kcmp(2): implement for generic file types

Reviewed by: brooks, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D43518

sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

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

freebsd32: semid_t -> int32_t

semid_t is historically an intptr_t so it should be an int32_t.

Reviewed by: kevans

vfs: remove thread argument from VOP_STAT

and fo_stat.

Convert remaining cap_rights_init users to cap_rights_init_one

semantic patch:

@@

expression rights, r;

@@

- cap_rights_init(&rights, r)
+ cap_rights_init_one(&rights, r)

Split out cwd/root/jail, cmask state from filedesc table

No functional change intended.

Tracking these structures separately for each proc enables future work to
correctly emulate clone(2) in linux(4).

__FreeBSD_version is bumped (to 1300130) for consumption by, e.g., lsof.

Reviewed by: kib
Discussed with: markj, mjg
Differential Revision: https://reviews.freebsd.org/D27037

kern: clean up empty lines in .c and .h files

vfs: remove the obsolete privused argument from vaccess

This brings argument count down to 6, which is passable without the
stack on amd64.

Remove unused argument to priv_check_cred.

Patch mostly generated with cocinnelle:

@@
expression E1,E2;
@@

- priv_check_cred(E1,E2,0)
+ priv_check_cred(E1,E2)

Sponsored by: The FreeBSD Foundation

Make timespecadd(3) and friends public

The timespecadd(3) family of macros were imported from NetBSD back in
r35029. However, they were initially guarded by #ifdef _KERNEL. In the
meantime, we have grown at least 28 syscalls that use timespecs in some
way, leading many programs both inside and outside of the base system to
redefine those macros. It's better just to make the definitions public.

Our kernel currently defines two-argument versions of timespecadd and
timespecsub. NetBSD, OpenBSD, and FreeDesktop.org's libbsd, however, define
three-argument versions. Solaris also defines a three-argument version, but
only in its kernel. This revision changes our definition to match the
common three-argument version.

Bump _FreeBSD_version due to the breaking KPI change.

Discussed with: cem, jilles, ian, bde
Differential Revision: https://reviews.freebsd.org/D14725

Eliminate the overhead of gratuitous repeated reinitialization of cap_rights

- Add macros to allow preinitialization of cap_rights_t.

- Convert most commonly used code paths to use preinitialized cap_rights_t.
A 3.6% speedup in fstat was measured with this change.

Reported by: mjg
Reviewed by: oshogbo
Approved by: sbruno
MFC after: 1 month

Move most of the contents of opt_compat.h to opt_global.h.

opt_compat.h is mentioned in nearly 180 files. In-progress network
driver compabibility improvements may add over 100 more so this is
closer to "just about everywhere" than "only some files" per the
guidance in sys/conf/options.

Keep COMPAT_LINUX32 in opt_compat.h as it is confined to a subset of
sys/compat/linux/*.c. A fake _COMPAT_LINUX option ensure opt_compat.h
is created on all architectures.

Move COMPAT_LINUXKPI to opt_dontuse.h as it is only used to control the
set of compiled files.

Reviewed by: kib, cem, jhb, jtl
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D14941

sys/kern: adoption of SPDX licensing ID tags.

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.

Audit arguments to POSIX message queues, semaphores, and shared memory.

This requires minor changes to the audit framework to allow capturing
paths that are not filesystem paths (i.e., will not be canonicalised
relative to the process current working directory and/or filesystem
root).

Obtained from: TrustedBSD Project
MFC after: 3 weeks
Sponsored by: DARPA, AFRL

Clean up some style(9) violations.

Separate POSIX sem/shm objects in jails, by prepending the jail's path
name to the object's "path". While the objects don't have real path
names, it's a filesystem-like namespace, which allows jails to be
kept to their own space, but still allows the system / jail parent to
access a jail's IPC.

PR: 208082

Call ksem_get() with initialized 'rights'.

ksem_get() consumes fget(), and it's mandatory there.

Reported by: truckman
Reviewed by: mjg

fd: remove filedesc argument from fdclose

Just accept a thread instead. This makes it consistent with fdalloc.

