+/* DOI definition struct */
+struct calipso_doi {
+	u32 doi;
+	u32 type;
+
+	refcount_t refcount;
+	struct list_head list;
+	struct rcu_head rcu;
+};
+
+/*
+ * Sysctl Variables
+ */
+extern int calipso_cache_enabled;
+extern int calipso_cache_bucketsize;
+
+#ifdef CONFIG_NETLABEL
+int __init calipso_init(void);
+void calipso_exit(void);
+bool calipso_validate(const struct sk_buff *skb, const unsigned char *option);
+#else
+static inline int __init calipso_init(void)
+{
+	return 0;
+}
+
+static inline void calipso_exit(void)
+{
+}
+static inline bool calipso_validate(const struct sk_buff *skb,
+				    const unsigned char *option)
+{
+	return true;
+}
+#endif /* CONFIG_NETLABEL */
+
+#endif /* _CALIPSO_H */