Toralf reported the following oops to the linux-nfs mailing list:

    -----------------[snip]------------------
    NFSD: unable to generate recoverydir name (-2).
    NFSD: disabling legacy clientid tracking. Reboot recovery will not function correctly!
    BUG: unable to handle kernel NULL pointer dereference at 000003c8
    IP: [<f90a3d91>] nfsd4_client_tracking_exit+0x11/0x50 [nfsd]
    *pdpt = 000000002ba33001 *pde = 0000000000000000
    Oops: 0000 [#1] SMP
    Modules linked in: loop nfsd auth_rpcgss ipt_MASQUERADE xt_owner xt_multiport ipt_REJECT xt_tcpudp xt_recent xt_conntrack nf_conntrack_ftp xt_limit xt_LOG iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_filter ip_tables x_tables af_packet pppoe pppox ppp_generic slhc bridge stp llc tun arc4 iwldvm mac80211 coretemp kvm_intel uvcvideo sdhci_pci sdhci mmc_core videobuf2_vmalloc videobuf2_memops usblp videobuf2_core i915 iwlwifi psmouse videodev cfg80211 kvm fbcon bitblit cfbfillrect acpi_cpufreq mperf evdev softcursor font cfbimgblt i2c_algo_bit cfbcopyarea intel_agp intel_gtt drm_kms_helper snd_hda_codec_conexant drm agpgart fb fbdev tpm_tis thinkpad_acpi tpm nvram e1000e rfkill thermal ptp wmi pps_core tpm_bios 8250_pci processor 8250 ac snd_hda_intel snd_hda_codec snd_pcm battery video i2c_i801 snd_page_alloc snd_timer button serial_core i2c_core snd soundcore thermal_sys hwmon aesni_intel ablk_helper cryp
td lrw aes_i586 xts gf128mul cbc fuse nfs lockd sunrpc dm_crypt dm_mod hid_monterey hid_microsoft hid_logitech hid_ezkey hid_cypress hid_chicony hid_cherry hid_belkin hid_apple hid_a4tech hid_generic usbhid hid sr_mod cdrom sg [last unloaded: microcode]
    Pid: 6374, comm: nfsd Not tainted 3.9.1 #6 LENOVO 4180F65/4180F65
    EIP: 0060:[<f90a3d91>] EFLAGS: 00010202 CPU: 0
    EIP is at nfsd4_client_tracking_exit+0x11/0x50 [nfsd]
    EAX: 00000000 EBX: fffffffe ECX: 00000007 EDX: 00000007
    ESI: eb9dcb00 EDI: eb2991c0 EBP: eb2bde38 ESP: eb2bde34
    DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
    CR0: 80050033 CR2: 000003c8 CR3: 2ba80000 CR4: 000407f0
    DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
    DR6: ffff0ff0 DR7: 00000400
    Process nfsd (pid: 6374, ti=eb2bc000 task=eb2711c0 task.ti=eb2bc000)
    Stack:
    fffffffe eb2bde4c f90a3e0c f90a7754 fffffffe eb0a9c00 eb2bdea0 f90a41ed
    eb2991c0 1b270000 eb2991c0 eb2bde7c f9099ce9 eb2bde98 0129a020 eb29a020
    eb2bdecc eb2991c0 eb2bdea8 f9099da5 00000000 eb9dcb00 00000001 67822f08
    Call Trace:
    [<f90a3e0c>] legacy_recdir_name_error+0x3c/0x40 [nfsd]
    [<f90a41ed>] nfsd4_create_clid_dir+0x15d/0x1c0 [nfsd]
    [<f9099ce9>] ? nfsd4_lookup_stateid+0x99/0xd0 [nfsd]
    [<f9099da5>] ? nfs4_preprocess_seqid_op+0x85/0x100 [nfsd]
    [<f90a4287>] nfsd4_client_record_create+0x37/0x50 [nfsd]
    [<f909d6ce>] nfsd4_open_confirm+0xfe/0x130 [nfsd]
    [<f90980b1>] ? nfsd4_encode_operation+0x61/0x90 [nfsd]
    [<f909d5d0>] ? nfsd4_free_stateid+0xc0/0xc0 [nfsd]
    [<f908fd0b>] nfsd4_proc_compound+0x41b/0x530 [nfsd]
    [<f9081b7b>] nfsd_dispatch+0x8b/0x1a0 [nfsd]
    [<f857b85d>] svc_process+0x3dd/0x640 [sunrpc]
    [<f908165d>] nfsd+0xad/0x110 [nfsd]
    [<f90815b0>] ? nfsd_destroy+0x70/0x70 [nfsd]
    [<c1054824>] kthread+0x94/0xa0
    [<c1486937>] ret_from_kernel_thread+0x1b/0x28
    [<c1054790>] ? flush_kthread_work+0xd0/0xd0
    Code: 86 b0 00 00 00 90 c5 0a f9 c7 04 24 70 76 0a f9 e8 74 a9 3d c8 eb ba 8d 76 00 55 89 e5 53 66 66 66 66 90 8b 15 68 c7 0a f9 85 d2 <8b> 88 c8 03 00 00 74 2c 3b 11 77 28 8b 5c 91 08 85 db 74 22 8b
    EIP: [<f90a3d91>] nfsd4_client_tracking_exit+0x11/0x50 [nfsd] SS:ESP 0068:eb2bde34
    CR2: 00000000000003c8
    ---[ end trace 09e54015d145c9c6 ]---