No functional changes.

Avoid dynamic syscall overhead for statically compiled modules.

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

Add a new fo_fill_kinfo fileops method to add type-specific information to
struct kinfo_file.
- Move the various fill_*_info() methods out of kern_descrip.c and into the
various file type implementations.
- Rework the support for kinfo_ofile to generate a suitable kinfo_file object
for each file and then convert that to a kinfo_ofile structure rather than
keeping a second, different set of code that directly manipulates
type-specific file information.
- Remove the shm_path() and ksem_info() layering violations.

Differential Revision: https://reviews.freebsd.org/D775
Reviewed by: kib, glebius (earlier version)

Fix various issues with invalid file operations:
- Add invfo_rdwr() (for read and write), invfo_ioctl(), invfo_poll(),
and invfo_kqfilter() for use by file types that do not support the
respective operations. Home-grown versions of invfo_poll() were
universally broken (they returned an errno value, invfo_poll()
uses poll_no_poll() to return an appropriate event mask). Home-grown
ioctl routines also tended to return an incorrect errno (invfo_ioctl
returns ENOTTY).
- Use the invfo_*() functions instead of local versions for
unsupported file operations.
- Reorder fileops members to match the order in the structure definition
to make it easier to spot missing members.
- Add several missing methods to linuxfileops used by the OFED shim
layer: fo_write(), fo_truncate(), fo_kqfilter(), and fo_stat(). Most
of these used invfo_*(), but a dummy fo_stat() implementation was
added.

Update kernel inclusions of capability.h to use capsicum.h instead; some
further refinement is required as some device drivers intended to be
portable over FreeBSD versions rely on __FreeBSD_version to decide whether
to include capability.h.

MFC after: 3 weeks

Change the cap_rights_t type from uint64_t to a structure that we can extend
in the future in a backward compatible (API and ABI) way.

The cap_rights_t represents capability rights. We used to use one bit to
represent one right, but we are running out of spare bits. Currently the new
structure provides place for 114 rights (so 50 more than the previous
cap_rights_t), but it is possible to grow the structure to hold at least 285
rights, although we can make it even larger if 285 rights won't be enough.

The structure definition looks like this:

struct cap_rights {
uint64_t cr_rights[CAP_RIGHTS_VERSION + 2];
};

The initial CAP_RIGHTS_VERSION is 0.

The top two bits in the first element of the cr_rights[] array contain total
number of elements in the array - 2. This means if those two bits are equal to
0, we have 2 array elements.

The top two bits in all remaining array elements should be 0.
The next five bits in all array elements contain array index. Only one bit is
used and bit position in this five-bits range defines array index. This means
there can be at most five array elements in the future.

To define new right the CAPRIGHT() macro must be used. The macro takes two
arguments - an array index and a bit to set, eg.

#define CAP_PDKILL CAPRIGHT(1, 0x0000000000000800ULL)

We still support aliases that combine few rights, but the rights have to belong
to the same array element, eg:

#define CAP_LOOKUP CAPRIGHT(0, 0x0000000000000400ULL)
#define CAP_FCHMOD CAPRIGHT(0, 0x0000000000002000ULL)

#define CAP_FCHMODAT (CAP_FCHMOD | CAP_LOOKUP)

There is new API to manage the new cap_rights_t structure:

cap_rights_t *cap_rights_init(cap_rights_t *rights, ...);
void cap_rights_set(cap_rights_t *rights, ...);
void cap_rights_clear(cap_rights_t *rights, ...);
bool cap_rights_is_set(const cap_rights_t *rights, ...);

bool cap_rights_is_valid(const cap_rights_t *rights);
void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src);
void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src);
bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little);

Capability rights to the cap_rights_init(), cap_rights_set(),
cap_rights_clear() and cap_rights_is_set() functions are provided by
separating them with commas, eg:

cap_rights_t rights;

cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT);

There is no need to terminate the list of rights, as those functions are
actually macros that take care of the termination, eg:

#define cap_rights_set(rights, ...) \
__cap_rights_set((rights), __VA_ARGS__, 0ULL)
void __cap_rights_set(cap_rights_t *rights, ...);

Thanks to using one bit as an array index we can assert in those functions that
there are no two rights belonging to different array elements provided
together. For example this is illegal and will be detected, because CAP_LOOKUP
belongs to element 0 and CAP_PDKILL to element 1:

cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL);

Providing several rights that belongs to the same array's element this way is
correct, but is not advised. It should only be used for aliases definition.

