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/vmalloc.h>
-#include <linux/smp_lock.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 <asm/uaccess.h>
/*
- * Extended attribute memory allocation wrappers, originally
- * based on the Intermezzo PRESTO_ALLOC/PRESTO_FREE macros.
- * The vmalloc use here is very uncommon - extended attributes
- * are supposed to be small chunks of metadata, and it is quite
- * unusual to have very many extended attributes, so lists tend
- * to be quite short as well. The 64K upper limit is derived
- * from the extended attribute size limit used by XFS.
- * Intentionally allow zero @size for value/list size requests.
+ * Check permissions for extended attribute access. This is a bit complicated
+ * because different namespaces have very different rules.
*/
-static void *
-xattr_alloc(size_t size, size_t limit)
+static int
+xattr_permission(struct inode *inode, const char *name, int mask)
{
- void *ptr;
+ /*
+ * 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;
+ }
- if (size > limit)
- return ERR_PTR(-E2BIG);
+ /*
+ * 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;
+ }
- if (!size) /* size request, no buffer is needed */
- return NULL;
- else if (size <= PAGE_SIZE)
- ptr = kmalloc((unsigned long) size, GFP_KERNEL);
+ /*
+ * 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);
+}
+
+/**
+ * __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 = -EOPNOTSUPP;
+ int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
+ XATTR_SECURITY_PREFIX_LEN);
+
+ if (issec)
+ inode->i_flags &= ~S_NOSEC;
+ if (inode->i_op->setxattr) {
+ error = inode->i_op->setxattr(dentry, name, value, size, flags);
+ if (!error) {
+ fsnotify_xattr(dentry);
+ security_inode_post_setxattr(dentry, name, value,
+ size, flags);
+ }
+ } else 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;
+
+ mutex_lock(&inode->i_mutex);
+ error = security_inode_setxattr(dentry, name, value, size, flags);
+ if (error)
+ goto out;
+
+ error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
+
+out:
+ mutex_unlock(&inode->i_mutex);
+ return error;
+}
+EXPORT_SYMBOL_GPL(vfs_setxattr);
+
+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:
+ security_release_secctx(buffer, len);
+out_noalloc:
+ return len;
+}
+EXPORT_SYMBOL_GPL(xattr_getsecurity);
+
+/*
+ * 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)
+{
+ struct inode *inode = dentry->d_inode;
+ char *value = *xattr_value;
+ int error;
+
+ error = xattr_permission(inode, name, MAY_READ);
+ if (error)
+ return error;
+
+ if (!inode->i_op->getxattr)
+ return -EOPNOTSUPP;
+
+ error = inode->i_op->getxattr(dentry, 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 = inode->i_op->getxattr(dentry, name, value, error);
+ *xattr_value = value;
+ return error;
+}
+
+/* Compare an extended attribute value with the given value */
+int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,
+ const char *value, size_t size, gfp_t flags)
+{
+ char *xattr_value = NULL;
+ int rc;
+
+ rc = vfs_getxattr_alloc(dentry, xattr_name, &xattr_value, 0, flags);
+ if (rc < 0)
+ return rc;
+
+ if ((rc != size) || (memcmp(xattr_value, value, rc) != 0))
+ rc = -EINVAL;
else
- ptr = vmalloc((unsigned long) size);
- if (!ptr)
- return ERR_PTR(-ENOMEM);
- return ptr;
+ rc = 0;
+ kfree(xattr_value);
+ return rc;
}
-static void
-xattr_free(void *ptr, size_t size)
+ssize_t
+vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
{
- if (!size) /* size request, no buffer was needed */
- return;
- else if (size <= PAGE_SIZE)
- kfree(ptr);
+ 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:
