Commit Graph

117 Commits

Author SHA1 Message Date
James Morris
8fcc995495 Merge branch 'next' into for-linus
Conflicts:
	security/integrity/evm/evm_crypto.c

Resolved upstream fix vs. next conflict manually.

Signed-off-by: James Morris <jmorris@namei.org>
2012-01-09 12:16:48 +11:00
Dmitry Kasatkin
97426f9857 evm: prevent racing during tfm allocation
There is a small chance of racing during tfm allocation.
This patch fixes it.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-12-20 17:50:08 +02:00
Dmitry Kasatkin
d21b594518 evm: key must be set once during initialization
On multi-core systems, setting of the key before every caclculation,
causes invalid HMAC calculation for other tfm users, because internal
state (ipad, opad) can be invalid before set key call returns.
It needs to be set only once during initialization.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-12-20 17:45:45 +02:00
Roberto Sassu
7b7e5916aa ima: fix invalid memory reference
Don't free a valid measurement entry on TPM PCR extend failure.

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Cc: stable@vger.kernel.org
2011-12-19 22:07:54 -05:00
Roberto Sassu
45fae74939 ima: free duplicate measurement memory
Info about new measurements are cached in the iint for performance.  When
the inode is flushed from cache, the associated iint is flushed as well.
Subsequent access to the inode will cause the inode to be re-measured and
will attempt to add a duplicate entry to the measurement list.

This patch frees the duplicate measurement memory, fixing a memory leak.

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Cc: stable@vger.kernel.org
2011-12-19 22:04:32 -05:00
Dmitry Kasatkin
143b01d332 evm: prevent racing during tfm allocation
There is a small chance of racing during tfm allocation.
This patch fixes it.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-12-08 10:06:12 +11:00
Dmitry Kasatkin
88d7ed3508 evm: key must be set once during initialization
On multi-core systems, setting of the key before every caclculation,
causes invalid HMAC calculation for other tfm users, because internal
state (ipad, opad) can be invalid before set key call returns.
It needs to be set only once during initialization.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-12-08 10:06:09 +11:00
Dmitry Kasatkin
de35353375 digsig: build dependency fix
Fix build errors by adding Kconfig dependency on KEYS.
CRYPTO dependency removed.

  CC      security/integrity/digsig.o
security/integrity/digsig.c: In function ?integrity_digsig_verify?:
security/integrity/digsig.c:38:4: error: implicit declaration of function ?request_key?
security/integrity/digsig.c:38:17: error: ?key_type_keyring? undeclared (first use in this function)
security/integrity/digsig.c:38:17: note: each undeclared identifier is reported only once for each function it appears in
make[2]: *** [security/integrity/digsig.o] Error 1

Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-11-22 10:02:32 +11:00
Dmitry Kasatkin
15647eb398 evm: digital signature verification support
This patch adds support for digital signature verification to EVM.
With this feature file metadata can be protected using digital
signature instead of an HMAC. When building an image,
which has to be flashed to different devices, an HMAC cannot
be used to sign file metadata, because the HMAC key should be
different on every device.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
2011-11-09 16:51:14 +02:00
Dmitry Kasatkin
8607c50147 integrity: digital signature verification using multiple keyrings
Define separate keyrings for each of the different use cases - evm, ima,
and modules. Using different keyrings improves search performance, and also
allows "locking" specific keyring to prevent adding new keys.
This is useful for evm and module keyrings, when keys are usually only
added from initramfs.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
2011-11-09 16:51:09 +02:00
Linus Torvalds
de0a5345a5 Merge branch 'for-linus' of git://github.com/richardweinberger/linux
* 'for-linus' of git://github.com/richardweinberger/linux: (90 commits)
  um: fix ubd cow size
  um: Fix kmalloc argument order in um/vdso/vma.c
  um: switch to use of drivers/Kconfig
  UserModeLinux-HOWTO.txt: fix a typo
  UserModeLinux-HOWTO.txt: remove ^H characters
  um: we need sys/user.h only on i386
  um: merge delay_{32,64}.c
  um: distribute exports to where exported stuff is defined
  um: kill system-um.h
  um: generic ftrace.h will do...
  um: segment.h is x86-only and needed only there
  um: asm/pda.h is not needed anymore
  um: hw_irq.h can go generic as well
  um: switch to generic-y
  um: clean Kconfig up a bit
  um: a couple of missing dependencies...
  um: kill useless argument of free_chan() and free_one_chan()
  um: unify ptrace_user.h
  um: unify KSTK_...
  um: fix gcov build breakage
  ...
2011-11-02 09:45:39 -07:00
Al Viro
3369465ed1 um: switch to use of drivers/Kconfig
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02 14:15:41 +01:00
Dmitry Kasatkin
fb788d8b98 evm: clean verification status
When allocating from slab, initialization is done the first time in
init_once() and subsequently on free.  Because evm_status was not
re-initialized on free, evm_verify_hmac() skipped verifications.

