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Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Browse Source 
Pull integrity updates from James Morris:
 "This contains a mixture of bug fixes, code cleanup, and new
  functionality. Of note is the integrity cache locking fix, file change
  detection, and support for a new EVM portable and immutable signature
  type.

  The re-introduction of the integrity cache lock (iint) fixes the
  problem of attempting to take the i_rwsem shared a second time, when
  it was previously taken exclusively. Defining atomic flags resolves
  the original iint/i_rwsem circular locking - accessing the file data
  vs. modifying the file metadata. Although it fixes the O_DIRECT
  problem as well, a subsequent patch is needed to remove the explicit
  O_DIRECT prevention.

  For performance reasons, detecting when a file has changed and needs
  to be re-measured, re-appraised, and/or re-audited, was limited to
  after the last writer has closed, and only if the file data has
  changed. Detecting file change is based on i_version. For filesystems
  that do not support i_version, remote filesystems, or userspace
  filesystems, the file was measured, appraised and/or audited once and
  never re-evaluated. Now local filesystems, which do not support
  i_version or are not mounted with the i_version option, assume the
  file has changed and are required to re-evaluate the file. This change
  does not address detecting file change on remote or userspace
  filesystems.

  Unlike file data signatures, which can be included and distributed in
  software packages (eg. rpm, deb), the existing EVM signature, which
  protects the file metadata, could not be included in software
  packages, as it includes file system specific information (eg. i_ino,
  possibly the UUID). This pull request defines a new EVM portable and
  immutable file metadata signature format, which can be included in
  software packages"

* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  ima/policy: fix parsing of fsuuid
  ima: Use i_version only when filesystem supports it
  integrity: remove unneeded initializations in integrity_iint_cache entries
  ima: log message to module appraisal error
  ima: pass filename to ima_rdwr_violation_check()
  ima: Fix line continuation format
  ima: support new "hash" and "dont_hash" policy actions
  ima: re-introduce own integrity cache lock
  EVM: Add support for portable signature format
  EVM: Allow userland to permit modification of EVM-protected metadata
  ima: relax requiring a file signature for new files with zero length
This commit is contained in:
Linus Torvalds 2018-01-31 13:07:35 -08:00
commit 3c29548f87
14 changed files with 332 additions and 125 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
Documentation/ABI/testing/evm
View File

@ -14,30 +14,46 @@ Description:
generated either locally or remotely using an
asymmetric key. These keys are loaded onto root's
keyring using keyctl, and EVM is then enabled by
echoing a value to <securityfs>/evm:
echoing a value to <securityfs>/evm made up of the
following bits:
1: enable HMAC validation and creation
2: enable digital signature validation
3: enable HMAC and digital signature validation and HMAC
creation
Bit Effect
0 Enable HMAC validation and creation
1 Enable digital signature validation
2 Permit modification of EVM-protected metadata at
runtime. Not supported if HMAC validation and
creation is enabled.
31 Disable further runtime modification of EVM policy
Further writes will be blocked if HMAC support is enabled or
if bit 32 is set:
For example:
echo 0x80000002 ><securityfs>/evm
echo 1 ><securityfs>/evm
will enable digital signature validation and block
further writes to <securityfs>/evm.
will enable HMAC validation and creation
Until this is done, EVM can not create or validate the
'security.evm' xattr, but returns INTEGRITY_UNKNOWN.
Loading keys 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:
echo 0x80000003 ><securityfs>/evm
Documentation/security/keys/trusted-encrypted.rst. Both dracut
(via 97masterkey and 98integrity) and systemd (via
will enable HMAC and digital signature validation and
HMAC creation and disable all further modification of policy.
echo 0x80000006 ><securityfs>/evm
will enable digital signature validation, permit
modification of EVM-protected metadata and
disable all further modification of policy
Note that once a key has been loaded, it will no longer be
possible to enable metadata modification.
Until key loading has been signaled EVM can not create
or validate the 'security.evm' xattr, but returns
INTEGRITY_UNKNOWN. Loading keys 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/security/keys/trusted-encrypted.rst. Both
dracut (via 97masterkey and 98integrity) and systemd (via
core/ima-setup) have support for loading keys at boot
time.

