Make the kern_fsync() function public, so that it can be used by other
parts of the kernel. Fix up existing consumers to make use of it.
Requested by: kib
The type definitions and constants that were used by COMPAT_CLOUDABI64
are a literal copy of some headers stored inside of CloudABI's C
library, cloudlibc. What is annoying is that we can't make use of
cloudlibc's system call list, as the format is completely different and
doesn't provide enough information. It had to be synced in manually.
We recently decided to solve this (and some other problems) by moving
the ABI definitions into a separate file:
https://github.com/NuxiNL/cloudabi/blob/master/cloudabi.txt
This file is processed by a pile of Python scripts to generate the
header files like before, documentation (markdown), but in our case more
importantly: a FreeBSD system call table.
This change discards the old files in sys/contrib/cloudabi and replaces
them by the latest copies, which requires some minor changes here and
there. Because cloudabi.txt also enforces consistent names of the system
call arguments, we have to patch up a small number of system call
implementations to use the new argument names.
The new header files can also be included directly in FreeBSD kernel
space without needing any includes/defines, so we can now remove
cloudabi_syscalldefs.h and cloudabi64_syscalldefs.h. Patch up the
sources to include the definitions directly from sys/contrib/cloudabi
instead.
To make it easier to understand how Capsicum interacts with linkat() and
renameat(), rename the rights to CAP_{LINK,RENAME}AT_{SOURCE,TARGET}.
This also addresses a shortcoming in Capsicum, where it isn't possible
to disable linking to files stored in a directory. Creating hardlinks
essentially makes it possible to access files with additional rights.
Reviewed by: rwatson, wblock
Differential Revision: https://reviews.freebsd.org/D3411
The cloudlibc pdwait() function ends up using FreeBSD's kqueue() in
combination with EVFILT_PROCDESC. This depends on CAP_EVENT -- not
CAP_PDWAIT.
Obtained from: https://github.com/NuxiNL/freebsd
CloudABI purely operates on file descriptor rights (CAP_*). File
descriptor access modes (O_ACCMODE) are emulated on top of rights.
Instead of accepting the traditional flags argument, file_open() copies
in an fdstat_t object that contains the initial rights the descriptor
should have, but also file descriptor flags that should persist after
opening (APPEND, NONBLOCK, *SYNC). Only flags that don't persist (EXCL,
TRUNC, CREAT, DIRECTORY) are passed in as an argument.
file_open() first converts the rights, the persistent flags and the
non-persistent flags to fflags. It then calls into vn_open(). If
successful, it installs the file descriptor with the requested
rights, trimming off rights that don't apply to the type of
the file that has been opened.
Unlike kern_openat(), this function does not support /dev/fd/*. I can't
think of a reason why we need to support this for CloudABI.
Obtained from: https://github.com/NuxiNL/freebsd
Differential Revision: https://reviews.freebsd.org/D3235
The stat_put() system call can be used to modify file descriptor
attributes, such as flags, but also Capsicum permission bits. Support
for changing Capsicum bits will be added as soon as its dependent
changes have been pushed through code review.
Obtained from: https://github.com/NuxiNL/freebsd
Summary:
Use the newly created `kern_shm_open()` function to create objects with
just the rights that are actually needed.
Reviewers: jhb, kib
Subscribers: imp
Differential Revision: https://reviews.freebsd.org/D3260
Summary:
Pipes in CloudABI are unidirectional. The reason for this is that
CloudABI attempts to provide a uniform runtime environment across
different flavours of UNIX.
Instead of implementing a custom pipe that is unidirectional, we can
simply reuse Capsicum permission bits to support this. This is nice,
because CloudABI already attempts to restrict permission bits to
correspond with the operations that apply to a certain file descriptor.
Replace kern_pipe() and kern_pipe2() by a single kern_pipe() that takes
a pair of filecaps. These filecaps are passed to the newly introduced
falloc_caps() function that creates the descriptors with rights in
place.