This patch re-initializes evm_status.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-09-14 15:24:52 -04:00
Mimi Zohar
566be59ab8 evm: permit mode bits to be updated
Before permitting 'security.evm' to be updated, 'security.evm' must
exist and be valid.  In the case that there are no existing EVM protected
xattrs, it is safe for posix acls to update the mode bits.

To differentiate between no 'security.evm' xattr and no xattrs used to
calculate 'security.evm', this patch defines INTEGRITY_NOXATTR.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-09-14 15:24:52 -04:00
Mimi Zohar
bf6d0f5dcd evm: posix acls modify i_mode
The posix xattr acls are 'system' prefixed, which normally would not
affect security.evm.  An interesting side affect of writing posix xattr
acls is their modifying of the i_mode, which is included in security.evm.

This patch updates security.evm when posix xattr acls are written.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-09-14 15:24:51 -04:00
Mimi Zohar
a924ce0b35 evm: limit verifying current security.evm integrity
evm_protect_xattr unnecessarily validates the current security.evm
integrity, before updating non-evm protected extended attributes
and other file metadata. This patch limits validating the current
security.evm integrity to evm protected metadata.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-09-14 15:24:51 -04:00
Mimi Zohar
1d714057ef evm: remove TCG_TPM dependency
All tristates selected by EVM(boolean) are forced to be builtin, except
in the TCG_TPM(tristate) dependency case. Arnaud Lacombe summarizes the
Kconfig bug as, "So it would seem direct dependency state influence the
state of reverse dependencies.."  For a detailed explanation, refer to
Arnaud Lacombe's posting http://lkml.org/lkml/2011/8/23/498.

With the "encrypted-keys: remove trusted-keys dependency" patch, EVM
can now be built without a dependency on TCG_TPM.  The trusted-keys
dependency requires trusted-keys to either be builtin or not selected.
This dependency will prevent the boolean/tristate mismatch from
occuring.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>,
             Randy Dunlap <rdunlap@xenotimenet>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-09-14 15:24:49 -04:00
James Morris
d5813a5718 ima: sparse fix: include linux/ima.h in ima_main.c
Fixes sparse warnings:
security/integrity/ima/ima_main.c:105:6: warning: symbol 'ima_file_free' was not declared. Should it be static?
security/integrity/ima/ima_main.c:167:5: warning: symbol 'ima_file_mmap' was not declared. Should it be static?
security/integrity/ima/ima_main.c:192:5: warning: symbol 'ima_bprm_check' was not declared. Should it be static?
security/integrity/ima/ima_main.c:211:5: warning: symbol 'ima_file_check' was not declared. Should it be static?

Signed-off-by: James Morris <jmorris@namei.org>
2011-09-09 16:56:30 -07:00
James Morris
b97e145202 ima: sparse fix: make ima_open_policy static
Fixes sparse warning:
security/integrity/ima/ima_fs.c:290:5: warning: symbol 'ima_open_policy' was not declared. Should it be static?

Signed-off-by: James Morris <jmorris@namei.org>
2011-09-09 16:56:29 -07:00
James Morris
4892722e06 integrity: sparse fix: move iint_initialized to integrity.h
Sparse fix: move iint_initialized to integrity.h

Signed-off-by: James Morris <jmorris@namei.org>
2011-09-09 16:56:24 -07:00
Mimi Zohar
dbe5ad17ec evm: add Kconfig TCG_TPM dependency
Although the EVM encrypted-key should be encrypted/decrypted using a
trusted-key, a user-defined key could be used instead. When using a user-
defined key, a TCG_TPM dependency should not be required.  Unfortunately,
the encrypted-key code needs to be refactored a bit in order to remove
this dependency.

