libsepol/0002-libsepol-implement-POLICYDB_VERSION_COMP_FTRANS.patch

From 8206b8cb00392aab358f4eeae38f98850438085c Mon Sep 17 00:00:00 2001
From: Ondrej Mosnacek <omosnace@redhat.com>
Date: Fri, 31 Jul 2020 13:10:35 +0200
Subject: [PATCH] libsepol: implement POLICYDB_VERSION_COMP_FTRANS

Implement a new, more space-efficient form of storing filename
transitions in the binary policy. The internal structures have already
been converted to this new representation; this patch just implements
reading/writing an equivalent representation from/to the binary policy.

This new format reduces the size of Fedora policy from 7.6 MB to only
3.3 MB (with policy optimization enabled in both cases). With the
unconfined module disabled, the size is reduced from 3.3 MB to 2.4 MB.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
---
 libsepol/include/sepol/policydb/policydb.h |   3 +-
 libsepol/src/policydb.c                    | 209 +++++++++++++++++----
 libsepol/src/write.c                       |  73 ++++++-
 3 files changed, 242 insertions(+), 43 deletions(-)

diff --git a/libsepol/include/sepol/policydb/policydb.h b/libsepol/include/sepol/policydb/policydb.h
index c3180c611c64..9ef43abc2f12 100644
--- a/libsepol/include/sepol/policydb/policydb.h
+++ b/libsepol/include/sepol/policydb/policydb.h
@@ -755,10 +755,11 @@ extern int policydb_set_target_platform(policydb_t *p, int platform);
 #define POLICYDB_VERSION_XPERMS_IOCTL	30 /* Linux-specific */
 #define POLICYDB_VERSION_INFINIBAND		31 /* Linux-specific */
 #define POLICYDB_VERSION_GLBLUB		32
+#define POLICYDB_VERSION_COMP_FTRANS	33 /* compressed filename transitions */
 
 /* Range of policy versions we understand*/
 #define POLICYDB_VERSION_MIN	POLICYDB_VERSION_BASE
-#define POLICYDB_VERSION_MAX	POLICYDB_VERSION_GLBLUB
+#define POLICYDB_VERSION_MAX	POLICYDB_VERSION_COMP_FTRANS
 
 /* Module versions and specific changes*/
 #define MOD_POLICYDB_VERSION_BASE		4
diff --git a/libsepol/src/policydb.c b/libsepol/src/policydb.c
index 0b98d50b8096..ce8f3ad77005 100644
--- a/libsepol/src/policydb.c
+++ b/libsepol/src/policydb.c
@@ -200,6 +200,13 @@ static struct policydb_compat_info policydb_compat[] = {
 	 .ocon_num = OCON_IBENDPORT + 1,
 	 .target_platform = SEPOL_TARGET_SELINUX,
 	},
+	{
+	 .type = POLICY_KERN,
+	 .version = POLICYDB_VERSION_COMP_FTRANS,
+	 .sym_num = SYM_NUM,
+	 .ocon_num = OCON_IBENDPORT + 1,
+	 .target_platform = SEPOL_TARGET_SELINUX,
+	},
 	{
 	 .type = POLICY_BASE,
 	 .version = MOD_POLICYDB_VERSION_BASE,
@@ -2669,65 +2676,201 @@ int policydb_filetrans_insert(policydb_t *p, uint32_t stype, uint32_t ttype,
 	return ebitmap_set_bit(&datum->stypes, stype - 1, 1);
 }
 
-int filename_trans_read(policydb_t *p, struct policy_file *fp)
+static int filename_trans_read_one_compat(policydb_t *p, struct policy_file *fp)
 {
-	unsigned int i;
-	uint32_t buf[4], nel, len, stype, ttype, tclass, otype;
+	uint32_t buf[4], len, stype, ttype, tclass, otype;
+	char *name = NULL;
 	int rc;
-	char *name;
 
 	rc = next_entry(buf, fp, sizeof(uint32_t));
 	if (rc < 0)
 		return -1;
-	nel = le32_to_cpu(buf[0]);
+	len = le32_to_cpu(buf[0]);
+	if (zero_or_saturated(len))
+		return -1;
 
-	for (i = 0; i < nel; i++) {
-		name = NULL;
+	name = calloc(len + 1, sizeof(*name));
+	if (!name)
+		return -1;
 
