Commit Graph

18 Commits

Author SHA1 Message Date
Christian S.J. Peron
c297f0e497 Allow sigwait(2) in capabilities mode.
It's common for multi-threaded processes to create a thread for
the purpose of synchronously processing signals. Allow such processes to
utilize a capabilities sandbox.

Discussed with:	rwatson, pjd
MFC after:	2 weeks
2014-01-28 01:49:49 +00:00
Pawel Jakub Dawidek
e1e16d2419 Allow for pselect(2) in capability mode.
Noticed by:	David Drysdale <drysdale@google.com>
2013-12-15 23:14:27 +00:00
Pawel Jakub Dawidek
e7b1ce0769 - Remove mac_get_fd/mac_set_fd - those are not syscalls. The __mac_get_fd() and
__mac_set_fd() syscalls are listed earlier.
- Correct typo in syscall name. It should be sched_rr_get_interval,
  not sched_rr_getinterval.

Submitted by:	David Drysdale <drysdale@google.com>
MFC after:	3 days
2013-11-06 07:46:10 +00:00
Pawel Jakub Dawidek
013075d557 Sort properly. 2013-09-07 19:16:02 +00:00
Pawel Jakub Dawidek
7008be5bd7 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
2013-09-05 00:09:56 +00:00
Jilles Tjoelker
dc570d5e56 Add pipe2() system call.
The pipe2() function is similar to pipe() but allows setting FD_CLOEXEC and
O_NONBLOCK (on both sides) as part of the function.

If p points to two writable ints, pipe2(p, 0) is equivalent to pipe(p).

If the pointer is not valid, behaviour differs: pipe2() writes into the
array from the kernel like socketpair() does, while pipe() writes into the
array from an architecture-specific assembler wrapper.

Reviewed by:	kan, kib
2013-05-01 22:42:42 +00:00
Jilles Tjoelker
da7d2afb6d Add accept4() system call.
The accept4() function, compared to accept(), allows setting the new file
descriptor atomically close-on-exec and explicitly controlling the
non-blocking status on the new socket. (Note that the latter point means
that accept() is not equivalent to any form of accept4().)

The linuxulator's accept4 implementation leaves a race window where the new
file descriptor is not close-on-exec because it calls sys_accept(). This
implementation leaves no such race window (by using falloc() flags). The
linuxulator could be fixed and simplified by using the new code.

Like accept(), accept4() is async-signal-safe, a cancellation point and
permitted in capability mode.
2013-05-01 20:10:21 +00:00
Pawel Jakub Dawidek
e948704e4b Implement chflagsat(2) system call, similar to fchmodat(2), but operates on
file flags.

Reviewed by:	kib, jilles
Sponsored by:	The FreeBSD Foundation
2013-03-21 22:59:01 +00:00
Pawel Jakub Dawidek
c9cea47007 Sort syscalls properly. 2013-03-15 23:00:13 +00:00
Pawel Jakub Dawidek
7493f24ee6 - Implement two new system calls:
int bindat(int fd, int s, const struct sockaddr *addr, socklen_t addrlen);
	int connectat(int fd, int s, const struct sockaddr *name, socklen_t namelen);

  which allow to bind and connect respectively to a UNIX domain socket with a
  path relative to the directory associated with the given file descriptor 'fd'.

- Add manual pages for the new syscalls.

- Make the new syscalls available for processes in capability mode sandbox.

- Add capability rights CAP_BINDAT and CAP_CONNECTAT that has to be present on
  the directory descriptor for the syscalls to work.

- Update audit(4) to support those two new syscalls and to handle path
  in sockaddr_un structure relative to the given directory descriptor.

- Update procstat(1) to recognize the new capability rights.

- Document the new capability rights in cap_rights_limit(2).

Sponsored by:	The FreeBSD Foundation
Discussed with:	rwatson, jilles, kib, des
2013-03-02 21:11:30 +00:00
Pawel Jakub Dawidek
2609222ab4 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
2013-03-02 00:53:12 +00:00
Pawel Jakub Dawidek
8890f5d020 Allow to use kill(2) in capability mode, but process can send a signal only
to himself. For example abort(3) at first tries to do kill(getpid(), SIGABRT)
which was failing in capability mode, so the code was failing back to exit(1).

Reviewed by:	rwatson
Obtained from:	WHEEL Systems
MFC after:	2 weeks
2012-11-27 10:22:40 +00:00
Pawel Jakub Dawidek
6ba7e8178a Add missing system calls.
MFC after:	3 days
2012-05-31 19:32:37 +00:00
Pawel Jakub Dawidek
243f67938e There is no rmdirat system call. Weird, I know.
MFC after:	3 days
2012-05-31 19:31:28 +00:00
Jonathan Anderson
cfb5f76865 Add experimental support for process descriptors
A "process descriptor" file descriptor is used to manage processes
without using the PID namespace. This is required for Capsicum's
Capability Mode, where the PID namespace is unavailable.

New system calls pdfork(2) and pdkill(2) offer the functional equivalents
of fork(2) and kill(2). pdgetpid(2) allows querying the PID of the remote
process for debugging purposes. The currently-unimplemented pdwait(2) will,
in the future, allow querying rusage/exit status. In the interim, poll(2)
may be used to check (and wait for) process termination.

When a process is referenced by a process descriptor, it does not issue
SIGCHLD to the parent, making it suitable for use in libraries---a common
scenario when using library compartmentalisation from within large
applications (such as web browsers). Some observers may note a similarity
to Mach task ports; process descriptors provide a subset of this behaviour,
but in a UNIX style.

This feature is enabled by "options PROCDESC", but as with several other
Capsicum kernel features, is not enabled by default in GENERIC 9.0.

Reviewed by: jhb, kib
Approved by: re (kib), mentor (rwatson)
Sponsored by: Google Inc
2011-08-18 22:51:30 +00:00
Robert Watson
359b396113 Trim some warnings and notes from capabilities.conf -- these are left over
from Capsicum development, and no longer apply.

Approved by:	re (kib)
Sponsored by:	Google Inc
2011-08-13 17:22:16 +00:00
Jonathan Anderson
bc69c09054 Allow openat(2), fstatat(2), etc. in capability mode.
namei() and lookup() can now perform "strictly relative" lookups.
Such lookups, performed when in capability mode or when looking up
relative to a directory capability, enforce two policies:
 - absolute paths are disallowed (including symlinks to absolute paths)
 - paths containing '..' components are disallowed

These constraints make it safe to enable openat() and friends.
These system calls are instrumental in supporting Capsicum
components such as the capability-mode-aware runtime linker.

Finally, adjust comments in capabilities.conf to reflect the actual state
of the world (e.g. shm_open(2) already has the appropriate constraints,
getdents(2) already requires CAP_SEEK).

Approved by: re (bz), mentor (rwatson)
Sponsored by: Google Inc.
2011-08-13 10:43:21 +00:00
Robert Watson
08e6d9fad8 Continue to introduce Capsicum Capability Mode support:
Add a new system call flag, SYF_CAPENABLED, which indicates that a
particular system call is available in capability mode.

Add a new configuration file, kern/capabilities.conf (similar files
may be introduced for other ABIs in the future), which enumerates
system calls that are available in capability mode.  When a new
system call is added to syscalls.master, it will also need to be
added here (if needed).  Teach sysent parts to use this file to set
values for SYF_CAPENABLED for the native ABI.

Reviewed by:	anderson
Discussed with:	benl, kris, pjd
Obtained from:	Capsicum Project
MFC after:	3 months
2011-03-01 13:28:27 +00:00