Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.
Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/
Sponsored by: Netflix
During recent testing related to the IETF NFSv4 Bakeathon, it was
discovered that Kerberized NFSv4.1/4.2 mounts to pNFS servers
(sec=krb5[ip],pnfs mount options) was broken.
The FreeBSD client was using the "service principal" for
the MDS to try and establish a rpcsec_gss credential for a DS,
which is incorrect. (A "service principal" looks like
"nfs@<fqdn-of-server>" and the <fqdn-of-server> for the DS is not
the same as the MDS for most pNFS servers.)
To fix this, the rpcsec_gss code needs to be able to do a
reverse DNS lookup of the DS's IP address. A new kgssapi upcall
to the gssd(8) daemon is added by this patch to do the reverse DNS
along with a new rpcsec_gss function to generate the "service
principal".
A separate patch to the gssd(8) will be committed, so that this
patch will fix the problem. Without the gssd(8) patch, the new
upcall fails and current/incorrect behaviour remains.
This bug only affects the rare case of a Kerberized (sec=krb5[ip],pnfs)
mount using pNFS.
This patch changes the internal KAPI between the kgssapi and
nfscl modules, but since I did a version bump a few days ago,
I will not do one this time.
MFC after: 1 month
A future commit needs a new upcall function that can do reverse
DNS in order to generate a "service principal".
This patch adds the file.
MFC after: 1 month
The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.
Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix
Several commits have added front end macros for the vnet
macros to the NFS server, krpc and kgssapi. These macros
are now null, but this patch changes them to front end
the vnet macros.
With this commit, many global variables in the code become
vnet'd, so that nfsd(8), nfsuserd(8), rpc.tlsservd(8) and
gssd(8) can run in a vnet prison, once enabled.
To run the NFS server in a vnet prison still requires a
couple of patches (in D37741 and D38371) that allow mountd(8)
to export file systems from within a vnet prison. Once
these are committed to main, a small patch to kern_jail.c
allowing "allow.nfsd" without VNET_NFSD defined will allow
the NFS server to run in a vnet prison.
One area that still needs to be settled is cleanup when a
prison is removed. Without this, everything should work
except there will be a leak of malloc'd data and mutex locks
when a vnet prison is removed.
MFC after: 3 months
Commit 7344856e3a6d added a lot of macros that will front end
vnet macros so that nfsd(8) can run in vnet prison.
This patch adds similar macros named KGSS_VNETxxx so that
the gssd(8) daemon can run in a vnet prison, once the
macros front end the vnet ones. For now, they are null macros.
This is the last commit that adds macros. The next step is
to change the macros to front end the vnet ones.
MFC after: 3 months
It turns out that the underlying problem that caused
a Kerberized NFS mount with the "gssname" option to
fail was that the kernel upcall to the gssd(8) daemon
would time out prematurely after 25 seconds. The
gss_acquire_cred() GSSAPI library call
takes about 27 seconds for the case where a desired_name
argument is specified. A similarly long delay occurs
when the gss_init_sec_context() call is made and the
user principal's TGT has expired.
Once the upcall timed out, the kernel code assumed that
the gssd(8) daemon had died and closed the socket.
Ironically, closing the socket did cause the gssd(8)
daemon to terminate via a SIGPIPE signal.
This patch increases the timeout to 5 minutes. Since
a timeout should only occur when the gssd(8) daemon
has died, a long timeout should be ok and seems to fix this
problem.
I still think that commit c33509d49a should remain in the
system, since it allows the mount to complete quickly
and not take nearly 30 seconds.
PR: 268823
MFC after: 2 weeks
Currently, OpenCrypto consumers can request asynchronous dispatch by
setting a flag in the cryptop. (Currently only IPSec may do this.) I
think this is a bit confusing: we (conditionally) set cryptop flags to
request async dispatch, and then crypto_dispatch() immediately examines
those flags to see if the consumer wants async dispatch. The flag names
are also confusing since they don't specify what "async" applies to:
dispatch or completion.
