v4.19.13 snapshot.
diff --git a/fs/xattr.c b/fs/xattr.c
new file mode 100644
index 0000000..0d6a6a4
--- /dev/null
+++ b/fs/xattr.c
@@ -0,0 +1,991 @@
+/*
+ File: fs/xattr.c
+
+ Extended attribute handling.
+
+ Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
+ Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
+ Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ */
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/xattr.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/evm.h>
+#include <linux/syscalls.h>
+#include <linux/export.h>
+#include <linux/fsnotify.h>
+#include <linux/audit.h>
+#include <linux/vmalloc.h>
+#include <linux/posix_acl_xattr.h>
+
+#include <linux/uaccess.h>
+
+static const char *
+strcmp_prefix(const char *a, const char *a_prefix)
+{
+ while (*a_prefix && *a == *a_prefix) {
+ a++;
+ a_prefix++;
+ }
+ return *a_prefix ? NULL : a;
+}
+
+/*
+ * In order to implement different sets of xattr operations for each xattr
+ * prefix, a filesystem should create a null-terminated array of struct
+ * xattr_handler (one for each prefix) and hang a pointer to it off of the
+ * s_xattr field of the superblock.
+ */
+#define for_each_xattr_handler(handlers, handler) \
+ if (handlers) \
+ for ((handler) = *(handlers)++; \
+ (handler) != NULL; \
+ (handler) = *(handlers)++)
+
+/*
+ * Find the xattr_handler with the matching prefix.
+ */
+static const struct xattr_handler *
+xattr_resolve_name(struct inode *inode, const char **name)
+{
+ const struct xattr_handler **handlers = inode->i_sb->s_xattr;
+ const struct xattr_handler *handler;
+
+ if (!(inode->i_opflags & IOP_XATTR)) {
+ if (unlikely(is_bad_inode(inode)))
+ return ERR_PTR(-EIO);
+ return ERR_PTR(-EOPNOTSUPP);
+ }
+ for_each_xattr_handler(handlers, handler) {
+ const char *n;
+
+ n = strcmp_prefix(*name, xattr_prefix(handler));
+ if (n) {
+ if (!handler->prefix ^ !*n) {
+ if (*n)
+ continue;
+ return ERR_PTR(-EINVAL);
+ }
+ *name = n;
+ return handler;
+ }
+ }
+ return ERR_PTR(-EOPNOTSUPP);
+}
+
+/*
+ * Check permissions for extended attribute access. This is a bit complicated
+ * because different namespaces have very different rules.
+ */
+static int
+xattr_permission(struct inode *inode, const char *name, int mask)
+{
+ /*
+ * We can never set or remove an extended attribute on a read-only
+ * filesystem or on an immutable / append-only inode.
+ */
+ if (mask & MAY_WRITE) {
+ if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+ return -EPERM;
+ /*
+ * Updating an xattr will likely cause i_uid and i_gid
+ * to be writen back improperly if their true value is
+ * unknown to the vfs.
+ */
+ if (HAS_UNMAPPED_ID(inode))
+ return -EPERM;
+ }
+
+ /*
+ * No restriction for security.* and system.* from the VFS. Decision
+ * on these is left to the underlying filesystem / security module.
+ */
+ if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
+ !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+ return 0;
+
+ /*
+ * The trusted.* namespace can only be accessed by privileged users.
+ */
+ if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
+ if (!capable(CAP_SYS_ADMIN))
+ return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
+ return 0;
+ }
+
+ /*
+ * In the user.* namespace, only regular files and directories can have
+ * extended attributes. For sticky directories, only the owner and
+ * privileged users can write attributes.
