Bug fixes:
- Fix crash reported by Scott Ellis on current-users@.
- Fix race conditions in enforcing the Veriexec rename and remove
policies. These are NOT security issues.
- Fix memory leak in rename handling when overwriting a monitored
file.
- Fix table deletion logic.
- Don't prevent query requests if not in learning mode.
KPI updates:
- fileassoc_table_run() now takes a cookie to pass to the callback.
- veriexec_table_add() was removed, it is now done internally. As a
result, there's no longer a need for VERIEXEC_TABLESIZE.
- veriexec_report() was removed, it is now internal.
- Perform sanity checks on the entry type, and enforce default type
in veriexec_file_add() rather than in veriexecctl.
- Add veriexec_flush(), used to delete all Veriexec tables, and
veriexec_dump(), used to fill an array with all Veriexec entries.
New features:
- Add a '-k' flag to veriexecctl, to keep the filenames in the kernel
database. This allows Veriexec to produce slightly more accurate
logs under certain circumstances. In the future, this can be either
replaced by vnode->pathname translation, or combined with it.
- Add a VERIEXEC_DUMP ioctl, to dump the entire Veriexec database.
This can be used to recover a database if the file was lost.
Example usage:
# veriexecctl dump > /etc/signatures
Note that only entries with the filename kept (that is, were loaded
with the '-k' flag) will be dumped.
Idea from Brett Lymn.
- Add a VERIEXEC_FLUSH ioctl, to delete all Veriexec entries. Sample
usage:
# veriexecctl flush
- Add a 'veriexec_flags' rc(8) variable, and make its default have
the '-k' flag. On systems using the default signatures file
(generaetd from running 'veriexecgen' with no arguments), this will
use additional 32kb of kernel memory on average.
- Add a '-e' flag to veriexecctl, to evaluate the fingerprint during
load. This is done automatically for files marked as 'untrusted'.
Misc. stuff:
- The code for veriexecctl was massively simplified as a result of
eliminating the need for VERIEXEC_TABLESIZE, and now uses a single
pass of the signatures file, making the loading somewhat faster.
- Lots of minor fixes found using the (still under development)
Veriexec regression testsuite.
- Some of the messages Veriexec prints were improved.
- Various documentation fixes.
All relevant man-pages were updated to reflect the above changes.
Binary compatibility with existing veriexecctl binaries is maintained.
handle a single entry and veriexec_table_delete() to handle an entire
table. veriexec_convert() now takes a struct vnode *, and made
veriexec_table_lookup() take struct mount * (that's entirely internal
now).
Tested on amd64, built successfully on amd64, i386, sparc, and sparc64.
for work on some future functionality.
- Veriexec data-structures are no longer exposed.
- Thanks to using proplib for data passing now, the interface
changes further to accomodate that.
Introduce four new functions. First, veriexec_file_add(), to add
a new file to be monitored by Veriexec, to replace both
veriexec_load() and veriexec_hashadd(). veriexec_table_add(), to
replace veriexec_newtable(), will be used to optimize hash table
size (during preload), and finally, veriexec_convert(), to convert
an internal entry to one userland can read.
- Introduce veriexec_unmountchk(), to enforce Veriexec unmount
policy. This cleans up a bit of code in kern/vfs_syscalls.c.
- Rename veriexec_tblfind() with veriexec_table_lookup(), and make
it static. More functions that became static: veriexec_fp_cmp(),
veriexec_fp_calc().
- veriexec_verify() no longer returns the entry as well, but just
sets a boolean indicating whether an entry was found or not.
- veriexec_purge() now takes a struct vnode *.
- veriexec_add_fp_name() was merged into veriexec_add_fp_ops(), that
changed its name to veriexec_fpops_add(). veriexec_find_ops() was
also renamed to veriexec_fpops_lookup().
Also on the fp-ops front, the three function types used to initialize,
update, and finalize a hash context were renamed to
veriexec_fpop_init_t, veriexec_fpop_update_t, and veriexec_fpop_final_t
respectively.
- Introduce a new malloc(9) type, M_VERIEXEC, and use it instead of
M_TEMP, so we can tell exactly how much memory is used by Veriexec.
- And, most importantly, whitespace and indentation nits.
Built successfuly for amd64, i386, sparc, and sparc64. Tested on amd64.
Obviously, this breaks the already unstable Veriexec ABI, but that's
it. Some cool additions are planned to be introduced, and this just
makes it so that NetBSD 4.0 users will be able to easily use them as
well.
