This makes it possible to support ftruncate() on non-vnode file types in
the future.
- 'struct fileops' grows a 'fo_truncate' method to handle an ftruncate() on
a given file descriptor.
- ftruncate() moves to kern/sys_generic.c and now just fetches a file
object and invokes fo_truncate().
- The vnode-specific portions of ftruncate() move to vn_truncate() in
vfs_vnops.c which implements fo_truncate() for vnode file types.
- Non-vnode file types return EINVAL in their fo_truncate() method.
Submitted by: rwatson
- Introduce a finit() which is used to initailize the fields of struct file
in such a way that the ops vector is only valid after the data, type,
and flags are valid.
- Protect f_flag and f_count with atomic operations.
- Remove the global list of all files and associated accounting.
- Rewrite the unp garbage collection such that it no longer requires
the global list of all files and instead uses a list of all unp sockets.
- Mark sockets in the accept queue so we don't incorrectly gc them.
Tested by: kris, pho
details from consumers.
- Track individual selecters on a per-descriptor basis such that there
are no longer collisions and after sleeping for events only those
descriptors which triggered events must be rescaned.
- Protect the selinfo (per descriptor) structure with a mtx pool mutex.
mtx pool mutexes were chosen to preserve api compatibility with
existing code which does nothing but bzero() to setup selinfo
structures.
- Use a per-thread wait channel rather than a global wait channel.
- Hide select implementation details in a seltd structure which is
opaque to the rest of the kernel.
- Provide a 'selsocket' interface for those kernel consumers who wish to
select on a socket when they have no fd so they no longer have to
be aware of select implementation details.
Tested by: kris
Reviewed on: arch
and flags with an sxlock. This leads to a significant and measurable
performance improvement as a result of access to shared locking for
frequent lookup operations, reduced general overhead, and reduced overhead
in the event of contention. All of these are imported for threaded
applications where simultaneous access to a shared file descriptor array
occurs frequently. Kris has reported 2x-4x transaction rate improvements
on 8-core MySQL benchmarks; smaller improvements can be expected for many
workloads as a result of reduced overhead.
- Generally eliminate the distinction between "fast" and regular
acquisisition of the filedesc lock; the plan is that they will now all
be fast. Change all locking instances to either shared or exclusive
locks.
- Correct a bug (pointed out by kib) in fdfree() where previously msleep()
was called without the mutex held; sx_sleep() is now always called with
the sxlock held exclusively.
- Universally hold the struct file lock over changes to struct file,
rather than the filedesc lock or no lock. Always update the f_ops
field last. A further memory barrier is required here in the future
(discussed with jhb).
- Improve locking and reference management in linux_at(), which fails to
properly acquire vnode references before using vnode pointers. Annotate
improper use of vn_fullpath(), which will be replaced at a future date.
In fcntl(), we conservatively acquire an exclusive lock, even though in
some cases a shared lock may be sufficient, which should be revisited.
The dropping of the filedesc lock in fdgrowtable() is no longer required
as the sxlock can be held over the sleep operation; we should consider
removing that (pointed out by attilio).
Tested by: kris
Discussed with: jhb, kris, attilio, jeff
system calls now enter without Giant held, and then in some cases, acquire
Giant explicitly.
Remove a number of other MPSAFE annotations in the credential code and
tweak one or two other adjacent comments.
programs to find out exactly which events were registered and which were
returned... This should be lower in kern_kevent, but that would require
special munging due to locks and the functions used to copyin/copyout
kevents...
If someone wants to teach ktrace how to output pretty kevents, I have a
kevent prety printer that can be used...
than keeping it locked until we exit the function to optimize the case
where the lock would be dropped and later reacquired. The optimization
was broken when kevent's were moved from UFS to VFS and the knote list
lock for a vnode kevent became the lockmgr vnode lock. If one tried
to use a kqueue that contained events for a kqueue fd followed by a vnode,
then the kq global lock would end up being held when the vnode lock was
acquired which could result in sleeping with a mutex held (and subsequent
panics) if the vnode lock was contested.
Reviewed by: jmg
Tested by: ps (on 6.x)
MFC after: 3 days
a race where data could come in before we clear the INFLUX flag, and get
skipped over by knote (and hence never be activated, though it should of
been)...
Found by: glebius & co.