+ */
+ if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
+ if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
+ return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
+ if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
+ (mask & MAY_WRITE) && !inode_owner_or_capable(inode))
+ return -EPERM;
+ }
+
+ return inode_permission(inode, mask);
+}
+
+int
+__vfs_setxattr(struct dentry *dentry, struct inode *inode, const char *name,
+ const void *value, size_t size, int flags)
+{
+ const struct xattr_handler *handler;
+
+ handler = xattr_resolve_name(inode, &name);
+ if (IS_ERR(handler))
+ return PTR_ERR(handler);
+ if (!handler->set)
+ return -EOPNOTSUPP;
+ if (size == 0)
+ value = ""; /* empty EA, do not remove */
+ return handler->set(handler, dentry, inode, name, value, size, flags);
+}
+EXPORT_SYMBOL(__vfs_setxattr);
+
+/**
+ * __vfs_setxattr_noperm - perform setxattr operation without performing
+ * permission checks.
+ *
+ * @dentry - object to perform setxattr on
+ * @name - xattr name to set
+ * @value - value to set @name to
+ * @size - size of @value
+ * @flags - flags to pass into filesystem operations
+ *
+ * returns the result of the internal setxattr or setsecurity operations.
+ *
+ * This function requires the caller to lock the inode's i_mutex before it
+ * is executed. It also assumes that the caller will make the appropriate
+ * permission checks.
+ */
+int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ struct inode *inode = dentry->d_inode;
+ int error = -EAGAIN;
+ int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
+ XATTR_SECURITY_PREFIX_LEN);
+
+ if (issec)
+ inode->i_flags &= ~S_NOSEC;
+ if (inode->i_opflags & IOP_XATTR) {
+ error = __vfs_setxattr(dentry, inode, name, value, size, flags);
+ if (!error) {
+ fsnotify_xattr(dentry);
+ security_inode_post_setxattr(dentry, name, value,
+ size, flags);
+ }
+ } else {
+ if (unlikely(is_bad_inode(inode)))
+ return -EIO;
+ }
+ if (error == -EAGAIN) {
+ error = -EOPNOTSUPP;
+
+ if (issec) {
+ const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+
+ error = security_inode_setsecurity(inode, suffix, value,
+ size, flags);
+ if (!error)
+ fsnotify_xattr(dentry);
+ }
+ }
+
+ return error;
+}
+
+
+int
+vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+ size_t size, int flags)
+{
+ struct inode *inode = dentry->d_inode;
+ int error;
+
+ error = xattr_permission(inode, name, MAY_WRITE);
+ if (error)
+ return error;
+
+ inode_lock(inode);
+ error = security_inode_setxattr(dentry, name, value, size, flags);
+ if (error)
+ goto out;
+
+ error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
+
+out:
+ inode_unlock(inode);
+ return error;
+}
+EXPORT_SYMBOL_GPL(vfs_setxattr);
+
+static ssize_t
+xattr_getsecurity(struct inode *inode, const char *name, void *value,
+ size_t size)
+{
+ void *buffer = NULL;
+ ssize_t len;
+
+ if (!value || !size) {
+ len = security_inode_getsecurity(inode, name, &buffer, false);
+ goto out_noalloc;
+ }
+
+ len = security_inode_getsecurity(inode, name, &buffer, true);
+ if (len < 0)
+ return len;
+ if (size < len) {
+ len = -ERANGE;
+ goto out;
+ }
+ memcpy(value, buffer, len);
+out:
+ kfree(buffer);
+out_noalloc:
+ return len;
+}
+
+/*
+ * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
+ *
+ * Allocate memory, if not already allocated, or re-allocate correct size,
+ * before retrieving the extended attribute.
+ *
+ * Returns the result of alloc, if failed, or the getxattr operation.