-		rc = next_entry(buf, fp, sizeof(uint32_t));
-		if (rc < 0)
-			goto err;
-		len = le32_to_cpu(buf[0]);
-		if (zero_or_saturated(len))
+	rc = next_entry(name, fp, len);
+	if (rc < 0)
+		goto err;
+
+	rc = next_entry(buf, fp, sizeof(uint32_t) * 4);
+	if (rc < 0)
+		goto err;
+
+	stype  = le32_to_cpu(buf[0]);
+	ttype  = le32_to_cpu(buf[1]);
+	tclass = le32_to_cpu(buf[2]);
+	otype  = le32_to_cpu(buf[3]);
+
+	rc = policydb_filetrans_insert(p, stype, ttype, tclass, name, &name,
+				       otype, NULL);
+	if (rc) {
+		if (rc != SEPOL_EEXIST)
 			goto err;
+		/*
+		 * Some old policies were wrongly generated with
+		 * duplicate filename transition rules.  For backward
+		 * compatibility, do not reject such policies, just
+		 * ignore the duplicate.
+		 */
+	}
+	free(name);
+	return 0;
+err:
+	free(name);
+	return -1;
+}
+
+static int filename_trans_check_datum(filename_trans_datum_t *datum)
+{
+	ebitmap_t stypes, otypes;
+	int rc = -1;
+
+	ebitmap_init(&stypes);
+	ebitmap_init(&otypes);
+
+	while (datum) {
+		if (ebitmap_get_bit(&otypes, datum->otype))
+			goto out;
+
+		if (ebitmap_set_bit(&otypes, datum->otype, 1))
+			goto out;
+
+		if (ebitmap_match_any(&stypes, &datum->stypes))
+			goto out;
 
-		name = calloc(len + 1, sizeof(*name));
-		if (!name)
+		if (ebitmap_union(&stypes, &datum->stypes))
+			goto out;
+
+		datum = datum->next;
+	}
+	rc = 0;
+out:
+	ebitmap_destroy(&stypes);
+	ebitmap_destroy(&otypes);
+	return rc;
+}
+
+static int filename_trans_read_one(policydb_t *p, struct policy_file *fp)
+{
+	filename_trans_key_t *ft = NULL;
+	filename_trans_datum_t **dst, *datum, *first = NULL;
+	unsigned int i;
+	uint32_t buf[3], len, ttype, tclass, ndatum;
+	char *name = NULL;
+	int rc;
+
+	rc = next_entry(buf, fp, sizeof(uint32_t));
+	if (rc < 0)
+		return -1;
+	len = le32_to_cpu(buf[0]);
+	if (zero_or_saturated(len))
+		return -1;
+
+	name = calloc(len + 1, sizeof(*name));
+	if (!name)
+		return -1;
+
+	rc = next_entry(name, fp, len);
+	if (rc < 0)
+		goto err;
+
+	rc = next_entry(buf, fp, sizeof(uint32_t) * 3);
+	if (rc < 0)
+		goto err;
+
+	ttype = le32_to_cpu(buf[0]);
+	tclass = le32_to_cpu(buf[1]);
+	ndatum = le32_to_cpu(buf[2]);
+	if (ndatum == 0)
+		goto err;
+
+	dst = &first;
+	for (i = 0; i < ndatum; i++) {
+		datum = malloc(sizeof(*datum));
+		if (!datum)
 			goto err;
 
-		rc = next_entry(name, fp, len);
+		*dst = datum;
+
+		/* ebitmap_read() will at least init the bitmap */
+		rc = ebitmap_read(&datum->stypes, fp);
 		if (rc < 0)
 			goto err;
 
-		rc = next_entry(buf, fp, sizeof(uint32_t) * 4);
+		rc = next_entry(buf, fp, sizeof(uint32_t));
 		if (rc < 0)
 			goto err;
 
-		stype  = le32_to_cpu(buf[0]);
-		ttype  = le32_to_cpu(buf[1]);
-		tclass = le32_to_cpu(buf[2]);
-		otype  = le32_to_cpu(buf[3]);
+		datum->otype = le32_to_cpu(buf[0]);
 
-		rc = policydb_filetrans_insert(p, stype, ttype, tclass, name,
-					       &name, otype, NULL);
-		if (rc) {
-			if (rc != SEPOL_EEXIST)
-				goto err;
-			/*
-			 * Some old policies were wrongly generated with
-			 * duplicate filename transition rules.  For backward
-			 * compatibility, do not reject such policies, just
-			 * ignore the duplicate.
-			 */
-		}
-		free(name);
+		p->filename_trans_count += ebitmap_cardinality(&datum->stypes);
+
+		dst = &datum->next;
 	}
+	*dst = NULL;
+
+	if (ndatum > 1 && filename_trans_check_datum(first))
+		goto err;
+
+	ft = malloc(sizeof(*ft));
+	if (!ft)
+		goto err;
+
+	ft->ttype = ttype;
+	ft->tclass = tclass;
+	ft->name = name;
+
+	rc = hashtab_insert(p->filename_trans, (hashtab_key_t)ft,
+			    (hashtab_datum_t)first);
+	if (rc)
+		goto err;
+
 	return 0;
 err:
+	free(ft);
 	free(name);
+	while (first) {
+		datum = first;
+		first = first->next;
+
+		ebitmap_destroy(&datum->stypes);
+		free(datum);
+	}
 	return -1;
 }
 
