lkml.org 
[lkml]   [2010]   [Oct]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 12/20] fanotify: allow userspace to override max marks
    Date
    Some fanotify groups, especially those like AV scanners, will need to place
    lots of marks, particularly ignore marks. Since ignore marks do not pin
    inodes in cache and are cleared if the inode is removed from core (usually
    under memory pressure) we expose an interface for listeners, with
    CAP_SYS_ADMIN, to override the maximum number of marks and be allowed to
    set and 'unlimited' number of marks. Programs which make use of this
    feature will be able to OOM a machine.

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

    fs/notify/fanotify/fanotify_user.c | 9 ++++++++-
    include/linux/fanotify.h | 4 +++-
    2 files changed, 11 insertions(+), 2 deletions(-)

    diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
    index 1d33d7d..f921610 100644
    --- a/fs/notify/fanotify/fanotify_user.c
    +++ b/fs/notify/fanotify/fanotify_user.c
    @@ -707,7 +707,14 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
    group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
    }

    - group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
    + if (flags & FAN_UNLIMITED_MARKS) {
    + fd = -EPERM;
    + if (!capable(CAP_SYS_ADMIN))
    + goto out_put_group;
    + group->fanotify_data.max_marks = UINT_MAX;
    + } else {
    + group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
    + }

    fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
    if (fd < 0)
    diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
    index e37f559..7592a36 100644
    --- a/include/linux/fanotify.h
    +++ b/include/linux/fanotify.h
    @@ -32,9 +32,11 @@
    FAN_CLASS_PRE_CONTENT)

    #define FAN_UNLIMITED_QUEUE 0x00000010
    +#define FAN_UNLIMITED_MARKS 0x00000020

    #define FAN_ALL_INIT_FLAGS (FAN_CLOEXEC | FAN_NONBLOCK | \
    - FAN_ALL_CLASS_BITS | FAN_UNLIMITED_QUEUE)
    + FAN_ALL_CLASS_BITS | FAN_UNLIMITED_QUEUE |\
    + FAN_UNLIMITED_MARKS)

    /* flags used for fanotify_modify_mark() */
    #define FAN_MARK_ADD 0x00000001


    \
     
     \ /
      Last update: 2010-10-28 23:37    [W:0.032 / U:121.356 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site