Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1189 insertions, 0 deletions

diff --git a/fs/xattr.c b/fs/xattr.c
new file mode 100644
index 000000000..427b8cea1
--- /dev/null
+++ b/fs/xattr.c
@@ -0,0 +1,1189 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+  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>
+
+#include "internal.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 user_namespace *mnt_userns, 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(mnt_userns, 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(mnt_userns, inode))
+			return -EPERM;
+	}
+
+	return inode_permission(mnt_userns, inode, mask);
+}
+
+/*
+ * Look for any handler that deals with the specified namespace.
+ */
+int
+xattr_supported_namespace(struct inode *inode, const char *prefix)
+{
+	const struct xattr_handler **handlers = inode->i_sb->s_xattr;
+	const struct xattr_handler *handler;
+	size_t preflen;
+
+	if (!(inode->i_opflags & IOP_XATTR)) {
+		if (unlikely(is_bad_inode(inode)))
+			return -EIO;
+		return -EOPNOTSUPP;
+	}
+
+	preflen = strlen(prefix);
+
+	for_each_xattr_handler(handlers, handler) {
+		if (!strncmp(xattr_prefix(handler), prefix, preflen))
+			return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL(xattr_supported_namespace);
+
+int
+__vfs_setxattr(struct user_namespace *mnt_userns, 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, mnt_userns, dentry, inode, name, value,
+			    size, flags);
+}
+EXPORT_SYMBOL(__vfs_setxattr);
+
+/**
+ *  __vfs_setxattr_noperm - perform setxattr operation without performing
+ *  permission checks.
+ *
+ *  @mnt_userns: user namespace of the mount the inode was found from
+ *  @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 user_namespace *mnt_userns,
+			  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(mnt_userns, 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;
+}
+
+/**
+ * __vfs_setxattr_locked - set an extended attribute while holding the inode
+ * lock
+ *
+ *  @mnt_userns: user namespace of the mount of the target inode
+ *  @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
+ *  @delegated_inode: on return, will contain an inode pointer that
+ *  a delegation was broken on, NULL if none.
+ */
+int
+__vfs_setxattr_locked(struct user_namespace *mnt_userns, struct dentry *dentry,
+		      const char *name, const void *value, size_t size,
+		      int flags, struct inode **delegated_inode)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	error = security_inode_setxattr(mnt_userns, dentry, name, value, size,
+					flags);
+	if (error)
+		goto out;
+
+	error = try_break_deleg(inode, delegated_inode);
+	if (error)
+		goto out;
+
+	error = __vfs_setxattr_noperm(mnt_userns, dentry, name, value,
+				      size, flags);
+
+out:
+	return error;
+}
+EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
+
+static inline bool is_posix_acl_xattr(const char *name)
+{
+	return (strcmp(name, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
+	       (strcmp(name, XATTR_NAME_POSIX_ACL_DEFAULT) == 0);
+}
+
+int
+vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+	     const char *name, const void *value, size_t size, int flags)
+{
+	struct inode *inode = dentry->d_inode;
+	struct inode *delegated_inode = NULL;
+	const void  *orig_value = value;
+	int error;
+
+	if (size && strcmp(name, XATTR_NAME_CAPS) == 0) {
+		error = cap_convert_nscap(mnt_userns, dentry, &value, size);
+		if (error < 0)
+			return error;
+		size = error;
+	}
+
+retry_deleg:
+	inode_lock(inode);
+	error = __vfs_setxattr_locked(mnt_userns, dentry, name, value, size,
+				      flags, &delegated_inode);
+	inode_unlock(inode);
+
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry_deleg;
+	}
+	if (value != orig_value)
+		kfree(value);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_setxattr);
+
+static ssize_t
+xattr_getsecurity(struct user_namespace *mnt_userns, struct inode *inode,
+		  const char *name, void *value, size_t size)
+{
+	void *buffer = NULL;
+	ssize_t len;
+
+	if (!value || !size) {
+		len = security_inode_getsecurity(mnt_userns, inode, name,
+						 &buffer, false);
+		goto out_noalloc;
+	}
+
+	len = security_inode_getsecurity(mnt_userns, 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 user_namespace *mnt_userns, 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(mnt_userns, 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 user_namespace *mnt_userns, struct dentry *dentry,
+	     const char *name, void *value, size_t size)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(mnt_userns, 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(mnt_userns, inode, suffix, value,
+					    size);
+		/*
+		 * Only overwrite the return value if a security module
+		 * is actually active.
