Re: [PATCH v13 04/11] LSM: syscalls for current process attributes

+/**
+ * sys_lsm_get_self_attr - Return current task's security module attributes
+ * @attr: which attribute to set
+ * @ctx: the LSM contexts
+ * @size: size of @ctx, updated on return
+ * @flags: reserved for future use

+ *
+ * Returns the calling task's LSM contexts. On success this
+ * function returns the number of @ctx array elements. This value
+ * may be zero if there are no LSM contexts assigned. If @size is
+ * insufficient to contain the return data -E2BIG is returned and
+ * @size is set to the minimum required size. In all other cases
+ * a negative value indicating the error is returned.
+ */
+SYSCALL_DEFINE4(lsm_get_self_attr, unsigned int, attr, struct lsm_ctx __user *,
+		ctx, size_t __user *, size, u32, flags)
+{
+	return security_getselfattr(attr, ctx, size, flags);
+}

diff --git a/security/security.c b/security/security.c
index 5e9cd548dd95..cde7f3a13e7c 100644
--- a/security/security.c
+++ b/security/security.c

@@ -3798,6 +3798,131 @@ void security_d_instantiate(struct dentry *dentry, struct inode *inode)
 }
 EXPORT_SYMBOL(security_d_instantiate);
 
+/**
+ * security_getselfattr - Read an LSM attribute of the current process.
+ * @attr: which attribute to return
+ * @ctx: the user-space destination for the information, or NULL
+ * @size: pointer to the size of space available to receive the data
+ * @flags: special handling options. LSM_FLAG_SINGLE indicates that only
+ * attributes associated with the LSM identified in the passed @ctx be
+ * reported

+ *
+ * A NULL value for @ctx can be used to get both the number of attributes
+ * and the size of the data.
+ *
+ * Returns the number of attributes found on success, negative value
+ * on error. @size is reset to the total size of the data.
+ * If @size is insufficient to contain the data -E2BIG is returned.
+ */
+int security_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
+			 size_t __user *size, u32 flags)
+{
+	struct security_hook_list *hp;
+	struct lsm_ctx lctx = { .id = LSM_ID_UNDEF, };
+	u8 __user *base = (u8 __user *)ctx;
+	size_t total = 0;
+	size_t entrysize;
+	size_t left;
+	bool toobig = false;
+	int count = 0;
+	int rc;
+
+	if (attr == LSM_ATTR_UNDEF)
+		return -EINVAL;
+	if (size == NULL)
+		return -EINVAL;
+	if (get_user(left, size))
+		return -EFAULT;
+
+	if ((flags & LSM_FLAG_SINGLE) == LSM_FLAG_SINGLE) {
+		if (!ctx)

+			return -EFAULT;
+		if (lctx.id == LSM_ID_UNDEF)
+			return -EINVAL;
+	} else if (flags) {

+		return -EINVAL;
+	}
+

+	hlist_for_each_entry(hp, &security_hook_heads.getselfattr, list) {
+		if (lctx.id != LSM_ID_UNDEF && lctx.id != hp->lsmid->id)
+			continue;
+		entrysize = left;
+		if (base)
+			ctx = (struct lsm_ctx __user *)(base + total);

+		rc = hp->hook.getselfattr(attr, ctx, &entrysize, flags);
+		if (rc == -EOPNOTSUPP) {
+			rc = 0;
+			continue;
+		}
+		if (rc == -E2BIG) {
+			toobig = true;
+			left = 0;
+			continue;
+		}
+		if (rc < 0)
+			return rc;
+
+		left -= entrysize;
+		total += entrysize;
+		count += rc;
+	}
+	if (put_user(total, size))
+		return -EFAULT;
+	if (toobig)
+		return -E2BIG;
+	if (count == 0)
+		return LSM_RET_DEFAULT(getselfattr);
+	return count;
+}
+
+/**
+ * security_setselfattr - Set an LSM attribute on the current process.
+ * @attr: which attribute to set
+ * @ctx: the user-space source for the information
+ * @size: the size of the data
+ * @flags: reserved for future use, must be 0
+ *
+ * Set an LSM attribute for the current process. The LSM, attribute
+ * and new value are included in @ctx.
+ *
+ * Returns 0 on success, -EINVAL if the input is inconsistent, -EFAULT
+ * if the user buffer is inaccessible or an LSM specific failure.
+ */
+int security_setselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
+			 size_t size, u32 flags)
+{
+	struct security_hook_list *hp;
+	struct lsm_ctx *lctx;
+	int rc = LSM_RET_DEFAULT(setselfattr);
+
+	if (flags)
+		return -EINVAL;
+	if (size < sizeof(*ctx))
+		return -EINVAL;
+
+	lctx = kmalloc(size, GFP_KERNEL);

+	if (lctx == NULL)
+		return -ENOMEM;
+
+	if (copy_from_user(&lctx, ctx, size))
+		return -EFAULT;
+
+	if (size < lctx->len || size < lctx->ctx_len + sizeof(ctx) ||

+	    lctx->len < lctx->ctx_len + sizeof(ctx))
+		return -EINVAL;
+
+	hlist_for_each_entry(hp, &security_hook_heads.setselfattr, list)
+		if ((hp->lsmid->id) == lctx->id) {
+			rc = hp->hook.setselfattr(attr, lctx, size, flags);