+ if (inode->i_op->getxattr)
+ error = inode->i_op->getxattr(dentry, name, value, size);
else
- vfree(ptr);
+ error = -EOPNOTSUPP;
+
+ return error;
+}
+EXPORT_SYMBOL_GPL(vfs_getxattr);
+
+ssize_t
+vfs_listxattr(struct dentry *d, char *list, size_t size)
+{
+ ssize_t error;
+
+ error = security_inode_listxattr(d);
+ if (error)
+ return error;
+ error = -EOPNOTSUPP;
+ if (d->d_inode->i_op->listxattr) {
+ error = d->d_inode->i_op->listxattr(d, list, size);
+ } else {
+ error = security_inode_listsecurity(d->d_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 = dentry->d_inode;
+ int error;
+
+ if (!inode->i_op->removexattr)
+ return -EOPNOTSUPP;
+
+ error = xattr_permission(inode, name, MAY_WRITE);
+ if (error)
+ return error;
+
+ error = security_inode_removexattr(dentry, name);
+ if (error)
+ return error;
+
+ mutex_lock(&inode->i_mutex);
+ error = inode->i_op->removexattr(dentry, name);
+ mutex_unlock(&inode->i_mutex);
+
+ if (!error) {
+ fsnotify_xattr(dentry);
+ evm_inode_post_removexattr(dentry, name);
+ }
+ return error;
}
+EXPORT_SYMBOL_GPL(vfs_removexattr);
+
/*
* Extended attribute SET operations
*/
static long
-setxattr(struct dentry *d, char *name, void *value, size_t size, int flags)
+setxattr(struct dentry *d, const char __user *name, const void __user *value,
+ size_t size, int flags)
{
int error;
- void *kvalue;
+ void *kvalue = NULL;
+ void *vvalue = NULL; /* If non-NULL, we used vmalloc() */
char kname[XATTR_NAME_MAX + 1];
if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
if (error < 0)
return error;
- kvalue = xattr_alloc(size, XATTR_SIZE_MAX);
- if (IS_ERR(kvalue))
- return PTR_ERR(kvalue);
-
- if (size > 0 && copy_from_user(kvalue, value, size)) {
- xattr_free(kvalue, size);
- return -EFAULT;
- }
-
- error = -EOPNOTSUPP;
- if (d->d_inode->i_op && d->d_inode->i_op->setxattr) {
- error = security_inode_setxattr(d, kname, kvalue, size, flags);
- if (error)
+ if (size) {
+ if (size > XATTR_SIZE_MAX)
+ return -E2BIG;
+ kvalue = kmalloc(size, GFP_KERNEL | __GFP_NOWARN);
+ if (!kvalue) {
+ vvalue = vmalloc(size);
+ if (!vvalue)
+ return -ENOMEM;
+ kvalue = vvalue;
+ }
+ if (copy_from_user(kvalue, value, size)) {
+ error = -EFAULT;
goto out;
- down(&d->d_inode->i_sem);
- error = d->d_inode->i_op->setxattr(d, kname, kvalue, size, flags);
- up(&d->d_inode->i_sem);
+ }
}
+ error = vfs_setxattr(d, kname, kvalue, size, flags);
out:
- xattr_free(kvalue, size);
+ if (vvalue)
+ vfree(vvalue);
+ else
+ kfree(kvalue);
return error;
}
-asmlinkage long
-sys_setxattr(char *path, char *name, void *value, size_t size, int flags)
+SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
+ const char __user *, name, const void __user *, value,
+ size_t, size, int, flags)
{
- struct nameidata nd;
+ struct path path;
int error;
- error = user_path_walk(path, &nd);
+ error = user_path(pathname, &path);
if (error)
return error;
- error = setxattr(nd.dentry, name, value, size, flags);
- path_release(&nd);
+ error = mnt_want_write(path.mnt);
+ if (!error) {
+ error = setxattr(path.dentry, name, value, size, flags);
+ mnt_drop_write(path.mnt);
+ }
+ path_put(&path);
return error;
}
-asmlinkage long
-sys_lsetxattr(char *path, char *name, void *value, size_t size, int flags)
+SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
+ const char __user *, name, const void __user *, value,
+ size_t, size, int, flags)
{
- struct nameidata nd;
+ struct path path;
int error;
- error = user_path_walk_link(path, &nd);
+ error = user_lpath(pathname, &path);
if (error)
return error;
