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-rw-r--r--security/integrity/ima/ima_appraise.c78
1 files changed, 71 insertions, 7 deletions
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index ef9dcfce45d4..dbba51583e7c 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -77,8 +77,9 @@ int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
return 0;
security_task_getsecid_subj(current, &secid);
- return ima_match_policy(mnt_userns, inode, current_cred(), secid, func,
- mask, IMA_APPRAISE | IMA_HASH, NULL, NULL, NULL);
+ return ima_match_policy(mnt_userns, inode, current_cred(), secid,
+ func, mask, IMA_APPRAISE | IMA_HASH, NULL,
+ NULL, NULL, NULL);
}
static int ima_fix_xattr(struct dentry *dentry,
@@ -171,7 +172,7 @@ static void ima_cache_flags(struct integrity_iint_cache *iint,
}
}
-enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value,
+enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value,
int xattr_len)
{
struct signature_v2_hdr *sig;
@@ -184,7 +185,8 @@ enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value,
switch (xattr_value->type) {
case EVM_IMA_XATTR_DIGSIG:
sig = (typeof(sig))xattr_value;
- if (sig->version != 2 || xattr_len <= sizeof(*sig))
+ if (sig->version != 2 || xattr_len <= sizeof(*sig)
+ || sig->hash_algo >= HASH_ALGO__LAST)
return ima_hash_algo;
return sig->hash_algo;
break;
@@ -357,7 +359,7 @@ int ima_check_blacklist(struct integrity_iint_cache *iint,
if ((rc == -EPERM) && (iint->flags & IMA_MEASURE))
process_buffer_measurement(&init_user_ns, NULL, digest, digestsize,
"blacklisted-hash", NONE,
- pcr, NULL, false);
+ pcr, NULL, false, NULL, 0);
}
return rc;
@@ -575,6 +577,66 @@ static void ima_reset_appraise_flags(struct inode *inode, int digsig)
clear_bit(IMA_DIGSIG, &iint->atomic_flags);
}
+/**
+ * validate_hash_algo() - Block setxattr with unsupported hash algorithms
+ * @dentry: object of the setxattr()
+ * @xattr_value: userland supplied xattr value
+ * @xattr_value_len: length of xattr_value
+ *
+ * The xattr value is mapped to its hash algorithm, and this algorithm
+ * must be built in the kernel for the setxattr to be allowed.
+ *
+ * Emit an audit message when the algorithm is invalid.
+ *
+ * Return: 0 on success, else an error.
+ */
+static int validate_hash_algo(struct dentry *dentry,
+ const struct evm_ima_xattr_data *xattr_value,
+ size_t xattr_value_len)
+{
+ char *path = NULL, *pathbuf = NULL;
+ enum hash_algo xattr_hash_algo;
+ const char *errmsg = "unavailable-hash-algorithm";
+ unsigned int allowed_hashes;
+
+ xattr_hash_algo = ima_get_hash_algo(xattr_value, xattr_value_len);
+
+ allowed_hashes = atomic_read(&ima_setxattr_allowed_hash_algorithms);
+
+ if (allowed_hashes) {
+ /* success if the algorithm is allowed in the ima policy */
+ if (allowed_hashes & (1U << xattr_hash_algo))
+ return 0;
+
+ /*
+ * We use a different audit message when the hash algorithm
+ * is denied by a policy rule, instead of not being built
+ * in the kernel image
+ */
+ errmsg = "denied-hash-algorithm";
+ } else {
+ if (likely(xattr_hash_algo == ima_hash_algo))
+ return 0;
+
+ /* allow any xattr using an algorithm built in the kernel */
+ if (crypto_has_alg(hash_algo_name[xattr_hash_algo], 0, 0))
+ return 0;
+ }
+
+ pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!pathbuf)
+ return -EACCES;
+
+ path = dentry_path(dentry, pathbuf, PATH_MAX);
+
+ integrity_audit_msg(AUDIT_INTEGRITY_DATA, d_inode(dentry), path,
+ "set_data", errmsg, -EACCES, 0);
+
+ kfree(pathbuf);
+
+ return -EACCES;
+}
+
int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
@@ -592,9 +654,11 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG);
}
if (result == 1 || evm_revalidate_status(xattr_name)) {
+ result = validate_hash_algo(dentry, xvalue, xattr_value_len);
+ if (result)
+ return result;
+
ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
- if (result == 1)
- result = 0;
}
return result;
}

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