From: David Howells <dhowells@redhat.com>
To: torvalds@linux-foundation.org, viro@zeniv.linux.org.uk
Cc: dhowells@redhat.comdhowells@redhat.com, casey@schaufler-ca.com,
sds@tycho.nsa.gov, nicolas.dichtel@6wind.com, raven@themaw.net,
christian@brauner.io, andres@anarazel.de, jlayton@redhat.com,
dray@redhat.com, kzak@redhat.com, keyrings@vger.kernel.org,
linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [RFC PATCH 14/17] watch_queue: sample: Display mount tree change notifications [ver #4]
Date: Mon, 09 Mar 2020 12:19:19 +0000 [thread overview]
Message-ID: <158375635995.334846.2649345497111333226.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <158375623086.334846.16121725232323108842.stgit@warthog.procyon.org.uk>
This is run like:
./watch_test
and watches "/" for changes to the mount topology and the attributes of
individual mount objects.
# mount -t tmpfs none /mnt
# mount -o remount,ro /mnt
# mount -o remount,rw /mnt
producing:
# ./watch_test
read() = 16
NOTIFY[000]: ty\00002 sy\0 i\x02000010
MOUNT 00000060 change=0[new_mount] auxA6
read() = 16
NOTIFY[000]: ty\00002 sy\x04 i\x02010010
MOUNT 000001a0 change=4[setattr] aux=0
read() = 16
NOTIFY[000]: ty\00002 sy\x04 i\x02010010
MOUNT 000001a0 change=4[setattr] aux=0
Signed-off-by: David Howells <dhowells@redhat.com>
---
samples/watch_queue/watch_test.c | 39 +++++++++++++++++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/samples/watch_queue/watch_test.c b/samples/watch_queue/watch_test.c
index 0eaff5dc04c3..49d185150506 100644
--- a/samples/watch_queue/watch_test.c
+++ b/samples/watch_queue/watch_test.c
@@ -26,6 +26,9 @@
#ifndef __NR_watch_devices
#define __NR_watch_devices -1
#endif
+#ifndef __NR_watch_mount
+#define __NR_watch_mount -1
+#endif
#define BUF_SIZE 256
@@ -58,6 +61,27 @@ static void saw_key_change(struct watch_notification *n, size_t len)
k->key_id, n->subtype, key_subtypes[n->subtype], k->aux);
}
+static const char *mount_subtypes[256] = {
+ [NOTIFY_MOUNT_NEW_MOUNT] = "new_mount",
+ [NOTIFY_MOUNT_UNMOUNT] = "unmount",
+ [NOTIFY_MOUNT_EXPIRY] = "expiry",
+ [NOTIFY_MOUNT_READONLY] = "readonly",
+ [NOTIFY_MOUNT_SETATTR] = "setattr",
+ [NOTIFY_MOUNT_MOVE_FROM] = "move_from",
+ [NOTIFY_MOUNT_MOVE_TO] = "move_to",
+};
+
+static void saw_mount_change(struct watch_notification *n, size_t len)
+{
+ struct mount_notification *m = (struct mount_notification *)n;
+
+ if (len != sizeof(struct mount_notification))
+ return;
+
+ printf("MOUNT %08x change=%u[%s] aux=%u\n",
+ m->triggered_on, n->subtype, mount_subtypes[n->subtype], m->changed_mount);
+}
+
/*
* Consume and display events.
*/
@@ -134,6 +158,9 @@ static void consumer(int fd)
default:
printf("other type\n");
break;
+ case WATCH_TYPE_MOUNT_NOTIFY:
+ saw_mount_change(&n.n, len);
+ break;
}
p += len;
@@ -142,12 +169,17 @@ static void consumer(int fd)
}
static struct watch_notification_filter filter = {
- .nr_filters = 1,
+ .nr_filters = 2,
.filters = {
[0] = {
.type = WATCH_TYPE_KEY_NOTIFY,
.subtype_filter[0] = UINT_MAX,
},
+ [1] = {
+ .type = WATCH_TYPE_MOUNT_NOTIFY,
+ // Reject move-from notifications
+ .subtype_filter[0] = UINT_MAX & ~(1 << NOTIFY_MOUNT_MOVE_FROM),
+ },
},
};
@@ -181,6 +213,11 @@ int main(int argc, char **argv)
exit(1);
}
+ if (syscall(__NR_watch_mount, AT_FDCWD, "/", 0, fd, 0x02) = -1) {
+ perror("watch_mount");
+ exit(1);
+ }
+
consumer(fd);
exit(0);
}
next prev parent reply other threads:[~2020-03-09 12:19 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-09 12:17 [RFC PATCH 00/17] pipe: Keyrings, mount and superblock notifications [ver #4] David Howells
2020-03-09 12:17 ` [RFC PATCH 01/17] uapi: General notification queue definitions " David Howells
2020-03-09 12:17 ` [RFC PATCH 02/17] security: Add hooks to rule on setting a watch " David Howells
2020-03-09 12:17 ` [RFC PATCH 03/17] security: Add a hook for the point of notification insertion " David Howells
2020-03-09 12:17 ` [RFC PATCH 04/17] pipe: Add O_NOTIFICATION_PIPE " David Howells
2020-03-09 12:17 ` [RFC PATCH 05/17] pipe: Add general notification queue support " David Howells
2020-03-09 12:18 ` [RFC PATCH 06/17] watch_queue: Add a key/keyring notification facility " David Howells
2020-03-09 12:18 ` [RFC PATCH 07/17] Add sample notification program " David Howells
2020-03-09 12:18 ` [RFC PATCH 08/17] pipe: Allow buffers to be marked read-whole-or-error for notifications " David Howells
2020-03-09 12:18 ` [RFC PATCH 09/17] pipe: Add notification lossage handling " David Howells
2020-03-09 12:18 ` [RFC PATCH 10/17] selinux: Implement the watch_key security hook " David Howells
2020-03-09 12:18 ` [RFC PATCH 11/17] smack: Implement the watch_key and post_notification hooks " David Howells
2020-03-09 12:19 ` [RFC PATCH 12/17] watch_queue: Add security hooks to rule on setting mount and sb watches " David Howells
2020-03-09 12:19 ` [RFC PATCH 13/17] watch_queue: Implement mount topology and attribute change notifications " David Howells
2020-03-09 12:19 ` David Howells [this message]
2020-03-09 12:19 ` [RFC PATCH 15/17] watch_queue: Introduce a non-repeating system-unique superblock ID " David Howells
2020-03-09 12:19 ` [RFC PATCH 16/17] watch_queue: Add superblock notifications " David Howells
2020-03-09 12:19 ` [RFC PATCH 17/17] watch_queue: sample: Display " David Howells
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