Commit Graph

29 Commits

Author SHA1 Message Date
Ed Schouten
aa04a06df5 Introduce kern_cap_rights_limit().
The existing sys_cap_rights_limit() expects that a cap_rights_t object
lives in userspace. It is therefore hard to call into it from
kernelspace.

Move the interesting bits of sys_cap_rights_limit() into
kern_cap_rights_limit(), so that we can call into it from the CloudABI
compatibility layer.

Obtained from:	https://github.com/NuxiNL/freebsd
Differential Revision:	https://reviews.freebsd.org/D3314
2015-08-11 08:43:50 +00:00
Mateusz Guzik
daf63fd2f9 cred: add proc_set_cred helper
The goal here is to provide one place altering process credentials.

This eases debugging and opens up posibilities to do additional work when such
an action is performed.
2015-03-16 00:10:03 +00:00
Mark Johnston
bbd685e3a5 Use crcopysafe(9) to make a copy of a process' credential struct. crcopy(9)
may perform a blocking memory allocation, which is unsafe when holding a
mutex.

Differential Revision:	https://reviews.freebsd.org/D1443
Reviewed by:	rwatson
MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division
2015-01-05 23:07:22 +00:00
Mateusz Guzik
a1bf811596 Prepare fget_unlocked for reading fd table only once.
Some capsicum functions accept fdp + fd and lookup fde based on that.
Add variants which accept fde.

Reviewed by:	pjd
MFC after:	1 week
2014-07-23 19:33:49 +00:00
Robert Watson
4a14441044 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
2014-03-16 10:55:57 +00:00
Sean Bruno
88eb548859 This looks like a typo that breaks the build. Yell at me if this isn't the
intended declaration.
2013-09-05 03:36:57 +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
Pawel Jakub Dawidek
0dac22d8ea Implement 32bit versions of the cap_ioctls_limit(2) and cap_ioctls_get(2)
system calls as unsigned longs have different size on i386 and amd64.

Reported by:	jilles
Sponsored by:	The FreeBSD Foundation
2013-08-18 10:30:41 +00:00
Pawel Jakub Dawidek
92981fdf9e Use proper malloc type for ioctls white-list.
Reported by:	pho
Tested by:	pho
2013-05-23 21:07:26 +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
11b0cfe3cd Remove redundant parenthesis. 2013-02-17 11:49:21 +00:00
Pawel Jakub Dawidek
297f11037f Style: move opt_*.h includes in the proper place.
MFC after:	1 month
2012-06-10 20:22:10 +00:00
Peter Holm
62a9fc76df Allways call fdrop(). 2012-03-12 11:56:57 +00:00
Dag-Erling Smørgrav
e141be6f79 Revisit the capability failure trace points. The initial implementation
only logged instances where an operation on a file descriptor required
capabilities which the file descriptor did not have.  By adding a type enum
to struct ktr_cap_fail, we can catch other types of capability failures as
well, such as disallowed system calls or attempts to wrap a file descriptor
with more capabilities than it had to begin with.
2011-10-18 07:28:58 +00:00
Dag-Erling Smørgrav
c601ad8eeb Add a new trace point, KTRFAC_CAPFAIL, which traces capability check
failures.  It is included in the default set for ktrace(1) and kdump(1).
2011-10-11 20:37:10 +00:00
Kip Macy
8451d0dd78 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)
2011-09-16 13:58:51 +00:00
Konstantin Belousov
9c00bb9190 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)
2011-08-16 20:07:47 +00:00
Robert Watson
854d7b9fc8 Update use of the FEATURE() macro in sys_capability.c to reflect the move
to two different kernel options for capability mode vs. capabilities.

Approved by:	re (bz)
2011-08-13 13:34:01 +00:00
Robert Watson
73516dbd27 Now that capability support has been committed, update and expand the
comment at the type of sys_capability.c to describe its new contents.

Approved by:  re (xxx)
2011-08-13 13:26:40 +00:00
Jonathan Anderson
69d377fe1b Allow Capsicum capabilities to delegate constrained
access to file system subtrees to sandboxed processes.