This commit also breaks compatibility with some existing Capsicum system calls,
but I see no other way to do that. This should be fine as Capsicum is still
experimental and this change is not going to 9.x.

Sponsored by: The FreeBSD Foundation

Make sendfile() a method in the struct fileops. Currently only
vnode backed file descriptors have this method implemented.

Reviewed by: kib
Sponsored by: Nginx, Inc.
Sponsored by: Netflix

Similar to 233760 and 236717, export some more useful info about the
kernel-based POSIX semaphore descriptors to userland via procstat(1) and
fstat(1):
- Change sem file descriptors to track the pathname they are associated
with and add a ksem_info() method to copy the path out to a
caller-supplied buffer.
- Use the fo_stat() method of shared memory objects and ksem_info() to
export the path, mode, and value of a semaphore via struct kinfo_file.
- Add a struct semstat to the libprocstat(3) interface along with a
procstat_get_sem_info() to export the mode and value of a semaphore.
- Teach fstat about semaphores and to display their path, mode, and value.

MFC after: 2 weeks

sem: Restart the POSIX sem_* calls after signals with SA_RESTART set.

Programs often do not expect an [EINTR] return from sem_wait() and POSIX
only allows it if the signal was installed without SA_RESTART. The timeout
in sem_timedwait() is absolute so it can be restarted normally.

The umtx call can be invoked with a relative timeout and in that case
[ERESTART] must be changed to [EINTR]. However, libc does not do this.

The old POSIX semaphore implementation did this correctly (before r249566),
unlike the new umtx one.

It may be desirable to avoid [EINTR] completely, which matches the pthread
functions and is explicitly permitted by POSIX. However, the kernel must
return [EINTR] at least for signals with SA_RESTART clear, otherwise pthread
cancellation will not abort a semaphore wait. In this commit, only restore
the 8.x behaviour which is also permitted by POSIX.

Discussed with: jhb
MFC after: 1 week

- Document that sem_wait() can fail with EINTR if it is interrupted by a
signal.
- Fix the old ksem implementation for POSIX semaphores to not restart
sem_wait() or sem_timedwait() if interrupted by a signal.

MFC after: 1 week

mqueue,ksem,shm: Fix race condition with setting UF_EXCLOSE.

POSIX mqueue, compatibility ksem and POSIX shm create a file descriptor that
has close-on-exec set. However, they do this incorrectly, leaving a window
where a thread may fork and exec while the flag has not been set yet. The
race is easily reproduced on a multicore system with one thread doing
shm_open and close and another thread doing posix_spawnp and waitpid.

Set UF_EXCLOSE via falloc()'s flags argument instead. This also simplifies
the code.

MFC after: 1 week

Merge Capsicum overhaul:

- Capability is no longer separate descriptor type. Now every descriptor
has set of its own capability rights.

- The cap_new(2) system call is left, but it is no longer documented and
should not be used in new code.

- The new syscall cap_rights_limit(2) should be used instead of
cap_new(2), which limits capability rights of the given descriptor
without creating a new one.

- The cap_getrights(2) syscall is renamed to cap_rights_get(2).

- If CAP_IOCTL capability right is present we can further reduce allowed
ioctls list with the new cap_ioctls_limit(2) syscall. List of allowed
ioctls can be retrived with cap_ioctls_get(2) syscall.

- If CAP_FCNTL capability right is present we can further reduce fcntls
that can be used with the new cap_fcntls_limit(2) syscall and retrive
them with cap_fcntls_get(2).