3
Documentation/ABI/testing/ima_policy
View File

@ -17,7 +17,8 @@ Description:
rule format: action [condition ...]
action: measure | dont_measure | appraise | dont_appraise | audit
action: measure | dont_measure | appraise | dont_appraise |
audit | hash | dont_hash
condition:= base | lsm [option]
base: [[func=] [mask=] [fsmagic=] [fsuuid=] [uid=]
[euid=] [fowner=]]

1
include/linux/integrity.h
View File

@ -14,6 +14,7 @@
enum integrity_status {
INTEGRITY_PASS = 0,
INTEGRITY_PASS_IMMUTABLE,
INTEGRITY_FAIL,
INTEGRITY_NOLABEL,
INTEGRITY_NOXATTRS,

9
security/integrity/evm/evm.h
View File

@ -23,9 +23,12 @@
#define EVM_INIT_HMAC 0x0001
#define EVM_INIT_X509 0x0002
#define EVM_SETUP 0x80000000 /* userland has signaled key load */
#define EVM_ALLOW_METADATA_WRITES 0x0004
#define EVM_SETUP_COMPLETE 0x80000000 /* userland has signaled key load */
#define EVM_INIT_MASK (EVM_INIT_HMAC | EVM_INIT_X509 | EVM_SETUP)
#define EVM_KEY_MASK (EVM_INIT_HMAC | EVM_INIT_X509)
#define EVM_INIT_MASK (EVM_INIT_HMAC | EVM_INIT_X509 | EVM_SETUP_COMPLETE | \
EVM_ALLOW_METADATA_WRITES)
extern int evm_initialized;
extern char *evm_hmac;
@ -51,7 +54,7 @@ int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
size_t req_xattr_value_len, char *digest);
int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
const char *req_xattr_value,
size_t req_xattr_value_len, char *digest);
size_t req_xattr_value_len, char type, char *digest);
int evm_init_hmac(struct inode *inode, const struct xattr *xattr,
char *hmac_val);
int evm_init_secfs(void);

75
security/integrity/evm/evm_crypto.c
View File

@ -138,7 +138,7 @@ out:
* protection.)
*/
static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
char *digest)
char type, char *digest)
{
struct h_misc {
unsigned long ino;
@ -149,8 +149,13 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
} hmac_misc;
memset(&hmac_misc, 0, sizeof(hmac_misc));
hmac_misc.ino = inode->i_ino;
hmac_misc.generation = inode->i_generation;
/* Don't include the inode or generation number in portable
* signatures
*/
if (type != EVM_XATTR_PORTABLE_DIGSIG) {
hmac_misc.ino = inode->i_ino;
hmac_misc.generation = inode->i_generation;
}
/* The hmac uid and gid must be encoded in the initial user
* namespace (not the filesystems user namespace) as encoding
* them in the filesystems user namespace allows an attack
@ -163,7 +168,8 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
hmac_misc.gid = from_kgid(&init_user_ns, inode->i_gid);
hmac_misc.mode = inode->i_mode;
crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
if (evm_hmac_attrs & EVM_ATTR_FSUUID)
if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
type != EVM_XATTR_PORTABLE_DIGSIG)
crypto_shash_update(desc, &inode->i_sb->s_uuid.b[0],
sizeof(inode->i_sb->s_uuid));
crypto_shash_final(desc, digest);
@ -189,6 +195,7 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
char *xattr_value = NULL;
int error;
int size;
bool ima_present = false;
if (!(inode->i_opflags & IOP_XATTR))
return -EOPNOTSUPP;
@ -199,11 +206,18 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
error = -ENODATA;
for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) {
bool is_ima = false;
if (strcmp(*xattrname, XATTR_NAME_IMA) == 0)
is_ima = true;
if ((req_xattr_name && req_xattr_value)
&& !strcmp(*xattrname, req_xattr_name)) {
error = 0;
crypto_shash_update(desc, (const u8 *)req_xattr_value,
req_xattr_value_len);
if (is_ima)
ima_present = true;
continue;
}
size = vfs_getxattr_alloc(dentry, *xattrname,
@ -218,9 +232,14 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
error = 0;
xattr_size = size;
crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
if (is_ima)
ima_present = true;
}
hmac_add_misc(desc, inode, digest);
hmac_add_misc(desc, inode, type, digest);
/* Portable EVM signatures must include an IMA hash */
if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
return -EPERM;
out:
kfree(xattr_value);
kfree(desc);
@ -232,17 +251,45 @@ int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
char *digest)
{
return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
req_xattr_value_len, EVM_XATTR_HMAC, digest);
req_xattr_value_len, EVM_XATTR_HMAC, digest);
}
int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
const char *req_xattr_value, size_t req_xattr_value_len,
char *digest)
char type, char *digest)
{
return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
req_xattr_value_len, IMA_XATTR_DIGEST, digest);
req_xattr_value_len, type, digest);
}
static int evm_is_immutable(struct dentry *dentry, struct inode *inode)
{
const struct evm_ima_xattr_data *xattr_data = NULL;
struct integrity_iint_cache *iint;
int rc = 0;
iint = integrity_iint_find(inode);
if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
return 1;
/* Do this the hard way */
rc = vfs_getxattr_alloc(dentry, XATTR_NAME_EVM, (char **)&xattr_data, 0,
GFP_NOFS);
if (rc <= 0) {
if (rc == -ENODATA)
return 0;
return rc;
}
if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
rc = 1;
else
rc = 0;
kfree(xattr_data);
return rc;
}
/*
* Calculate the hmac and update security.evm xattr
*
@ -255,6 +302,16 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name,
struct evm_ima_xattr_data xattr_data;
int rc = 0;
/*
* Don't permit any transformation of the EVM xattr if the signature
* is of an immutable type
*/
rc = evm_is_immutable(dentry, inode);
if (rc < 0)
return rc;
if (rc)
return -EPERM;
rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
xattr_value_len, xattr_data.digest);
if (rc == 0) {
@ -280,7 +337,7 @@ int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr,
}
crypto_shash_update(desc, lsm_xattr->value, lsm_xattr->value_len);
hmac_add_misc(desc, inode, hmac_val);
hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
kfree(desc);
return 0;
}

