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path: root/security/integrity/ima/ima_appraise.c
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Diffstat (limited to 'security/integrity/ima/ima_appraise.c')
-rw-r--r--security/integrity/ima/ima_appraise.c194
1 files changed, 129 insertions, 65 deletions
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 89b83194d1dc..136ae4e0ee92 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -200,6 +200,110 @@ int ima_read_xattr(struct dentry *dentry,
}
/*
+ * xattr_verify - verify xattr digest or signature
+ *
+ * Verify whether the hash or signature matches the file contents.
+ *
+ * Return 0 on success, error code otherwise.
+ */
+static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint,
+ struct evm_ima_xattr_data *xattr_value, int xattr_len,
+ enum integrity_status *status, const char **cause)
+{
+ int rc = -EINVAL, hash_start = 0;
+
+ switch (xattr_value->type) {
+ case IMA_XATTR_DIGEST_NG:
+ /* first byte contains algorithm id */
+ hash_start = 1;
+ /* fall through */
+ case IMA_XATTR_DIGEST:
+ if (iint->flags & IMA_DIGSIG_REQUIRED) {
+ *cause = "IMA-signature-required";
+ *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
+ * version occupied 20 bytes in xattr, instead of 16
+ */
+ rc = memcmp(&xattr_value->data[hash_start],
+ iint->ima_hash->digest,
+ iint->ima_hash->length);
+ else
+ rc = -EINVAL;
+ if (rc) {
+ *cause = "invalid-hash";
+ *status = INTEGRITY_FAIL;
+ break;
+ }
+ *status = INTEGRITY_PASS;
+ break;
+ case EVM_IMA_XATTR_DIGSIG:
+ set_bit(IMA_DIGSIG, &iint->atomic_flags);
+ rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
+ (const char *)xattr_value,
+ xattr_len,
+ iint->ima_hash->digest,
+ iint->ima_hash->length);
+ if (rc == -EOPNOTSUPP) {
+ *status = INTEGRITY_UNKNOWN;
+ break;
+ }
+ if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
+ func == KEXEC_KERNEL_CHECK)
+ rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM,
+ (const char *)xattr_value,
+ xattr_len,
+ iint->ima_hash->digest,
+ iint->ima_hash->length);
+ if (rc) {
+ *cause = "invalid-signature";
+ *status = INTEGRITY_FAIL;
+ } else {
+ *status = INTEGRITY_PASS;
+ }
+ break;
+ default:
+ *status = INTEGRITY_UNKNOWN;
+ *cause = "unknown-ima-data";
+ break;
+ }
+
+ return rc;
+}
+
+/*
+ * modsig_verify - verify modsig signature
+ *
+ * Verify whether the signature matches the file contents.
+ *
+ * Return 0 on success, error code otherwise.
+ */
+static int modsig_verify(enum ima_hooks func, const struct modsig *modsig,
+ enum integrity_status *status, const char **cause)
+{
+ int rc;
+
+ rc = integrity_modsig_verify(INTEGRITY_KEYRING_IMA, modsig);
+ if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
+ func == KEXEC_KERNEL_CHECK)
+ rc = integrity_modsig_verify(INTEGRITY_KEYRING_PLATFORM,
+ modsig);
+ if (rc) {
+ *cause = "invalid-signature";
+ *status = INTEGRITY_FAIL;
+ } else {
+ *status = INTEGRITY_PASS;
+ }
+
+ return rc;
+}
+
+/*
* ima_appraise_measurement - appraise file measurement
*
* Call evm_verifyxattr() to verify the integrity of 'security.ima'.
