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| author | Chuck Lever <chuck.lever@oracle.com> | 2013-07-24 18:28:28 +0200 |
|---|---|---|
| committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2013-08-07 19:05:10 +0200 |
| commit | d688f7b8f62857c252b886fa16e8b38b83cfaf7e (patch) | |
| tree | 4e404f49e105802f979e9344c8268c48b33518e2 /fs/nfs/nfs4state.c | |
| parent | NFSv4: Refuse mount attempts with proto=udp (diff) | |
| download | linux-d688f7b8f62857c252b886fa16e8b38b83cfaf7e.tar.xz linux-d688f7b8f62857c252b886fa16e8b38b83cfaf7e.zip | |
NFS: Use root's credential for lease management when keytab is missing
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>
Diffstat (limited to '')
| -rw-r--r-- | fs/nfs/nfs4state.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c index ad1a7533ce6d..f27760b1b06f 100644 --- a/fs/nfs/nfs4state.c +++ b/fs/nfs/nfs4state.c @@ -154,6 +154,19 @@ struct rpc_cred *nfs4_get_machine_cred_locked(struct nfs_client *clp) return cred; } +static void nfs4_root_machine_cred(struct nfs_client *clp) +{ + struct rpc_cred *cred, *new; + + new = rpc_lookup_machine_cred(NULL); + spin_lock(&clp->cl_lock); + cred = clp->cl_machine_cred; + clp->cl_machine_cred = new; + spin_unlock(&clp->cl_lock); + if (cred != NULL) + put_rpccred(cred); +} + static struct rpc_cred * nfs4_get_renew_cred_server_locked(struct nfs_server *server) { @@ -1896,7 +1909,11 @@ again: __func__, status); goto again; case -EACCES: - if (i++) + if (i++ == 0) { + nfs4_root_machine_cred(clp); + goto again; + } + if (i > 2) break; case -NFS4ERR_CLID_INUSE: case -NFS4ERR_WRONGSEC: |