This patch adds the TCG_TPM dependency.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>,
	     Randy Dunlap <rdunlap@xenotimenet>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-08-18 12:58:12 +10:00
Mimi Zohar
5a4730ba95 evm: fix evm_inode_init_security return code
evm_inode_init_security() should return 0, when EVM is not enabled.
(Returning an error is a remnant of evm_inode_post_init_security.)

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-08-11 17:42:41 +10:00
James Morris
0b024d2446 EVM: ensure trusted and encypted key symbols are available to EVM
Select trusted and encrypted keys if EVM is selected, to ensure
the requisite symbols are available.  Otherwise, these can be
selected as modules while EVM is static, leading to a kernel
build failure.

Signed-off-by: James Morris <jmorris@namei.org>
2011-08-09 11:33:36 +10:00
James Morris
5a2f3a02ae Merge branch 'next-evm' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/ima-2.6 into next
Conflicts:
	fs/attr.c

Resolve conflict manually.

Signed-off-by: James Morris <jmorris@namei.org>
2011-08-09 10:31:03 +10:00
Al Viro
4b2a2c6741 ima: fmode_t misspelled as mode_t...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-26 13:04:32 -04:00
Mimi Zohar
817b54aa45 evm: add evm_inode_setattr to prevent updating an invalid security.evm
Permit changing of security.evm only when valid, unless in fixmode.

Reported-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-07-18 12:29:50 -04:00
Mimi Zohar
7102ebcd65 evm: permit only valid security.evm xattrs to be updated
In addition to requiring CAP_SYS_ADMIN permission to modify/delete
security.evm, prohibit invalid security.evm xattrs from changing,
unless in fixmode. This patch prevents inadvertent 'fixing' of
security.evm to reflect offline modifications.

Changelog v7:
- rename boot paramater 'evm_mode' to 'evm'

Reported-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-07-18 12:29:49 -04:00
Dmitry Kasatkin
24e0198efe evm: replace hmac_status with evm_status
We will use digital signatures in addtion to hmac.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-07-18 12:29:48 -04:00
Dmitry Kasatkin
6d38ca01c0 evm: evm_verify_hmac must not return INTEGRITY_UNKNOWN
If EVM is not supported or enabled, evm_verify_hmac() returns
INTEGRITY_UNKNOWN, which ima_appraise_measurement() ignores and sets
the appraisal status based solely on the security.ima verification.

evm_verify_hmac() also returns INTEGRITY_UNKNOWN for other failures, such
as temporary failures like -ENOMEM, resulting in possible attack vectors.
This patch changes the default return code for temporary/unexpected
failures, like -ENOMEM, from INTEGRITY_UNKNOWN to INTEGRITY_FAIL, making
evm_verify_hmac() fail safe.

As a result, failures need to be re-evaluated in order to catch both
temporary errors, such as the -ENOMEM, as well as errors that have been
resolved in fix mode.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-07-18 12:29:48 -04:00
Dmitry Kasatkin
2960e6cb5f evm: additional parameter to pass integrity cache entry 'iint'
Additional iint parameter allows to skip lookup in the cache.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2011-07-18 12:29:47 -04:00
Dmitry Kasatkin
d46eb36995 evm: crypto hash replaced by shash
Using shash is more efficient, because the algorithm is allocated only
once. Only the descriptor to store the hash state needs to be allocated
for every operation.

Changelog v6:
- check for crypto_shash_setkey failure

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2011-07-18 12:29:46 -04:00
Mimi Zohar
cb72318069 evm: add evm_inode_init_security to initialize new files
Initialize 'security.evm' for new files.

Changelog v7:
- renamed evm_inode_post_init_security to evm_inode_init_security
- moved struct xattr definition to earlier patch
- allocate xattr name
Changelog v6:
- Use 'struct evm_ima_xattr_data'

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-07-18 12:29:45 -04:00
Mimi Zohar
3e1be52d6c security: imbed evm calls in security hooks
Imbed the evm calls evm_inode_setxattr(), evm_inode_post_setxattr(),
evm_inode_removexattr() in the security hooks.  evm_inode_setxattr()
protects security.evm xattr.  evm_inode_post_setxattr() and
evm_inode_removexattr() updates the hmac associated with an inode.

(Assumes an LSM module protects the setting/removing of xattr.)