Reviewed by: glebius
MFC after: 3 days
notifications when LIO operations completed. These were the problems
with LIO event complete notification:
- Move all LIO/AIO event notification into one general function
so we don't have bugs in different data paths. This unification
got rid of several notification bugs one of which if kqueue was
used a SIGILL could get sent to the process.
- Change the LIO event accounting to count all AIO request that
could have been split across the fast path and daemon mode.
The prior accounting only kept track of AIO op's in that
mode and not the entire list of operations. This could cause
a bogus LIO event complete notification to occur when all of
the fast path AIO op's completed and not the AIO op's that
ended up queued for the daemon.
Suggestions from: alc
- Introducing the possibility of using locks different than mutexes
for the knlist locking. In order to do this, we add three arguments to
knlist_init() to specify the functions to use to lock, unlock and
check if the lock is owned. If these arguments are NULL, we assume
mtx_lock, mtx_unlock and mtx_owned, respectively.
- Using the vnode lock for the knlist locking, when doing kqueue operations
on a vnode. This way, we don't have to lock the vnode while holding a
mutex, in filt_vfsread.
Reviewed by: jmg
Approved by: re (scottl), scottl (mentor override)
Pointyhat to: ssouhlal
Will be happy: everyone
w/o problems than I was before... This simply brings back the knote_delete
as knlist_delete which will also drop the knote's, instead of just clearing
the list and seeing _ONESHOT...
Fix a race where if a note was _INFLUX and _DETACHED, it could end up being
modified... whoopse..
MFC after: 1 week
Prodded by: ambrisko and dwhite
Use this in all the places where sleeping with the lock held is not
an issue.
The distinction will become significant once we finalize the exact
lock-type to use for this kind of case.
happens when a proc exits, but needs to inform the user that this has
happened.. This also means we can remove the check for detached from
proc and sig f_detach functions as this is doing in kqueue now...
MFC after: 5 days
a more complete subsystem, and removes the knowlege of how things are
implemented from the drivers. Include locking around filter ops, so a
module like aio will know when not to be unloaded if there are outstanding
knotes using it's filter ops.
Currently, it uses the MTX_DUPOK even though it is not always safe to
aquire duplicate locks. Witness currently doesn't support the ability
to discover if a dup lock is ok (in some cases).
Reviewed by: green, rwatson (both earlier versions)
Giant conditional on debug.mpsafenet in the socket soo_stat() routine,
unconditionally in vn_statfile() for VFS, and otherwise don't acquire
Giant. Accept an unlocked read in kqueue_stat(), and cryptof_stat() is
a no-op. Don't acquire Giant in fstat() system call.
Note: in fdescfs, fo_stat() is called while holding Giant due to the VFS
stack sitting on top, and therefore there will still be Giant recursion
in this case.
individual file object implementations can optionally acquire Giant if
they require it:
- soo_close(): depends on debug.mpsafenet
- pipe_close(): Giant not acquired
- kqueue_close(): Giant required
- vn_close(): Giant required
- cryptof_close(): Giant required (conservative)
Notes:
Giant is still acquired in close() even when closing MPSAFE objects
due to kqueue requiring Giant in the calling closef() code.
Microbenchmarks indicate that this removal of Giant cuts 3%-3% off
of pipe create/destroy pairs from user space with SMP compiled into
the kernel.
The cryptodev and opencrypto code appears MPSAFE, but I'm unable to
test it extensively and so have left Giant over fo_close(). It can
probably be removed given some testing and review.
generic filesystem events to userspace. Currently only mount and unmount
of filesystems are signalled. Soon to be added, up/down status of NFS.
Introduce a sysctl node used to route requests to/from filesystems
based on filesystem ids.
Introduce a new vfsop, vfs_sysctl(mp, req) that is used as the callback/
entrypoint by the sysctl code to change individual filesystems.
a callout, and use the new callout_drain API to make sure that a callout
has finished before we deallocate memory it is using.
PR: kern/64121
Discussed with: gallatin
in exit1(), make sure the p_klist is empty after sending NOTE_EXIT.
The process won't report fork() or execve() and won't be able to handle
NOTE_SIGNAL knotes anyway.
This fixes some race conditions with do_tdsignal() calling knote() while
the process is exiting.
Reported by: Stefan Farfeleder <stefan@fafoe.narf.at>
MFC after: 1 week
thread being waken up. The thread waken up can run at a priority as
high as after tsleep().
- Replace selwakeup()s with selwakeuppri()s and pass appropriate
priorities.
- Add cv_broadcastpri() which raises the priority of the broadcast
threads. Used by selwakeuppri() if collision occurs.