+		 */
+		if (ret == -EOPNOTSUPP)
+			goto nolsm;
+		return ret;
+	}
+nolsm:
+	error = __vfs_getxattr(dentry, inode, name, value, size);
+	if (error > 0 && is_posix_acl_xattr(name))
+		posix_acl_getxattr_idmapped_mnt(mnt_userns, inode, value, size);
+	return error;
+}
+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 user_namespace *mnt_userns, 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, mnt_userns, dentry, inode, name, NULL, 0,
+			    XATTR_REPLACE);
+}
+EXPORT_SYMBOL(__vfs_removexattr);
+
+/**
+ * __vfs_removexattr_locked - set an extended attribute while holding the inode
+ * lock
+ *
+ *  @mnt_userns: user namespace of the mount of the target inode
+ *  @dentry: object to perform setxattr on
+ *  @name: name of xattr to remove
+ *  @delegated_inode: on return, will contain an inode pointer that
+ *  a delegation was broken on, NULL if none.
+ */
+int
+__vfs_removexattr_locked(struct user_namespace *mnt_userns,
+			 struct dentry *dentry, const char *name,
+			 struct inode **delegated_inode)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	error = security_inode_removexattr(mnt_userns, dentry, name);
+	if (error)
+		goto out;
+
+	error = try_break_deleg(inode, delegated_inode);
+	if (error)
+		goto out;
+
+	error = __vfs_removexattr(mnt_userns, dentry, name);
+
+	if (!error) {
+		fsnotify_xattr(dentry);
+		evm_inode_post_removexattr(dentry, name);
+	}
+
+out:
+	return error;
+}
+EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
+
+int
+vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		const char *name)
+{
+	struct inode *inode = dentry->d_inode;
+	struct inode *delegated_inode = NULL;
+	int error;
+
+retry_deleg:
+	inode_lock(inode);
+	error = __vfs_removexattr_locked(mnt_userns, dentry,
+					 name, &delegated_inode);
+	inode_unlock(inode);
+
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry_deleg;
+	}
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_removexattr);
+
+/*
+ * Extended attribute SET operations
+ */
+
+int setxattr_copy(const char __user *name, struct xattr_ctx *ctx)
+{
+	int error;
+
+	if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
+		return -EINVAL;
+
+	error = strncpy_from_user(ctx->kname->name, name,
+				sizeof(ctx->kname->name));
+	if (error == 0 || error == sizeof(ctx->kname->name))
+		return  -ERANGE;
+	if (error < 0)
+		return error;
+
+	error = 0;
+	if (ctx->size) {
+		if (ctx->size > XATTR_SIZE_MAX)
+			return -E2BIG;
+
+		ctx->kvalue = vmemdup_user(ctx->cvalue, ctx->size);
+		if (IS_ERR(ctx->kvalue)) {
+			error = PTR_ERR(ctx->kvalue);
+			ctx->kvalue = NULL;
+		}
+	}
+
+	return error;
+}
+
+static void setxattr_convert(struct user_namespace *mnt_userns,
+			     struct dentry *d, struct xattr_ctx *ctx)
+{
+	if (ctx->size && is_posix_acl_xattr(ctx->kname->name))
+		posix_acl_fix_xattr_from_user(ctx->kvalue, ctx->size);
+}
+
+int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		struct xattr_ctx *ctx)
+{
+	setxattr_convert(mnt_userns, dentry, ctx);
+	return vfs_setxattr(mnt_userns, dentry, ctx->kname->name,
+			ctx->kvalue, ctx->size, ctx->flags);
+}
+
+static long
+setxattr(struct user_namespace *mnt_userns, struct dentry *d,
+	const char __user *name, const void __user *value, size_t size,
+	int flags)
+{
+	struct xattr_name kname;
+	struct xattr_ctx ctx = {
+		.cvalue   = value,
+		.kvalue   = NULL,