67
security/integrity/evm/evm_main.c
View File

@ -31,7 +31,7 @@
int evm_initialized;
static char *integrity_status_msg[] = {
"pass", "fail", "no_label", "no_xattrs", "unknown"
"pass", "pass_immutable", "fail", "no_label", "no_xattrs", "unknown"
};
char *evm_hmac = "hmac(sha1)";
char *evm_hash = "sha1";
@ -76,6 +76,11 @@ static void __init evm_init_config(void)
pr_info("HMAC attrs: 0x%x\n", evm_hmac_attrs);
}
static bool evm_key_loaded(void)
{
return (bool)(evm_initialized & EVM_KEY_MASK);
}
static int evm_find_protected_xattrs(struct dentry *dentry)
{
struct inode *inode = d_backing_inode(dentry);
@ -123,7 +128,8 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
enum integrity_status evm_status = INTEGRITY_PASS;
int rc, xattr_len;
if (iint && iint->evm_status == INTEGRITY_PASS)
if (iint && (iint->evm_status == INTEGRITY_PASS ||
iint->evm_status == INTEGRITY_PASS_IMMUTABLE))
return iint->evm_status;
/* if status is not PASS, try to check again - against -ENOMEM */
@ -164,22 +170,26 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
rc = -EINVAL;
break;
case EVM_IMA_XATTR_DIGSIG:
case EVM_XATTR_PORTABLE_DIGSIG:
rc = evm_calc_hash(dentry, xattr_name, xattr_value,
xattr_value_len, calc.digest);
xattr_value_len, xattr_data->type,
calc.digest);
if (rc)
break;
rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
(const char *)xattr_data, xattr_len,
calc.digest, sizeof(calc.digest));
if (!rc) {
/* Replace RSA with HMAC if not mounted readonly and
* not immutable
*/
if (!IS_RDONLY(d_backing_inode(dentry)) &&
!IS_IMMUTABLE(d_backing_inode(dentry)))
if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG) {
if (iint)
iint->flags |= EVM_IMMUTABLE_DIGSIG;
evm_status = INTEGRITY_PASS_IMMUTABLE;
} else if (!IS_RDONLY(d_backing_inode(dentry)) &&
!IS_IMMUTABLE(d_backing_inode(dentry))) {
evm_update_evmxattr(dentry, xattr_name,
xattr_value,
xattr_value_len);
}
}
break;
default:
@ -241,7 +251,7 @@ enum integrity_status evm_verifyxattr(struct dentry *dentry,
void *xattr_value, size_t xattr_value_len,
struct integrity_iint_cache *iint)
{
if (!evm_initialized || !evm_protected_xattr(xattr_name))
if (!evm_key_loaded() || !evm_protected_xattr(xattr_name))
return INTEGRITY_UNKNOWN;
if (!iint) {
@ -265,7 +275,7 @@ static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
{
struct inode *inode = d_backing_inode(dentry);
if (!evm_initialized || !S_ISREG(inode->i_mode) || evm_fixmode)
if (!evm_key_loaded() || !S_ISREG(inode->i_mode) || evm_fixmode)
return 0;
return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
}
@ -280,7 +290,7 @@ static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
* 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.
* For posix xattr acls only, permit security.evm, even if it currently
* doesn't exist, to be updated.
* doesn't exist, to be updated unless the EVM signature is immutable.
*/
static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
@ -299,6 +309,7 @@ static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
return 0;
goto out;
}
evm_status = evm_verify_current_integrity(dentry);
if (evm_status == INTEGRITY_NOXATTRS) {
struct integrity_iint_cache *iint;
@ -345,10 +356,17 @@ int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
{
const struct evm_ima_xattr_data *xattr_data = xattr_value;
/* Policy permits modification of the protected xattrs even though
* there's no HMAC key loaded
*/
if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
return 0;
if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
if (!xattr_value_len)
return -EINVAL;
if (xattr_data->type != EVM_IMA_XATTR_DIGSIG)
if (xattr_data->type != EVM_IMA_XATTR_DIGSIG &&
xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG)
return -EPERM;
}
return evm_protect_xattr(dentry, xattr_name, xattr_value,
@ -365,6 +383,12 @@ int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
*/
int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name)
{
/* Policy permits modification of the protected xattrs even though
* there's no HMAC key loaded
*/
if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
return 0;
return evm_protect_xattr(dentry, xattr_name, NULL, 0);
}
@ -393,8 +417,8 @@ static void evm_reset_status(struct inode *inode)
void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
if (!evm_initialized || (!evm_protected_xattr(xattr_name)
&& !posix_xattr_acl(xattr_name)))
if (!evm_key_loaded() || (!evm_protected_xattr(xattr_name)
&& !posix_xattr_acl(xattr_name)))
return;
evm_reset_status(dentry->d_inode);
@ -414,7 +438,7 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
*/
void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
{
if (!evm_initialized || !evm_protected_xattr(xattr_name))
if (!evm_key_loaded() || !evm_protected_xattr(xattr_name))
return;
evm_reset_status(dentry->d_inode);
@ -425,12 +449,21 @@ void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
/**
* evm_inode_setattr - prevent updating an invalid EVM extended attribute
* @dentry: pointer to the affected dentry
*
* Permit update of file attributes when files have a valid EVM signature,
* except in the case of them having an immutable portable signature.
*/
int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
{
unsigned int ia_valid = attr->ia_valid;
enum integrity_status evm_status;
/* Policy permits modification of the protected attrs even though
* there's no HMAC key loaded
*/
if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
return 0;
if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
return 0;
evm_status = evm_verify_current_integrity(dentry);
@ -456,7 +489,7 @@ int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
*/
void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
{
if (!evm_initialized)
if (!evm_key_loaded())
return;
if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
@ -473,7 +506,7 @@ int evm_inode_init_security(struct inode *inode,
struct evm_ima_xattr_data *xattr_data;
int rc;
if (!evm_initialized || !evm_protected_xattr(lsm_xattr->name))
if (!evm_key_loaded() || !evm_protected_xattr(lsm_xattr->name))
return 0;
xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);