- To support ioctl and fcntl white-listing the filedesc structure was
heavly modified.

- The audit subsystem, kdump and procstat tools were updated to
recognize new syscalls.

- Capability rights were revised and eventhough I tried hard to provide
backward API and ABI compatibility there are some incompatible changes
that are described in detail below:

CAP_CREATE old behaviour:
- Allow for openat(2)+O_CREAT.
- Allow for linkat(2).
- Allow for symlinkat(2).
CAP_CREATE new behaviour:
- Allow for openat(2)+O_CREAT.

Added CAP_LINKAT:
- Allow for linkat(2). ABI: Reuses CAP_RMDIR bit.
- Allow to be target for renameat(2).

Added CAP_SYMLINKAT:
- Allow for symlinkat(2).

Removed CAP_DELETE. Old behaviour:
- Allow for unlinkat(2) when removing non-directory object.
- Allow to be source for renameat(2).

Removed CAP_RMDIR. Old behaviour:
- Allow for unlinkat(2) when removing directory.

Added CAP_RENAMEAT:
- Required for source directory for the renameat(2) syscall.

Added CAP_UNLINKAT (effectively it replaces CAP_DELETE and CAP_RMDIR):
- Allow for unlinkat(2) on any object.
- Required if target of renameat(2) exists and will be removed by this
call.

Removed CAP_MAPEXEC.

CAP_MMAP old behaviour:
- Allow for mmap(2) with any combination of PROT_NONE, PROT_READ and
PROT_WRITE.
CAP_MMAP new behaviour:
- Allow for mmap(2)+PROT_NONE.

Added CAP_MMAP_R:
- Allow for mmap(PROT_READ).
Added CAP_MMAP_W:
- Allow for mmap(PROT_WRITE).
Added CAP_MMAP_X:
- Allow for mmap(PROT_EXEC).
Added CAP_MMAP_RW:
- Allow for mmap(PROT_READ | PROT_WRITE).
Added CAP_MMAP_RX:
- Allow for mmap(PROT_READ | PROT_EXEC).
Added CAP_MMAP_WX:
- Allow for mmap(PROT_WRITE | PROT_EXEC).
Added CAP_MMAP_RWX:
- Allow for mmap(PROT_READ | PROT_WRITE | PROT_EXEC).

Renamed CAP_MKDIR to CAP_MKDIRAT.
Renamed CAP_MKFIFO to CAP_MKFIFOAT.
Renamed CAP_MKNODE to CAP_MKNODEAT.

CAP_READ old behaviour:
- Allow pread(2).
- Disallow read(2), readv(2) (if there is no CAP_SEEK).
CAP_READ new behaviour:
- Allow read(2), readv(2).
- Disallow pread(2) (CAP_SEEK was also required).

CAP_WRITE old behaviour:
- Allow pwrite(2).
- Disallow write(2), writev(2) (if there is no CAP_SEEK).
CAP_WRITE new behaviour:
- Allow write(2), writev(2).
- Disallow pwrite(2) (CAP_SEEK was also required).

Added convinient defines:

#define CAP_PREAD (CAP_SEEK | CAP_READ)
#define CAP_PWRITE (CAP_SEEK | CAP_WRITE)
#define CAP_MMAP_R (CAP_MMAP | CAP_SEEK | CAP_READ)
#define CAP_MMAP_W (CAP_MMAP | CAP_SEEK | CAP_WRITE)
#define CAP_MMAP_X (CAP_MMAP | CAP_SEEK | 0x0000000000000008ULL)
#define CAP_MMAP_RW (CAP_MMAP_R | CAP_MMAP_W)
#define CAP_MMAP_RX (CAP_MMAP_R | CAP_MMAP_X)
#define CAP_MMAP_WX (CAP_MMAP_W | CAP_MMAP_X)
#define CAP_MMAP_RWX (CAP_MMAP_R | CAP_MMAP_W | CAP_MMAP_X)
#define CAP_RECV CAP_READ
#define CAP_SEND CAP_WRITE

