Close subtle but relatively unlikely race conditions when
propagating the vnode write error to other active sessions
tracing to the same vnode, without holding a reference on
the vnode anymore. [2]
PR: kern/126368 [1]
Submitted by: rwatson [2]
Reviewed by: kib, rwatson
MFC after: 4 weeks
consists of the null-terminated name and the contents of any structure
you wish to record. A new ktrstruct() function constructs and emits a
KTR_STRUCT record. It is accompanied by convenience macros for struct
stat and struct sockaddr.
In kdump(1), KTR_STRUCT records are handled by a dispatcher function
that runs stringent sanity checks on its contents before handing it
over to individual decoding funtions for each type of structure.
Currently supported structures are struct stat and struct sockaddr for
the AF_INET, AF_INET6 and AF_UNIX families; support for AF_APPLETALK
and AF_IPX is present but disabled, as I am unable to test it properly.
Since 's' was already taken, the letter 't' is used by ktrace(1) to
enable KTR_STRUCT trace points, and in kdump(1) to enable their
decoding.
Derived from patches by Andrew Li <andrew2.li@citi.com>.
PR: kern/117836
MFC after: 3 weeks
conjuction with 'thread' argument passing which is always curthread.
Remove the unuseful extra-argument and pass explicitly curthread to lower
layer functions, when necessary.
KPI results broken by this change, which should affect several ports, so
version bumping and manpage update will be further committed.
Tested by: kris, pho, Diego Sardina <siarodx at gmail dot com>
Remove this argument and pass curthread directly to underlying
VOP_LOCK1() VFS method. This modify makes the code cleaner and in
particular remove an annoying dependence helping next lockmgr() cleanup.
KPI results, obviously, changed.
Manpage and FreeBSD_version will be updated through further commits.
As a side note, would be valuable to say that next commits will address
a similar cleanup about VFS methods, in particular vop_lock1 and
vop_unlock.
Tested by: Diego Sardina <siarodx at gmail dot com>,
Andrea Di Pasquale <whyx dot it at gmail dot com>
from Mac OS X Leopard--rationalize naming for entry points to
the following general forms:
mac_<object>_<method/action>
mac_<object>_check_<method/action>
The previous naming scheme was inconsistent and mostly
reversed from the new scheme. Also, make object types more
consistent and remove spaces from object types that contain
multiple parts ("posix_sem" -> "posixsem") to make mechanical
parsing easier. Introduce a new "netinet" object type for
certain IPv4/IPv6-related methods. Also simplify, slightly,
some entry point names.
All MAC policy modules will need to be recompiled, and modules
not updates as part of this commit will need to be modified to
conform to the new KPI.
Sponsored by: SPARTA (original patches against Mac OS X)
Obtained from: TrustedBSD Project, Apple Computer
ktruserret() is invoked, an unlocked check of the per-process queue
is performed inline, thus, we don't lock the ktrace_sx on every userret().
Pointy hat to: jhb
Approved by: re (kensmith)
Pointy hat recovered from: rwatson
- Depessimize userret() in kernels where KTRACE is enabled by doing an
unlocked check of the per-process queue of pending events before
acquiring any locks. Previously ktr_userret() unconditionally acquired
the global ktrace_sx lock on every return to userland for every thread,
even if ktrace wasn't enabled for the thread.
- Optimize the locking in exit() to first perform an unlocked read of
p_traceflag to see if ktrace is enabled and only acquire locks and
teardown ktrace if the test succeeds. Also, explicitly disable tracing
before draining any pending events so the pending events actually get
written out. The unlocked read is safe because proc lock is acquired
earlier after single-threading so p_traceflag can't change between then
and this check (well, it can currently due to a bug in ktrace I will fix
next, but that race existed prior to this change as well).
Reviewed by: rwatson
some cases, move to priv_check() if it was an operation on a thread and
no other flags were present.
Eliminate caller-side jail exception checking (also now-unused); jail
privilege exception code now goes solely in kern_jail.c.
We can't yet eliminate suser() due to some cases in the KAME code where
a privilege check is performed and then used in many different deferred
paths. Do, however, move those prototypes to priv.h.