+ */
+ssize_t
+vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,
+ size_t xattr_size, gfp_t flags)
+{
+ const struct xattr_handler *handler;
+ struct inode *inode = dentry->d_inode;
+ char *value = *xattr_value;
+ int error;
+
+ error = xattr_permission(inode, name, MAY_READ);
+ if (error)
+ return error;
+
+ handler = xattr_resolve_name(inode, &name);
+ if (IS_ERR(handler))
+ return PTR_ERR(handler);
+ if (!handler->get)
+ return -EOPNOTSUPP;
+ error = handler->get(handler, dentry, inode, name, NULL, 0);
+ if (error < 0)
+ return error;
+
+ if (!value || (error > xattr_size)) {
+ value = krealloc(*xattr_value, error + 1, flags);
+ if (!value)
+ return -ENOMEM;
+ memset(value, 0, error + 1);
+ }
+
+ error = handler->get(handler, dentry, inode, name, value, error);
+ *xattr_value = value;
+ return error;
+}
+
+ssize_t
+__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
+ void *value, size_t size)
+{
+ const struct xattr_handler *handler;
+
+ handler = xattr_resolve_name(inode, &name);
+ if (IS_ERR(handler))
+ return PTR_ERR(handler);
+ if (!handler->get)
+ return -EOPNOTSUPP;
+ return handler->get(handler, dentry, inode, name, value, size);
+}
+EXPORT_SYMBOL(__vfs_getxattr);
+
+ssize_t
+vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
+{
+ struct inode *inode = dentry->d_inode;
+ int error;
+
+ error = xattr_permission(inode, name, MAY_READ);
+ if (error)
+ return error;
+
+ error = security_inode_getxattr(dentry, name);
+ if (error)
+ return error;
+
+ if (!strncmp(name, XATTR_SECURITY_PREFIX,
+ XATTR_SECURITY_PREFIX_LEN)) {
+ const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+ int ret = xattr_getsecurity(inode, suffix, value, size);
+ /*
+ * Only overwrite the return value if a security module
+ * is actually active.
+ */
+ if (ret == -EOPNOTSUPP)
+ goto nolsm;
+ return ret;
+ }
+nolsm:
+ return __vfs_getxattr(dentry, inode, name, value, size);
+}
+EXPORT_SYMBOL_GPL(vfs_getxattr);
+
+ssize_t
+vfs_listxattr(struct dentry *dentry, char *list, size_t size)
+{
+ struct inode *inode = d_inode(dentry);
+ ssize_t error;
+
+ error = security_inode_listxattr(dentry);
+ if (error)
+ return error;
+ if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) {
+ error = inode->i_op->listxattr(dentry, list, size);
+ } else {
+ error = security_inode_listsecurity(inode, list, size);
+ if (size && error > size)
+ error = -ERANGE;
+ }
+ return error;
+}
+EXPORT_SYMBOL_GPL(vfs_listxattr);
+
+int
+__vfs_removexattr(struct dentry *dentry, const char *name)
+{
+ struct inode *inode = d_inode(dentry);
+ const struct xattr_handler *handler;
+
+ handler = xattr_resolve_name(inode, &name);
+ if (IS_ERR(handler))
+ return PTR_ERR(handler);
+ if (!handler->set)
+ return -EOPNOTSUPP;
+ return handler->set(handler, dentry, inode, name, NULL, 0, XATTR_REPLACE);
+}
+EXPORT_SYMBOL(__vfs_removexattr);
+
+int
+vfs_removexattr(struct dentry *dentry, const char *name)
+{
+ struct inode *inode = dentry->d_inode;
+ int error;
+
+ error = xattr_permission(inode, name, MAY_WRITE);
+ if (error)
+ return error;
+
+ inode_lock(inode);
+ error = security_inode_removexattr(dentry, name);
+ if (error)
+ goto out;
+
+ error = __vfs_removexattr(dentry, name);
+
+ if (!error) {
+ fsnotify_xattr(dentry);
+ evm_inode_post_removexattr(dentry, name);
+ }
+
+out:
+ inode_unlock(inode);
+ return error;
+}
+EXPORT_SYMBOL_GPL(vfs_removexattr);
+
+
+/*
+ * Extended attribute SET operations
+ */
+static long
+setxattr(struct dentry *d, const char __user *name, const void __user *value,
+ size_t size, int flags)
+{
+ int error;
+ void *kvalue = NULL;
+ char kname[XATTR_NAME_MAX + 1];
+
+ if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