#define CAP_SOCK_CLIENT \
(CAP_CONNECT | CAP_GETPEERNAME | CAP_GETSOCKNAME | CAP_GETSOCKOPT | \
CAP_PEELOFF | CAP_RECV | CAP_SEND | CAP_SETSOCKOPT | CAP_SHUTDOWN)
#define CAP_SOCK_SERVER \
(CAP_ACCEPT | CAP_BIND | CAP_GETPEERNAME | CAP_GETSOCKNAME | \
CAP_GETSOCKOPT | CAP_LISTEN | CAP_PEELOFF | CAP_RECV | CAP_SEND | \
CAP_SETSOCKOPT | CAP_SHUTDOWN)

Added defines for backward API compatibility:

#define CAP_MAPEXEC CAP_MMAP_X
#define CAP_DELETE CAP_UNLINKAT
#define CAP_MKDIR CAP_MKDIRAT
#define CAP_RMDIR CAP_UNLINKAT
#define CAP_MKFIFO CAP_MKFIFOAT
#define CAP_MKNOD CAP_MKNODAT
#define CAP_SOCK_ALL (CAP_SOCK_CLIENT | CAP_SOCK_SERVER)

Sponsored by: The FreeBSD Foundation
Reviewed by: Christoph Mallon <christoph.mallon@gmx.de>
Many aspects discussed with: rwatson, benl, jonathan
ABI compatibility discussed with: kib

In order to maximize the re-usability of kernel code in user space this
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)

Fix build breakage. Initialize error variables explicitely for !MAC case.

Pointy hat to: kib
Approved by: re (bz)

Add the fo_chown and fo_chmod methods to struct fileops and use them
to implement fchown(2) and fchmod(2) support for several file types
that previously lacked it. Add MAC entries for chown/chmod done on
posix shared memory and (old) in-kernel posix semaphores.

Based on the submission by: glebius
Reviewed by: rwatson
Approved by: re (bz)

Second-to-last commit implementing Capsicum capabilities in the FreeBSD
kernel for FreeBSD 9.0:

Add a new capability mask argument to fget(9) and friends, allowing system
call code to declare what capabilities are required when an integer file
descriptor is converted into an in-kernel struct file *. With options
CAPABILITIES compiled into the kernel, this enforces capability
protection; without, this change is effectively a no-op.

Some cases require special handling, such as mmap(2), which must preserve
information about the maximum rights at the time of mapping in the memory
map so that they can later be enforced in mprotect(2) -- this is done by
narrowing the rights in the existing max_protection field used for similar
purposes with file permissions.

In namei(9), we assert that the code is not reached from within capability
mode, as we're not yet ready to enforce namespace capabilities there.
This will follow in a later commit.

Update two capability names: CAP_EVENT and CAP_KEVENT become
CAP_POST_KEVENT and CAP_POLL_KEVENT to more accurately indicate what they
represent.

Approved by: re (bz)
Submitted by: jonathan
Sponsored by: Google Inc

After the r219999 is merged to stable/8, rename fallocf(9) to falloc(9)
and remove the falloc() version that lacks flag argument. This is done
to reduce the KPI bloat.

Requested by: jhb
X-MFC-note: do not

Make the description of the feature consistent with another similar
description for another feature.

Noticed by: trasz

Add some FEATURE macros for various features (AUDIT/CAM/IPC/KTR/MAC/NFS/NTP/
PMC/SYSV/...).

No FreeBSD version bump, the userland application to query the features will
be committed last and can serve as an indication of the availablility if
needed.

Sponsored by: Google Summer of Code 2010
Submitted by: kibab
Reviewed by: arch@ (parts by rwatson, trasz, jhb)
X-MFC after: to be determined in last commit with code from this project

Set the POSIX semaphore capability when the semaphore module is enabled.
This is ignored in HEAD where semaphores are marked as always enabled in
<unistd.h>.

MFC after: 1 week

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

MFC r208731:
Add a facility to dynamically adjust or unconfigure p1003_1b mib.
Use it to allow to tune sem_nsem_max at runtime, only when sem.ko
module is present in kernel.