Reviewed by: csjp
Obtained from: TrustedBSD Project
Change the VOP_OPEN(), vn_open() vnode operation and d_fdopen() cdev operation
argument from being file descriptor index into the pointer to struct file.
Proposed and reviewed by: jhb
Reviewed by: daichi (unionfs)
Approved by: re (kensmith)
- Remove also "MP SAFE" after prior "MPSAFE" pass. (suggested by bde)
- Remove extra blank lines in some cases.
- Add extra blank lines in some cases.
- Remove no-op comments consisting solely of the function name, the word
"syscall", or the system call name.
- Add punctuation.
- Re-wrap some comments.
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.
doing a CLEARFILE option. Do a vrele instead. This prevents
a panic later due to v_writecount being negative when the vnode
is taken off the freelist.
Submitted by: jhb
specific privilege names to a broad range of privileges. These may
require some future tweaking.
Sponsored by: nCircle Network Security, Inc.
Obtained from: TrustedBSD Project
Discussed on: arch@
Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri,
Alex Lyashkov <umka at sevcity dot net>,
Skip Ford <skip dot ford at verizon dot net>,
Antoine Brodin <antoine dot brodin at laposte dot net>
begun with a repo-copy of mac.h to mac_framework.h. sys/mac.h now
contains the userspace and user<->kernel API and definitions, with all
in-kernel interfaces moved to mac_framework.h, which is now included
across most of the kernel instead.
This change is the first step in a larger cleanup and sweep of MAC
Framework interfaces in the kernel, and will not be MFC'd.
Obtained from: TrustedBSD Project
Sponsored by: SPARTA
generating a coredump as the result of a signal.
- Fix a bug where we could leak a Giant lock if vn_start_write() failed
in coredump().
Reported by: jmg (2)
currently present is minor and offers no real semantic issues, it also
doesn't make sense since an earlier lockless check has already
occurred. Also hold the mutex longer, over a manipulation of
per-process ktrace state, which requires synchronization.
MFC after: 1 month
Pointed out by: jhb
reliability when tracing fast-moving processes or writing traces to
slow file systems by avoiding unbounded queueuing and dropped records.
Record loss was previously possible when the global pool of records
become depleted as a result of record generation outstripping record
commit, which occurred quickly in many common situations.
These changes partially restore the 4.x model of committing ktrace
records at the point of trace generation (synchronous), but maintain
the 5.x deferred record commit behavior (asynchronous) for situations
where entering VFS and sleeping is not possible (i.e., in the
scheduler). Records are now queued per-process as opposed to
globally, with processes responsible for committing records from their
own context as required.
- Eliminate the ktrace worker thread and global record queue, as they
are no longer used. Keep the global free record list, as records
are still used.
- Add a per-process record queue, which will hold any asynchronously
generated records, such as from context switches. This replaces the
global queue as the place to submit asynchronous records to.
- When a record is committed asynchronously, simply queue it to the
process.
- When a record is committed synchronously, first drain any pending
per-process records in order to maintain ordering as best we can.
Currently ordering between competing threads is provided via a global
ktrace_sx, but a per-process flag or lock may be desirable in the
future.
- When a process returns to user space following a system call, trap,
signal delivery, etc, flush any pending records.
- When a process exits, flush any pending records.
- Assert on process tear-down that there are no pending records.
- Slightly abstract the notion of being "in ktrace", which is used to
prevent the recursive generation of records, as well as generating
traces for ktrace events.
Future work here might look at changing the set of events marked for
synchronous and asynchronous record generation, re-balancing queue
depth, timeliness of commit to disk, and so on. I.e., performing a
drain every (n) records.
MFC after: 1 month
Discussed with: jhb
Requested by: Marc Olzheim <marcolz at stack dot nl>
ktr_tid as part of gathering of ktr header data for new ktrace
records. The continued use of intptr_t is required for file layout
reasons, and cannot be changed to lwpid_t at this point.
