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authorLinus Torvalds <torvalds@linux-foundation.org>2012-10-02 21:50:47 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-02 21:50:47 +0400
commitc0e8a139a5bb8add02b4111e9e1957d810d7285e (patch)
treef5f0695c7553c0f651ea3c714191dedf76e06c78 /fs
parent033d9959ed2dc1029217d4165f80a71702dc578e (diff)
parenta6f00298b2ceaf50b4ab00e6ee3eb0206ac72fac (diff)
downloadlinux-c0e8a139a5bb8add02b4111e9e1957d810d7285e.tar.xz
Merge branch 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo: - xattr support added. The implementation is shared with tmpfs. The usage is restricted and intended to be used to manage per-cgroup metadata by system software. tmpfs changes are routed through this branch with Hugh's permission. - cgroup subsystem ID handling simplified. * 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: Define CGROUP_SUBSYS_COUNT according the configuration cgroup: Assign subsystem IDs during compile time cgroup: Do not depend on a given order when populating the subsys array cgroup: Wrap subsystem selection macro cgroup: Remove CGROUP_BUILTIN_SUBSYS_COUNT cgroup: net_prio: Do not define task_netpioidx() when not selected cgroup: net_cls: Do not define task_cls_classid() when not selected cgroup: net_cls: Move sock_update_classid() declaration to cls_cgroup.h cgroup: trivial fixes for Documentation/cgroups/cgroups.txt xattr: mark variable as uninitialized to make both gcc and smatch happy fs: add missing documentation to simple_xattr functions cgroup: add documentation on extended attributes usage cgroup: rename subsys_bits to subsys_mask cgroup: add xattr support cgroup: revise how we re-populate root directory xattr: extract simple_xattr code from tmpfs
Diffstat (limited to 'fs')
-rw-r--r--fs/xattr.c180
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);
+}