20
security/integrity/evm/evm_secfs.c
View File

@ -40,7 +40,7 @@ static ssize_t evm_read_key(struct file *filp, char __user *buf,
if (*ppos != 0)
return 0;
sprintf(temp, "%d", (evm_initialized & ~EVM_SETUP));
sprintf(temp, "%d", (evm_initialized & ~EVM_SETUP_COMPLETE));
rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
return rc;
@ -63,7 +63,7 @@ static ssize_t evm_write_key(struct file *file, const char __user *buf,
{
int i, ret;
if (!capable(CAP_SYS_ADMIN) || (evm_initialized & EVM_SETUP))
if (!capable(CAP_SYS_ADMIN) || (evm_initialized & EVM_SETUP_COMPLETE))
return -EPERM;
ret = kstrtoint_from_user(buf, count, 0, &i);
@ -75,16 +75,30 @@ static ssize_t evm_write_key(struct file *file, const char __user *buf,
if (!i || (i & ~EVM_INIT_MASK) != 0)
return -EINVAL;
/* Don't allow a request to freshly enable metadata writes if
* keys are loaded.
*/
if ((i & EVM_ALLOW_METADATA_WRITES) &&
((evm_initialized & EVM_KEY_MASK) != 0) &&
!(evm_initialized & EVM_ALLOW_METADATA_WRITES))
return -EPERM;
if (i & EVM_INIT_HMAC) {
ret = evm_init_key();
if (ret != 0)
return ret;
/* Forbid further writes after the symmetric key is loaded */
i |= EVM_SETUP;
i |= EVM_SETUP_COMPLETE;
}
evm_initialized |= i;
/* Don't allow protected metadata modification if a symmetric key
* is loaded
*/
if (evm_initialized & EVM_INIT_HMAC)
evm_initialized &= ~(EVM_ALLOW_METADATA_WRITES);
return count;
}

