#include <linux/fcntl.h>
+#include <linux/file.h>
#include <linux/fs.h>
#include <linux/anon_inodes.h>
#include <linux/fsnotify_backend.h>
+#include <linux/init.h>
+#include <linux/namei.h>
#include <linux/security.h>
#include <linux/syscalls.h>
+#include <linux/types.h>
#include "fanotify.h"
+static struct kmem_cache *fanotify_mark_cache __read_mostly;
+
static int fanotify_release(struct inode *ignored, struct file *file)
{
struct fsnotify_group *group = file->private_data;
.compat_ioctl = NULL,
};
+static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
+{
+ kmem_cache_free(fanotify_mark_cache, fsn_mark);
+}
+
+static int fanotify_find_path(int dfd, const char __user *filename,
+ struct path *path, unsigned int flags)
+{
+ int ret;
+
+ pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
+ dfd, filename, flags);
+
+ if (filename == NULL) {
+ struct file *file;
+ int fput_needed;
+
+ ret = -EBADF;
+ file = fget_light(dfd, &fput_needed);
+ if (!file)
+ goto out;
+
+ ret = -ENOTDIR;
+ if ((flags & FAN_MARK_ONLYDIR) &&
+ !(S_ISDIR(file->f_path.dentry->d_inode->i_mode))) {
+ fput_light(file, fput_needed);
+ goto out;
+ }
+
+ *path = file->f_path;
+ path_get(path);
+ fput_light(file, fput_needed);
+ } else {
+ unsigned int lookup_flags = 0;
+
+ if (!(flags & FAN_MARK_DONT_FOLLOW))
+ lookup_flags |= LOOKUP_FOLLOW;
+ if (flags & FAN_MARK_ONLYDIR)
+ lookup_flags |= LOOKUP_DIRECTORY;
+
+ ret = user_path_at(dfd, filename, lookup_flags, path);
+ if (ret)
+ goto out;
+ }
+
+ /* you can only watch an inode if you have read permissions on it */
+ ret = inode_permission(path->dentry->d_inode, MAY_READ);
+ if (ret)
+ path_put(path);
+out:
+ return ret;
+}
+
+static int fanotify_remove_mark(struct fsnotify_group *group,
+ struct inode *inode,
+ __u32 mask)
+{
+ struct fsnotify_mark *fsn_mark;
+ __u32 new_mask;
+
+ pr_debug("%s: group=%p inode=%p mask=%x\n", __func__,
+ group, inode, mask);
+
+ fsn_mark = fsnotify_find_mark(group, inode);
+ if (!fsn_mark)
+ return -ENOENT;
+
+ spin_lock(&fsn_mark->lock);
+ fsn_mark->mask &= ~mask;
+ new_mask = fsn_mark->mask;
+ spin_unlock(&fsn_mark->lock);
+
+ if (!new_mask)
+ fsnotify_destroy_mark(fsn_mark);
+ else
+ fsnotify_recalc_inode_mask(inode);
+
+ fsnotify_recalc_group_mask(group);
+
+ /* matches the fsnotify_find_mark() */
+ fsnotify_put_mark(fsn_mark);
+
+ return 0;
+}
+
+static int fanotify_add_mark(struct fsnotify_group *group,
+ struct inode *inode,
+ __u32 mask)
+{
+ struct fsnotify_mark *fsn_mark;
+ __u32 old_mask, new_mask;
+ int ret;
+
+ pr_debug("%s: group=%p inode=%p mask=%x\n", __func__,
+ group, inode, mask);
+
+ fsn_mark = fsnotify_find_mark(group, inode);
+ if (!fsn_mark) {
+ struct fsnotify_mark *new_fsn_mark;
+
+ ret = -ENOMEM;
+ new_fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
+ if (!new_fsn_mark)
+ goto out;
+
+ fsnotify_init_mark(new_fsn_mark, fanotify_free_mark);
+ ret = fsnotify_add_mark(new_fsn_mark, group, inode, 0);
+ if (ret) {
+ fanotify_free_mark(new_fsn_mark);
+ goto out;
+ }
+
+ fsn_mark = new_fsn_mark;
+ }
+
+ ret = 0;
+
+ spin_lock(&fsn_mark->lock);
+ old_mask = fsn_mark->mask;
+ fsn_mark->mask |= mask;
+ new_mask = fsn_mark->mask;
+ spin_unlock(&fsn_mark->lock);