+		.size     = size,
+		.kname    = &kname,
+		.flags    = flags,
+	};
+	int error;
+
+	error = setxattr_copy(name, &ctx);
+	if (error)
+		return error;
+
+	error = do_setxattr(mnt_userns, d, &ctx);
+
+	kvfree(ctx.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(mnt_user_ns(path.mnt), 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(file_mnt_user_ns(f.file),
+				 f.file->f_path.dentry, name,
+				 value, size, flags);
+		mnt_drop_write_file(f.file);
+	}
+	fdput(f);
+	return error;
+}
+
+/*
+ * Extended attribute GET operations
+ */
+ssize_t
+do_getxattr(struct user_namespace *mnt_userns, struct dentry *d,
+	struct xattr_ctx *ctx)
+{
+	ssize_t error;
+	char *kname = ctx->kname->name;
+
+	if (ctx->size) {
+		if (ctx->size > XATTR_SIZE_MAX)
+			ctx->size = XATTR_SIZE_MAX;
+		ctx->kvalue = kvzalloc(ctx->size, GFP_KERNEL);
+		if (!ctx->kvalue)
+			return -ENOMEM;
+	}
+
+	error = vfs_getxattr(mnt_userns, d, kname, ctx->kvalue, ctx->size);
+	if (error > 0) {
+		if (is_posix_acl_xattr(kname))
+			posix_acl_fix_xattr_to_user(ctx->kvalue, error);
+		if (ctx->size && copy_to_user(ctx->value, ctx->kvalue, error))
+			error = -EFAULT;
+	} else if (error == -ERANGE && ctx->size >= XATTR_SIZE_MAX) {
+		/* The file system tried to returned a value bigger
+		   than XATTR_SIZE_MAX bytes. Not possible. */
+		error = -E2BIG;
+	}
+
+	return error;
+}
+
+static ssize_t
+getxattr(struct user_namespace *mnt_userns, struct dentry *d,
+	 const char __user *name, void __user *value, size_t size)
+{
+	ssize_t error;
+	struct xattr_name kname;
+	struct xattr_ctx ctx = {
+		.value    = value,
+		.kvalue   = NULL,
+		.size     = size,
+		.kname    = &kname,
+		.flags    = 0,
+	};
+
+	error = strncpy_from_user(kname.name, name, sizeof(kname.name));
+	if (error == 0 || error == sizeof(kname.name))
+		error = -ERANGE;
+	if (error < 0)
+		return error;
+
+	error =  do_getxattr(mnt_userns, d, &ctx);
+
+	kvfree(ctx.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(mnt_user_ns(path.mnt), 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(file_mnt_user_ns(f.file), 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 user_namespace *mnt_userns, 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(mnt_userns, 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(mnt_user_ns(path.mnt), 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(file_mnt_user_ns(f.file),
+				    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 = kvmalloc(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}
+ * @removed_size: returns size of the removed xattr, -1 if none removed
+ *
+ * %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,
+		     ssize_t *removed_size)
+{
+	struct simple_xattr *xattr;
+	struct simple_xattr *new_xattr = NULL;
+	int err = 0;
+
+	if (removed_size)
+		*removed_size = -1;
+
+	/* 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) {
+			kvfree(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);
+				if (removed_size)
+					*removed_size = xattr->size;
+			} else {
+				list_del(&xattr->list);
+				if (removed_size)
+					*removed_size = xattr->size;
+			}
+			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);
+		kvfree(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 = ns_capable_noaudit(&init_user_ns, 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);
+}