Approved by: re (bz)

Add a facility to dynamically adjust or unconfigure p1003_1b mib.
Use it to allow to tune sem_nsem_max at runtime, only when sem.ko
module is present in kernel.

Requested and tested by: amdmi3
Reviewed by: jhb
MFC after: 3 days

MFC r205324:
Implement compat32 shims for ksem syscalls.

Rename st_*timespec fields to st_*tim for POSIX 2008 compliance.

A nice thing about POSIX 2008 is that it finally standardizes a way to
obtain file access/modification/change times in sub-second precision,
namely using struct timespec, which we already have for a very long
time. Unfortunately POSIX uses different names.

This commit adds compatibility macros, so existing code should still
build properly. Also change all source code in the kernel to work
without any of the compatibility macros. This makes it all a less
ambiguous.

I am also renaming st_birthtime to st_birthtim, even though it was a
local extension anyway. It seems Cygwin also has a st_birthtim.

Implement compat32 shims for ksem syscalls.

Reviewed by: jhb
MFC after: 2 weeks

Use umtx to implement process sharable semaphore, to make this work,
now type sema_t is a structure which can be put in a shared memory area,
and multiple processes can operate it concurrently.
User can either use mmap(MAP_SHARED) + sem_init(pshared=1) or use sem_open()
to initialize a shared semaphore.
Named semaphore uses file system and is located in /tmp directory, and its
file name is prefixed with 'SEMD', so now it is chroot or jail friendly.
In simplist cases, both for named and un-named semaphore, userland code
does not have to enter kernel to reduce/increase semaphore's count.
The semaphore is designed to be crash-safe, it means even if an application
is crashed in the middle of operating semaphore, the semaphore state is
still safely recovered by later use, there is no waiter counter maintained
by userland code.
The main semaphore code is in libc and libthr only has some necessary stubs,
this makes it possible that a non-threaded application can use semaphore
without linking to thread library.
Old semaphore implementation is kept libc to maintain binary compatibility.
The kernel ksem API is no longer used in the new implemenation.

Discussed on: threads@

Move "options MAC" from opt_mac.h to opt_global.h, as it's now in GENERIC
and used in a large number of files, but also because an increasing number
of incorrect uses of MAC calls were sneaking in due to copy-and-paste of
MAC-aware code without the associated opt_mac.h include.

Discussed with: pjd

Ensure that the semaphore value is re-checked after sem_lock
is re-acquired, after the condition variable is signalled.

PR: http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/127545
MFC after: 5 days
Reviewed by: attilio

Make semaphore debugging output more useful.

PR: http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/127545
MFC after: 5 days
Submitted by: Philip Semanchuk

- Import the HEAD csup code which is the basis for the cvsmode work.

Rework the lifetime management of the kernel implementation of POSIX
semaphores. Specifically, semaphores are now represented as new file
descriptor type that is set to close on exec. This removes the need for
all of the manual process reference counting (and fork, exec, and exit
event handlers) as the normal file descriptor operations handle all of
that for us nicely. It is also suggested as one possible implementation
in the spec and at least one other OS (OS X) uses this approach.

Some bugs that were fixed as a result include:
- References to a named semaphore whose name is removed still work after
the sem_unlink() operation. Prior to this patch, if a semaphore's name
was removed, valid handles from sem_open() would get EINVAL errors from
sem_getvalue(), sem_post(), etc. This fixes that.
- Unnamed semaphores created with sem_init() were not cleaned up when a
process exited or exec'd. They were only cleaned up if the process
did an explicit sem_destroy(). This could result in a leak of semaphore
objects that could never be cleaned up.
- On the other hand, if another process guessed the id (kernel pointer to
'struct ksem' of an unnamed semaphore (created via sem_init)) and had
write access to the semaphore based on UID/GID checks, then that other
process could manipulate the semaphore via sem_destroy(), sem_post(),
sem_wait(), etc.
- As part of the permission check (UID/GID), the umask of the proces
creating the semaphore was not honored. Thus if your umask denied group
read/write access but the explicit mode in the sem_init() call allowed
it, the semaphore would be readable/writable by other users in the
same group, for example. This includes access via the previous bug.
- If the module refused to unload because there were active semaphores,
then it might have deregistered one or more of the semaphore system
calls before it noticed that there was a problem. I'm not sure if
this actually happened as the order that modules are discovered by the
kernel linker depends on how the actual .ko file is linked. One can
make the order deterministic by using a single module with a mod_event
handler that explicitly registers syscalls (and deregisters during
unload after any checks). This also fixes a race where even if the
sem_module unloaded first it would have destroyed locks that the
syscalls might be trying to access if they are still executing when
they are unloaded.

