1 files changed, 180 insertions, 0 deletions

diff --git a/fs/xattr.c b/fs/xattr.c
index 4d45b7189e7e..014f11321fd9 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -791,3 +791,183 @@ EXPORT_SYMBOL(generic_getxattr);
 EXPORT_SYMBOL(generic_listxattr);
 EXPORT_SYMBOL(generic_setxattr);
 EXPORT_SYMBOL(generic_removexattr);
+
+/*
+ * Allocate new xattr and copy in the value; but leave the name to callers.
+ */
+struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
+{
+        struct simple_xattr *new_xattr;
+        size_t len;
+
+        /* wrap around? */
+        len = sizeof(*new_xattr) + size;
+        if (len <= sizeof(*new_xattr))
+                return NULL;
+
+        new_xattr = kmalloc(len, GFP_KERNEL);
+        if (!new_xattr)
+                return NULL;
+
+        new_xattr->size = size;
+        memcpy(new_xattr->value, value, size);
+        return new_xattr;
+}
+
+/*
+ * xattr GET operation for in-memory/pseudo filesystems
+ */
+int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
+                     void *buffer, size_t size)
+{
+        struct simple_xattr *xattr;
+        int ret = -ENODATA;
+
+        spin_lock(&xattrs->lock);
+        list_for_each_entry(xattr, &xattrs->head, list) {
+                if (strcmp(name, xattr->name))
+                        continue;
+
+                ret = xattr->size;
+                if (buffer) {
+                        if (size < xattr->size)
+                                ret = -ERANGE;
+                        else
+                                memcpy(buffer, xattr->value, xattr->size);
+                }
+                break;
+        }
+        spin_unlock(&xattrs->lock);
+        return ret;
+}
+
+static int __simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
+                              const void *value, size_t size, int flags)
+{
+        struct simple_xattr *xattr;
+        struct simple_xattr *uninitialized_var(new_xattr);
+        int err = 0;
+
+        /* value == NULL means remove */
+        if (value) {
+                new_xattr = simple_xattr_alloc(value, size);
+                if (!new_xattr)
+                        return -ENOMEM;
+
+                new_xattr->name = kstrdup(name, GFP_KERNEL);
+                if (!new_xattr->name) {
+                        kfree(new_xattr);
+                        return -ENOMEM;
+                }
+        }
+
+        spin_lock(&xattrs->lock);
+        list_for_each_entry(xattr, &xattrs->head, list) {
+                if (!strcmp(name, xattr->name)) {
+                        if (flags & XATTR_CREATE) {
+                                xattr = new_xattr;
+                                err = -EEXIST;
+                        } else if (new_xattr) {
+                                list_replace(&xattr->list, &new_xattr->list);
+                        } else {
+                                list_del(&xattr->list);
+                        }
+                        goto out;
+                }
+        }
+        if (flags & XATTR_REPLACE) {
+                xattr = new_xattr;
+                err = -ENODATA;
+        } else {
+                list_add(&new_xattr->list, &xattrs->head);
+                xattr = NULL;
+        }
+out:
+        spin_unlock(&xattrs->lock);
+        if (xattr) {
+                kfree(xattr->name);
+                kfree(xattr);
+        }
+        return err;
+
+}
+
+/**
+ * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
+ * @xattrs: target simple_xattr list
+ * @name: name of the new extended attribute
+ * @value: value of the new xattr. If %NULL, will remove the attribute
+ * @size: size of the new xattr
+ * @flags: %XATTR_{CREATE|REPLACE}
+ *
+ * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
+ * with -EEXIST.  If %XATTR_REPLACE is set, the xattr should exist;
+ * otherwise, fails with -ENODATA.
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
+                     const void *value, size_t size, int flags)
+{
+        if (size == 0)
+                value = ""; /* empty EA, do not remove */
+        return __simple_xattr_set(xattrs, name, value, size, flags);
+}
+
+/*
+ * xattr REMOVE operation for in-memory/pseudo filesystems
+ */
+int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)
+{
+        return __simple_xattr_set(xattrs, name, NULL, 0, XATTR_REPLACE);
+}
+
+static bool xattr_is_trusted(const char *name)
+{
+        return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
+}
+
+/*
+ * xattr LIST operation for in-memory/pseudo filesystems
+ */
+ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,
+                          size_t size)
+{
+        bool trusted = capable(CAP_SYS_ADMIN);
+        struct simple_xattr *xattr;
+        size_t used = 0;
+
+        spin_lock(&xattrs->lock);
+        list_for_each_entry(xattr, &xattrs->head, list) {
+                size_t len;
+
+                /* skip "trusted." attributes for unprivileged callers */
+                if (!trusted && xattr_is_trusted(xattr->name))
+                        continue;
+
+                len = strlen(xattr->name) + 1;
+                used += len;
+                if (buffer) {
+                        if (size < used) {
+                                used = -ERANGE;
+                                break;
+                        }
+                        memcpy(buffer, xattr->name, len);
+                        buffer += len;
+                }
+        }
+        spin_unlock(&xattrs->lock);
+
+        return used;
+}
+
+/*
+ * Adds an extended attribute to the list
+ */
+void simple_xattr_list_add(struct simple_xattrs *xattrs,
+                           struct simple_xattr *new_xattr)
+{
+        spin_lock(&xattrs->lock);
+        list_add(&new_xattr->list, &xattrs->head);
+        spin_unlock(&xattrs->lock);
+}