linux-kernel - [RFC PATCH 15/22] selinux: introduce ebitmap_highest_set

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241115133619.114393-15-cgoettsche@seltendoof.de>
Date: Fri, 15 Nov 2024 14:35:34 +0100
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>,
	Eric Suen <ericsu@...ux.microsoft.com>,
	Canfeng Guo <guocanfeng@...ontech.com>,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH 15/22] selinux: introduce ebitmap_highest_set_bit()

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

Introduce an ebitmap function to calculate the highest set bit.

Signed-off-by: Christian Göttsche <cgzones@...glemail.com>
---
 security/selinux/ss/ebitmap.c | 27 +++++++++++++++++++++++++++
 security/selinux/ss/ebitmap.h |  1 +
 2 files changed, 28 insertions(+)

diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
index cd84357db2c4..74686b8a4c35 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 e0150695566c..99a21d83a0b3 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);
-- 
2.45.2