The problem appears to be a regression that was introduced in commit
9a9c6478 "nfsd: make NFSv4 recovery client tracking options per net".
Prior to that commit, it was safe to pass a NULL net pointer to
nfsd4_client_tracking_exit in the legacy recdir case, and
legacy_recdir_name_error did so. After that comit, the net pointer must
be valid.

This patch just fixes legacy_recdir_name_error to pass in a valid net
pointer to that function.

Cc: <stable@vger.kernel.org> # v3.8+
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Reported-and-tested-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

The current code works, but sort of by accident: it obviously didn't
intend the error return to be interpreted as "true".
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

net/sunrpc/auth_gss/gss_rpc_xdr.c: In function ‘gssx_dec_option_array’:
net/sunrpc/auth_gss/gss_rpc_xdr.c:258: warning: ‘creds’ may be used uninitialized in this function

Return early if count is zero, to make it clearer to the compiler (and the
casual reviewer) that no more processing is done.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

The Linux client is using CLAIM_FH to implement regular opens, not just
recovery cases, so it depends on the server to check permissions
correctly.

Therefore the owner override, which may make sense in the delegation
recovery case, isn't right in the CLAIM_FH case.

Symptoms: on a client with 49f9a0fa
"NFSv4.1: Enable open-by-filehandle", Bryan noticed this:

	touch test.txt
	chmod 000 test.txt
	echo test > test.txt

succeeding.

Cc: stable@kernel.org
Reported-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

If nfsd4_do_encode_secinfo() can't find GSS info that matches an
export security flavor, it assumes the flavor is not a GSS
pseudoflavor, and simply puts it on the wire.

However, if this XDR encoding logic is given a legitimate GSS
pseudoflavor but the RPC layer says it does not support that
pseudoflavor for some reason, then the server leaks GSS pseudoflavor
numbers onto the wire.

I confirmed this happens by blacklisting rpcsec_gss_krb5, then
attempted a client transition from the pseudo-fs to a Kerberos-only
share.  The client received a flavor list containing the Kerberos
pseudoflavor numbers, rather than GSS tuples.

The encoder logic can check that each pseudoflavor in flavs[] is
less than MAXFLAVOR before writing it into the buffer, to prevent
this.  But after "nflavs" is written into the XDR buffer, the
encoder can't skip writing flavor information into the buffer when
it discovers the RPC layer doesn't support that flavor.

So count the number of valid flavors as they are written into the
XDR buffer, then write that count into a placeholder in the XDR
buffer when all recognized flavors have been encoded.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Clean up.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

symbol 'nfsd_reply_cache_shrinker' only used within this file. It should
be static.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Fix to return a negative error code from the error handling
case instead of 0, as returned elsewhere in this function.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

We're going out of our way here to remap an error to make rfc 3530
happy--but the rfc itself (nor rfc 1813, which has similar language)
gives no justification.  And disagrees with local filesystem behavior,
with Linux and posix man pages, and knfsd's implemented behavior for v2
and v3.

And the documented behavior seems better, in that it gives a little more
information--you could implement the 3530 behavior using the posix
behavior, but not the other way around.

Also, the Linux client makes no attempt to remap this error in the v4
case, so it can end up just returning EEXIST to the application in a
case where it should return EISDIR.

So honestly I think the rfc's are just buggy here--or in any case it
doesn't see worth the trouble to remap this error.
Reported-by: Frank S Filz <ffilz@us.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Cc: Simo Sorce <simo@redhat.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>

Though I wonder whether we should really just depend on CONFIG_PROC_FS
at some point.
Reported-by: kbuild test robot <fengguang.wu@intel.com>

Note conflict: Chuck's patches modified (and made static)
gss_mech_get_by_OID, which is still needed by gss-proxy patches.

The conflict resolution is a bit minimal; we may want some more cleanup.