XXX: By the way, deregistering system calls doesn't do any blocking
to drain any threads from the calls.
- Some minor fixes to errno values on error. For example, sem_init()
isn't documented to return ENFILE or EMFILE if we run out of semaphores
the way that sem_open() can. Instead, it should return ENOSPC in that
case.

Other changes:
- Kernel semaphores now use a hash table to manage the namespace of
named semaphores nearly in a similar fashion to the POSIX shared memory
object file descriptors. Kernel semaphores can now also have names
longer than 14 chars (up to MAXPATHLEN) and can include subdirectories
in their pathname.
- The UID/GID permission checks for access to a named semaphore are now
done via vaccess() rather than a home-rolled set of checks.
- Now that kernel semaphores have an associated file object, the various
MAC checks for POSIX semaphores accept both a file credential and an
active credential. There is also a new posixsem_check_stat() since it
is possible to fstat() a semaphore file descriptor.
- A small set of regression tests (using the ksem API directly) is present
in src/tools/regression/posixsem.

Reported by: kris (1)
Tested by: kris
Reviewed by: rwatson (lightly)
MFC after: 1 month

Remove the posixsem_check_destroy() MAC check. It is semantically identical
to doing a MAC check for close(), but no other types of close() (including
close(2) and ksem_close(2)) have MAC checks.

Discussed with: rwatson

Keep proper track of nsegs counter: sem_free is called for all
allocated semaphores, so it's wrong to increase it conditionally,
in this case for every over-the-limit semaphore nsegs is decreased
without being previously increased.

PR: kern/123685
Approved by: cognet (mentor)

Attempt to improve convergence of POSIX semaphore code with style(9).

MFC after: 3 days

Free MAC label on a POSIX semaphore when the semaphore is freed.

MFC after: 3 days
Submitted by: jhb

Merge first in a series of TrustedBSD MAC Framework KPI changes
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

Further system call comment cleanup:

- 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.

Merge posix4/* into normal kernel hierarchy.

Reviewed by: glanced at by jhb
Approved by: silence on -arch@ and -standards@

Sweep kernel replacing suser(9) calls with priv(9) calls, assigning
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>

Complete break-out of sys/sys/mac.h into sys/security/mac/mac_framework.h
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

Swap the names "sem_exithook" and "sem_exechook" in the previous commit to
match up with reality and the prototype definitions.

Register the sem_exechook as the "process_exec" event handler, not
sem_exithook.

Submitted by: rdivacky
Sponsored by: SoC 2006

- Change process_exec function handlers prototype to include struct
image_params arg.
- Change struct image_params to include struct sysentvec pointer and
initialize it.
- Change all consumers of process_exit/process_exec eventhandlers to
new prototypes (includes splitting up into distinct exec/exit functions).
- Add eventhandler to userret.

Sponsored by: Google SoC 2006
Submitted by: rdivacky
Parts suggested by: jhb (on hackers@)

Convert remaining functions to ANSI C function declarations.

MFC after: 1 week

Const-qualify ksem_timedwait's parameter abstime as it's only passed in.

In sem_forkhook(), don't attempt to generate a copy of the process semaphore
list on fork() if the process doesn't actually have references to any
semaphores. This avoids extra work, as well as potentially asking to
allocate storage for 0 references.