Test Plan:
CloudABI pipes seem to be created with proper rights in place:
https://github.com/NuxiNL/cloudlibc/blob/master/src/libc/unistd/pipe_test.c#L44
Reviewers: jilles, mjg
Reviewed By: mjg
Subscribers: imp
Differential Revision: https://reviews.freebsd.org/D3236
CloudABI's openat() ensures that files are opened with the smallest set
of relevant rights. For example, when opening a FIFO, unrelated rights
like CAP_RECV are automatically removed. To remove unrelated rights, we
can just reuse the code for this that was already present in the rights
conversion function.
Summary:
CloudABI provides access to two different stat structures:
- fdstat, containing file descriptor level status: oflags, file
descriptor type and Capsicum rights, used by cap_rights_get(),
fcntl(F_GETFL), getsockopt(SO_TYPE).
- filestat, containing your regular file status: timestamps, inode
number, used by fstat().
Unlike FreeBSD's stat::st_mode, CloudABI file descriptor types don't
have overloaded meanings (e.g., returning S_ISCHR() for kqueues). Add a
utility function to extract the type of a file descriptor accurately.
CloudABI does not work with O_ACCMODEs. File descriptors have two sets
of Capsicum-style rights: rights that apply to the file descriptor
itself ('base') and rights that apply to any new file descriptors
yielded through openat() ('inheriting'). Though not perfect, we can
pretty safely decompose Capsicum rights to such a pair. This is done in
convert_capabilities().
Test Plan: Tests for these system calls are fairly extensive in cloudlibc.
Reviewers: jonathan, mjg, #manpages
Reviewed By: mjg
Subscribers: imp
Differential Revision: https://reviews.freebsd.org/D3171
All of the CloudABI system calls that operate on file descriptors of an
arbitrary type are prefixed with fd_. This change adds wrappers for
most of these system calls around their FreeBSD equivalents.
The dup2() system call present on CloudABI deviates from POSIX, in the
sense that it can only be used to replace existing file descriptor. It
cannot be used to create new ones. The reason for this is that this is
inherently thread-unsafe. Furthermore, there is no need on CloudABI to
use fixed file descriptor numbers. File descriptors 0, 1 and 2 have no
special meaning.
This change exposes the kern_dup() through <sys/syscallsubr.h> and puts
the FDDUP_* flags in <sys/filedesc.h>. It then adds a new flag,
FDDUP_MUSTREPLACE to force that file descriptors are replaced -- not
allocated.
Differential Revision: https://reviews.freebsd.org/D3035
Reviewed by: mjg
CloudABI is a pure capability-based runtime environment for UNIX. It
works similar to Capsicum, except that processes already run in
capabilities mode on startup. All functionality that conflicts with this
model has been omitted, making it a compact binary interface that can be
supported by other operating systems without too much effort.
CloudABI is 'secure by default'; the idea is that it should be safe to
run arbitrary third-party binaries without requiring any explicit
hardware virtualization (Bhyve) or namespace virtualization (Jails). The
rights of an application are purely determined by the set of file
descriptors that you grant it on startup.
The datatypes and constants used by CloudABI's C library (cloudlibc) are
defined in separate files called syscalldefs_mi.h (pointer size
independent) and syscalldefs_md.h (pointer size dependent). We import
these files in sys/contrib/cloudabi and wrap around them in
cloudabi*_syscalldefs.h.
We then add stubs for all of the system calls in sys/compat/cloudabi or
sys/compat/cloudabi64, depending on whether the system call depends on
the pointer size. We only have nine system calls that depend on the
pointer size. If we ever want to support 32-bit binaries, we can simply
add sys/compat/cloudabi32 and implement these nine system calls again.
The next step is to send in code reviews for the individual system call
implementations, but also add a sysentvec, to allow CloudABI executabled
to be started through execve().
More information about CloudABI:
- GitHub: https://github.com/NuxiNL/cloudlibc
- Talk at BSDCan: https://www.youtube.com/watch?v=SVdF84x1EdA
Differential Revision: https://reviews.freebsd.org/D2848
Reviewed by: emaste, brooks
Obtained from: https://github.com/NuxiNL/freebsd