Not objected in: -arch, -current
Use zpfind() to see if the process became a zombie if pfind() doesn't find it
and if the caller wants to know about process death, so that the caller knows
the process died even if it happened before the kevent was actually registered.
MFC after: 1 week
This fixes a race condition (specifically with signal events) that could
lead to the kn being re-inserted into the list after it has been destroyed,
which is not something we want to happen.
PR: kern/58258
table, acquiring the necessary locks as it works. It usually returns
two references to the new descriptor: one in the descriptor table
and one via a pointer argument.
As falloc releases the FILEDESC lock before returning, there is a
potential for a process to close the reference in the file descriptor
table before falloc's caller gets to use the file. I don't think this
can happen in practice at the moment, because Giant indirectly protects
closes.
To stop the file being completly closed in this situation, this change
makes falloc set the refcount to two when both references are returned.
This makes life easier for several of falloc's callers, because the
first thing they previously did was grab an extra reference on the
file.
Reviewed by: iedowse
Idea run past: jhb
the target process exiting which causes attempts to register the kevent
to randomly fail depending on whether the target runs to completion before
the parent can call kevent(2). The bug actually effects EVFILT_PROC
events on any zombie process, but the most common manifestation is with
parents trying to monitor child processes.
MFC after: 2 weeks
Sponsored by: NTT Multimedia Communications Labs
barrier between free'ing filedesc structures. Basically if you want to
access another process's filedesc, you want to hold this mutex over the
entire operation.
1. eliminate unnecessary loop which frees and re-allocates
the just allocated array
2. eliminate the newsize recomputation
3. eliminate unnecessary unlock and relock around free
4. correctly match the free with the malloc into M_KQUEUE instead of M_TEMP
5. eliminate conditional assignment of oldlist, which is equivalent to a
simple assignment
6. eliminate the oldlist temporary variable completely
Reviewed by: jhb
pointer types, and remove a huge number of casts from code using it.
Change struct xfile xf_data to xun_data (ABI is still compatible).
If we need to add a #define for f_data and xf_data we can, but I don't
think it will be necessary. There are no operational changes in this
commit.
this was causing filedesc work to be very painful.
In order to make this work split out sigio definitions to thier own header
(sigio.h) which is included from proc.h for the time being.
accept an 'active_cred' argument reflecting the credential of the thread
initiating the ioctl operation.
- Change fo_ioctl() to accept active_cred; change consumers of the
fo_ioctl() interface to generally pass active_cred from td->td_ucred.
- In fifofs, initialize filetmp.f_cred to ap->a_cred so that the
invocations of soo_ioctl() are provided access to the calling f_cred.
Pass ap->a_td->td_ucred as the active_cred, but note that this is
required because we don't yet distinguish file_cred and active_cred
in invoking VOP's.
- Update kqueue_ioctl() for its new argument.
- Update pipe_ioctl() for its new argument, pass active_cred rather
than td_ucred to MAC for authorization.
- Update soo_ioctl() for its new argument.
- Update vn_ioctl() for its new argument, use active_cred rather than
td->td_ucred to authorize VOP_IOCTL() and the associated VOP_GETATTR().
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
fo_read() and fo_write(): explicitly use the cred argument to fo_poll()
as "active_cred" using the passed file descriptor's f_cred reference
to provide access to the file credential. Add an active_cred
argument to fo_stat() so that implementers have access to the active
credential as well as the file credential. Generally modify callers
of fo_stat() to pass in td->td_ucred rather than fp->f_cred, which
was redundantly provided via the fp argument. This set of modifications
also permits threads to perform these operations on behalf of another
thread without modifying their credential.
Trickle this change down into fo_stat/poll() implementations:
- badfo_poll(), badfo_stat(): modify/add arguments.
- kqueue_poll(), kqueue_stat(): modify arguments.
- pipe_poll(), pipe_stat(): modify/add arguments, pass active_cred to
MAC checks rather than td->td_ucred.
- soo_poll(), soo_stat(): modify/add arguments, pass fp->f_cred rather
than cred to pru_sopoll() to maintain current semantics.
- sopoll(): moidfy arguments.
- vn_poll(), vn_statfile(): modify/add arguments, pass new arguments
to vn_stat(). Pass active_cred to MAC and fp->f_cred to VOP_POLL()
to maintian current semantics.
- vn_close(): rename cred to file_cred to reflect reality while I'm here.
