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Chuck Lever authored
Commit 05f4c350 "NFS: Discover NFSv4 server trunking when mounting" Fri Sep 14 17:24:32 2012 introduced Uniform Client String support, which forces our NFS client to establish a client ID immediately during a mount operation rather than waiting until a user wants to open a file. Normally machine credentials (eg. from a keytab) are used to perform a mount operation that is protected by Kerberos. Before 05fc350, SETCLIENTID used a machine credential, or fell back to a regular user's credential if no keytab is available. On clients that don't have a keytab, performing SETCLIENTID early means there's no user credential to fall back on, since no regular user has kinit'd yet. 05f4c350 seems to have broken the ability to mount with sec=krb5 on clients that don't have a keytab in kernels 3.7 - 3.10. To address this regression, commit 4edaa308 (NFS: Use "krb5i" to establish NFSv4 state whenever possible), Sat Mar 16 15:56:20 2013, was merged in 3.10. This commit forces the NFS client to fall back to AUTH_SYS for lease management operations if no keytab is available. Neil Brown noticed that, since root is required to kinit to do a sec=krb5 mount when a client doesn't have a keytab, we can try to use root's Kerberos credential before AUTH_SYS. Now, when determining a principal and flavor to use for lease management, the NFS client tries in this order: 1. Flavor: AUTH_GSS, krb5i Principal: service principal (via keytab) 2. Flavor: AUTH_GSS, krb5i Principal: user principal established for UID 0 (via kinit) 3. Flavor: AUTH_SYS Principal: UID 0 / GID 0 Signed-off-by:
Chuck Lever <chuck.lever@oracle.com> Signed-off-by:
Trond Myklebust <Trond.Myklebust@netapp.com>
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