lsm: cleanup the LSM blob size code

Convert the lsm_blob_size fields to unsigned integers as there is no
current need for them to be negative, change "lsm_set_blob_size()" to
"lsm_blob_size_update()" to better reflect reality, and perform some
other minor cleanups to the associated code.

Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Author: pcmoore

include/linux/lsm_hooks.h

@@ -102,23 +102,23 @@ struct security_hook_list {
  * Security blob size or offset data.
  */
 struct lsm_blob_sizes {
-	int lbs_cred;
-	int lbs_file;
-	int lbs_ib;
-	int lbs_inode;
-	int lbs_sock;
-	int lbs_superblock;
-	int lbs_ipc;
-	int lbs_key;
-	int lbs_msg_msg;
-	int lbs_perf_event;
-	int lbs_task;
-	int lbs_xattr_count; /* number of xattr slots in new_xattrs array */
-	int lbs_tun_dev;
-	int lbs_bdev;
-	int lbs_bpf_map;
-	int lbs_bpf_prog;
-	int lbs_bpf_token;
+	unsigned int lbs_cred;
+	unsigned int lbs_file;
+	unsigned int lbs_ib;
+	unsigned int lbs_inode;
+	unsigned int lbs_sock;
+	unsigned int lbs_superblock;
+	unsigned int lbs_ipc;
+	unsigned int lbs_key;
+	unsigned int lbs_msg_msg;
+	unsigned int lbs_perf_event;
+	unsigned int lbs_task;
+	unsigned int lbs_xattr_count; /* num xattr slots in new_xattrs array */
+	unsigned int lbs_tun_dev;
+	unsigned int lbs_bdev;
+	unsigned int lbs_bpf_map;
+	unsigned int lbs_bpf_prog;
+	unsigned int lbs_bpf_token;
 };
 
 /*

security/lsm_init.c

@@ -169,16 +169,22 @@ static void __init lsm_order_append(struct lsm_info *lsm, const char *src)
 		   lsm_is_enabled(lsm) ? "enabled" : "disabled");
 }
 
-static void __init lsm_set_blob_size(int *need, int *lbs)
+/**
+ * lsm_blob_size_update - Update the LSM blob size and offset information
+ * @sz_req: the requested additional blob size
+ * @sz_cur: the existing blob size
+ */
+static void __init lsm_blob_size_update(unsigned int *sz_req,
+					unsigned int *sz_cur)
 {
-	int offset;
+	unsigned int offset;
 
-	if (*need <= 0)
+	if (*sz_req == 0)
 		return;
 
-	offset = ALIGN(*lbs, sizeof(void *));
-	*lbs = offset + *need;
-	*need = offset;
+	offset = ALIGN(*sz_cur, sizeof(void *));
+	*sz_cur = offset + *sz_req;
+	*sz_req = offset;
 }
 
 /**
@@ -193,27 +199,30 @@ static void __init lsm_prepare(struct lsm_info *lsm)
 		return;
 
 	/* Register the LSM blob sizes. */
-	lsm_set_blob_size(&blobs->lbs_cred, &blob_sizes.lbs_cred);
-	lsm_set_blob_size(&blobs->lbs_file, &blob_sizes.lbs_file);
-	lsm_set_blob_size(&blobs->lbs_ib, &blob_sizes.lbs_ib);
+	blobs = lsm->blobs;
+	lsm_blob_size_update(&blobs->lbs_cred, &blob_sizes.lbs_cred);
+	lsm_blob_size_update(&blobs->lbs_file, &blob_sizes.lbs_file);
+	lsm_blob_size_update(&blobs->lbs_ib, &blob_sizes.lbs_ib);
 	/* inode blob gets an rcu_head in addition to LSM blobs. */
 	if (blobs->lbs_inode && blob_sizes.lbs_inode == 0)
 		blob_sizes.lbs_inode = sizeof(struct rcu_head);
-	lsm_set_blob_size(&blobs->lbs_inode, &blob_sizes.lbs_inode);
-	lsm_set_blob_size(&blobs->lbs_ipc, &blob_sizes.lbs_ipc);
-	lsm_set_blob_size(&blobs->lbs_key, &blob_sizes.lbs_key);
-	lsm_set_blob_size(&blobs->lbs_msg_msg, &blob_sizes.lbs_msg_msg);
-	lsm_set_blob_size(&blobs->lbs_perf_event, &blob_sizes.lbs_perf_event);
-	lsm_set_blob_size(&blobs->lbs_sock, &blob_sizes.lbs_sock);
-	lsm_set_blob_size(&blobs->lbs_superblock, &blob_sizes.lbs_superblock);
-	lsm_set_blob_size(&blobs->lbs_task, &blob_sizes.lbs_task);
-	lsm_set_blob_size(&blobs->lbs_tun_dev, &blob_sizes.lbs_tun_dev);
-	lsm_set_blob_size(&blobs->lbs_xattr_count,
-			  &blob_sizes.lbs_xattr_count);
-	lsm_set_blob_size(&blobs->lbs_bdev, &blob_sizes.lbs_bdev);
-	lsm_set_blob_size(&blobs->lbs_bpf_map, &blob_sizes.lbs_bpf_map);
-	lsm_set_blob_size(&blobs->lbs_bpf_prog, &blob_sizes.lbs_bpf_prog);
-	lsm_set_blob_size(&blobs->lbs_bpf_token, &blob_sizes.lbs_bpf_token);
+	lsm_blob_size_update(&blobs->lbs_inode, &blob_sizes.lbs_inode);
+	lsm_blob_size_update(&blobs->lbs_ipc, &blob_sizes.lbs_ipc);
+	lsm_blob_size_update(&blobs->lbs_key, &blob_sizes.lbs_key);
+	lsm_blob_size_update(&blobs->lbs_msg_msg, &blob_sizes.lbs_msg_msg);
+	lsm_blob_size_update(&blobs->lbs_perf_event,
+			     &blob_sizes.lbs_perf_event);
+	lsm_blob_size_update(&blobs->lbs_sock, &blob_sizes.lbs_sock);
+	lsm_blob_size_update(&blobs->lbs_superblock,
+			     &blob_sizes.lbs_superblock);
+	lsm_blob_size_update(&blobs->lbs_task, &blob_sizes.lbs_task);
+	lsm_blob_size_update(&blobs->lbs_tun_dev, &blob_sizes.lbs_tun_dev);
+	lsm_blob_size_update(&blobs->lbs_xattr_count,
+			     &blob_sizes.lbs_xattr_count);
+	lsm_blob_size_update(&blobs->lbs_bdev, &blob_sizes.lbs_bdev);
+	lsm_blob_size_update(&blobs->lbs_bpf_map, &blob_sizes.lbs_bpf_map);
+	lsm_blob_size_update(&blobs->lbs_bpf_prog, &blob_sizes.lbs_bpf_prog);
+	lsm_blob_size_update(&blobs->lbs_bpf_token, &blob_sizes.lbs_bpf_token);
 }
 
 /* Initialize a given LSM, if it is enabled. */