- vn_stat(): Add active_cred and file_cred arguments to vn_stat()
and consumers so that this distinction is maintained at the VFS
as well as 'struct file' layer. Pass active_cred instead of
td->td_ucred to MAC and to VOP_GETATTR() to maintain current semantics.
- fifofs: modify the creation of a "filetemp" so that the file
credential is properly initialized and can be used in the socket
code if desired. Pass ap->a_td->td_ucred as the active
credential to soo_poll(). If we teach the vnop interface about
the distinction between file and active credentials, we would use
the active credential here.
Note that current inconsistent passing of active_cred vs. file_cred to
VOP's is maintained. It's not clear why GETATTR would be authorized
using active_cred while POLL would be authorized using file_cred at
the file system level.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
make a series of modifications to the credential arguments relating
to file read and write operations to cliarfy which credential is
used for what:
- Change fo_read() and fo_write() to accept "active_cred" instead of
"cred", and change the semantics of consumers of fo_read() and
fo_write() to pass the active credential of the thread requesting
an operation rather than the cached file cred. The cached file
cred is still available in fo_read() and fo_write() consumers
via fp->f_cred. These changes largely in sys_generic.c.
For each implementation of fo_read() and fo_write(), update cred
usage to reflect this change and maintain current semantics:
- badfo_readwrite() unchanged
- kqueue_read/write() unchanged
pipe_read/write() now authorize MAC using active_cred rather
than td->td_ucred
- soo_read/write() unchanged
- vn_read/write() now authorize MAC using active_cred but
VOP_READ/WRITE() with fp->f_cred
Modify vn_rdwr() to accept two credential arguments instead of a
single credential: active_cred and file_cred. Use active_cred
for MAC authorization, and select a credential for use in
VOP_READ/WRITE() based on whether file_cred is NULL or not. If
file_cred is provided, authorize the VOP using that cred,
otherwise the active credential, matching current semantics.
Modify current vn_rdwr() consumers to pass a file_cred if used
in the context of a struct file, and to always pass active_cred.
When vn_rdwr() is used without a file_cred, pass NOCRED.
These changes should maintain current semantics for read/write,
but avoid a redundant passing of fp->f_cred, as well as making
it more clear what the origin of each credential is in file
descriptor read/write operations.
Follow-up commits will make similar changes to other file descriptor
operations, and modify the MAC framework to pass both credentials
to MAC policy modules so they can implement either semantic for
revocation.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
pointer instead of a proc pointer and require the process pointed to
by the second argument to be locked. We now use the thread ucred reference
for the credential checks in p_can*() as a result. p_canfoo() should now
no longer need Giant.
Seigo Tanimura (tanimura) posted the initial delta.
I've polished it quite a bit reducing the need for locking and
adapting it for KSE.
Locks:
1 mutex in each filedesc
protects all the fields.
protects "struct file" initialization, while a struct file
is being changed from &badfileops -> &pipeops or something
the filedesc should be locked.
1 mutex in each struct file
protects the refcount fields.
doesn't protect anything else.
the flags used for garbage collection have been moved to
f_gcflag which was the FILLER short, this doesn't need
locking because the garbage collection is a single threaded
container.
could likely be made to use a pool mutex.
1 sx lock for the global filelist.
struct file * fhold(struct file *fp);
/* increments reference count on a file */
struct file * fhold_locked(struct file *fp);
/* like fhold but expects file to locked */
struct file * ffind_hold(struct thread *, int fd);
/* finds the struct file in thread, adds one reference and
returns it unlocked */
struct file * ffind_lock(struct thread *, int fd);
/* ffind_hold, but returns file locked */
I still have to smp-safe the fget cruft, I'll get to that asap.
Remove the explicit call to aio_proc_rundown() from exit1(), instead AIO
will use at_exit(9).
Add functions at_exec(9), rm_at_exec(9) which function nearly the
same as at_exec(9) and rm_at_exec(9), these functions are called
on behalf of modules at the time of execve(2) after the image
activator has run.
Use a modified version of tegge's suggestion via at_exec(9) to close
an exploitable race in AIO.
Fix SYSCALL_MODULE_HELPER such that it's archetecuterally neutral,
the problem was that one had to pass it a paramater indicating the
number of arguments which were actually the number of "int". Fix
it by using an inline version of the AS macro against the syscall
arguments. (AS should be available globally but we'll get to that
later.)