4
security/integrity/iint.c
View File

@ -153,14 +153,12 @@ static void init_once(void *foo)
struct integrity_iint_cache *iint = foo;
memset(iint, 0, sizeof(*iint));
iint->version = 0;
iint->flags = 0UL;
iint->ima_file_status = INTEGRITY_UNKNOWN;
iint->ima_mmap_status = INTEGRITY_UNKNOWN;
iint->ima_bprm_status = INTEGRITY_UNKNOWN;
iint->ima_read_status = INTEGRITY_UNKNOWN;
iint->evm_status = INTEGRITY_UNKNOWN;
iint->measured_pcrs = 0;
mutex_init(&iint->mutex);
}
static int __init integrity_iintcache_init(void)

2
security/integrity/ima/ima_api.c
View File

@ -175,7 +175,7 @@ err_out:
*/
int ima_get_action(struct inode *inode, int mask, enum ima_hooks func, int *pcr)
{
int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE;
int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE | IMA_HASH;
flags &= ima_policy_flag;

46
security/integrity/ima/ima_appraise.c
View File

@ -46,14 +46,15 @@ bool is_ima_appraise_enabled(void)
/*
* ima_must_appraise - set appraise flag
*
* Return 1 to appraise
* Return 1 to appraise or hash
*/
int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
{
if (!ima_appraise)
return 0;
return ima_match_policy(inode, func, mask, IMA_APPRAISE, NULL);
return ima_match_policy(inode, func, mask, IMA_APPRAISE | IMA_HASH,
NULL);
}
static int ima_fix_xattr(struct dentry *dentry,
@ -223,13 +224,16 @@ int ima_appraise_measurement(enum ima_hooks func,
if (opened & FILE_CREATED)
iint->flags |= IMA_NEW_FILE;
if ((iint->flags & IMA_NEW_FILE) &&
!(iint->flags & IMA_DIGSIG_REQUIRED))
(!(iint->flags & IMA_DIGSIG_REQUIRED) ||
(inode->i_size == 0)))
status = INTEGRITY_PASS;
goto out;
}
status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
if ((status != INTEGRITY_PASS) &&
(status != INTEGRITY_PASS_IMMUTABLE) &&
(status != INTEGRITY_UNKNOWN)) {
if ((status == INTEGRITY_NOLABEL)
|| (status == INTEGRITY_NOXATTRS))
cause = "missing-HMAC";
@ -248,6 +252,7 @@ int ima_appraise_measurement(enum ima_hooks func,
status = INTEGRITY_FAIL;
break;
}
clear_bit(IMA_DIGSIG, &iint->atomic_flags);
if (xattr_len - sizeof(xattr_value->type) - hash_start >=
iint->ima_hash->length)
/* xattr length may be longer. md5 hash in previous
@ -266,7 +271,7 @@ int ima_appraise_measurement(enum ima_hooks func,
status = INTEGRITY_PASS;
break;
case EVM_IMA_XATTR_DIGSIG:
iint->flags |= IMA_DIGSIG;
set_bit(IMA_DIGSIG, &iint->atomic_flags);
rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
(const char *)xattr_value, rc,
iint->ima_hash->digest,
@ -317,17 +322,20 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
int rc = 0;
/* do not collect and update hash for digital signatures */
if (iint->flags & IMA_DIGSIG)
if (test_bit(IMA_DIGSIG, &iint->atomic_flags))
return;
if (iint->ima_file_status != INTEGRITY_PASS)
if ((iint->ima_file_status != INTEGRITY_PASS) &&
!(iint->flags & IMA_HASH))
return;
rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
if (rc < 0)
return;
inode_lock(file_inode(file));
ima_fix_xattr(dentry, iint);
inode_unlock(file_inode(file));
}
/**
@ -343,23 +351,21 @@ void ima_inode_post_setattr(struct dentry *dentry)
{
struct inode *inode = d_backing_inode(dentry);
struct integrity_iint_cache *iint;
int must_appraise;
int action;
if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)
|| !(inode->i_opflags & IOP_XATTR))
return;
must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
action = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
if (!action)
__vfs_removexattr(dentry, XATTR_NAME_IMA);
iint = integrity_iint_find(inode);
if (iint) {
iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
IMA_ACTION_RULE_FLAGS);
if (must_appraise)
iint->flags |= IMA_APPRAISE;
set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags);
if (!action)
clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
}
if (!must_appraise)
__vfs_removexattr(dentry, XATTR_NAME_IMA);
}
/*
@ -388,12 +394,12 @@ static void ima_reset_appraise_flags(struct inode *inode, int digsig)
iint = integrity_iint_find(inode);
if (!iint)
return;
iint->flags &= ~IMA_DONE_MASK;
iint->measured_pcrs = 0;
set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags);
if (digsig)
iint->flags |= IMA_DIGSIG;
return;
set_bit(IMA_DIGSIG, &iint->atomic_flags);
else
clear_bit(IMA_DIGSIG, &iint->atomic_flags);
}
int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,

