The following was filed automatically by setroubleshoot:
Got the following plugging in a LUKS USB hard drive.

Here is /var/log/messages:

Sep 23 06:11:43 tlondon kernel: usb 1-5.3: new high speed USB device using ehci_hcd and address 6
Sep 23 06:11:43 tlondon kernel: usb 1-5.3: New USB device found, idVendor=04b4, idProduct=6830
Sep 23 06:11:43 tlondon kernel: usb 1-5.3: New USB device strings: Mfr=56, Product=78, SerialNumber=100
Sep 23 06:11:43 tlondon kernel: usb 1-5.3: Product: USB2.0 Storage Device
Sep 23 06:11:43 tlondon kernel: usb 1-5.3: Manufacturer: Cypress Semiconductor
Sep 23 06:11:43 tlondon kernel: usb 1-5.3: SerialNumber: DEF107679C83
Sep 23 06:11:43 tlondon kernel: usb 1-5.3: configuration #1 chosen from 1 choice
Sep 23 06:11:44 tlondon kernel: scsi5 : SCSI emulation for USB Mass Storage devices
Sep 23 06:11:44 tlondon kernel: usbcore: registered new interface driver ums-cypress
Sep 23 06:11:50 tlondon kernel: scsi 5:0:0:0: Direct-Access     MAXTOR S TM3320620A            PQ: 0 ANSI: 0
Sep 23 06:11:50 tlondon kernel: sd 5:0:0:0: Attached scsi generic sg3 type 0
Sep 23 06:11:50 tlondon kernel: sd 5:0:0:0: [sdc] 625142448 512-byte logical blocks: (320 GB/298 GiB)
Sep 23 06:11:50 tlondon kernel: sd 5:0:0:0: [sdc] Write Protect is off
Sep 23 06:11:50 tlondon kernel: sd 5:0:0:0: [sdc] Assuming drive cache: write through
Sep 23 06:11:50 tlondon kernel: sd 5:0:0:0: [sdc] Assuming drive cache: write through
Sep 23 06:11:50 tlondon kernel: sdc: sdc1
Sep 23 06:11:50 tlondon kernel: sd 5:0:0:0: [sdc] Assuming drive cache: write through
Sep 23 06:11:50 tlondon kernel: sd 5:0:0:0: [sdc] Attached SCSI disk
Sep 23 06:11:58 tlondon kernel: usb 1-5.3: reset high speed USB device using ehci_hcd and address 6
Sep 23 06:11:59 tlondon kernel: Intel AES-NI instructions are not detected.
Sep 23 06:11:59 tlondon kernel: padlock: VIA PadLock not detected.
Sep 23 06:11:59 tlondon kernel: padlock: VIA PadLock Hash Engine not detected.
Sep 23 06:11:59 tlondon modprobe: FATAL: Error inserting padlock_sha (/lib/modules/2.6.31-33.fc12.x86_64/kernel/drivers/crypto/padlock-sha.ko): No such device
Sep 23 06:12:03 tlondon setroubleshoot: SELinux is preventing /sbin/cryptsetup "relabelto" access on temporary-cryptsetup-2339. For complete SELinux messages. run sealert -l 2fec7120-1c9a-49d2-a495-95e383c61799
Sep 23 06:12:03 tlondon kernel: EXT4-fs (dm-2): barriers enabled
Sep 23 06:12:03 tlondon kernel: kjournald2 starting: pid 2447, dev dm-2:8, commit interval 5 seconds
Sep 23 06:12:03 tlondon kernel: EXT4-fs (dm-2): warning: maximal mount count reached, running e2fsck is recommended
Sep 23 06:12:03 tlondon kernel: EXT4-fs (dm-2): internal journal on dm-2:8
Sep 23 06:12:03 tlondon kernel: EXT4-fs (dm-2): delayed allocation enabled
Sep 23 06:12:03 tlondon kernel: EXT4-fs: file extents enabled
Sep 23 06:12:03 tlondon kernel: EXT4-fs: mballoc enabled
Sep 23 06:12:03 tlondon kernel: EXT4-fs (dm-2): mounted filesystem with ordered data mode
Sep 23 06:12:45 tlondon setroubleshoot: [dbus.proxies.ERROR] Introspect error on :1.84:/org/fedoraproject/Setroubleshootd: dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

The mount appears to have worked nevertheless.

Summary:

SELinux is preventing /sbin/cryptsetup "relabelto" access on
temporary-cryptsetup-2339.

Detailed Description:

SELinux denied access requested by cryptsetup. It is not expected that this
access is required by cryptsetup and this access may signal an intrusion
attempt. It is also possible that the specific version or configuration of the
application is causing it to require additional access.

Allowing Access:

You can generate a local policy module to allow this access - see FAQ
(http://fedora.redhat.com/docs/selinux-faq-fc5/#id2961385) Please file a bug
report.

Additional Information:

Source Context                system_u:system_r:lvm_t:s0-s0:c0.c1023
Target Context                system_u:object_r:fixed_disk_device_t:s0
Target Objects                temporary-cryptsetup-2339 [ lnk_file ]
Source                        cryptsetup
Source Path                   /sbin/cryptsetup
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           cryptsetup-luks-1.1.0-0.1.fc12
Target RPM Packages           
Policy RPM                    selinux-policy-3.6.32-8.fc12
Selinux Enabled               True
Policy Type                   targeted
MLS Enabled                   True
Enforcing Mode                Enforcing
Plugin Name                   catchall
Host Name                     (removed)
Platform                      Linux (removed) 2.6.31-33.fc12.x86_64
                              #1 SMP Thu Sep 17 15:40:43 EDT 2009 x86_64 x86_64
Alert Count                   1
First Seen                    Wed 23 Sep 2009 06:11:59 AM PDT
Last Seen                     Wed 23 Sep 2009 06:11:59 AM PDT
Local ID                      2fec7120-1c9a-49d2-a495-95e383c61799
Line Numbers                  

Raw Audit Messages            

node=(removed) type=AVC msg=audit(1253711519.973:35): avc:  denied  { relabelto } for  pid=2339 comm="cryptsetup" name="temporary-cryptsetup-2339" dev=tmpfs ino=26912 scontext=system_u:system_r:lvm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:fixed_disk_device_t:s0 tclass=lnk_file

node=(removed) type=SYSCALL msg=audit(1253711519.973:35): arch=c000003e syscall=189 success=no exit=-13 a0=7fffb05ff890 a1=7f7d1833a649 a2=17d3f30 a3=29 items=0 ppid=1886 pid=2339 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="cryptsetup" exe="/sbin/cryptsetup" subj=system_u:system_r:lvm_t:s0-s0:c0.c1023 key=(null)
audit2allow suggests:

#============= lvm_t ==============
allow lvm_t fixed_disk_device_t:lnk_file relabelto;