Add a primative system for dynamically adding kqueue ops, it's really
not as sophisticated as it should be, but I'll discuss with jlemon when
he's around.
Replace uses of holdfp() with fget*() or fgetvp*() calls as appropriate
introduce fget(), fget_read(), fget_write() - these functions will take
a thread and file descriptor and return a file pointer with its ref
count bumped.
introduce fgetvp(), fgetvp_read(), fgetvp_write() - these functions will
take a thread and file descriptor and return a vref()'d vnode.
*_read() requires that the file pointer be FREAD, *_write that it be
FWRITE.
This continues the cleanup of struct filedesc and struct file access
routines which, when are all through with it, will allow us to then
make the API calls MP safe and be able to move Giant down into the fo_*
functions.
the static callout list allocated by the system.
Change malloc type from M_TEMP to M_KQUEUE to better track memory.
Add a kern.kq_calloutmax to globally limit the amount of kernel memory
that can be allocated by callouts.
Submitted by: iedowse (items 1, 2)
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.
Sorry john! (your next MFC will be a doosie!)
Reviewed by: peter@freebsd.org, dillon@freebsd.org
X-MFC after: ha ha ha ha
The p_can(...) construct was a premature (and, it turns out,
awkward) abstraction. The individual calls to p_canxxx() better
reflect differences between the inter-process authorization checks,
such as differing checks based on the type of signal. This has
a side effect of improving code readability.
o Replace direct credential authorization checks in ktrace() with
invocation of p_candebug(), while maintaining the special case
check of KTR_ROOT. This allows ktrace() to "play more nicely"
with new mandatory access control schemes, as well as making its
authorization checks consistent with other "debugging class"
checks.
o Eliminate "privused" construct for p_can*() calls which allowed the
caller to determine if privilege was required for successful
evaluation of the access control check. This primitive is currently
unused, and as such, serves only to complicate the API.
Approved by: ({procfs,linprocfs} changes) des
Obtained from: TrustedBSD Project
other "system" header files.
Also help the deprecation of lockmgr.h by making it a sub-include of
sys/lock.h and removing sys/lockmgr.h form kernel .c files.
Sort sys/*.h includes where possible in affected files.
OK'ed by: bde (with reservations)
by p_can(...P_CAN_SEE), rather than returning EACCES directly. This
brings the error code used here into line with similar arrangements
elsewhere, and prevents the leakage of pid usage information.
Reviewed by: jlemon
Obtained from: TrustedBSD Project
Pre-rfork code assumed inherent locking of a process's file descriptor
array. However, with the advent of rfork() the file descriptor table
could be shared between processes. This patch closes over a dozen
serious race conditions related to one thread manipulating the table
(e.g. closing or dup()ing a descriptor) while another is blocked in
an open(), close(), fcntl(), read(), write(), etc...
PR: kern/11629
Discussed with: Alexander Viro <viro@math.psu.edu>
int p_can(p1, p2, operation, privused)
which allows specification of subject process, object process,
inter-process operation, and an optional call-by-reference privused
flag, allowing the caller to determine if privilege was required
for the call to succeed. This allows jail, kern.ps_showallprocs and
regular credential-based interaction checks to occur in one block of
code. Possible operations are P_CAN_SEE, P_CAN_SCHED, P_CAN_KILL,
and P_CAN_DEBUG. p_can currently breaks out as a wrapper to a
series of static function checks in kern_prot, which should not
be invoked directly.
o Commented out capabilities entries are included for some checks.
o Update most inter-process authorization to make use of p_can() instead
of manual checks, PRISON_CHECK(), P_TRESPASS(), and
kern.ps_showallprocs.
o Modify suser{,_xxx} to use const arguments, as it no longer modifies
process flags due to the disabling of ASU.
o Modify some checks/errors in procfs so that ENOENT is returned instead
of ESRCH, further improving concealment of processes that should not
be visible to other processes. Also introduce new access checks to
improve hiding of processes for procfs_lookup(), procfs_getattr(),
procfs_readdir(). Correct a bug reported by bp concerning not
handling the CREATE case in procfs_lookup(). Remove volatile flag in
procfs that caused apparently spurious qualifier warnigns (approved by
bde).
o Add comment noting that ktrace() has not been updated, as its access
control checks are different from ptrace(), whereas they should
probably be the same. Further discussion should happen on this topic.
Reviewed by: bde, green, phk, freebsd-security, others
Approved by: bde
Obtained from: TrustedBSD Project