Add a new KPI, crypto_dispatch_async(), rather than encoding the
requested dispatch type in each cryptop. crypto_dispatch_async() falls
back to crypto_dispatch() if the session's driver provides asynchronous
dispatch. Get rid of CRYPTOP_ASYNC() and CRYPTOP_ASYNC_KEEPORDER().
Similarly, add crypto_dispatch_batch() to request processing of a tailq
of cryptops, rather than encoding the scheduling policy using cryptop
flags. Convert GELI, the only user of this interface (disabled by
default) to use the new interface.
Add CRYPTO_SESS_SYNC(), which can be used by consumers to determine
whether crypto requests will be dispatched synchronously. This is just
a helper macro. Use it instead of looking at cap flags directly.
Fix style in crypto_done(). Also get rid of CRYPTO_RETW_EMPTY() and
just check the relevant queues directly. This could result in some
unnecessary wakeups but I think it's very uncommon to be using more than
one queue per worker in a given workload, so checking all three queues
is a waste of cycles.
Reviewed by: jhb
Sponsored by: Ampere Computing
Submitted by: Klara, Inc.
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D28194
Some crypto consumers such as GELI and KTLS for file-backed sendfile
need to store their output in a separate buffer from the input.
Currently these consumers copy the contents of the input buffer into
the output buffer and queue an in-place crypto operation on the output
buffer. Using a separate output buffer avoids this copy.
- Create a new 'struct crypto_buffer' describing a crypto buffer
containing a type and type-specific fields. crp_ilen is gone,
instead buffers that use a flat kernel buffer have a cb_buf_len
field for their length. The length of other buffer types is
inferred from the backing store (e.g. uio_resid for a uio).
Requests now have two such structures: crp_buf for the input buffer,
and crp_obuf for the output buffer.
- Consumers now use helper functions (crypto_use_*,
e.g. crypto_use_mbuf()) to configure the input buffer. If an output
buffer is not configured, the request still modifies the input
buffer in-place. A consumer uses a second set of helper functions
(crypto_use_output_*) to configure an output buffer.
- Consumers must request support for separate output buffers when
creating a crypto session via the CSP_F_SEPARATE_OUTPUT flag and are
only permitted to queue a request with a separate output buffer on
sessions with this flag set. Existing drivers already reject
sessions with unknown flags, so this permits drivers to be modified
to support this extension without requiring all drivers to change.
- Several data-related functions now have matching versions that
operate on an explicit buffer (e.g. crypto_apply_buf,
crypto_contiguous_subsegment_buf, bus_dma_load_crp_buf).
- Most of the existing data-related functions operate on the input
buffer. However crypto_copyback always writes to the output buffer
if a request uses a separate output buffer.
- For the regions in input/output buffers, the following conventions
are followed:
- AAD and IV are always present in input only and their
fields are offsets into the input buffer.
- payload is always present in both buffers. If a request uses a
separate output buffer, it must set a new crp_payload_start_output
field to the offset of the payload in the output buffer.
- digest is in the input buffer for verify operations, and in the
output buffer for compute operations. crp_digest_start is relative
to the appropriate buffer.
- Add a crypto buffer cursor abstraction. This is a more general form
of some bits in the cryptosoft driver that tried to always use uio's.
However, compared to the original code, this avoids rewalking the uio
iovec array for requests with multiple vectors. It also avoids
allocate an iovec array for mbufs and populating it by instead walking
the mbuf chain directly.
- Update the cryptosoft(4) driver to support separate output buffers
making use of the cursor abstraction.
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D24545
This removes support for using DES, Triple DES, and RC4.
Reviewed by: cem, kp
Tested by: kp
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D24344
Assertions in crypto_dispatch() depend on this value being set to
verify that payload and AAD regions are in bounds. Also, requests
that use a single kernel buffer rely on this to know how long the
buffer is for bus_dma, etc.