@@ -211,19 +315,22 @@ int ima_appraise_measurement(enum ima_hooks func,
struct integrity_iint_cache *iint,
struct file *file, const unsigned char *filename,
struct evm_ima_xattr_data *xattr_value,
- int xattr_len)
+ int xattr_len, const struct modsig *modsig)
{
static const char op[] = "appraise_data";
const char *cause = "unknown";
struct dentry *dentry = file_dentry(file);
struct inode *inode = d_backing_inode(dentry);
enum integrity_status status = INTEGRITY_UNKNOWN;
- int rc = xattr_len, hash_start = 0;
+ int rc = xattr_len;
+ bool try_modsig = iint->flags & IMA_MODSIG_ALLOWED && modsig;
- if (!(inode->i_opflags & IOP_XATTR))
+ /* If not appraising a modsig, we need an xattr. */
+ if (!(inode->i_opflags & IOP_XATTR) && !try_modsig)
return INTEGRITY_UNKNOWN;
- if (rc <= 0) {
+ /* If reading the xattr failed and there's no modsig, error out. */
+ if (rc <= 0 && !try_modsig) {
if (rc && rc != -ENODATA)
goto out;
@@ -246,6 +353,10 @@ int ima_appraise_measurement(enum ima_hooks func,
case INTEGRITY_UNKNOWN:
break;
case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */
+ /* It's fine not to have xattrs when using a modsig. */
+ if (try_modsig)
+ break;
+ /* fall through */
case INTEGRITY_NOLABEL: /* No security.evm xattr. */
cause = "missing-HMAC";
goto out;
@@ -256,65 +367,18 @@ int ima_appraise_measurement(enum ima_hooks func,
WARN_ONCE(true, "Unexpected integrity status %d\n", status);
}
- switch (xattr_value->type) {
- case IMA_XATTR_DIGEST_NG:
- /* first byte contains algorithm id */
- hash_start = 1;
- /* fall through */
- case IMA_XATTR_DIGEST:
- if (iint->flags & IMA_DIGSIG_REQUIRED) {
- cause = "IMA-signature-required";
- 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
- version occupied 20 bytes in xattr, instead of 16
- */
- rc = memcmp(&xattr_value->data[hash_start],
- iint->ima_hash->digest,
- iint->ima_hash->length);
- else
- rc = -EINVAL;
- if (rc) {
- cause = "invalid-hash";
- status = INTEGRITY_FAIL;
- break;
- }
- status = INTEGRITY_PASS;
- break;
- case EVM_IMA_XATTR_DIGSIG:
- set_bit(IMA_DIGSIG, &iint->atomic_flags);
- rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
- (const char *)xattr_value,
- xattr_len,
- iint->ima_hash->digest,
- iint->ima_hash->length);
- if (rc == -EOPNOTSUPP) {
- status = INTEGRITY_UNKNOWN;
- break;
- }
- if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
- func == KEXEC_KERNEL_CHECK)
- rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM,
- (const char *)xattr_value,
- xattr_len,
- iint->ima_hash->digest,
- iint->ima_hash->length);
- if (rc) {
- cause = "invalid-signature";
- status = INTEGRITY_FAIL;
- } else {
- status = INTEGRITY_PASS;
- }
- break;
- default:
- status = INTEGRITY_UNKNOWN;
- cause = "unknown-ima-data";
- break;
- }
+ if (xattr_value)
+ rc = xattr_verify(func, iint, xattr_value, xattr_len, &status,
+ &cause);
+
+ /*
+ * If we have a modsig and either no imasig or the imasig's key isn't
+ * known, then try verifying the modsig.
+ */
+ if (try_modsig &&
+ (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG ||
+ rc == -ENOKEY))
+ rc = modsig_verify(func, modsig, &status, &cause);
out:
/*
@@ -332,7 +396,7 @@ out:
op, cause, rc, 0);
} else if (status != INTEGRITY_PASS) {
/* Fix mode, but don't replace file signatures. */
- if ((ima_appraise & IMA_APPRAISE_FIX) &&
+ if ((ima_appraise & IMA_APPRAISE_FIX) && !try_modsig &&
(!xattr_value ||
xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
if (!ima_fix_xattr(dentry, iint))
@@ -371,7 +435,7 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
!(iint->flags & IMA_HASH))
return;
- rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
+ rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL);
if (rc < 0)
return;
generated by cgit (git 2.34.1) at 2024-05-04 19:59:30 +0000