1 files changed, 238 insertions, 1 deletions

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 55d6e379f2b6..bc4fa48157f1 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1,12 +1,18 @@
 #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;
@@ -28,6 +34,185 @@ static const struct file_operations fanotify_fops = {
 	.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)
@@ -74,5 +259,57 @@ out_put_group:
 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);