Reported by: kp
- The linked list of cryptoini structures used in session
initialization is replaced with a new flat structure: struct
crypto_session_params. This session includes a new mode to define
how the other fields should be interpreted. Available modes
include:
- COMPRESS (for compression/decompression)
- CIPHER (for simply encryption/decryption)
- DIGEST (computing and verifying digests)
- AEAD (combined auth and encryption such as AES-GCM and AES-CCM)
- ETA (combined auth and encryption using encrypt-then-authenticate)
Additional modes could be added in the future (e.g. if we wanted to
support TLS MtE for AES-CBC in the kernel we could add a new mode
for that. TLS modes might also affect how AAD is interpreted, etc.)
The flat structure also includes the key lengths and algorithms as
before. However, code doesn't have to walk the linked list and
switch on the algorithm to determine which key is the auth key vs
encryption key. The 'csp_auth_*' fields are always used for auth
keys and settings and 'csp_cipher_*' for cipher. (Compression
algorithms are stored in csp_cipher_alg.)
- Drivers no longer register a list of supported algorithms. This
doesn't quite work when you factor in modes (e.g. a driver might
support both AES-CBC and SHA2-256-HMAC separately but not combined
for ETA). Instead, a new 'crypto_probesession' method has been
added to the kobj interface for symmteric crypto drivers. This
method returns a negative value on success (similar to how
device_probe works) and the crypto framework uses this value to pick
the "best" driver. There are three constants for hardware
(e.g. ccr), accelerated software (e.g. aesni), and plain software
(cryptosoft) that give preference in that order. One effect of this
is that if you request only hardware when creating a new session,
you will no longer get a session using accelerated software.
Another effect is that the default setting to disallow software
crypto via /dev/crypto now disables accelerated software.
Once a driver is chosen, 'crypto_newsession' is invoked as before.
- Crypto operations are now solely described by the flat 'cryptop'
structure. The linked list of descriptors has been removed.
A separate enum has been added to describe the type of data buffer
in use instead of using CRYPTO_F_* flags to make it easier to add
more types in the future if needed (e.g. wired userspace buffers for
zero-copy). It will also make it easier to re-introduce separate
input and output buffers (in-kernel TLS would benefit from this).
Try to make the flags related to IV handling less insane:
- CRYPTO_F_IV_SEPARATE means that the IV is stored in the 'crp_iv'
member of the operation structure. If this flag is not set, the
IV is stored in the data buffer at the 'crp_iv_start' offset.
- CRYPTO_F_IV_GENERATE means that a random IV should be generated
and stored into the data buffer. This cannot be used with
CRYPTO_F_IV_SEPARATE.
If a consumer wants to deal with explicit vs implicit IVs, etc. it
can always generate the IV however it needs and store partial IVs in
the buffer and the full IV/nonce in crp_iv and set
CRYPTO_F_IV_SEPARATE.
The layout of the buffer is now described via fields in cryptop.
crp_aad_start and crp_aad_length define the boundaries of any AAD.
Previously with GCM and CCM you defined an auth crd with this range,
but for ETA your auth crd had to span both the AAD and plaintext
(and they had to be adjacent).
crp_payload_start and crp_payload_length define the boundaries of
the plaintext/ciphertext. Modes that only do a single operation
(COMPRESS, CIPHER, DIGEST) should only use this region and leave the
AAD region empty.
If a digest is present (or should be generated), it's starting
location is marked by crp_digest_start.
Instead of using the CRD_F_ENCRYPT flag to determine the direction
of the operation, cryptop now includes an 'op' field defining the
operation to perform. For digests I've added a new VERIFY digest
mode which assumes a digest is present in the input and fails the
request with EBADMSG if it doesn't match the internally-computed
digest. GCM and CCM already assumed this, and the new AEAD mode
requires this for decryption. The new ETA mode now also requires
this for decryption, so IPsec and GELI no longer do their own
authentication verification. Simple DIGEST operations can also do
this, though there are no in-tree consumers.
To eventually support some refcounting to close races, the session
cookie is now passed to crypto_getop() and clients should no longer
set crp_sesssion directly.