- error = setxattr(nd.dentry, name, value, size, flags);
- path_release(&nd);
+ error = mnt_want_write(path.mnt);
+ if (!error) {
+ error = setxattr(path.dentry, name, value, size, flags);
+ mnt_drop_write(path.mnt);
+ }
+ path_put(&path);
return error;
}
-asmlinkage long
-sys_fsetxattr(int fd, char *name, void *value, size_t size, int flags)
+SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
+ const void __user *,value, size_t, size, int, flags)
{
struct file *f;
+ struct dentry *dentry;
int error = -EBADF;
f = fget(fd);
if (!f)
return error;
- error = setxattr(f->f_dentry, name, value, size, flags);
+ dentry = f->f_path.dentry;
+ audit_inode(NULL, dentry);
+ error = mnt_want_write_file(f);
+ if (!error) {
+ error = setxattr(dentry, name, value, size, flags);
+ mnt_drop_write_file(f);
+ }
fput(f);
return error;
}
* Extended attribute GET operations
*/
static ssize_t
-getxattr(struct dentry *d, char *name, void *value, size_t size)
+getxattr(struct dentry *d, const char __user *name, void __user *value,
+ size_t size)
{
ssize_t error;
- void *kvalue;
+ void *kvalue = NULL;
char kname[XATTR_NAME_MAX + 1];
error = strncpy_from_user(kname, name, sizeof(kname));
if (error < 0)
return error;
- kvalue = xattr_alloc(size, XATTR_SIZE_MAX);
- if (IS_ERR(kvalue))
- return PTR_ERR(kvalue);
-
- error = -EOPNOTSUPP;
- if (d->d_inode->i_op && d->d_inode->i_op->getxattr) {
- error = security_inode_getxattr(d, kname);
- if (error)
- goto out;
- down(&d->d_inode->i_sem);
- error = d->d_inode->i_op->getxattr(d, kname, kvalue, size);
- up(&d->d_inode->i_sem);
+ if (size) {
+ if (size > XATTR_SIZE_MAX)
+ size = XATTR_SIZE_MAX;
+ kvalue = kzalloc(size, GFP_KERNEL);
+ if (!kvalue)
+ return -ENOMEM;
}
- if (kvalue && error > 0)
- if (copy_to_user(value, kvalue, error))
+ error = vfs_getxattr(d, kname, kvalue, size);
+ if (error > 0) {
+ if (size && copy_to_user(value, kvalue, error))
error = -EFAULT;
-out:
- xattr_free(kvalue, size);
+ } 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;
+ }
+ kfree(kvalue);
return error;
}
-asmlinkage ssize_t
-sys_getxattr(char *path, char *name, void *value, size_t size)
+SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
+ const char __user *, name, void __user *, value, size_t, size)
{
- struct nameidata nd;
+ struct path path;
ssize_t error;
- error = user_path_walk(path, &nd);
+ error = user_path(pathname, &path);
if (error)
return error;
- error = getxattr(nd.dentry, name, value, size);
- path_release(&nd);
+ error = getxattr(path.dentry, name, value, size);
+ path_put(&path);
return error;
}
-asmlinkage ssize_t
-sys_lgetxattr(char *path, char *name, void *value, size_t size)
+SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
+ const char __user *, name, void __user *, value, size_t, size)
{
- struct nameidata nd;
+ struct path path;
ssize_t error;
- error = user_path_walk_link(path, &nd);
+ error = user_lpath(pathname, &path);
if (error)
return error;
- error = getxattr(nd.dentry, name, value, size);
- path_release(&nd);
+ error = getxattr(path.dentry, name, value, size);
+ path_put(&path);
return error;
}
-asmlinkage ssize_t
-sys_fgetxattr(int fd, char *name, void *value, size_t size)
+SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
+ void __user *, value, size_t, size)
{
struct file *f;
ssize_t error = -EBADF;
f = fget(fd);
if (!f)
return error;
- error = getxattr(f->f_dentry, name, value, size);
+ audit_inode(NULL, f->f_path.dentry);
+ error = getxattr(f->f_path.dentry, name, value, size);
fput(f);
return error;
}
* Extended attribute LIST operations
*/
static ssize_t