Debugging aid to help identify servers that incorrectly apply open mode
checks to setattr requests that are not changing the file size.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The NFSv4 and NFSv4.1 specs are both clear that the server should only check
stateid open mode if a SETATTR specifies the size attribute. If the
open mode is not one that allows writing, then it returns NFS4ERR_OPENMODE.

In the case where the SETATTR is not changing the size, the client will
still pass it the delegation stateid to ensure that the server does not
recall that delegation. In that case, the server should _ignore_ the
delegation open mode, and simply apply standard permission checks.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

As 4.1 becomes less experimental and SSV still isn't implemented, we
have to admit it's not going to be, and return some sensible error
rather than just saying "our server's broken".  Discussion in the ietf
group hasn't turned up any objections to using NFS4ERR_ENC_ALG_UNSUPP
for that purpose.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

We again check for the EXDEV a little later on, so the first check is
redundant.  This check is also slightly racier, since a badly timed
eviction from the export cache could leave us with the two fh_export
pointers pointing to two different cache entries which each refer to the
same underlying export.

It's better to compare vfsmounts as the later check does, but that
leaves a minor security hole in the case where the two exports refer to
two different directories especially if (for example) they have
different root-squashing options.

So, compare ex_path.dentry too.
Reported-by: Joe Habermann <joe.habermann@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

The main advantge of this new upcall mechanism is that it can handle
big tickets as seen in Kerberos implementations where tickets carry
authorization data like the MS-PAC buffer with AD or the Posix Authorization
Data being discussed in IETF on the krbwg working group.

The Gssproxy program is used to perform the accept_sec_context call on the
kernel's behalf. The code is changed to also pass the input buffer straight
to upcall mechanism to avoid allocating and copying many pages as tokens can
be as big (potentially more in future) as 64KiB.
Signed-off-by: Simo Sorce <simo@redhat.com>
[bfields: containerization, negotiation api]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

This patch implements a sunrpc client to use the services of the gssproxy
userspace daemon.

In particular it allows to perform calls in user space using an RPC
call instead of custom hand-coded upcall/downcall messages.

Currently only accept_sec_context is implemented as that is all is needed for
the server case.

File server modules like NFS and CIFS can use full gssapi services this way,
once init_sec_context is also implemented.

For the NFS server case this code allow to lift the limit of max 2k krb5
tickets. This limit is prevents legitimate kerberos deployments from using krb5
authentication with the Linux NFS server as they have normally ticket that are
many kilobytes large.

It will also allow to lift the limitation on the size of the credential set
(uid,gid,gids) passed down from user space for users that have very many groups
associated. Currently the downcall mechanism used by rpc.svcgssd is limited
to around 2k secondary groups of the 65k allowed by kernel structures.
Signed-off-by: Simo Sorce <simo@redhat.com>
[bfields: containerization, concurrent upcalls, misc. fixes and cleanup]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

We expose this parameter for a future caller.
It will be used to extract the endtime from the gss-proxy upcall mechanism,
in order to set the rsc cache expiration time.
Signed-off-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

In the gss-proxy case we don't want to have to reconnect at random--we
want to connect only on gss-proxy startup when we can steal gss-proxy's
context to do the connect in the right namespace.

So, provide a flag that allows the rpc_create caller to turn off the
idle timeout.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

In the gss-proxy case, setup time is when I know I'll have the right
namespace for the connect.

In other cases, it might be useful to get any connection errors
earlier--though actually in practice it doesn't make any difference for
rpcbind.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Merging Trond's nfs-for-next branch, mainly to get
b7993ceb "SUNRPC: Allow rpc_create() to
request that TCP slots be unlimited", which a small piece of the
gss-proxy work depends on.

Fix up a conflict between the linux-next branch and mainline.
Conflicts:
	fs/nfs/nfs4proc.c

* rpcsec_gss-from_cel: (21 commits)
  NFS: Retry SETCLIENTID with AUTH_SYS instead of AUTH_NONE
  NFSv4: Don't clear the machine cred when client establish returns EACCES
  NFSv4: Fix issues in nfs4_discover_server_trunking
  NFSv4: Fix the fallback to AUTH_NULL if krb5i is not available
  NFS: Use server-recommended security flavor by default (NFSv3)
  SUNRPC: Don't recognize RPC_AUTH_MAXFLAVOR
  NFS: Use "krb5i" to establish NFSv4 state whenever possible
  NFS: Try AUTH_UNIX when PUTROOTFH gets NFS4ERR_WRONGSEC
  NFS: Use static list of security flavors during root FH lookup recovery
  NFS: Avoid PUTROOTFH when managing leases
  NFS: Clean up nfs4_proc_get_rootfh
  NFS: Handle missing rpc.gssd when looking up root FH
  SUNRPC: Remove EXPORT_SYMBOL_GPL() from GSS mech switch
  SUNRPC: Make gss_mech_get() static
  SUNRPC: Refactor nfsd4_do_encode_secinfo()
  SUNRPC: Consider qop when looking up pseudoflavors
  SUNRPC: Load GSS kernel module by OID
  SUNRPC: Introduce rpcauth_get_pseudoflavor()
  SUNRPC: Define rpcsec_gss_info structure
  NFS: Remove unneeded forward declaration
  ...

