3 files changed, 269 insertions, 1 deletions

diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index dd656cfab1ba..59c3331a0e81 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -6,6 +6,24 @@
 
 extern const struct fsnotify_ops fanotify_fsnotify_ops;
 
+static inline bool fanotify_mark_flags_valid(unsigned int flags)
+{
+        /* must be either and add or a remove */
+        if (!(flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)))
+                return false;
+
+        /* cannot be both add and remove */
+        if ((flags & FAN_MARK_ADD) &&
+            (flags & FAN_MARK_REMOVE))
+                return false;
+
+        /* cannot have more flags than we know about */
+        if (flags & ~FAN_ALL_MARK_FLAGS)
+                return false;
+
+        return true;
+}
+
 static inline bool fanotify_mask_valid(__u32 mask)
 {
         if (mask & ~((__u32)FAN_ALL_INCOMING_EVENTS))
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);
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index 00bc6d4fbb58..95aeea2a3ca6 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -18,10 +18,23 @@
 /* helper events */
 #define FAN_CLOSE               (FAN_CLOSE_WRITE | FAN_CLOSE_NOWRITE) /* close */
 
+/* flags used for fanotify_init() */
 #define FAN_CLOEXEC             0x00000001
 #define FAN_NONBLOCK            0x00000002
 
 #define FAN_ALL_INIT_FLAGS      (FAN_CLOEXEC | FAN_NONBLOCK)
+
+/* flags used for fanotify_modify_mark() */
+#define FAN_MARK_ADD            0x00000001
+#define FAN_MARK_REMOVE         0x00000002
+#define FAN_MARK_DONT_FOLLOW    0x00000004
+#define FAN_MARK_ONLYDIR        0x00000008
+
+#define FAN_ALL_MARK_FLAGS      (FAN_MARK_ADD |\
+                                 FAN_MARK_REMOVE |\
+                                 FAN_MARK_DONT_FOLLOW |\
+                                 FAN_MARK_ONLYDIR)
+
 /*
  * All of the events - we build the list by hand so that we can add flags in
  * the future and not break backward compatibility.  Apps will get only the