-listxattr(struct dentry *d, char *list, size_t size)
+listxattr(struct dentry *d, char __user *list, size_t size)
{
ssize_t error;
- char *klist;
-
- klist = (char *)xattr_alloc(size, XATTR_LIST_MAX);
- if (IS_ERR(klist))
- return PTR_ERR(klist);
-
- error = -EOPNOTSUPP;
- if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
- error = security_inode_listxattr(d);
- if (error)
- goto out;
- down(&d->d_inode->i_sem);
- error = d->d_inode->i_op->listxattr(d, klist, size);
- up(&d->d_inode->i_sem);
+ char *klist = NULL;
+ char *vlist = NULL; /* If non-NULL, we used vmalloc() */
+
+ if (size) {
+ if (size > XATTR_LIST_MAX)
+ size = XATTR_LIST_MAX;
+ klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL);
+ if (!klist) {
+ vlist = vmalloc(size);
+ if (!vlist)
+ return -ENOMEM;
+ klist = vlist;
+ }
}
- if (klist && error > 0)
- if (copy_to_user(list, klist, error))
+ error = vfs_listxattr(d, klist, size);
+ if (error > 0) {
+ if (size && copy_to_user(list, klist, error))
error = -EFAULT;
-out:
- xattr_free(klist, size);
+ } 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;
+ }
+ if (vlist)
+ vfree(vlist);
+ else
+ kfree(klist);
return error;
}
-asmlinkage ssize_t
-sys_listxattr(char *path, char *list, size_t size)
+SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
+ size_t, size)
{
- struct nameidata nd;
+ struct path path;
ssize_t error;
- error = user_path_walk(path, &nd);
+ error = user_path(pathname, &path);
if (error)
return error;
- error = listxattr(nd.dentry, list, size);
- path_release(&nd);
+ error = listxattr(path.dentry, list, size);
+ path_put(&path);
return error;
}
-asmlinkage ssize_t
-sys_llistxattr(char *path, char *list, size_t size)
+SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
+ size_t, size)
{
- struct nameidata nd;
+ struct path path;
ssize_t error;
- error = user_path_walk_link(path, &nd);
+ error = user_lpath(pathname, &path);
if (error)
return error;
- error = listxattr(nd.dentry, list, size);
- path_release(&nd);
+ error = listxattr(path.dentry, list, size);
+ path_put(&path);
return error;
}
-asmlinkage ssize_t
-sys_flistxattr(int fd, char *list, size_t size)
+SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
{
struct file *f;
ssize_t error = -EBADF;
f = fget(fd);
if (!f)
return error;
- error = listxattr(f->f_dentry, list, size);
+ audit_inode(NULL, f->f_path.dentry);
+ error = listxattr(f->f_path.dentry, list, size);
fput(f);
return error;
}
* Extended attribute REMOVE operations
*/
static long
-removexattr(struct dentry *d, char *name)
+removexattr(struct dentry *d, const char __user *name)
{
int error;
char kname[XATTR_NAME_MAX + 1];
if (error < 0)
return error;
- error = -EOPNOTSUPP;
- if (d->d_inode->i_op && d->d_inode->i_op->removexattr) {
- error = security_inode_removexattr(d, kname);
- if (error)
- goto out;
- down(&d->d_inode->i_sem);
- error = d->d_inode->i_op->removexattr(d, kname);
- up(&d->d_inode->i_sem);
- }
-out:
- return error;
+ return vfs_removexattr(d, kname);
}
-asmlinkage long
-sys_removexattr(char *path, char *name)
+SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
+ const char __user *, name)
{
- struct nameidata nd;
+ struct path path;
int error;
- error = user_path_walk(path, &nd);
+ error = user_path(pathname, &path);
if (error)
return error;
- error = removexattr(nd.dentry, name);
- path_release(&nd);
+ error = mnt_want_write(path.mnt);
+ if (!error) {
+ error = removexattr(path.dentry, name);
+ mnt_drop_write(path.mnt);
+ }
+ path_put(&path);
return error;
}
-asmlinkage long
-sys_lremovexattr(char *path, char *name)
+SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
+ const char __user *, name)
{
- struct nameidata nd;
+ struct path path;
int error;
- error = user_path_walk_link(path, &nd);
+ error = user_lpath(pathname, &path);
if (error)
return error;
- error = removexattr(nd.dentry, name);
- path_release(&nd);
+ error = mnt_want_write(path.mnt);
+ if (!error) {
+ error = removexattr(path.dentry, name);
+ mnt_drop_write(path.mnt);
+ }
+ path_put(&path);
return error;
}
-asmlinkage long
-sys_fremovexattr(int fd, char *name)
+SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
{
struct file *f;
+ struct dentry *dentry;
int error = -EBADF;
f = fget(fd);
if (!f)
return error;
- error = removexattr(f->f_dentry, name);
+ dentry = f->f_path.dentry;
+ audit_inode(NULL, dentry);
+ error = mnt_want_write_file(f);
+ if (!error) {
+ error = removexattr(dentry, name);
+ mnt_drop_write_file(f);
+ }
fput(f);
return error;
}
+
+
+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 with the generic xattr API, 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.
+ *
+ * The generic_fooxattr() functions will use this list to dispatch xattr
+ * operations to the correct xattr_handler.
+ */
+#define for_each_xattr_handler(handlers, handler) \
+ for ((handler) = *(handlers)++; \
+ (handler) != NULL; \
+ (handler) = *(handlers)++)
+
+/*
+ * Find the xattr_handler with the matching prefix.
+ */
+static const struct xattr_handler *
+xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
+{
+ const struct xattr_handler *handler;
+
+ if (!*name)
+ return NULL;
+
+ for_each_xattr_handler(handlers, handler) {
+ const char *n = strcmp_prefix(*name, handler->prefix);
+ if (n) {
+ *name = n;
+ break;
+ }
+ }
+ return handler;
+}
+
+/*
+ * Find the handler for the prefix and dispatch its get() operation.
+ */
+ssize_t
+generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
+{
+ const struct xattr_handler *handler;
+
+ handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
+ if (!handler)
+ return -EOPNOTSUPP;
+ return handler->get(dentry, name, buffer, size, handler->flags);
+}
+
+/*
+ * 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) {
+ size += handler->list(dentry, NULL, 0, NULL, 0,
+ handler->flags);
+ }
+ } else {
+ char *buf = buffer;
+
+ for_each_xattr_handler(handlers, handler) {
+ size = handler->list(dentry, buf, buffer_size,
+ NULL, 0, handler->flags);
+ if (size > buffer_size)
+ return -ERANGE;
+ buf += size;
+ buffer_size -= size;
+ }
+ size = buf - buffer;
+ }
+ return size;
+}
+
+/*
+ * Find the handler for the prefix and dispatch its set() operation.
+ */
+int
+generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
+{
+ const struct xattr_handler *handler;
+
+ if (size == 0)
+ value = ""; /* empty EA, do not remove */
+ handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
+ if (!handler)
+ return -EOPNOTSUPP;
+ return handler->set(dentry, name, value, size, flags, handler->flags);
+}
+
+/*
+ * Find the handler for the prefix and dispatch its set() operation to remove
+ * any associated extended attribute.
+ */
+int
+generic_removexattr(struct dentry *dentry, const char *name)
+{
+ const struct xattr_handler *handler;
+
+ handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
+ if (!handler)
+ return -EOPNOTSUPP;
+ return handler->set(dentry, name, NULL, 0,
+ XATTR_REPLACE, handler->flags);
+}
+
+EXPORT_SYMBOL(generic_getxattr);
+EXPORT_SYMBOL(generic_listxattr);
+EXPORT_SYMBOL(generic_setxattr);
+EXPORT_SYMBOL(generic_removexattr);
projects / linux-flexiantxendom0-3.2.10.git / blobdiff