09 Jan, 2012
1 commit
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Conflicts:
security/integrity/evm/evm_crypto.cResolved upstream fix vs. next conflict manually.
Signed-off-by: James Morris
20 Dec, 2011
2 commits
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There is a small chance of racing during tfm allocation.
This patch fixes it.Signed-off-by: Dmitry Kasatkin
Acked-by: Mimi Zohar
Signed-off-by: James Morris -
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
Acked-by: Mimi Zohar
Signed-off-by: James Morris
08 Dec, 2011
2 commits
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There is a small chance of racing during tfm allocation.
This patch fixes it.Signed-off-by: Dmitry Kasatkin
Acked-by: Mimi Zohar
Signed-off-by: James Morris -
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
Acked-by: Mimi Zohar
Signed-off-by: James Morris
09 Nov, 2011
1 commit
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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
Acked-by: Mimi Zohar
15 Sep, 2011
4 commits
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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
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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
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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
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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 ,
Randy Dunlap
Signed-off-by: Mimi Zohar
18 Aug, 2011
1 commit
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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 ,
Randy Dunlap
Signed-off-by: Mimi Zohar
Signed-off-by: James Morris
11 Aug, 2011
1 commit
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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
Signed-off-by: James Morris
09 Aug, 2011
1 commit
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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
19 Jul, 2011
10 commits
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Permit changing of security.evm only when valid, unless in fixmode.
Reported-by: Roberto Sassu
Signed-off-by: Mimi Zohar -
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
Signed-off-by: Mimi Zohar -
We will use digital signatures in addtion to hmac.
Signed-off-by: Dmitry Kasatkin
Signed-off-by: Mimi Zohar -
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
Signed-off-by: Mimi Zohar -
Additional iint parameter allows to skip lookup in the cache.
Signed-off-by: Dmitry Kasatkin
Signed-off-by: Mimi Zohar -
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 failureSigned-off-by: Dmitry Kasatkin
Signed-off-by: Mimi Zohar -
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
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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
Acked-by: Serge Hallyn -
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 memsetSigned-off-by: Dmitry Kasatkin
Signed-off-by: Mimi Zohar
Acked-by: Serge Hallyn -
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 > /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 documentationChangelog 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 namesChangelog:
- 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 EVMSigned-off-by: Mimi Zohar
Acked-by: Serge Hallyn