Changelog:
  - Don't define evm_verifyxattr(), unless CONFIG_INTEGRITY is enabled.
  - xattr_name is a 'const', value is 'void *'

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
2011-07-18 12:29:42 -04:00
Dmitry Kasatkin
6be5cc5246 evm: add support for different security.evm data types
EVM protects a file's security extended attributes(xattrs) against integrity
attacks. The current patchset maintains an HMAC-sha1 value across the security
xattrs, storing the value as the extended attribute 'security.evm'. We
anticipate other methods for protecting the security extended attributes.
This patch reserves the first byte of 'security.evm' as a place holder for
the type of method.

Changelog v6:
- move evm_ima_xattr_type definition to security/integrity/integrity.h
- defined a structure for the EVM xattr called evm_ima_xattr_data
  (based on Serge Hallyn's suggestion)
- removed unnecessary memset

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
2011-07-18 12:29:41 -04:00
Mimi Zohar
66dbc325af evm: re-release
EVM protects a file's security extended attributes(xattrs) against integrity
attacks.  This patchset provides the framework and an initial method.  The
initial method maintains an HMAC-sha1 value across the security extended
attributes, storing the HMAC value as the extended attribute 'security.evm'.
Other methods of validating the integrity of a file's metadata will be posted
separately (eg. EVM-digital-signatures).

While this patchset does authenticate the security xattrs, and
cryptographically binds them to the inode, coming extensions will bind other
directory and inode metadata for more complete protection.  To help simplify
the review and upstreaming process, each extension will be posted separately
(eg. IMA-appraisal, IMA-appraisal-directory).  For a general overview of the
proposed Linux integrity subsystem, refer to Dave Safford's whitepaper:
http://downloads.sf.net/project/linux-ima/linux-ima/Integrity_overview.pdf.

EVM depends on the Kernel Key Retention System to provide it with a
trusted/encrypted key for the HMAC-sha1 operation. The key is loaded onto the
root's keyring using keyctl.  Until EVM receives notification that the key has
been successfully loaded onto the keyring (echo 1 > <securityfs>/evm), EVM can
not create or validate the 'security.evm' xattr, but returns INTEGRITY_UNKNOWN.
Loading the key and signaling EVM should be done as early as possible. Normally
this is done in the initramfs, which has already been measured as part of the
trusted boot.  For more information on creating and loading existing
trusted/encrypted keys, refer to Documentation/keys-trusted-encrypted.txt.  A
sample dracut patch, which loads the trusted/encrypted key and enables EVM, is
available from http://linux-ima.sourceforge.net/#EVM.

Based on the LSMs enabled, the set of EVM protected security xattrs is defined
at compile.  EVM adds the following three calls to the existing security hooks:
evm_inode_setxattr(), evm_inode_post_setxattr(), and evm_inode_removexattr.  To
initialize and update the 'security.evm' extended attribute, EVM defines three
calls: evm_inode_post_init(), evm_inode_post_setattr() and
evm_inode_post_removexattr() hooks.  To verify the integrity of a security
xattr, EVM exports evm_verifyxattr().

Changelog v7:
- Fixed URL in EVM ABI documentation

Changelog v6: (based on Serge Hallyn's review)
- fix URL in patch description
- remove evm_hmac_size definition
- use SHA1_DIGEST_SIZE (removed both MAX_DIGEST_SIZE and evm_hmac_size)
- moved linux include before other includes
- test for crypto_hash_setkey failure
- fail earlier for invalid key
- clear entire encrypted key, even on failure
- check xattr name length before comparing xattr names

Changelog:
- locking based on i_mutex, remove evm_mutex
- using trusted/encrypted keys for storing the EVM key used in the HMAC-sha1
  operation.
- replaced crypto hash with shash (Dmitry Kasatkin)
- support for additional methods of verifying the security xattrs
  (Dmitry Kasatkin)
- iint not allocated for all regular files, but only for those appraised
- Use cap_sys_admin in lieu of cap_mac_admin
- Use __vfs_setxattr_noperm(), without permission checks, from EVM

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
2011-07-18 12:29:40 -04:00
Mimi Zohar
f381c27222 integrity: move ima inode integrity data management
Move the inode integrity data(iint) management up to the integrity directory
in order to share the iint among the different integrity models.