92
security/integrity/ima/ima_main.c
View File

@ -85,10 +85,10 @@ static void ima_rdwr_violation_check(struct file *file,
struct integrity_iint_cache *iint,
int must_measure,
char **pathbuf,
const char **pathname)
const char **pathname,
char *filename)
{
struct inode *inode = file_inode(file);
char filename[NAME_MAX];
fmode_t mode = file->f_mode;
bool send_tomtou = false, send_writers = false;
@ -97,10 +97,13 @@ static void ima_rdwr_violation_check(struct file *file,
if (!iint)
iint = integrity_iint_find(inode);
/* IMA_MEASURE is set from reader side */
if (iint && (iint->flags & IMA_MEASURE))
if (iint && test_bit(IMA_MUST_MEASURE,
&iint->atomic_flags))
send_tomtou = true;
}
} else {
if (must_measure)
set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
send_writers = true;
}
@ -122,22 +125,25 @@ static void ima_check_last_writer(struct integrity_iint_cache *iint,
struct inode *inode, struct file *file)
{
fmode_t mode = file->f_mode;
bool update;
if (!(mode & FMODE_WRITE))
return;
inode_lock(inode);
mutex_lock(&iint->mutex);
if (atomic_read(&inode->i_writecount) == 1) {
update = test_and_clear_bit(IMA_UPDATE_XATTR,
&iint->atomic_flags);
if (!IS_I_VERSION(inode) ||
inode_cmp_iversion(inode, iint->version) ||
(iint->flags & IMA_NEW_FILE)) {
iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
iint->measured_pcrs = 0;
if (iint->flags & IMA_APPRAISE)
if (update)
ima_update_xattr(iint, file);
}
}
inode_unlock(inode);
mutex_unlock(&iint->mutex);
}
/**
@ -170,7 +176,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
char *pathbuf = NULL;
char filename[NAME_MAX];
const char *pathname = NULL;
int rc = -ENOMEM, action, must_appraise;
int rc = 0, action, must_appraise = 0;
int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
struct evm_ima_xattr_data *xattr_value = NULL;
int xattr_len = 0;
@ -201,17 +207,31 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
if (action) {
iint = integrity_inode_get(inode);
if (!iint)
goto out;
rc = -ENOMEM;
}
if (violation_check) {
if (!rc && violation_check)
ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
&pathbuf, &pathname);
if (!action) {
rc = 0;
goto out_free;
}
}
&pathbuf, &pathname, filename);
inode_unlock(inode);
if (rc)
goto out;
if (!action)
goto out;
mutex_lock(&iint->mutex);
if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
/* reset appraisal flags if ima_inode_post_setattr was called */
iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
IMA_ACTION_FLAGS);
if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags))
/* reset all flags if ima_inode_setxattr was called */
iint->flags &= ~IMA_DONE_MASK;
/* Determine if already appraised/measured based on bitmask
* (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
@ -225,11 +245,23 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
action ^= IMA_MEASURE;
/* HASH sets the digital signature and update flags, nothing else */
if ((action & IMA_HASH) &&
!(test_bit(IMA_DIGSIG, &iint->atomic_flags))) {
xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
if ((xattr_value && xattr_len > 2) &&
(xattr_value->type == EVM_IMA_XATTR_DIGSIG))
set_bit(IMA_DIGSIG, &iint->atomic_flags);
iint->flags |= IMA_HASHED;
action ^= IMA_HASH;
set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
}
/* Nothing to do, just return existing appraised status */
if (!action) {
if (must_appraise)
rc = ima_get_cache_status(iint, func);
goto out_digsig;
goto out_locked;
}
template_desc = ima_template_desc_current();
@ -242,7 +274,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
if (rc != 0 && rc != -EBADF && rc != -EINVAL)
goto out_digsig;
goto out_locked;
if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
pathname = ima_d_path(&file->f_path, &pathbuf, filename);
@ -250,26 +282,32 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
if (action & IMA_MEASURE)
ima_store_measurement(iint, file, pathname,
xattr_value, xattr_len, pcr);
if (rc == 0 && (action & IMA_APPRAISE_SUBMASK))
if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
inode_lock(inode);
rc = ima_appraise_measurement(func, iint, file, pathname,
xattr_value, xattr_len, opened);
inode_unlock(inode);
}
if (action & IMA_AUDIT)
ima_audit_measurement(iint, pathname);
if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
rc = 0;
out_digsig:
if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) &&
out_locked:
if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) &&
!(iint->flags & IMA_NEW_FILE))
rc = -EACCES;
mutex_unlock(&iint->mutex);
kfree(xattr_value);
out_free:
out:
if (pathbuf)
__putname(pathbuf);
out:
inode_unlock(inode);
if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
return -EACCES;
if (must_appraise) {
if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE))
return -EACCES;
if (file->f_mode & FMODE_WRITE)
set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
}
return 0;
}
@ -368,8 +406,10 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
if (!file && read_id == READING_MODULE) {
if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) &&
(ima_appraise & IMA_APPRAISE_ENFORCE))
(ima_appraise & IMA_APPRAISE_ENFORCE)) {
pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
return -EACCES; /* INTEGRITY_UNKNOWN */
}
return 0; /* We rely on module signature checking */
}
return 0;

