linux-kernel - [PATCH v3 07/14] selinux: check type attr map overflows

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Message-ID: <20250511173055.406906-7-cgoettsche@seltendoof.de>
Date: Sun, 11 May 2025 19:30:07 +0200
From: Christian Göttsche <cgoettsche@...tendoof.de>
To: selinux@...r.kernel.org
Cc: Christian Göttsche <cgzones@...glemail.com>,
	Paul Moore <paul@...l-moore.com>,
	Stephen Smalley <stephen.smalley.work@...il.com>,
	Ondrej Mosnacek <omosnace@...hat.com>,
	linux-kernel@...r.kernel.org,
	Eric Suen <ericsu@...ux.microsoft.com>,
	Canfeng Guo <guocanfeng@...ontech.com>
Subject: [PATCH v3 07/14] selinux: check type attr map overflows

From: Christian Göttsche <cgzones@...glemail.com>

Validate that no types with an invalid too high ID are present in the
attribute map.  Gaps are still not checked.

Signed-off-by: Christian Göttsche <cgzones@...glemail.com>
---
v3: squash with previous patch ("selinux: introduce
    ebitmap_highest_set_bit()")
---
 security/selinux/ss/ebitmap.c  | 27 +++++++++++++++++++++++++++
 security/selinux/ss/ebitmap.h  |  1 +
 security/selinux/ss/policydb.c |  5 +++++
 3 files changed, 33 insertions(+)

diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
index 43bc19e21960..5d6b5b72b3e5 100644
--- a/security/selinux/ss/ebitmap.c
+++ b/security/selinux/ss/ebitmap.c
@@ -257,6 +257,33 @@ int ebitmap_contains(const struct ebitmap *e1, const struct ebitmap *e2,
 	return 1;
 }
 
+u32 ebitmap_highest_set_bit(const struct ebitmap *e)
+{
+	const struct ebitmap_node *n;
+	unsigned long unit;
+	u32 pos = 0;
+
+	n = e->node;
+	if (!n)
+		return 0;
+
+	while (n->next)
+		n = n->next;
+
+	for (unsigned int i = EBITMAP_UNIT_NUMS; i > 0; i--) {
+		unit = n->maps[i - 1];
+		if (unit == 0)
+			continue;
+
+		pos = (i - 1) * EBITMAP_UNIT_SIZE;
+		while (unit >>= 1)
+			pos++;
+		break;
+	}
+
+	return n->startbit + pos;
+}
+
 int ebitmap_get_bit(const struct ebitmap *e, u32 bit)
 {
 	const struct ebitmap_node *n;
diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h
index c9569998f287..12bb359e83ff 100644
--- a/security/selinux/ss/ebitmap.h
+++ b/security/selinux/ss/ebitmap.h
@@ -126,6 +126,7 @@ 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_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);
diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 8969f7c8637c..27f6809b562a 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -2955,6 +2955,11 @@ int policydb_read(struct policydb *p, struct policy_file *fp)
 			if (rc)
 				goto bad;
 		}
+
+		rc = -EINVAL;
+		if (ebitmap_highest_set_bit(e) >= p->p_types.nprim)
+			goto bad;
+
 		/* add the type itself as the degenerate case */
 		rc = ebitmap_set_bit(e, i, 1);
 		if (rc)
-- 
2.49.0