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, 48 insertions, 0 deletions

diff --git a/rust/helpers/security.c b/rust/helpers/security.c
new file mode 100644
index 000000000..8d0a25fcf
--- /dev/null
+++ b/rust/helpers/security.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/security.h>
+
+#ifndef CONFIG_SECURITY
+__rust_helper void rust_helper_security_cred_getsecid(const struct cred *c,
+						      u32 *secid)
+{
+	security_cred_getsecid(c, secid);
+}
+
+__rust_helper int rust_helper_security_secid_to_secctx(u32 secid,
+						       struct lsm_context *cp)
+{
+	return security_secid_to_secctx(secid, cp);
+}
+
+__rust_helper void rust_helper_security_release_secctx(struct lsm_context *cp)
+{
+	security_release_secctx(cp);
+}
+
+__rust_helper int
+rust_helper_security_binder_set_context_mgr(const struct cred *mgr)
+{
+	return security_binder_set_context_mgr(mgr);
+}
+
+__rust_helper int
+rust_helper_security_binder_transaction(const struct cred *from,
+					const struct cred *to)
+{
+	return security_binder_transaction(from, to);
+}
+
+__rust_helper int
+rust_helper_security_binder_transfer_binder(const struct cred *from,
+					    const struct cred *to)
+{
+	return security_binder_transfer_binder(from, to);
+}
+
+__rust_helper int rust_helper_security_binder_transfer_file(
+	const struct cred *from, const struct cred *to, const struct file *file)
+{
+	return security_binder_transfer_file(from, to, file);
+}
+#endif