Commit graph

21 commits

Author SHA1 Message Date
Mimi Zohar
1adace9bb0 ima: remove unnecessary call to ima_must_measure
The original ima_must_measure() function based its results on cached
iint information, which required an iint be allocated for all files.
Currently, an iint is allocated only for files in policy.  As a result,
for those files in policy, ima_must_measure() is now called twice: once
to determine if the inode is in the measurement policy and, the second
time, to determine if it needs to be measured/re-measured.

The second call to ima_must_measure() unnecessarily checks to see if
the file is in policy. As we already know the file is in policy, this
patch removes the second unnecessary call to ima_must_measure(), removes
the vestige iint parameter, and just checks the iint directly to determine
if the inode has been measured or needs to be measured/re-measured.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
2011-02-23 16:38:52 -05:00
Eric Paris
64c62f06be IMA: drop refcnt from ima_iint_cache since it isn't needed
Since finding a struct ima_iint_cache requires a valid struct inode, and
the struct ima_iint_cache is supposed to have the same lifetime as a
struct inode (technically they die together but don't need to be created
at the same time) we don't have to worry about the ima_iint_cache
outliving or dieing before the inode.  So the refcnt isn't useful.  Just
get rid of it and free the structure when the inode is freed.

Signed-off-by: Eric Paris <eapris@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 11:37:19 -07:00
Eric Paris
a178d2027d IMA: move read counter into struct inode
IMA currently allocated an inode integrity structure for every inode in
core.  This stucture is about 120 bytes long.  Most files however
(especially on a system which doesn't make use of IMA) will never need
any of this space.  The problem is that if IMA is enabled we need to
know information about the number of readers and the number of writers
for every inode on the box.  At the moment we collect that information
in the per inode iint structure and waste the rest of the space.  This
patch moves those counters into the struct inode so we can eventually
stop allocating an IMA integrity structure except when absolutely
needed.

This patch does the minimum needed to move the location of the data.
Further cleanups, especially the location of counter updates, may still
be possible.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 11:37:18 -07:00
Eric Paris
b9593d309d IMA: use i_writecount rather than a private counter
IMA tracks the number of struct files which are holding a given inode
readonly and the number which are holding the inode write or r/w.  It
needs this information so when a new reader or writer comes in it can
tell if this new file will be able to invalidate results it already made
about existing files.

aka if a task is holding a struct file open RO, IMA measured the file
and recorded those measurements and then a task opens the file RW IMA
needs to note in the logs that the old measurement may not be correct.
It's called a "Time of Measure Time of Use" (ToMToU) issue.  The same is
true is a RO file is opened to an inode which has an open writer.  We
cannot, with any validity, measure the file in question since it could
be changing.

This patch attempts to use the i_writecount field to track writers.  The
i_writecount field actually embeds more information in it's value than
IMA needs but it should work for our purposes and allow us to shrink the
struct inode even more.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 11:37:18 -07:00
Eric Paris
ad16ad00c3 IMA: use inode->i_lock to protect read and write counters
Currently IMA used the iint->mutex to protect the i_readcount and
i_writecount.  This patch uses the inode->i_lock since we are going to
start using in inode objects and that is the most appropriate lock.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 11:37:18 -07:00
Eric Paris
15aac67677 IMA: convert internal flags from long to char
The IMA flags is an unsigned long but there is only 1 flag defined.
Lets save a little space and make it a char.  This packs nicely next to
the array of u8's.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 11:37:18 -07:00
Eric Paris
497f323370 IMA: use unsigned int instead of long for counters
Currently IMA uses 2 longs in struct inode.  To save space (and as it
seems impossible to overflow 32 bits) we switch these to unsigned int.
The switch to unsigned does require slightly different checks for
underflow, but it isn't complex.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 11:37:18 -07:00
Eric Paris
b575156daf IMA: drop the inode opencount since it isn't needed for operation
The opencount was used to help debugging to make sure that everything
which created a struct file also correctly made the IMA calls.  Since we
moved all of that into the VFS this isn't as necessary.  We should be
able to get the same amount of debugging out of just the reader and
write count.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 11:37:17 -07:00
Eric Paris
8549164143 IMA: use rbtree instead of radix tree for inode information cache
The IMA code needs to store the number of tasks which have an open fd
granting permission to write a file even when IMA is not in use.  It
needs this information in order to be enabled at a later point in time
without losing it's integrity garantees.

At the moment that means we store a little bit of data about every inode
in a cache.  We use a radix tree key'd on the inode's memory address.
Dave Chinner pointed out that a radix tree is a terrible data structure
for such a sparse key space.  This patch switches to using an rbtree
which should be more efficient.

Bug report from Dave:

 "I just noticed that slabtop was reporting an awfully high usage of
  radix tree nodes:

   OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME
  4200331 2778082  66%    0.55K 144839       29   2317424K radix_tree_node
  2321500 2060290  88%    1.00K  72581       32   2322592K xfs_inode
  2235648 2069791  92%    0.12K  69864       32    279456K iint_cache

  That is, 2.7M radix tree nodes are allocated, and the cache itself is
  consuming 2.3GB of RAM.  I know that the XFS inodei caches are indexed
  by radix tree node, but for 2 million cached inodes that would mean a
  density of 1 inode per radix tree node, which for a system with 16M
  inodes in the filsystems is an impossibly low density.  The worst I've
  seen in a production system like kernel.org is about 20-25% density,
  which would mean about 150-200k radix tree nodes for that many inodes.
  So it's not the inode cache.

