selinux: policydb - fix byte order and alignment issues

Do the LE conversions before doing the Infiniband-related range checks.
The incorrect checks are otherwise causing a failure to load any policy
with an ibendportcon rule on BE systems. This can be reproduced by
running (on e.g. ppc64):

cat >my_module.cil <<EOF
(type test_ibendport_t)
(roletype object_r test_ibendport_t)
(ibendportcon mlx4_0 1 (system_u object_r test_ibendport_t ((s0) (s0))))
EOF
semodule -i my_module.cil

Also, fix loading/storing the 64-bit subnet prefix for OCON_IBPKEY to
use a correctly aligned buffer.

Finally, do not use the 'nodebuf' (u32) buffer where 'buf' (__le32)
should be used instead.

Tested internally on a ppc64 machine with a RHEL 7 kernel with this
patch applied.

Cc: Daniel Jurgens <danielj@mellanox.com>
Cc: Eli Cohen <eli@mellanox.com>
Cc: James Morris <jmorris@namei.org>
Cc: Doug Ledford <dledford@redhat.com>
Cc: <stable@vger.kernel.org> # 4.13+
Fixes: a806f7a1 ("selinux: Create policydb version for Infiniband support")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/ss/policydb.c

@@ -2108,6 +2108,7 @@ static int ocontext_read(struct policydb *p, struct policydb_compat_info *info,
 {
 	int i, j, rc;
 	u32 nel, len;
+	__be64 prefixbuf[1];
 	__le32 buf[3];
 	struct ocontext *l, *c;
 	u32 nodebuf[8];
@@ -2217,21 +2218,30 @@ static int ocontext_read(struct policydb *p, struct policydb_compat_info *info,
 					goto out;
 				break;
 			}
-			case OCON_IBPKEY:
-				rc = next_entry(nodebuf, fp, sizeof(u32) * 4);
+			case OCON_IBPKEY: {
+				u32 pkey_lo, pkey_hi;
+
+				rc = next_entry(prefixbuf, fp, sizeof(u64));
+				if (rc)
+					goto out;
+
+				/* we need to have subnet_prefix in CPU order */
+				c->u.ibpkey.subnet_prefix = be64_to_cpu(prefixbuf[0]);
+
+				rc = next_entry(buf, fp, sizeof(u32) * 2);
 				if (rc)
 					goto out;
 
-				c->u.ibpkey.subnet_prefix = be64_to_cpu(*((__be64 *)nodebuf));
+				pkey_lo = le32_to_cpu(buf[0]);
+				pkey_hi = le32_to_cpu(buf[1]);
 
-				if (nodebuf[2] > 0xffff ||
-				    nodebuf[3] > 0xffff) {
+				if (pkey_lo > U16_MAX || pkey_hi > U16_MAX) {
 					rc = -EINVAL;
 					goto out;
 				}
 
-				c->u.ibpkey.low_pkey = le32_to_cpu(nodebuf[2]);
-				c->u.ibpkey.high_pkey = le32_to_cpu(nodebuf[3]);
+				c->u.ibpkey.low_pkey  = pkey_lo;
+				c->u.ibpkey.high_pkey = pkey_hi;
 
 				rc = context_read_and_validate(&c->context[0],
 							       p,
@@ -2239,7 +2249,10 @@ static int ocontext_read(struct policydb *p, struct policydb_compat_info *info,
 				if (rc)
 					goto out;
 				break;
-			case OCON_IBENDPORT:
+			}
+			case OCON_IBENDPORT: {
+				u32 port;
+
 				rc = next_entry(buf, fp, sizeof(u32) * 2);
 				if (rc)
 					goto out;
@@ -2249,12 +2262,13 @@ static int ocontext_read(struct policydb *p, struct policydb_compat_info *info,
 				if (rc)
 					goto out;
 
-				if (buf[1] > 0xff || buf[1] == 0) {
+				port = le32_to_cpu(buf[1]);
+				if (port > U8_MAX || port == 0) {
 					rc = -EINVAL;
 					goto out;
 				}
 
-				c->u.ibendport.port = le32_to_cpu(buf[1]);
+				c->u.ibendport.port = port;
 
 				rc = context_read_and_validate(&c->context[0],
 							       p,
@@ -2262,7 +2276,8 @@ static int ocontext_read(struct policydb *p, struct policydb_compat_info *info,
 				if (rc)
 					goto out;
 				break;
-			}
+			} /* end case */
+			} /* end switch */
 		}
 	}
 	rc = 0;
@@ -3105,6 +3120,7 @@ static int ocontext_write(struct policydb *p, struct policydb_compat_info *info,
 {
 	unsigned int i, j, rc;
 	size_t nel, len;
+	__be64 prefixbuf[1];
 	__le32 buf[3];
 	u32 nodebuf[8];
 	struct ocontext *c;
@@ -3192,12 +3208,17 @@ static int ocontext_write(struct policydb *p, struct policydb_compat_info *info,
 					return rc;
 				break;
 			case OCON_IBPKEY:
-				*((__be64 *)nodebuf) = cpu_to_be64(c->u.ibpkey.subnet_prefix);
+				/* subnet_prefix is in CPU order */
+				prefixbuf[0] = cpu_to_be64(c->u.ibpkey.subnet_prefix);
 
-				nodebuf[2] = cpu_to_le32(c->u.ibpkey.low_pkey);
-				nodebuf[3] = cpu_to_le32(c->u.ibpkey.high_pkey);
+				rc = put_entry(prefixbuf, sizeof(u64), 1, fp);
+				if (rc)
+					return rc;
+
+				buf[0] = cpu_to_le32(c->u.ibpkey.low_pkey);
+				buf[1] = cpu_to_le32(c->u.ibpkey.high_pkey);
 
-				rc = put_entry(nodebuf, sizeof(u32), 4, fp);
+				rc = put_entry(buf, sizeof(u32), 2, fp);
 				if (rc)
 					return rc;
 				rc = context_write(p, &c->context[0], fp);