- Assymteric crypto operation structures should be allocated via
crypto_getkreq() and freed via crypto_freekreq(). This permits the
crypto layer to track open asym requests and close races with a
driver trying to unregister while asym requests are in flight.
- crypto_copyback, crypto_copydata, crypto_apply, and
crypto_contiguous_subsegment now accept the 'crp' object as the
first parameter instead of individual members. This makes it easier
to deal with different buffer types in the future as well as
separate input and output buffers. It's also simpler for driver
writers to use.
- bus_dmamap_load_crp() loads a DMA mapping for a crypto buffer.
This understands the various types of buffers so that drivers that
use DMA do not have to be aware of different buffer types.
- Helper routines now exist to build an auth context for HMAC IPAD
and OPAD. This reduces some duplicated work among drivers.
- Key buffers are now treated as const throughout the framework and in
device drivers. However, session key buffers provided when a session
is created are expected to remain alive for the duration of the
session.
- GCM and CCM sessions now only specify a cipher algorithm and a cipher
key. The redundant auth information is not needed or used.
- For cryptosoft, split up the code a bit such that the 'process'
callback now invokes a function pointer in the session. This
function pointer is set based on the mode (in effect) though it
simplifies a few edge cases that would otherwise be in the switch in
'process'.
It does split up GCM vs CCM which I think is more readable even if there
is some duplication.
- I changed /dev/crypto to support GMAC requests using CRYPTO_AES_NIST_GMAC
as an auth algorithm and updated cryptocheck to work with it.
- Combined cipher and auth sessions via /dev/crypto now always use ETA
mode. The COP_F_CIPHER_FIRST flag is now a no-op that is ignored.
This was actually documented as being true in crypto(4) before, but
the code had not implemented this before I added the CIPHER_FIRST
flag.
- I have not yet updated /dev/crypto to be aware of explicit modes for
sessions. I will probably do that at some point in the future as well
as teach it about IV/nonce and tag lengths for AEAD so we can support
all of the NIST KAT tests for GCM and CCM.
- I've split up the exising crypto.9 manpage into several pages
of which many are written from scratch.
- I have converted all drivers and consumers in the tree and verified
that they compile, but I have not tested all of them. I have tested
the following drivers:
- cryptosoft
- aesni (AES only)
- blake2
- ccr
and the following consumers:
- cryptodev
- IPsec
- ktls_ocf
- GELI (lightly)
I have not tested the following:
- ccp
- aesni with sha
- hifn
- kgssapi_krb5
- ubsec
- padlock
- safe
- armv8_crypto (aarch64)
- glxsb (i386)
- sec (ppc)
- cesa (armv7)
- cryptocteon (mips64)
- nlmsec (mips64)
Discussed with: cem
Relnotes: yes
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D23677
This amounts to a char ** since it is a char[8] *. Evil casts mostly
resolved the fact that what was actually passed in were plain char *.
Instead, change the DES functions to use 'unsigned char *' for keys
and for input and output buffers.
Reviewed by: cem, imp
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D21389
New sysctl/tunables can now set the interval (in seconds) between
rate-limited crypto warnings. The new sysctls are:
- kern.cryptodev_warn_interval for /dev/crypto
- net.inet.ipsec.crypto_warn_interval for IPsec
- kern.kgssapi_warn_interval for KGSSAPI
Reviewed by: cem
MFC after: 1 month
Relnotes: yes
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D20555
All of these algorithms are explicitly marked SHOULD NOT in one of these
RFCs.
Specifically, RFC 6649 deprecates all algorithms using DES as well as
the "export-friendly" variant of RC4. RFC 8429 deprecates Triple DES
and the remaining RC4 algorithms.
Reviewed by: cem
MFC after: 1 month
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D20343
We've got some cases where the other end of gssd's AF_LOCAL socket gets
closed, resulting in an error (and SIGPIPE) when it tries to do I/O to it.