This also removes the fingerprint type name limit, so relevant code
was adjusted.
Thoroughly tested (even uncovered a bug in proplib! thanks for fixing
that cube@!). Documentation updated.
If we already have an entry, we only print a message mentioning it if the
fingerprints mismatch; that may indicate a security issue.
If the fingerprints match, there's a good chance it's the same file
appearing multiple times as a hard-link, in which case print a message
only if the verbose level is 1 or more.
The passed size doesn't mean anything really and can only help detect
corrupted configuration files, which should be done in userland anyway.
Note it's possible to trigger a kernel panic by passing a junk
pointer in the 'fingerprint' member of the parameters, but then again
that's true for anything that copies in data from a userland-supplied
pointer. And we have plenty of those.
At the moment, Veriexec only allows the super-user to open the pseudo
device, so it's ~okay. Maybe we should address that in copy(9) or
something?
First one was incorrectly loading entries -- we were treating each file as
a mount, which resulted in huge mess. I have no excuse for how I didn't
catch this earlier.
Second, use the table name we create for the Veriexec sysctl node and not
the fixed "table0".
Both are fileassoc(9) integration fallout.
introduce fileassoc(9), a kernel interface for associating meta-data with
files using in-kernel memory. this is very similar to what we had in
veriexec till now, only abstracted so it can be used more easily by more
consumers.
this also prompted the redesign of the interface, making it work on vnodes
and mounts and not directly on devices and inodes. internally, we still
use file-id but that's gonna change soon... the interface will remain
consistent.
as a result, veriexec went under some heavy changes to conform to the new
interface. since we no longer use device numbers to identify file-systems,
the veriexec sysctl stuff changed too: kern.veriexec.count.dev_N is now
kern.veriexec.tableN.* where 'N' is NOT the device number but rather a
way to distinguish several mounts.
also worth noting is the plugging of unmount/delete operations
wrt/fileassoc and veriexec.
tons of input from yamt@, wrstuden@, martin@, and christos@.
We can now delete an entry from the tables using
veriexecctl delete /path/to/file
or remove an entire table using
veriexecctl delete /mount_point
(any directory will work for the mount point it's on)
This closes a hole pointed out by Thor Lancelot Simon on tech-kern ~3
years ago.
The problem was with running binaries from remote storage, where our
kernel (and Veriexec) has no control over any changes to files.
An attacker could, after the fingerprint has been verified and
program loaded to memory, inject malicious code into the backing
store on the remote storage, followed by a forced flush, causing
a page-in of the malicious data from backing store, bypassing
integrity checks.
Initial implementation by Brett Lymn.
VOP_GETATTR() fills a struct vattr, where va_fsid and va_fileid (device
and inode..) are typed as long.
Add some casts when using these values and surround them with XXXs about
the potential size mismatch, as long can be 64 bits but dev_t and ino_t
are always 32 bits. This is safe because *for now* we're still using
32 bit inode numbers.
Discussed with blymn@.
- Change #ifdef VERIFIED_EXEC_VERBOSE to another verbose level, 2. Add
sysctl(3) bits.
- Simplify access type conflict handling during load. This depends on
the values of access type defines to be ordered from least to most
'strict'.
in the veriexec table entry; the lookups are very cheap now. Suggested
by Chuq.
- Handle non-regular (!VREG) files correctly).
- Remove (no longer needed) FINGERPRINT_NOENTRY.
- Better organize strict level. Now we have 4 levels:
- Level 0, learning mode: Warnings only about anything that might've
resulted in 'access denied' or similar in a higher strict level.
- Level 1, IDS mode:
- Deny access on fingerprint mismatch.
- Deny modification of veriexec tables.
- Level 2, IPS mode:
- All implications of strict level 1.
- Deny write access to monitored files.
- Prevent removal of monitored files.
- Enforce access type - 'direct', 'indirect', or 'file'.
- Level 3, lockdown mode:
- All implications of strict level 2.
- Prevent creation of new files.
- Deny access to non-monitored files.
- Update sysctl(3) man-page with above. (date bumped too :)
- Remove FINGERPRINT_INDIRECT from possible fp_status values; it's no
longer needed.
- Simplify veriexec_removechk() in light of new strict level policies.
- Eliminate use of 'securelevel'; veriexec now behaves according to
its strict level only.
elad