+ return -EINVAL;
+
+ error = strncpy_from_user(kname, name, sizeof(kname));
+ if (error == 0 || error == sizeof(kname))
+ error = -ERANGE;
+ if (error < 0)
+ return error;
+
+ if (size) {
+ if (size > XATTR_SIZE_MAX)
+ return -E2BIG;
+ kvalue = kvmalloc(size, GFP_KERNEL);
+ if (!kvalue)
+ return -ENOMEM;
+ if (copy_from_user(kvalue, value, size)) {
+ error = -EFAULT;
+ goto out;
+ }
+ if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
+ (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
+ posix_acl_fix_xattr_from_user(kvalue, size);
+ else if (strcmp(kname, XATTR_NAME_CAPS) == 0) {
+ error = cap_convert_nscap(d, &kvalue, size);
+ if (error < 0)
+ goto out;
+ size = error;
+ }
+ }
+
+ error = vfs_setxattr(d, kname, kvalue, size, flags);
+out:
+ kvfree(kvalue);
+
+ return error;
+}
+
+static int path_setxattr(const char __user *pathname,
+ const char __user *name, const void __user *value,
+ size_t size, int flags, unsigned int lookup_flags)
+{
+ struct path path;
+ int error;
+retry:
+ error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+ if (error)
+ return error;
+ error = mnt_want_write(path.mnt);
+ if (!error) {
+ error = setxattr(path.dentry, name, value, size, flags);
+ mnt_drop_write(path.mnt);
+ }
+ path_put(&path);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
+SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
+ const char __user *, name, const void __user *, value,
+ size_t, size, int, flags)
+{
+ return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
+}
+
+SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
+ const char __user *, name, const void __user *, value,
+ size_t, size, int, flags)
+{
+ return path_setxattr(pathname, name, value, size, flags, 0);
+}
+
+SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
+ const void __user *,value, size_t, size, int, flags)
+{
+ struct fd f = fdget(fd);
+ int error = -EBADF;
+
+ if (!f.file)
+ return error;
+ audit_file(f.file);
+ error = mnt_want_write_file(f.file);
+ if (!error) {
+ error = setxattr(f.file->f_path.dentry, name, value, size, flags);
+ mnt_drop_write_file(f.file);
+ }
+ fdput(f);
+ return error;
+}
+
+/*
+ * Extended attribute GET operations
+ */
+static ssize_t
+getxattr(struct dentry *d, const char __user *name, void __user *value,
+ size_t size)
+{
+ ssize_t error;
+ void *kvalue = NULL;
+ char kname[XATTR_NAME_MAX + 1];
+
+ error = strncpy_from_user(kname, name, sizeof(kname));
+ if (error == 0 || error == sizeof(kname))
+ error = -ERANGE;
+ if (error < 0)
+ return error;
+
+ if (size) {
+ if (size > XATTR_SIZE_MAX)
+ size = XATTR_SIZE_MAX;
+ kvalue = kvzalloc(size, GFP_KERNEL);
+ if (!kvalue)
+ return -ENOMEM;
+ }
+
+ error = vfs_getxattr(d, kname, kvalue, size);
+ if (error > 0) {
+ if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
+ (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
+ posix_acl_fix_xattr_to_user(kvalue, error);
+ if (size && copy_to_user(value, kvalue, error))
+ error = -EFAULT;
+ } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
+ /* The file system tried to returned a value bigger
+ than XATTR_SIZE_MAX bytes. Not possible. */
+ error = -E2BIG;
+ }
+
+ kvfree(kvalue);
+
+ return error;
+}
+
+static ssize_t path_getxattr(const char __user *pathname,
+ const char __user *name, void __user *value,
+ size_t size, unsigned int lookup_flags)
+{
+ struct path path;
+ ssize_t error;
+retry:
+ error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+ if (error)
+ return error;
+ error = getxattr(path.dentry, name, value, size);
+ path_put(&path);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
+SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