Closing without cleaning up means the next time nfsd starts up, it hangs,
unkillably; this allows gssd to handle that particular error.
* Limit the retry cound in gssd_syscall to 5.
The default is INT_MAX, which effectively means forever. And it's an
uninterruptable RPC call, so it will never stop.
The two changes mitigate the problem.
Reviewed by: macklem
MFC after: 2 weeks
Sponsored by: iXsystems Inc.
Differential Revision: https://reviews.freebsd.org/D19153
Track session objects in the framework, and pass handles between the
framework (OCF), consumers, and drivers. Avoid redundancy and complexity in
individual drivers by allocating session memory in the framework and
providing it to drivers in ::newsession().
Session handles are no longer integers with information encoded in various
high bits. Use of the CRYPTO_SESID2FOO() macros should be replaced with the
appropriate crypto_ses2foo() function on the opaque session handle.
Convert OCF drivers (in particular, cryptosoft, as well as myriad others) to
the opaque handle interface. Discard existing session tracking as much as
possible (quick pass). There may be additional code ripe for deletion.
Convert OCF consumers (ipsec, geom_eli, krb5, cryptodev) to handle-style
interface. The conversion is largely mechnical.
The change is documented in crypto.9.
Inspired by
https://lists.freebsd.org/pipermail/freebsd-arch/2018-January/018835.html .
No objection from: ae (ipsec portion)
Reported by: jhb
The usage is simpler, documented, and more common.
Reviewed by: cem
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D14227
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
No functional change intended.
An over-long path argument to gssd_syscall could overrun the stack sockaddr_un
buffer. Fix gssd_syscall to not permit that.
If an over-long path is provided, gssd_syscall now returns EINVAL.
It looks like PRIV_NFS_DAEMON isn't granted anywhere, so my best guess is that
this is likely only triggerable by root.
Reported by: Coverity
CID: 1006751
Sponsored by: EMC / Isilon Storage Division
Some hardware supports AES acceleration but not SHA1, e.g., AES-NI
extensions. It is useful to have accelerated AES even if SHA1 must be
software.
Suggested by: asomers
Reviewed by: asomers, dfr
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D5146
When gssd exits it leaves the kernel state set by
gssd_syscall(). nfsd sees this and waits endlessly
in an unkillable state for gssd to come back. If you
had acidentally started gssd then stopped it, then
started nfsd you'd be in a bad way until you either
restarted gssd or rebooted the system. This change
fixes that by setting the kernel state to "" when
gssd exits.
Reviewed by: rmacklem
MFC after: 1 week
Sponsored by: iXsystems
The kernel tracks syscall users so that modules can safely unregister them.
But if the module is not unloadable or was compiled into the kernel, there is
no need to do this.
Achieve this by adding SY_THR_STATIC_KLD macro which expands to SY_THR_STATIC
during kernel build and 0 otherwise.
Reviewed by: kib (previous version)
MFC after: 2 weeks
credentials to the kernel rpc. Modify the NFSv4 client to add
support for the gssname and allgssname mount options to use this
capability. Requires the gssd daemon to be running with the "-h" option.
Reviewed by: jhb
for the last mbuf of the list with an encrypted message. This patch replaces
the KASSERT() with code that handles this case.
Reported by: john.gemignani@isilon.com
Reviewed by: jhb
MFC after: 2 weeks
caused by use of an invalid kgss_gssd_handle during an upcall to
the gssd daemon when it has exited. This patch seems to avoid the
crashes by holding a reference count on the kgss_gssd_handle until
the upcall is done. It also adds a new mutex kgss_gssd_lock used to
make manipulation of kgss_gssd_handle SMP safe.
Tested by: Illias A. Marinos, Herbert Poeckl
Reviewed by: jhb
MFC after: 2 weeks
patch modifies makesyscalls.sh to prefix all of the non-compatibility
calls (e.g. not linux_, freebsd32_) with sys_ and updates the kernel
entry points and all places in the code that use them. It also
fixes an additional name space collision between the kernel function
psignal and the libc function of the same name by renaming the kernel
psignal kern_psignal(). By introducing this change now we will ease future
MFCs that change syscalls.