32
security/integrity/ima/ima_policy.c
View File

@ -40,6 +40,8 @@
#define APPRAISE 0x0004 /* same as IMA_APPRAISE */
#define DONT_APPRAISE 0x0008
#define AUDIT 0x0040
#define HASH 0x0100
#define DONT_HASH 0x0200
#define INVALID_PCR(a) (((a) < 0) || \
(a) >= (FIELD_SIZEOF(struct integrity_iint_cache, measured_pcrs) * 8))
@ -380,8 +382,10 @@ int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
action |= entry->flags & IMA_ACTION_FLAGS;
action |= entry->action & IMA_DO_MASK;
if (entry->action & IMA_APPRAISE)
if (entry->action & IMA_APPRAISE) {
action |= get_subaction(entry, func);
action ^= IMA_HASH;
}
if (entry->action & IMA_DO_MASK)
actmask &= ~(entry->action | entry->action << 1);
@ -521,7 +525,7 @@ enum {
Opt_err = -1,
Opt_measure = 1, Opt_dont_measure,
Opt_appraise, Opt_dont_appraise,
Opt_audit,
Opt_audit, Opt_hash, Opt_dont_hash,
Opt_obj_user, Opt_obj_role, Opt_obj_type,
Opt_subj_user, Opt_subj_role, Opt_subj_type,
Opt_func, Opt_mask, Opt_fsmagic,
@ -538,6 +542,8 @@ static match_table_t policy_tokens = {
{Opt_appraise, "appraise"},
{Opt_dont_appraise, "dont_appraise"},
{Opt_audit, "audit"},
{Opt_hash, "hash"},
{Opt_dont_hash, "dont_hash"},
{Opt_obj_user, "obj_user=%s"},
{Opt_obj_role, "obj_role=%s"},
{Opt_obj_type, "obj_type=%s"},
@ -671,6 +677,22 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
entry->action = AUDIT;
break;
case Opt_hash:
ima_log_string(ab, "action", "hash");
if (entry->action != UNKNOWN)
result = -EINVAL;
entry->action = HASH;
break;
case Opt_dont_hash:
ima_log_string(ab, "action", "dont_hash");
if (entry->action != UNKNOWN)
result = -EINVAL;
entry->action = DONT_HASH;
break;
case Opt_func:
ima_log_string(ab, "func", args[0].from);
@ -743,7 +765,7 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
case Opt_fsuuid:
ima_log_string(ab, "fsuuid", args[0].from);
if (uuid_is_null(&entry->fsuuid)) {
if (!uuid_is_null(&entry->fsuuid)) {
result = -EINVAL;
break;
}
@ -1040,6 +1062,10 @@ int ima_policy_show(struct seq_file *m, void *v)
seq_puts(m, pt(Opt_dont_appraise));
if (entry->action & AUDIT)
seq_puts(m, pt(Opt_audit));
if (entry->action & HASH)
seq_puts(m, pt(Opt_hash));
if (entry->action & DONT_HASH)
seq_puts(m, pt(Opt_dont_hash));
seq_puts(m, " ");