MFC after: 1 month
Reviewed by: davidxu
intptr_t. The buffer length needs to be written to disk as part
of the trace log, but the kernel pointer for the buffer does not.
Add a new ktr_buffer pointer to the kernel-only ktrace request
structure to hold that pointer. This frees up an integer in the
ktrace record format that can be used to hold the threadid,
although older ktrace files will have a garbage ktr_buffer field
(or more accurately, a kernel pointer value).
MFC after: 2 weeks
Space requested by: davidxu
security.bsd.see_other_uids is set to 0, etc.
One can check if invisible process is active, by doing:
# ktrace -p <pid>
If ktrace returns 'Operation not permitted' the process is alive and
if returns 'No such process' there is no such process.
MFC after: 1 week
somewhat clearer, but more importantly allows for a consistent naming
scheme for suser_cred flags.
The old name is still defined, but will be removed in a few days (unless I
hear any complaints...)
Discussed with: rwatson, scottl
Requested by: jhb
Add copyiniov() which copies a struct iovec array in from userland into
a malloc'ed struct iovec. Caller frees.
Change uiofromiov() to malloc the uio (caller frees) and name it
copyinuio() which is more appropriate.
Add cloneuio() which returns a malloc'ed copy. Caller frees.
Use them throughout.
Presumably, at some point, you had to include jail.h if you included
proc.h, but that is no longer required.
Result of: self injury involving adding something to struct prison
ktr_resize_pool(); this eliminates a potential livelock.
Return ENOSPC only if we encountered an out-of-memory condition when
trying to increase the pool size.
Reviewed by: jhb, bde (style)
semaphore and doing so can lead to a possible reversal. WITNESS would have
caught this if semaphores were used more often in the kernel.
Submitted by: Ted Unangst <tedu@stanford.edu>, Dawson Engler
curthread. Unlike td_flags, this field does not need any locking.
- Replace the td_inktr and td_inktrace variables with equivalent private
thread flags.
- Move TDF_OLDMASK over to the private flags field so it no longer requires
sched_lock.
- Mark the ktrace() and utrace() syscalls as being MP safe.
- Validate the facs argument to ktrace() prior to doing any vnode
operations or acquiring any locks.
- Share lock the proctree lock over the entire section that calls
ktrsetchildren() and ktrops(). We already did this for process groups.
Doing it for the process case closes a small race where a process might
go away after we look it up. As a result of this, ktrstchildren() now
just asserts that the proctree lock is locked rather than acquiring the
lock itself.
- Add some missing comments to #else and #endif.
KTRFAC_DROP to track instances when ktrace events are dropped due to the
request pool being exhausted. When a thread tries to post a ktrace event
and is unable to due to no available ktrace request objects, it sets
KTRFAC_DROP in its process' p_traceflag field. The next trace event to
successfully post from that process will set the KTR_DROP flag in the
header of the request going out and clear KTRFAC_DROP.
The KTR_DROP flag is the high bit in the type field of the ktr_header
structure. Older kdump binaries will simply complain about an unknown type
when seeing an entry with KTR_DROP set. Note that KTR_DROP being set on a
record in a ktrace file does not tell you anything except that at least one
event from this process was dropped prior to this event. The user has no
way of knowing what types of events were dropped nor how many were dropped.
Requested by: phk
struct proc as p_tracecred alongside the current cache of the vnode in
p_tracep. This credential is then used for all later ktrace operations on
this file rather than using the credential of the current thread at the
time of each ktrace event.
- Now that we have multiple ktrace-related items in struct proc that are
pointers, rename p_tracep to p_tracevp to make it less ambiguous.
Requested by: rwatson (1)
doesn't give them enough stack to do much before blowing away the pcb.
This adds MI and MD code to allow the allocation of an alternate kstack
who's size can be speficied when calling kthread_create. Passing the
value 0 prevents the alternate kstack from being created. Note that the
ia64 MD code is missing for now, and PowerPC was only partially written
due to the pmap.c being incomplete there.
Though this patch does not modify anything to make use of the alternate
kstack, acpi and usb are good candidates.
Reviewed by: jake, peter, jhb