- Use of absolute paths and '..' are limited in capability mode.
- Use of absolute paths and '..' are limited when looking up relative
  to a capability.
- When a name lookup is performed, identify what operation is to be
  performed (such as CAP_MKDIR) as well as check for CAP_LOOKUP.

With these constraints, openat() and friends are now safe in capability
mode, and can then be used by code such as the capability-mode runtime
linker.

Approved by: re (bz), mentor (rwatson)
Sponsored by: Google Inc
2011-08-13 09:21:16 +00:00
Robert Watson
a9d2f8d84f 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
2011-08-11 12:30:23 +00:00
Jonathan Anderson
7a270867e7 Turn on AUDIT_ARG_RIGHTS() for cap_new(2).
Now that the code is in place to audit capability method rights, start
using it to audit the 'rights' argument to cap_new(2).

Approved by: re (kib), mentor (rwatson)
Sponsored by: Google Inc
2011-07-22 12:50:21 +00:00
Jonathan Anderson
cfb9df5541 Add cap_new() and cap_getrights() system calls.
Implement two previously-reserved Capsicum system calls:
- cap_new() creates a capability to wrap an existing file descriptor
- cap_getrights() queries the rights mask of a capability.

Approved by: mentor (rwatson), re (Capsicum blanket)
Sponsored by: Google Inc
2011-07-15 18:26:19 +00:00
Jonathan Anderson
745bae379d Add implementation for capabilities.
Code to actually implement Capsicum capabilities, including fileops and
kern_capwrap(), which creates a capability to wrap an existing file
descriptor.

We also modify kern_close() and closef() to handle capabilities.

Finally, remove cap_filelist from struct capability, since we don't
actually need it.

Approved by: mentor (rwatson), re (Capsicum blanket)
Sponsored by: Google Inc
2011-07-15 09:37:14 +00:00
Jonathan Anderson
af098ed8e7 Add kernel functions to unwrap capabilities.
cap_funwrap() and cap_funwrap_mmap() unwrap capabilities, exposing the
underlying object. Attempting to unwrap a capability with an inadequate
rights mask (e.g. calling cap_funwrap(fp, CAP_WRITE | CAP_MMAP, &result)
on a capability whose rights mask is CAP_READ | CAP_MMAP) will result in
ENOTCAPABLE.

Unwrapping a non-capability is effectively a no-op.

These functions will be used by Capsicum-aware versions of _fget(), etc.

Approved by: mentor (rwatson), re (Capsicum blanket)
Sponsored by: Google Inc
2011-07-04 14:40:32 +00:00
Jonathan Anderson
24c1c3bf71 We may split today's CAPABILITIES into CAPABILITY_MODE (which has
to do with global namespaces) and CAPABILITIES (which has to do with
constraining file descriptors). Just in case, and because it's a better
name anyway, let's move CAPABILITIES out of the way.

Also, change opt_capabilities.h to opt_capsicum.h; for now, this will
only hold CAPABILITY_MODE, but it will probably also hold the new
CAPABILITIES (implying constrained file descriptors) in the future.

Approved by: rwatson
Sponsored by: Google UK Ltd
2011-06-29 13:03:05 +00:00
Jonathan Anderson
54350dfa33 Remove redundant Capsicum sysctl.
Since we're now declaring FEATURE(security_capabilities), there's no need for an explicit SYSCTL_NODE.

Approved by: rwatson
2011-06-25 12:37:06 +00:00
Alexander Leidinger
d783bbd2d2 - Add a FEATURE for capsicum (security_capabilities).
- Rename mac FEATURE to security_mac.

Discussed with:	rwatson
2011-03-04 09:03:54 +00:00
Robert Watson
96fcc75fdf Add initial support for Capsicum's Capability Mode to the FreeBSD kernel,
compiled conditionally on options CAPABILITIES:

Add a new credential flag, CRED_FLAG_CAPMODE, which indicates that a
subject (typically a process) is in capability mode.

Add two new system calls, cap_enter(2) and cap_getmode(2), which allow
setting and querying (but never clearing) the flag.

Export the capability mode flag via process information sysctls.

Sponsored by:	Google, Inc.
Reviewed by:	anderson
Discussed with:	benl, kris, pjd
Obtained from:	Capsicum Project
MFC after:	3 months
2011-03-01 13:23:37 +00:00