If we already checked the user access permissions on the original open,
then don't bother checking again on recovery. Doing so can cause a
deadlock with NFSv4.1, since the may_open() operation is not privileged.
Furthermore, we can't report an access permission failure here anyway.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The seconds field of an nfstime4 structure is 64bit, but we are assuming
that the first 32bits are zero-filled.  So if the client tries to set
atime to a value before the epoch (touch -t 196001010101), then the
server will save the wrong value on disk.
Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

If we're in a delegation recall situation, we can't do a delegated open.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

When we're doing open-by-filehandle in NFSv4.1, we shouldn't need to
do the cache consistency revalidation on the directory. It is
therefore more efficient to just use open_noattr, which returns the
file attributes, but not the directory attributes.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Recently I changed the SETCLIENTID code to use AUTH_GSS(krb5i), and
then retry with AUTH_NONE if that didn't work.  This was to enable
Kerberos NFS mounts to work without forcing Linux NFS clients to
have a keytab on hand.

Rick Macklem reports that the FreeBSD server accepts AUTH_NONE only
for NULL operations (thus certainly not for SETCLIENTID).  Falling
back to AUTH_NONE means our proposed 3.10 NFS client will not
interoperate with FreeBSD servers over NFSv4 unless Kerberos is
fully configured on both ends.

If the Linux client falls back to using AUTH_SYS instead for
SETCLIENTID, all should work fine as long as the NFS server is
configured to allow AUTH_SYS for SETCLIENTID.

This may still prevent access to Kerberos-only FreeBSD servers by
Linux clients with no keytab.  Rick is of the opinion that the
security settings the server applies to its pseudo-fs should also
apply to the SETCLIENTID operation.

Linux and Solaris NFS servers do not place that limitation on
SETCLIENTID.  The security settings for the server's pseudo-fs are
determined automatically as the union of security flavors allowed on
real exports, as recommended by RFC 3530bis; and the flavors allowed
for SETCLIENTID are all flavors supported by the respective server
implementation.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

We should always clear it before initiating file recovery.
Also ensure that we clear it after a CLOSE and/or after TEST_STATEID fails.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

After a server reboot, the reclaimer thread will recover all the existing
locks. For locks that are blocked, however, it will change the value
of block->b_status to nlm_lck_denied_grace_period in order to signal that
they need to wake up and resend the original blocking lock request.

Due to a bug, however, the block->b_status never gets reset after the
blocked locks have been woken up, and so the process goes into an
infinite loop of resends until the blocked lock is satisfied.
Reported-by: Marc Eshel <eshel@us.ibm.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org

Defensive patch to ensure that we copy the state->open_stateid, which
can never be set to the delegation stateid.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Fix nfs4_select_rw_stateid() so that it chooses the open stateid
(or an all-zero stateid) if the delegation does not match the selected
read/write mode.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

RFC 3530 says that the seconds value of a nfstime4 structure is a 64bit
value, but we are instead sending a 32-bit 0 and then a 32bit conversion
of the 64bit Linux value.  This means that if we try to set atime to a
value before the epoch (touch -t 196001010101) the client will only send
part of the new value due to lost precision.
Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Cleanup a piece I forgot to remove in
9411b1d4 "nfsd4: cleanup handling of
nfsv4.0 closed stateid's".
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

If we're doing NFSv4.1 against a server that has persistent sessions,
then we should not need to call SETATTR in order to reset the file
attributes immediately after doing an exclusive create.

Note that since the create mode depends on the type of session that
has been negotiated with the server, we should not choose the
mode until after we've got a session slot.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The "list_empty(&oo->oo_owner.so_stateids)" is aways true, so remove it.
Signed-off-by: fanchaoting <fanchaoting@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

A 4.1 server must notify a client that has had any state revoked using
the SEQ4_STATUS_RECALLABLE_STATE_REVOKED flag.  The client can figure
out exactly which state is the problem using CHECK_STATEID and then free
it using FREE_STATEID.  The status flag will be unset once all such
revoked stateids are freed.

Our server's only recallable state is delegations.  So we keep with each
4.1 client a list of delegations that have timed out and been recalled,
but haven't yet been freed by FREE_STATEID.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>