+ const char __user *, name, void __user *, value, size_t, size)
+{
+ return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
+}
+
+SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
+ const char __user *, name, void __user *, value, size_t, size)
+{
+ return path_getxattr(pathname, name, value, size, 0);
+}
+
+SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
+ void __user *, value, size_t, size)
+{
+ struct fd f = fdget(fd);
+ ssize_t error = -EBADF;
+
+ if (!f.file)
+ return error;
+ audit_file(f.file);
+ error = getxattr(f.file->f_path.dentry, name, value, size);
+ fdput(f);
+ return error;
+}
+
+/*
+ * Extended attribute LIST operations
+ */
+static ssize_t
+listxattr(struct dentry *d, char __user *list, size_t size)
+{
+ ssize_t error;
+ char *klist = NULL;
+
+ if (size) {
+ if (size > XATTR_LIST_MAX)
+ size = XATTR_LIST_MAX;
+ klist = kvmalloc(size, GFP_KERNEL);
+ if (!klist)
+ return -ENOMEM;
+ }
+
+ error = vfs_listxattr(d, klist, size);
+ if (error > 0) {
+ if (size && copy_to_user(list, klist, error))
+ error = -EFAULT;
+ } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
+ /* The file system tried to returned a list bigger
+ than XATTR_LIST_MAX bytes. Not possible. */
+ error = -E2BIG;
+ }
+
+ kvfree(klist);
+
+ return error;
+}
+
+static ssize_t path_listxattr(const char __user *pathname, char __user *list,
+ size_t size, unsigned int lookup_flags)
+{
+ struct path path;
+ ssize_t error;
+retry:
+ error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+ if (error)
+ return error;
+ error = listxattr(path.dentry, list, size);
+ path_put(&path);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
+SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
+ size_t, size)
+{
+ return path_listxattr(pathname, list, size, LOOKUP_FOLLOW);
+}
+
+SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
+ size_t, size)
+{
+ return path_listxattr(pathname, list, size, 0);
+}
+
+SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
+{
+ struct fd f = fdget(fd);
+ ssize_t error = -EBADF;
+
+ if (!f.file)
+ return error;
+ audit_file(f.file);
+ error = listxattr(f.file->f_path.dentry, list, size);
+ fdput(f);
+ return error;
+}
+
+/*
+ * Extended attribute REMOVE operations
+ */
+static long
+removexattr(struct dentry *d, const char __user *name)
+{
+ int error;
+ char kname[XATTR_NAME_MAX + 1];
+
+ error = strncpy_from_user(kname, name, sizeof(kname));
+ if (error == 0 || error == sizeof(kname))
+ error = -ERANGE;
+ if (error < 0)
+ return error;
+
+ return vfs_removexattr(d, kname);
+}
+
+static int path_removexattr(const char __user *pathname,
+ const char __user *name, unsigned int lookup_flags)
+{
+ struct path path;
+ int error;
+retry:
+ error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+ if (error)
+ return error;
+ error = mnt_want_write(path.mnt);
+ if (!error) {
+ error = removexattr(path.dentry, name);
+ mnt_drop_write(path.mnt);
+ }
+ path_put(&path);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
+SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
+ const char __user *, name)
+{
+ return path_removexattr(pathname, name, LOOKUP_FOLLOW);
+}
+
+SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
+ const char __user *, name)
+{
+ return path_removexattr(pathname, name, 0);
+}
+
+SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
+{
+ struct fd f = fdget(fd);
+ int error = -EBADF;
+
+ if (!f.file)
+ return error;
+ audit_file(f.file);
+ error = mnt_want_write_file(f.file);
+ if (!error) {
+ error = removexattr(f.file->f_path.dentry, name);
+ mnt_drop_write_file(f.file);
+ }
+ fdput(f);
+ return error;
+}
+
+/*
+ * Combine the results of the list() operation from every xattr_handler in the
+ * list.
