1 files changed, 43 insertions, 11 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index d6b9ed34ceae..5f7bfc65c446 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -471,16 +471,10 @@ static int may_context_mount_inode_relabel(u32 sid,
 	return rc;
 }
 
-static int selinux_is_sblabel_mnt(struct super_block *sb)
+static int selinux_is_genfs_special_handling(struct super_block *sb)
 {
-	struct superblock_security_struct *sbsec = sb->s_security;
-
-	return sbsec->behavior == SECURITY_FS_USE_XATTR ||
-		sbsec->behavior == SECURITY_FS_USE_TRANS ||
-		sbsec->behavior == SECURITY_FS_USE_TASK ||
-		sbsec->behavior == SECURITY_FS_USE_NATIVE ||
-		/* Special handling. Genfs but also in-core setxattr handler */
-		!strcmp(sb->s_type->name, "sysfs") ||
+	/* Special handling. Genfs but also in-core setxattr handler */
+	return	!strcmp(sb->s_type->name, "sysfs") ||
 		!strcmp(sb->s_type->name, "pstore") ||
 		!strcmp(sb->s_type->name, "debugfs") ||
 		!strcmp(sb->s_type->name, "tracefs") ||
@@ -490,6 +484,34 @@ static int selinux_is_sblabel_mnt(struct super_block *sb)
 		  !strcmp(sb->s_type->name, "cgroup2")));
 }
 
+static int selinux_is_sblabel_mnt(struct super_block *sb)
+{
+	struct superblock_security_struct *sbsec = sb->s_security;
+
+	/*
+	 * IMPORTANT: Double-check logic in this function when adding a new
+	 * SECURITY_FS_USE_* definition!
+	 */
+	BUILD_BUG_ON(SECURITY_FS_USE_MAX != 7);
+
+	switch (sbsec->behavior) {
+	case SECURITY_FS_USE_XATTR:
+	case SECURITY_FS_USE_TRANS:
+	case SECURITY_FS_USE_TASK:
+	case SECURITY_FS_USE_NATIVE:
+		return 1;
+
+	case SECURITY_FS_USE_GENFS:
+		return selinux_is_genfs_special_handling(sb);
+
+	/* Never allow relabeling on context mounts */
+	case SECURITY_FS_USE_MNTPOINT:
+	case SECURITY_FS_USE_NONE:
+	default:
+		return 0;
+	}
+}
+
 static int sb_finish_set_opts(struct super_block *sb)
 {
 	struct superblock_security_struct *sbsec = sb->s_security;
@@ -1000,8 +1022,11 @@ static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb,
 	BUG_ON(!(oldsbsec->flags & SE_SBINITIALIZED));
 
 	/* if fs is reusing a sb, make sure that the contexts match */
-	if (newsbsec->flags & SE_SBINITIALIZED)
+	if (newsbsec->flags & SE_SBINITIALIZED) {
+		if ((kern_flags & SECURITY_LSM_NATIVE_LABELS) && !set_context)
+			*set_kern_flags |= SECURITY_LSM_NATIVE_LABELS;
 		return selinux_cmp_sb_context(oldsb, newsb);
+	}
 
 	mutex_lock(&newsbsec->lock);
 
@@ -3336,12 +3361,16 @@ static int selinux_inode_setsecurity(struct inode *inode, const char *name,
 				     const void *value, size_t size, int flags)
 {
 	struct inode_security_struct *isec = inode_security_novalidate(inode);
+	struct superblock_security_struct *sbsec = inode->i_sb->s_security;
 	u32 newsid;
 	int rc;
 
 	if (strcmp(name, XATTR_SELINUX_SUFFIX))
 		return -EOPNOTSUPP;
 
+	if (!(sbsec->flags & SBLABEL_MNT))
+		return -EOPNOTSUPP;
+
 	if (!value || !size)
 		return -EACCES;
 
@@ -6100,7 +6129,10 @@ static void selinux_inode_invalidate_secctx(struct inode *inode)
  */
 static int selinux_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen)
 {
-	return selinux_inode_setsecurity(inode, XATTR_SELINUX_SUFFIX, ctx, ctxlen, 0);
+	int rc = selinux_inode_setsecurity(inode, XATTR_SELINUX_SUFFIX,
+					   ctx, ctxlen, 0);
+	/* Do not return error when suppressing label (SBLABEL_MNT not set). */
+	return rc == -EOPNOTSUPP ? 0 : rc;
 }
 
 /*