Description of problem:
file: fs/ecryptfs/keystore.c
When request_key() fails in ecryptfs_keyring_auth_tok_for_sig() the error code
is being processed by process_request_key_err() function. There's a switch
statement with the following code:

switch (err_code) {
    case ENOKEY:
        ecryptfs_printk(KERN_WARNING, "No key\n");
        rc = -ENOENT;
        break;
    case EKEYEXPIRED:
        ecryptfs_printk(KERN_WARNING, "Key expired\n");
        rc = -ETIME;
        break;
    case EKEYREVOKED:
        ecryptfs_printk(KERN_WARNING, "Key revoked\n");
        rc = -EINVAL;
        break;
    default:
        ecryptfs_printk(KERN_WARNING, "Unknown error code: "
                            "[0x%.16x]\n", err_code);
        rc = -EINVAL;
}


This will go through 'default' case for every kind of error because code is
checking negative value passed through err_code variable. ENOKEY, EKEYEXPIRED
etc. are all positive values and therefore check must be against '-ENOKEY',
'-EKEYEXPIRED' etc.

Version-Release number of selected component (if applicable):
kernel-2.6.18-87.el5

How reproducible:
100%

Steps to Reproduce:
Easy way is just use non-existing key signature in mount options. 
More convincing could be following procedure.
1. Add following line in fs/ecryptfs/keystore.c in process_request_key_err()
function in 'default' case:
if ( err_code == -ENOKEY ) printk( KERN_ERR "ENOKEY handled in default case!" );
2. rebuild ecryptfs kernel module
3. as root execute following commands:
rmmod ecryptfs && insmod ecryptfs
keyctl clear @u && keyctl show
mkdir .secret
mount -t ecryptfs
key=passphrase:sig=1fbdc89c046856c3,cipher=aes,ecryptfs_key_bytes=16,verbosity=0
.secret/ .secret/
  
Actual results:
in /var/log/messages I see 'Unknown error code' for known error ENOKEY ...
Could not find key with description: [1fbdc89c046856c3]
process_request_key_err: Unknown error code: [0x00000000ffffff82]
Could not find valid key in user session keyring for sig specified in mount
option: [1fbdc89c046856c3]


Expected results:
Could not find key with description: [1fbdc89c046856c3]
process_request_key_err: No key
Could not find valid key in user session keyring for sig specified in mount
option: [1fbdc89c046856c3]

Additional info:
I set priority/severity to low/low because the code does not behave incorrectly,
it just does not log errors when they occur. I would recommend adding check for
all possible error codes of request_key() function of kernel key retention
service or at least following two - EKEYREJECTED, EACCES according to 'man 2
request_key' man page.