Changelog:
- don't define MAX_DIGEST_SIZE
- rename several globally visible 'ima_' prefixed functions, structs,
  locks, etc to 'integrity_'
- replace '20' with SHA1_DIGEST_SIZE
- reflect location change in appropriate Kconfig and Makefiles
- remove unnecessary initialization of iint_initialized to 0
- rebased on current ima_iint.c
- define integrity_iint_store/lock as static

There should be no other functional changes.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
2011-07-18 12:29:38 -04:00
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
Mimi Zohar
854fdd55bf IMA: remove IMA imbalance checking
Now that i_readcount is maintained by the VFS layer, remove the
imbalance checking in IMA. Cleans up the IMA code nicely.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
2011-02-10 07:51:44 -05:00
Mimi Zohar
890275b5eb IMA: maintain i_readcount in the VFS layer
ima_counts_get() updated the readcount and invalidated the PCR,
as necessary. Only update the i_readcount in the VFS layer.
Move the PCR invalidation checks to ima_file_check(), where it
belongs.

Maintaining the i_readcount in the VFS layer, will allow other
subsystems to use i_readcount.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
2011-02-10 07:51:44 -05:00
Mimi Zohar
a68a27b6f2 IMA: convert i_readcount to atomic
Convert the inode's i_readcount from an unsigned int to atomic.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
2011-02-10 07:51:43 -05:00
Mimi Zohar
867c202654 ima: fix add LSM rule bug
If security_filter_rule_init() doesn't return a rule, then not everything
is as fine as the return code implies.

This bug only occurs when the LSM (eg. SELinux) is disabled at runtime.

Adding an empty LSM rule causes ima_match_rules() to always succeed,
ignoring any remaining rules.

 default IMA TCB policy:
  # PROC_SUPER_MAGIC
  dont_measure fsmagic=0x9fa0
  # SYSFS_MAGIC
  dont_measure fsmagic=0x62656572
  # DEBUGFS_MAGIC
  dont_measure fsmagic=0x64626720
  # TMPFS_MAGIC
  dont_measure fsmagic=0x01021994
  # SECURITYFS_MAGIC
  dont_measure fsmagic=0x73636673

  < LSM specific rule >
  dont_measure obj_type=var_log_t

  measure func=BPRM_CHECK
  measure func=FILE_MMAP mask=MAY_EXEC
  measure func=FILE_CHECK mask=MAY_READ uid=0

Thus without the patch, with the boot parameters 'tcb selinux=0', adding
the above 'dont_measure obj_type=var_log_t' rule to the default IMA TCB
measurement policy, would result in nothing being measured.  The patch
prevents the default TCB policy from being replaced.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Cc: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: David Safford <safford@watson.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-03 16:36:33 -08:00
Eric Paris
bade72d607 IMA: fix the ToMToU logic
Current logic looks like this:

        rc = ima_must_measure(NULL, inode, MAY_READ, FILE_CHECK);
        if (rc < 0)
                goto out;

        if (mode & FMODE_WRITE) {
                if (inode->i_readcount)
                        send_tomtou = true;
                goto out;
        }

        if (atomic_read(&inode->i_writecount) > 0)
                send_writers = true;

Lets assume we have a policy which states that all files opened for read
by root must be measured.

Lets assume the file has permissions 777.

Lets assume that root has the given file open for read.

Lets assume that a non-root process opens the file write.

The non-root process will get to ima_counts_get() and will check the
ima_must_measure().  Since it is not supposed to measure it will goto
out.

We should check the i_readcount no matter what since we might be causing
a ToMToU voilation!

This is close to correct, but still not quite perfect.  The situation
could have been that root, which was interested in the mesurement opened
and closed the file and another process which is not interested in the
measurement is the one holding the i_readcount ATM.  This is just overly
strict on ToMToU violations, which is better than not strict enough...

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 11:37:19 -07:00
Eric Paris
196f518128 IMA: explicit IMA i_flag to remove global lock on inode_delete
Currently for every removed inode IMA must take a global lock and search
the IMA rbtree looking for an associated integrity structure.  Instead
we explicitly mark an inode when we add an integrity structure so we
only have to take the global lock and do the removal if it exists.

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 11:37:19 -07:00
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
bc7d2a3e66 IMA: only allocate iint when needed
IMA always allocates an integrity structure to hold information about
every inode, but only needed this structure to track the number of
readers and writers currently accessing a given inode.  Since that
information was moved into struct inode instead of the integrity struct
this patch stops allocating the integrity stucture until it is needed.
Thus greatly reducing memory usage.

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
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