bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 156 insertions, 0 deletions

diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h
new file mode 100644
index 000000000..ae05cc8e4
--- /dev/null
+++ b/security/selinux/ss/ebitmap.h
@@ -0,0 +1,156 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * An extensible bitmap is a bitmap that supports an
+ * arbitrary number of bits.  Extensible bitmaps are
+ * used to represent sets of values, such as types,
+ * roles, categories, and classes.
+ *
+ * Each extensible bitmap is implemented as a linked
+ * list of bitmap nodes, where each bitmap node has
+ * an explicitly specified starting bit position within
+ * the total bitmap.
+ *
+ * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
+ */
+
+#ifndef _SS_EBITMAP_H_
+#define _SS_EBITMAP_H_
+
+#include <net/netlabel.h>
+
+#ifdef CONFIG_64BIT
+#define EBITMAP_NODE_SIZE 64
+#else
+#define EBITMAP_NODE_SIZE 32
+#endif
+
+#define EBITMAP_UNIT_NUMS                                     \
+	((EBITMAP_NODE_SIZE - sizeof(void *) - sizeof(u32)) / \
+	 sizeof(unsigned long))
+#define EBITMAP_UNIT_SIZE BITS_PER_LONG
+#define EBITMAP_SIZE	  (EBITMAP_UNIT_NUMS * EBITMAP_UNIT_SIZE)
+#define EBITMAP_BIT	  1UL
+#define EBITMAP_SHIFT_UNIT_SIZE(x) \
+	(((x) >> EBITMAP_UNIT_SIZE / 2) >> EBITMAP_UNIT_SIZE / 2)
+
+struct ebitmap_node {
+	struct ebitmap_node *next;
+	unsigned long maps[EBITMAP_UNIT_NUMS];
+	u32 startbit;
+};
+
+struct ebitmap {
+	struct ebitmap_node *node; /* first node in the bitmap */
+	u32 highbit; /* highest position in the total bitmap */
+};
+
+#define ebitmap_length(e) ((e)->highbit)
+
+static inline u32 ebitmap_start_positive(const struct ebitmap *e,
+					 struct ebitmap_node **n)
+{
+	u32 ofs;
+
+	for (*n = e->node; *n; *n = (*n)->next) {
+		ofs = find_first_bit((*n)->maps, EBITMAP_SIZE);
+		if (ofs < EBITMAP_SIZE)
+			return (*n)->startbit + ofs;
+	}
+	return ebitmap_length(e);
+}
+
+static inline void ebitmap_init(struct ebitmap *e)
+{
+	memset(e, 0, sizeof(*e));
+}
+
+static inline u32 ebitmap_next_positive(const struct ebitmap *e,
+					struct ebitmap_node **n, u32 bit)
+{
+	u32 ofs;
+
+	ofs = find_next_bit((*n)->maps, EBITMAP_SIZE, bit - (*n)->startbit + 1);
+	if (ofs < EBITMAP_SIZE)
+		return ofs + (*n)->startbit;
+
+	for (*n = (*n)->next; *n; *n = (*n)->next) {
+		ofs = find_first_bit((*n)->maps, EBITMAP_SIZE);
+		if (ofs < EBITMAP_SIZE)
+			return ofs + (*n)->startbit;
+	}
+	return ebitmap_length(e);
+}
+
+#define EBITMAP_NODE_INDEX(node, bit) \
+	(((bit) - (node)->startbit) / EBITMAP_UNIT_SIZE)
+#define EBITMAP_NODE_OFFSET(node, bit) \
+	(((bit) - (node)->startbit) % EBITMAP_UNIT_SIZE)
+
+static inline int ebitmap_node_get_bit(const struct ebitmap_node *n, u32 bit)
+{
+	u32 index = EBITMAP_NODE_INDEX(n, bit);
+	u32 ofs = EBITMAP_NODE_OFFSET(n, bit);
+
+	BUG_ON(index >= EBITMAP_UNIT_NUMS);
+	if ((n->maps[index] & (EBITMAP_BIT << ofs)))
+		return 1;
+	return 0;
+}
+
+static inline void ebitmap_node_set_bit(struct ebitmap_node *n, u32 bit)
+{
+	u32 index = EBITMAP_NODE_INDEX(n, bit);
+	u32 ofs = EBITMAP_NODE_OFFSET(n, bit);
+
+	BUG_ON(index >= EBITMAP_UNIT_NUMS);
+	n->maps[index] |= (EBITMAP_BIT << ofs);
+}
+
+static inline void ebitmap_node_clr_bit(struct ebitmap_node *n, u32 bit)
+{
+	u32 index = EBITMAP_NODE_INDEX(n, bit);
+	u32 ofs = EBITMAP_NODE_OFFSET(n, bit);
+
+	BUG_ON(index >= EBITMAP_UNIT_NUMS);
+	n->maps[index] &= ~(EBITMAP_BIT << ofs);
+}
+
+#define ebitmap_for_each_positive_bit(e, n, bit)      \
+	for ((bit) = ebitmap_start_positive(e, &(n)); \
+	     (bit) < ebitmap_length(e);               \
+	     (bit) = ebitmap_next_positive(e, &(n), bit))
+
+bool ebitmap_equal(const struct ebitmap *e1, const struct ebitmap *e2);
+int ebitmap_cpy(struct ebitmap *dst, const struct ebitmap *src);
+int ebitmap_and(struct ebitmap *dst, const struct ebitmap *e1,
+		const struct ebitmap *e2);
+int ebitmap_contains(const struct ebitmap *e1, const struct ebitmap *e2,
+		     u32 last_e2bit);
+u32 ebitmap_get_highest_set_bit(const struct ebitmap *e);
+int ebitmap_get_bit(const struct ebitmap *e, u32 bit);
+int ebitmap_set_bit(struct ebitmap *e, u32 bit, int value);
+void ebitmap_destroy(struct ebitmap *e);
+struct policy_file;
+int ebitmap_read(struct ebitmap *e, struct policy_file *fp);
+int ebitmap_write(const struct ebitmap *e, struct policy_file *fp);
+u32 ebitmap_hash(const struct ebitmap *e, u32 hash);
+
+#ifdef CONFIG_NETLABEL
+int ebitmap_netlbl_export(struct ebitmap *ebmap,
+			  struct netlbl_lsm_catmap **catmap);
+int ebitmap_netlbl_import(struct ebitmap *ebmap,
+			  struct netlbl_lsm_catmap *catmap);
+#else
+static inline int ebitmap_netlbl_export(struct ebitmap *ebmap,
+					struct netlbl_lsm_catmap **catmap)
+{
+	return -ENOMEM;
+}
+static inline int ebitmap_netlbl_import(struct ebitmap *ebmap,
+					struct netlbl_lsm_catmap *catmap)
+{
+	return -ENOMEM;
+}
+#endif
+
+#endif /* _SS_EBITMAP_H_ */