+int filename_trans_read(policydb_t *p, struct policy_file *fp)
+{
+	unsigned int i;
+	uint32_t buf[1], nel;
+	int rc;
+
+	rc = next_entry(buf, fp, sizeof(uint32_t));
+	if (rc < 0)
+		return -1;
+	nel = le32_to_cpu(buf[0]);
+
+	if (p->policyvers < POLICYDB_VERSION_COMP_FTRANS) {
+		for (i = 0; i < nel; i++) {
+			rc = filename_trans_read_one_compat(p, fp);
+			if (rc < 0)
+				return -1;
+		}
+	} else {
+		for (i = 0; i < nel; i++) {
+			rc = filename_trans_read_one(p, fp);
+			if (rc < 0)
+				return -1;
+		}
+	}
+	return 0;
+}
+
 static int ocontext_read_xen(struct policydb_compat_info *info,
 	policydb_t *p, struct policy_file *fp)
 {
diff --git a/libsepol/src/write.c b/libsepol/src/write.c
index d3aee8d5bf22..84bcaf3f57ca 100644
--- a/libsepol/src/write.c
+++ b/libsepol/src/write.c
@@ -569,7 +569,7 @@ static int role_allow_write(role_allow_t * r, struct policy_file *fp)
 	return POLICYDB_SUCCESS;
 }
 
-static int filename_write_helper(hashtab_key_t key, void *data, void *ptr)
+static int filename_write_one_compat(hashtab_key_t key, void *data, void *ptr)
 {
 	uint32_t bit, buf[4];
 	size_t items, len;
@@ -605,6 +605,54 @@ static int filename_write_helper(hashtab_key_t key, void *data, void *ptr)
 	return 0;
 }
 
+static int filename_write_one(hashtab_key_t key, void *data, void *ptr)
+{
+	uint32_t buf[3];
+	size_t items, len, ndatum;
+	filename_trans_key_t *ft = (filename_trans_key_t *)key;
+	filename_trans_datum_t *datum;
+	void *fp = ptr;
+
+	len = strlen(ft->name);
+	buf[0] = cpu_to_le32(len);
+	items = put_entry(buf, sizeof(uint32_t), 1, fp);
+	if (items != 1)
+		return POLICYDB_ERROR;
+
+	items = put_entry(ft->name, sizeof(char), len, fp);
+	if (items != len)
+		return POLICYDB_ERROR;
+
+	ndatum = 0;
+	datum = data;
+	do {
+		ndatum++;
+		datum = datum->next;
+	} while (datum);
+
+	buf[0] = cpu_to_le32(ft->ttype);
+	buf[1] = cpu_to_le32(ft->tclass);
+	buf[2] = cpu_to_le32(ndatum);
+	items = put_entry(buf, sizeof(uint32_t), 3, fp);
+	if (items != 3)
+		return POLICYDB_ERROR;
+
+	datum = data;
+	do {
+		if (ebitmap_write(&datum->stypes, fp))
+			return POLICYDB_ERROR;
+
+		buf[0] = cpu_to_le32(datum->otype);
+		items = put_entry(buf, sizeof(uint32_t), 1, fp);
+		if (items != 1)
+			return POLICYDB_ERROR;
+
+		datum = datum->next;
+	} while (datum);
+
+	return 0;
+}
+
 static int filename_trans_write(struct policydb *p, void *fp)
 {
 	size_t items;
@@ -614,16 +662,23 @@ static int filename_trans_write(struct policydb *p, void *fp)
 	if (p->policyvers < POLICYDB_VERSION_FILENAME_TRANS)
 		return 0;
 
-	buf[0] = cpu_to_le32(p->filename_trans_count);
-	items = put_entry(buf, sizeof(uint32_t), 1, fp);
-	if (items != 1)
-		return POLICYDB_ERROR;
+	if (p->policyvers < POLICYDB_VERSION_COMP_FTRANS) {
+		buf[0] = cpu_to_le32(p->filename_trans_count);
+		items = put_entry(buf, sizeof(uint32_t), 1, fp);
+		if (items != 1)
+			return POLICYDB_ERROR;
 
-	rc = hashtab_map(p->filename_trans, filename_write_helper, fp);
-	if (rc)
-		return rc;
+		rc = hashtab_map(p->filename_trans, filename_write_one_compat,
+				 fp);
+	} else {
+		buf[0] = cpu_to_le32(p->filename_trans->nel);
+		items = put_entry(buf, sizeof(uint32_t), 1, fp);
+		if (items != 1)
+			return POLICYDB_ERROR;
 
-	return 0;
+		rc = hashtab_map(p->filename_trans, filename_write_one, fp);
+	}
+	return rc;
 }
 
 static int role_set_write(role_set_t * x, struct policy_file *fp)
-- 
2.29.0.rc2