fanotify: allow users to set an ignored_mask

Change the sys_fanotify_mark() system call so users can set ignored_masks
on inodes.  Remember, if a user new sets a real mask, and only sets ignored
masks, the ignore will never be pinned in memory.  Thus ignored_masks can
be lost under memory pressure and the user may again get events they
previously thought were ignored.

Signed-off-by: Eric Paris <eparis@redhat.com>

1 files changed, 36 insertions, 18 deletions

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 3320f0c57e31..ad02d475770f 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -296,13 +296,20 @@ out:
         return ret;
 }
 
-static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, __u32 mask)
+static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
+                                            __u32 mask,
+                                            unsigned int flags)
 {
         __u32 oldmask;
 
         spin_lock(&fsn_mark->lock);
-        oldmask = fsn_mark->mask;
-        fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
+        if (!(flags & FAN_MARK_IGNORED_MASK)) {
+                oldmask = fsn_mark->mask;
+                fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
+        } else {
+                oldmask = fsn_mark->ignored_mask;
+                fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask));
+        }
         spin_unlock(&fsn_mark->lock);
 
         if (!(oldmask & ~mask))
@@ -312,7 +319,8 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, __u3
 }
 
 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
-                                         struct vfsmount *mnt, __u32 mask)
+                                         struct vfsmount *mnt, __u32 mask,
+                                         unsigned int flags)
 {
         struct fsnotify_mark *fsn_mark = NULL;
         __u32 removed;
@@ -321,7 +329,7 @@ static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
         if (!fsn_mark)
                 return -ENOENT;
 
-        removed = fanotify_mark_remove_from_mask(fsn_mark, mask);
+        removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
         fsnotify_put_mark(fsn_mark);
         if (removed & group->mask)
                 fsnotify_recalc_group_mask(group);
@@ -332,7 +340,8 @@ static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
 }
 
 static int fanotify_remove_inode_mark(struct fsnotify_group *group,
-                                      struct inode *inode, __u32 mask)
+                                      struct inode *inode, __u32 mask,
+                                      unsigned int flags)
 {
         struct fsnotify_mark *fsn_mark = NULL;
         __u32 removed;
@@ -341,7 +350,7 @@ static int fanotify_remove_inode_mark(struct fsnotify_group *group,
         if (!fsn_mark)
                 return -ENOENT;
 
-        removed = fanotify_mark_remove_from_mask(fsn_mark, mask);
+        removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
         /* matches the fsnotify_find_inode_mark() */
         fsnotify_put_mark(fsn_mark);
 
@@ -353,20 +362,28 @@ static int fanotify_remove_inode_mark(struct fsnotify_group *group,
         return 0;
 }
 
-static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, __u32 mask)
+static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
+                                       __u32 mask,
+                                       unsigned int flags)
 {
         __u32 oldmask;
 
         spin_lock(&fsn_mark->lock);
-        oldmask = fsn_mark->mask;
-        fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
+        if (!(flags & FAN_MARK_IGNORED_MASK)) {
+                oldmask = fsn_mark->mask;
+                fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
+        } else {
+                oldmask = fsn_mark->ignored_mask;
+                fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask | mask));
+        }
         spin_unlock(&fsn_mark->lock);
 
         return mask & ~oldmask;
 }
 
 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
-                                      struct vfsmount *mnt, __u32 mask)
+                                      struct vfsmount *mnt, __u32 mask,
+                                      unsigned int flags)
 {
         struct fsnotify_mark *fsn_mark;
         __u32 added;
@@ -386,7 +403,7 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
                         return ret;
                 }
         }
-        added = fanotify_mark_add_to_mask(fsn_mark, mask);
+        added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
         fsnotify_put_mark(fsn_mark);
         if (added) {
                 if (added & ~group->mask)
@@ -398,7 +415,8 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
 }
 
 static int fanotify_add_inode_mark(struct fsnotify_group *group,
-                                   struct inode *inode, __u32 mask)
+                                   struct inode *inode, __u32 mask,
+                                   unsigned int flags)
 {
         struct fsnotify_mark *fsn_mark;
         __u32 added;
@@ -420,7 +438,7 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
                         return ret;
                 }
         }
-        added = fanotify_mark_add_to_mask(fsn_mark, mask);
+        added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
         fsnotify_put_mark(fsn_mark);
         if (added) {
                 if (added & ~group->mask)
@@ -528,15 +546,15 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
         case FAN_MARK_ADD:
                 if (flags & FAN_MARK_MOUNT)
-                        ret = fanotify_add_vfsmount_mark(group, mnt, mask);
+                        ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
                 else
-                        ret = fanotify_add_inode_mark(group, inode, mask);
+                        ret = fanotify_add_inode_mark(group, inode, mask, flags);
                 break;
         case FAN_MARK_REMOVE:
                 if (flags & FAN_MARK_MOUNT)
-                        ret = fanotify_remove_vfsmount_mark(group, mnt, mask);
+                        ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
                 else
-                        ret = fanotify_remove_inode_mark(group, inode, mask);
+                        ret = fanotify_remove_inode_mark(group, inode, mask, flags);
                 break;
         default:
                 ret = -EINVAL;