+
+ /* we made changes to a mask, update the group mask and the inode mask
+ * so things happen quickly. */
+ if (old_mask != new_mask) {
+ /* more bits in old than in new? */
+ int dropped = (old_mask & ~new_mask);
+ /* more bits in this mark than the inode's mask? */
+ int do_inode = (new_mask & ~inode->i_fsnotify_mask);
+ /* more bits in this mark than the group? */
+ int do_group = (new_mask & ~group->mask);
+
+ /* update the inode with this new mark */
+ if (dropped || do_inode)
+ fsnotify_recalc_inode_mask(inode);
+
+ /* update the group mask with the new mask */
+ if (dropped || do_group)
+ fsnotify_recalc_group_mask(group);
+ }
+
+ /* match the init or the find.... */
+ fsnotify_put_mark(fsn_mark);
+out:
+ return ret;
+}
+
+static int fanotify_update_mark(struct fsnotify_group *group,
+ struct inode *inode, int flags,
+ __u32 mask)
+{
+ pr_debug("%s: group=%p inode=%p flags=%x mask=%x\n", __func__,
+ group, inode, flags, mask);
+
+ if (flags & FAN_MARK_ADD)
+ fanotify_add_mark(group, inode, mask);
+ else if (flags & FAN_MARK_REMOVE)
+ fanotify_remove_mark(group, inode, mask);
+ else
+ BUG();
+
+ return 0;
+}
+
+static bool fanotify_mark_validate_input(int flags,
+ __u32 mask)
+{
+ pr_debug("%s: flags=%x mask=%x\n", __func__, flags, mask);
+
+ /* are flags valid of this operation? */
+ if (!fanotify_mark_flags_valid(flags))
+ return false;
+ /* is the mask valid? */
+ if (!fanotify_mask_valid(mask))
+ return false;
+ return true;
+}
+
/* fanotify syscalls */
SYSCALL_DEFINE3(fanotify_init, unsigned int, flags, unsigned int, event_f_flags,
unsigned int, priority)
SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
__u64, mask, int, dfd, const char __user *, pathname)
{
- return -ENOSYS;
+ struct inode *inode;
+ struct fsnotify_group *group;
+ struct file *filp;
+ struct path path;
+ int ret, fput_needed;
+
+ pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
+ __func__, fanotify_fd, flags, dfd, pathname, mask);
+
+ /* we only use the lower 32 bits as of right now. */
+ if (mask & ((__u64)0xffffffff << 32))
+ return -EINVAL;
+
+ if (!fanotify_mark_validate_input(flags, mask))
+ return -EINVAL;
+
+ filp = fget_light(fanotify_fd, &fput_needed);
+ if (unlikely(!filp))
+ return -EBADF;
+
+ /* verify that this is indeed an fanotify instance */
+ ret = -EINVAL;
+ if (unlikely(filp->f_op != &fanotify_fops))
+ goto fput_and_out;
+
+ ret = fanotify_find_path(dfd, pathname, &path, flags);
+ if (ret)
+ goto fput_and_out;
+
+ /* inode held in place by reference to path; group by fget on fd */
+ inode = path.dentry->d_inode;
+ group = filp->private_data;
+
+ /* create/update an inode mark */
+ ret = fanotify_update_mark(group, inode, flags, mask);
+
+ path_put(&path);
+fput_and_out:
+ fput_light(filp, fput_needed);
+ return ret;
+}
+
+/*
+ * fanotify_user_setup - Our initialization function. Note that we cannnot return
+ * error because we have compiled-in VFS hooks. So an (unlikely) failure here
+ * must result in panic().
+ */
+static int __init fanotify_user_setup(void)
+{
+ fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
+
+ return 0;
}
+device_initcall(fanotify_user_setup);
projects / users / willy / pagecache.git / commitdiff