+ */
+ssize_t
+generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
+{
+ const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
+ unsigned int size = 0;
+
+ if (!buffer) {
+ for_each_xattr_handler(handlers, handler) {
+ if (!handler->name ||
+ (handler->list && !handler->list(dentry)))
+ continue;
+ size += strlen(handler->name) + 1;
+ }
+ } else {
+ char *buf = buffer;
+ size_t len;
+
+ for_each_xattr_handler(handlers, handler) {
+ if (!handler->name ||
+ (handler->list && !handler->list(dentry)))
+ continue;
+ len = strlen(handler->name);
+ if (len + 1 > buffer_size)
+ return -ERANGE;
+ memcpy(buf, handler->name, len + 1);
+ buf += len + 1;
+ buffer_size -= len + 1;
+ }
+ size = buf - buffer;
+ }
+ return size;
+}
+EXPORT_SYMBOL(generic_listxattr);
+
+/**
+ * xattr_full_name - Compute full attribute name from suffix
+ *
+ * @handler: handler of the xattr_handler operation
+ * @name: name passed to the xattr_handler operation
+ *
+ * The get and set xattr handler operations are called with the remainder of
+ * the attribute name after skipping the handler's prefix: for example, "foo"
+ * is passed to the get operation of a handler with prefix "user." to get
+ * attribute "user.foo". The full name is still "there" in the name though.
+ *
+ * Note: the list xattr handler operation when called from the vfs is passed a
+ * NULL name; some file systems use this operation internally, with varying
+ * semantics.
+ */
+const char *xattr_full_name(const struct xattr_handler *handler,
+ const char *name)
+{
+ size_t prefix_len = strlen(xattr_prefix(handler));
+
+ return name - prefix_len;
+}
+EXPORT_SYMBOL(xattr_full_name);
+
+/*
+ * 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;
+}
+
+/**
+ * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
+ * @xattrs: target simple_xattr list
+ * @name: name of the extended attribute
+ * @value: value of the 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)
+{
+ struct simple_xattr *xattr;
+ struct simple_xattr *new_xattr = NULL;
+ 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;
+
+}
+
+static bool xattr_is_trusted(const char *name)
+{
+ return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
+}
+
+static int xattr_list_one(char **buffer, ssize_t *remaining_size,
+ const char *name)
+{
+ size_t len = strlen(name) + 1;
+ if (*buffer) {
+ if (*remaining_size < len)
+ return -ERANGE;
+ memcpy(*buffer, name, len);
+ *buffer += len;
+ }
+ *remaining_size -= len;
+ return 0;
+}
+
+/*
+ * xattr LIST operation for in-memory/pseudo filesystems
+ */
+ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
+ char *buffer, size_t size)
+{
+ bool trusted = capable(CAP_SYS_ADMIN);
+ struct simple_xattr *xattr;
+ ssize_t remaining_size = size;
+ int err = 0;
+
+#ifdef CONFIG_FS_POSIX_ACL
+ if (IS_POSIXACL(inode)) {
+ if (inode->i_acl) {
+ err = xattr_list_one(&buffer, &remaining_size,
+ XATTR_NAME_POSIX_ACL_ACCESS);
+ if (err)
+ return err;
+ }
+ if (inode->i_default_acl) {
+ err = xattr_list_one(&buffer, &remaining_size,
+ XATTR_NAME_POSIX_ACL_DEFAULT);
+ if (err)
+ return err;
+ }
+ }
+#endif
+
+ spin_lock(&xattrs->lock);
+ list_for_each_entry(xattr, &xattrs->head, list) {
+ /* skip "trusted." attributes for unprivileged callers */
+ if (!trusted && xattr_is_trusted(xattr->name))
+ continue;
+
+ err = xattr_list_one(&buffer, &remaining_size, xattr->name);
+ if (err)
+ break;
+ }
+ spin_unlock(&xattrs->lock);
+
+ return err ? err : size - remaining_size;
+}
+
+/*
+ * 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);
+}