11
security/integrity/ima/ima_template.c
View File

@ -377,8 +377,7 @@ int ima_restore_measurement_list(loff_t size, void *buf)
break;
if (hdr[HDR_TEMPLATE_NAME].len >= MAX_TEMPLATE_NAME_LEN) {
pr_err("attempting to restore a template name \
that is too long\n");
pr_err("attempting to restore a template name that is too long\n");
ret = -EINVAL;
break;
}
@ -389,8 +388,8 @@ int ima_restore_measurement_list(loff_t size, void *buf)
template_name[hdr[HDR_TEMPLATE_NAME].len] = 0;
if (strcmp(template_name, "ima") == 0) {
pr_err("attempting to restore an unsupported \
template \"%s\" failed\n", template_name);
pr_err("attempting to restore an unsupported template \"%s\" failed\n",
template_name);
ret = -EINVAL;
break;
}
@ -410,8 +409,8 @@ int ima_restore_measurement_list(loff_t size, void *buf)
&(template_desc->fields),
&(template_desc->num_fields));
if (ret < 0) {
pr_err("attempting to restore the template fmt \"%s\" \
failed\n", template_desc->fmt);
pr_err("attempting to restore the template fmt \"%s\" failed\n",
template_desc->fmt);
ret = -EINVAL;
break;
}

41
security/integrity/integrity.h
View File

@ -25,39 +25,50 @@
#define IMA_COLLECTED 0x00000020
#define IMA_AUDIT 0x00000040
#define IMA_AUDITED 0x00000080
#define IMA_HASH 0x00000100
#define IMA_HASHED 0x00000200
/* iint cache flags */
#define IMA_ACTION_FLAGS 0xff000000
#define IMA_ACTION_RULE_FLAGS 0x06000000
#define IMA_DIGSIG 0x01000000
#define IMA_DIGSIG_REQUIRED 0x02000000
#define IMA_PERMIT_DIRECTIO 0x04000000
#define IMA_NEW_FILE 0x08000000
#define IMA_DIGSIG_REQUIRED 0x01000000
#define IMA_PERMIT_DIRECTIO 0x02000000
#define IMA_NEW_FILE 0x04000000
#define EVM_IMMUTABLE_DIGSIG 0x08000000
#define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \
IMA_APPRAISE_SUBMASK)
IMA_HASH | IMA_APPRAISE_SUBMASK)
#define IMA_DONE_MASK (IMA_MEASURED | IMA_APPRAISED | IMA_AUDITED | \
IMA_COLLECTED | IMA_APPRAISED_SUBMASK)
IMA_HASHED | IMA_COLLECTED | \
IMA_APPRAISED_SUBMASK)
/* iint subaction appraise cache flags */
#define IMA_FILE_APPRAISE 0x00000100
#define IMA_FILE_APPRAISED 0x00000200
#define IMA_MMAP_APPRAISE 0x00000400
#define IMA_MMAP_APPRAISED 0x00000800
#define IMA_BPRM_APPRAISE 0x00001000
#define IMA_BPRM_APPRAISED 0x00002000
#define IMA_READ_APPRAISE 0x00004000
#define IMA_READ_APPRAISED 0x00008000
#define IMA_FILE_APPRAISE 0x00001000
#define IMA_FILE_APPRAISED 0x00002000
#define IMA_MMAP_APPRAISE 0x00004000
#define IMA_MMAP_APPRAISED 0x00008000
#define IMA_BPRM_APPRAISE 0x00010000
#define IMA_BPRM_APPRAISED 0x00020000
#define IMA_READ_APPRAISE 0x00040000
#define IMA_READ_APPRAISED 0x00080000
#define IMA_APPRAISE_SUBMASK (IMA_FILE_APPRAISE | IMA_MMAP_APPRAISE | \
IMA_BPRM_APPRAISE | IMA_READ_APPRAISE)
#define IMA_APPRAISED_SUBMASK (IMA_FILE_APPRAISED | IMA_MMAP_APPRAISED | \
IMA_BPRM_APPRAISED | IMA_READ_APPRAISED)
/* iint cache atomic_flags */
#define IMA_CHANGE_XATTR 0
#define IMA_UPDATE_XATTR 1
#define IMA_CHANGE_ATTR 2
#define IMA_DIGSIG 3
#define IMA_MUST_MEASURE 4
enum evm_ima_xattr_type {
IMA_XATTR_DIGEST = 0x01,
EVM_XATTR_HMAC,
EVM_IMA_XATTR_DIGSIG,
IMA_XATTR_DIGEST_NG,
EVM_XATTR_PORTABLE_DIGSIG,
IMA_XATTR_LAST
};
@ -100,10 +111,12 @@ struct signature_v2_hdr {
/* integrity data associated with an inode */
struct integrity_iint_cache {
struct rb_node rb_node; /* rooted in integrity_iint_tree */
struct mutex mutex; /* protects: version, flags, digest */
struct inode *inode; /* back pointer to inode in question */
u64 version; /* track inode changes */
unsigned long flags;
unsigned long measured_pcrs;
unsigned long atomic_flags;
enum integrity_status ima_file_status:4;
enum integrity_status ima_mmap_status:4;
enum integrity_status ima_bprm_status:4;