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.
When a table is created for a new device, a new variable is created
under the kern.veriexec.count node named "dev_<id>". For example,
dev_0, dev_3, etc.
New features:
- Add a veriexec_report() routine to make most reporting consistent and
remove some common code.
- Add 'strict' mode that controls how veriexec behaves.
- Add sysctl knobs:
o kern.veriexec.verbose controls verbosity levels. Value: 0, 1.
o kern.veriexec.strict controls strict level. Values: 0, 1, 2. See
documentation in sysctl(3) for details.
o kern.veriexec.algorithms returns a string with a space separated
list of supported hashing algorithms in veriexec.
- Updated documentation in man pages for sysctl(3) and sysctl(8).
Bug fixes:
- veriexec_removechk(): Code cleanup + handle FINGERPRINT_NOTEVAL
correctly.
- exec_script(): Don't pass 0 as flag when executing a script; use the
defined VERIEXEC_INDIRECT - which is 1. Makes indirect execution
enforcement work.
- Fix some printing formats and types..
* We now use hash tables instead of a list to store the in kernel
fingerprints.
* Fingerprint methods handling has been made more flexible, it is now
even simpler to add new methods.
* the loader no longer passes in magic numbers representing the
fingerprint method so veriexecctl is not longer kernel specific.
* fingerprint methods can be tailored out using options in the kernel
config file.
* more fingerprint methods added - rmd160, sha256/384/512
* veriexecctl can now report the fingerprint methods supported by the
running kernel.
* regularised the naming of some portions of veriexec.
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.
Bump the kernel rev up to 1.6V