Found by: avatar
MFC after: 1 week

Introduce MAC Framework and MAC Policy entry points to label and control
access to POSIX Semaphores:

mac_init_posix_sem() Initialize label for POSIX semaphore
mac_create_posix_sem() Create POSIX semaphore
mac_destroy_posix_sem() Destroy POSIX semaphore
mac_check_posix_sem_destroy() Check whether semaphore may be destroyed
mac_check_posix_sem_getvalue() Check whether semaphore may be queried
mac_check_possix_sem_open() Check whether semaphore may be opened
mac_check_posix_sem_post() Check whether semaphore may be posted to
mac_check_posix_sem_unlink() Check whether semaphore may be unlinked
mac_check_posix_sem_wait() Check whether may wait on semaphore

Update Biba, MLS, Stub, and Test policies to implement these entry points.
For information flow policies, most semaphore operations are effectively
read/write.

Submitted by: Dandekar Hrishikesh <rishi_dandekar at sbcglobal dot net>
Sponsored by: DARPA, McAfee, SPARTA
Obtained from: TrustedBSD Project

Move definitions of 'struct kuser' and 'struct ksem' from uipc_sem.c
to ksem.h so that they are accessible from the MAC Framework for the
purposes of labeling and enforcing additional protections. #error
if these are included without _KERNEL, since they are not intended
(nor installed) for user application use.

Submitted by: Dandekar Hrishikesh <rishi_dandekar at sbcglobal dot net>
Sponsored by: DARPA, SPARTA
Obtained from: TrustedBSD Project

Insert missing increment of (i) when walking the temporary semaphore
vector during fork.

Fix assertion which contained an off-by-one error.

Submitted by: Antoine Brodin < antoine dot brodin at laposte dot net >

Add an exit hook, sem_forkhook(), which walks the list of POSIX semaphores
owned by a process when it forks, and creates a matching set of references
for the child process, as prescribed by POSIX.

In order to avoid races with other threads in the parent process during
fork(), it is necessary to allocate a temporary reference list while
holding the sem_lock, then transfer those references to the new process
once the sem_lock is released. The implementation is inefficient but
appears functional; in order to improve the efficiency, it will be
necessary to modify the existing structures and logic, which generally
rely on O(n) operations over the global set of semaphores.

Assert sem_lock in id_to_sem() and sem_lookup_byname(), since these
functions iterate over the global POSIX semaphore lists.

MFC after: 3 days

/* -> /*- for copyright notices, minor format tweaks as necessary

Assert the sem lock in sem_ref() and sem_rel(), as it is required to
safely manipulate the reference count.

Add missing #include <sys/module.h>

Add ksem_timedwait() to complement ksem_wait().

Glanced at by: alfred

Reduce gratuitous includes: don't include jail.h if it's not needed.
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

Use __FBSDID().

Replace the at_fork, at_exec, and at_exit functions with the slightly more
flexible process_fork, process_exec, and process_exit eventhandlers. This
reduces code duplication and also means that I don't have to go duplicate
the eventhandler locking three more times for each of at_fork, at_exec, and
at_exit.

Reviewed by: phk, jake, almost complete silence on arch@

Use td_ucred of curthread instead of p_ucred of curproc. This required
changing sem_perm() and sem_hasopen() to take a thread instead of a proc
for the first argument.

Back out M_* changes, per decision of the TRB.

Approved by: trb

Remove M_TRYWAIT/M_WAITOK/M_WAIT. Callers should use 0.
Merge M_NOWAIT/M_DONTWAIT into a single flag M_NOWAIT.

make sem_leave return a usable errno instead of -1.
make ksem_close return that usable errno instead of -1 (ERESTART).

PR: 46957

Be consistent about funtions being static.

Spotted by: FlexeLint

disable debug output by default.

Bring in my implementation of kernel support for posix realtime semaphores
that are shareable between processes.

There will be a cleanup shortly along with the necessary changes made to
libc, libc_r, libpthread as well as the hooks into sys/conf and sys/modules.