  So I looked up what the iint_cache was.  It appears to used for
  storing per-inode IMA information, and uses a radix tree for indexing.
  It uses the *address* of the struct inode as the indexing key.  That
  means the key space is extremely sparse - for XFS the struct inode
  addresses are approximately 1000 bytes apart, which means the closest
  the radix tree index keys get is ~1000.  Which means that there is a
  single entry per radix tree leaf node, so the radix tree is using
  roughly 550 bytes for every 120byte structure being cached.  For the
  above example, it's probably wasting close to 1GB of RAM...."

Reported-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 11:37:17 -07:00
Mimi Zohar
e950598d43 ima: always maintain counters
commit 8262bb85da allocated the inode integrity struct (iint) before any
inodes were created. Only after IMA was initialized in late_initcall were
the counters updated. This patch updates the counters, whether or not IMA
has been initialized, to resolve 'imbalance' messages.

This patch fixes the bug as reported in bugzilla: 15673.  When the i915
is builtin, the ring_buffer is initialized before IMA, causing the
imbalance message on suspend.

Reported-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Tested-by: Thomas Meyer <thomas@m3y3r.de>
Tested-by: David Safford<safford@watson.ibm.com>
Cc: Stable Kernel <stable@kernel.org>
Signed-off-by: James Morris <jmorris@namei.org>
2010-09-08 09:51:41 +10:00
Eric Paris
6ccd045630 ima: handle multiple rules per write
Currently IMA will only accept one rule per write().  This patch allows IMA to
accept writes which contain multiple rules but only processes one rule per
write.  \n is used as the delimiter between rules.  IMA will return a short
write indicating that it only accepted up to the first \n.

This allows simple userspace utilities like cat to be used to load an IMA
policy instead of needing a special userspace utility that understood 'one
write per rule'

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2010-04-21 09:58:13 +10:00
Mimi Zohar
1e93d0052d ima: rename PATH_CHECK to FILE_CHECK
With the movement of the ima hooks functions were renamed from *path* to
*file* since they always deal with struct file.  This patch renames some of
the ima internal flags to make them consistent with the rest of the code.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-02-07 03:06:23 -05:00
Eric Paris
54bb6552bd ima: initialize ima before inodes can be allocated
ima wants to create an inode information struct (iint) when inodes are
allocated.  This means that at least the part of ima which does this
allocation (the allocation is filled with information later) should
before any inodes are created.  To accomplish this we split the ima
initialization routine placing the kmem cache allocator inside a
security_initcall() function.  Since this makes use of radix trees we also
need to make sure that is initialized before security_initcall().

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-02-07 03:06:22 -05:00
Eric Paris
85a17f552d ima: call ima_inode_free ima_inode_free
ima_inode_free() has some funky #define just to confuse the crap out of me.

void ima_iint_delete(struct inode *inode)

and then things actually call ima_inode_free() and nothing calls
ima_iint_delete().

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-16 12:16:46 -05:00
Eric Paris
e0d5bd2aec IMA: clean up the IMA counts updating code
We currently have a lot of duplicated code around ima file counts.  Clean
that all up.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-16 12:16:46 -05:00
Eric Paris
9353384ec8 ima: only insert at inode creation time
iints are supposed to be allocated when an inode is allocated (during
security_inode_alloc())  But we have code which will attempt to allocate
an iint during measurement calls.  If we couldn't allocate the iint and we
cared, we should have died during security_inode_alloc().  Not make the
code more complex and less efficient.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-16 12:16:46 -05:00
Mimi Zohar
523979adfa integrity: audit update
Based on discussions on linux-audit, as per Steve Grubb's request
http://lkml.org/lkml/2009/2/6/269, the following changes were made:
- forced audit result to be either 0 or 1.
- made template names const
- Added new stand-alone message type: AUDIT_INTEGRITY_RULE

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-02-12 09:40:14 +11:00
Mimi Zohar
1df9f0a731 Integrity: IMA file free imbalance
The number of calls to ima_path_check()/ima_file_free()
should be balanced.  An extra call to fput(), indicates
the file could have been accessed without first being
measured.

Although f_count is incremented/decremented in places other
than fget/fput, like fget_light/fput_light and get_file, the
current task must already hold a file refcnt.  The call to
__fput() is delayed until the refcnt becomes 0, resulting
in ima_file_free() flagging any changes.

- add hook to increment opencount for IPC shared memory(SYSV),
  shmat files, and /dev/zero
- moved NULL iint test in opencount_get()

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-02-06 09:05:33 +11:00
Mimi Zohar
4af4662fa4 integrity: IMA policy
Support for a user loadable policy through securityfs
with support for LSM specific policy data.
- free invalid rule in ima_parse_add_rule()

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-02-06 09:05:31 +11:00
Mimi Zohar
bab7393787 integrity: IMA display
Make the measurement lists available through securityfs.
- removed test for NULL return code from securityfs_create_file/dir

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-02-06 09:05:31 +11:00
Mimi Zohar
3323eec921 integrity: IMA as an integrity service provider
IMA provides hardware (TPM) based measurement and attestation for
file measurements. As the Trusted Computing (TPM) model requires,
IMA measures all files before they are accessed in any way (on the
integrity_bprm_check, integrity_path_check and integrity_file_mmap
hooks), and commits the measurements to the TPM. Once added to the
TPM, measurements can not be removed.

In addition, IMA maintains a list of these file measurements, which
can be used to validate the aggregate value stored in the TPM.  The
TPM can sign these measurements, and thus the system can prove, to
itself and to a third party, the system's integrity in a way that
cannot be circumvented by malicious or compromised software.

- alloc ima_template_entry before calling ima_store_template()
- log ima_add_boot_aggregate() failure
- removed unused IMA_TEMPLATE_NAME_LEN
- replaced hard coded string length with #define name

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-02-06 09:05:30 +11:00