Reviewed by: rwatson
Approved by: re (bz)
the NFS subsystems use five of the rpcsec_gss/kgssapi entry points,
but since it was not obvious which others might be useful, all
nineteen were included. Basically the nineteen entry points are
set in a structure called rpc_gss_entries and inline functions
defined in sys/rpc/rpcsec_gss.h check for the entry points being
non-NULL and then call them. A default value is returned otherwise.
Requested by rwatson.
Reviewed by: jhb
MFC after: 2 weeks
compiler doing argument type checking. Since the prototypes in
kgss_if.h used the generic gss_ctx_id_t for the context argument,
but the functions in sys/kgssapi/krb5/krb5_mech.c used the
KerberosV specific context argument, the file would no longer build.
This patch fixes it so it will build by replacing the argument with
a gss_ctx_id_t one and setting a local "struct krb5_context *" variable
to it for use by the function.
Reviewed by: dfr
Approved by: kib (mentor)
The system hostname is now stored in prison0, and the global variable
"hostname" has been removed, as has the hostname_mtx mutex. Jails may
have their own host information, or they may inherit it from the
parent/system. The proper way to read the hostname is via
getcredhostname(), which will copy either the hostname associated with
the passed cred, or the system hostname if you pass NULL. The system
hostname can still be accessed directly (and without locking) at
prison0.pr_host, but that should be avoided where possible.
The "similar information" referred to is domainname, hostid, and
hostuuid, which have also become prison parameters and had their
associated global variables removed.
Approved by: bz (mentor)
and server. This replaces the RPC implementation of the NFS client and
server with the newer RPC implementation originally developed
(actually ported from the userland sunrpc code) to support the NFS
Lock Manager. I have tested this code extensively and I believe it is
stable and that performance is at least equal to the legacy RPC
implementation.
The NFS code currently contains support for both the new RPC
implementation and the older legacy implementation inherited from the
original NFS codebase. The default is to use the new implementation -
add the NFS_LEGACYRPC option to fall back to the old code. When I
merge this support back to RELENG_7, I will probably change this so
that users have to 'opt in' to get the new code.
To use RPCSEC_GSS on either client or server, you must build a kernel
which includes the KGSSAPI option and the crypto device. On the
userland side, you must build at least a new libc, mountd, mount_nfs
and gssd. You must install new versions of /etc/rc.d/gssd and
/etc/rc.d/nfsd and add 'gssd_enable=YES' to /etc/rc.conf.
As long as gssd is running, you should be able to mount an NFS
filesystem from a server that requires RPCSEC_GSS authentication. The
mount itself can happen without any kerberos credentials but all
access to the filesystem will be denied unless the accessing user has
a valid ticket file in the standard place (/tmp/krb5cc_<uid>). There
is currently no support for situations where the ticket file is in a
different place, such as when the user logged in via SSH and has
delegated credentials from that login. This restriction is also
present in Solaris and Linux. In theory, we could improve this in
future, possibly using Brooks Davis' implementation of variant
symlinks.
Supporting RPCSEC_GSS on a server is nearly as simple. You must create
service creds for the server in the form 'nfs/<fqdn>@<REALM>' and
install them in /etc/krb5.keytab. The standard heimdal utility ktutil
makes this fairly easy. After the service creds have been created, you
can add a '-sec=krb5' option to /etc/exports and restart both mountd
and nfsd.
The only other difference an administrator should notice is that nfsd
doesn't fork to create service threads any more. In normal operation,
there will be two nfsd processes, one in userland waiting for TCP
connections and one in the kernel handling requests. The latter
process will create as many kthreads as required - these should be
visible via 'top -H'. The code has some support for varying the number
of service threads according to load but initially at least, nfsd uses
a fixed number of threads according to the value supplied to its '-n'
option.
Sponsored by: Isilon Systems
MFC after: 1 month
