diff options
| author | Dave Wysochanski <dwysocha@redhat.com> | 2019-07-27 01:33:01 +0300 |
|---|---|---|
| committer | J. Bruce Fields <bfields@redhat.com> | 2019-07-30 18:55:53 +0300 |
| commit | 64a38e840ce5940253208eaba40265c73decc4ee (patch) | |
| tree | d4f490e97e05dcacfb8906222c32d7f57bae8e6a /include/linux/sunrpc/cache.h | |
| parent | 609488bc979f99f805f34e9a32c1e3b71179d10b (diff) | |
| download | linux-64a38e840ce5940253208eaba40265c73decc4ee.tar.xz | |
SUNRPC: Track writers of the 'channel' file to improve cache_listeners_exist
The sunrpc cache interface is susceptible to being fooled by a rogue
process just reading a 'channel' file. If this happens the kernel
may think a valid daemon exists to service the cache when it does not.
For example, the following may fool the kernel:
cat /proc/net/rpc/auth.unix.gid/channel
Change the tracking of readers to writers when considering whether a
listener exists as all valid daemon processes either open a channel
file O_RDWR or O_WRONLY. While this does not prevent a rogue process
from "stealing" a message from the kernel, it does at least improve
the kernels perception of whether a valid process servicing the cache
exists.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'include/linux/sunrpc/cache.h')
| -rw-r--r-- | include/linux/sunrpc/cache.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h index c7f38e897174..f7d086b77a21 100644 --- a/include/linux/sunrpc/cache.h +++ b/include/linux/sunrpc/cache.h @@ -107,9 +107,9 @@ struct cache_detail { /* fields for communication over channel */ struct list_head queue; - atomic_t readers; /* how many time is /chennel open */ - time_t last_close; /* if no readers, when did last close */ - time_t last_warn; /* when we last warned about no readers */ + atomic_t writers; /* how many time is /channel open */ + time_t last_close; /* if no writers, when did last close */ + time_t last_warn; /* when we last warned about no writers */ union { struct proc_dir_entry *procfs; |