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Diffstat (limited to 'security/integrity/ima/ima_crypto.c')
-rw-r--r--security/integrity/ima/ima_crypto.c187
1 files changed, 183 insertions, 4 deletions
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index ccd0ac8fa9a0..b9e5120559d4 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -16,6 +16,8 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
+#include <linux/moduleparam.h>
+#include <linux/ratelimit.h>
#include <linux/file.h>
#include <linux/crypto.h>
#include <linux/scatterlist.h>
@@ -25,7 +27,18 @@
#include <crypto/hash_info.h>
#include "ima.h"
+struct ahash_completion {
+ struct completion completion;
+ int err;
+};
+
+/* minimum file size for ahash use */
+static unsigned long ima_ahash_minsize;
+module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644);
+MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use");
+
static struct crypto_shash *ima_shash_tfm;
+static struct crypto_ahash *ima_ahash_tfm;
/**
* ima_kernel_read - read file content
@@ -93,9 +106,146 @@ static void ima_free_tfm(struct crypto_shash *tfm)
crypto_free_shash(tfm);
}
-/*
- * Calculate the MD5/SHA1 file digest
- */
+static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
+{
+ struct crypto_ahash *tfm = ima_ahash_tfm;
+ int rc;
+
+ if ((algo != ima_hash_algo && algo < HASH_ALGO__LAST) || !tfm) {
+ tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
+ if (!IS_ERR(tfm)) {
+ if (algo == ima_hash_algo)
+ ima_ahash_tfm = tfm;
+ } else {
+ rc = PTR_ERR(tfm);
+ pr_err("Can not allocate %s (reason: %d)\n",
+ hash_algo_name[algo], rc);
+ }
+ }
+ return tfm;
+}
+
+static void ima_free_atfm(struct crypto_ahash *tfm)
+{
+ if (tfm != ima_ahash_tfm)
+ crypto_free_ahash(tfm);
+}
+
+static void ahash_complete(struct crypto_async_request *req, int err)
+{
+ struct ahash_completion *res = req->data;
+
+ if (err == -EINPROGRESS)
+ return;
+ res->err = err;
+ complete(&res->completion);
+}
+
+static int ahash_wait(int err, struct ahash_completion *res)
+{
+ switch (err) {
+ case 0:
+ break;
+ case -EINPROGRESS:
+ case -EBUSY:
+ wait_for_completion(&res->completion);
+ reinit_completion(&res->completion);
+ err = res->err;
+ /* fall through */
+ default:
+ pr_crit_ratelimited("ahash calculation failed: err: %d\n", err);
+ }
+
+ return err;
+}
+
+static int ima_calc_file_hash_atfm(struct file *file,
+ struct ima_digest_data *hash,
+ struct crypto_ahash *tfm)
+{
+ loff_t i_size, offset;
+ char *rbuf;
+ int rc, read = 0, rbuf_len;
+ struct ahash_request *req;
+ struct scatterlist sg[1];
+ struct ahash_completion res;
+
+ hash->length = crypto_ahash_digestsize(tfm);
+
+ req = ahash_request_alloc(tfm, GFP_KERNEL);
+ if (!req)
+ return -ENOMEM;
+
+ init_completion(&res.completion);
+ ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
+ CRYPTO_TFM_REQ_MAY_SLEEP,
+ ahash_complete, &res);
+
+ rc = ahash_wait(crypto_ahash_init(req), &res);
+ if (rc)
+ goto out1;
+
+ i_size = i_size_read(file_inode(file));
+
+ if (i_size == 0)
+ goto out2;
+
+ rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!rbuf) {
+ rc = -ENOMEM;
+ goto out1;
+ }
+
+ if (!(file->f_mode & FMODE_READ)) {
+ file->f_mode |= FMODE_READ;
+ read = 1;
+ }
+
+ for (offset = 0; offset < i_size; offset += rbuf_len) {
+ rbuf_len = ima_kernel_read(file, offset, rbuf, PAGE_SIZE);
+ if (rbuf_len < 0) {
+ rc = rbuf_len;
+ break;
+ }
+ if (rbuf_len == 0)
+ break;
+
+ sg_init_one(&sg[0], rbuf, rbuf_len);
+ ahash_request_set_crypt(req, sg, NULL, rbuf_len);
+
+ rc = ahash_wait(crypto_ahash_update(req), &res);
+ if (rc)
+ break;
+ }
+ if (read)
+ file->f_mode &= ~FMODE_READ;
+ kfree(rbuf);
+out2:
+ if (!rc) {
+ ahash_request_set_crypt(req, NULL, hash->digest, 0);
+ rc = ahash_wait(crypto_ahash_final(req), &res);
+ }
+out1:
+ ahash_request_free(req);
+ return rc;
+}
+
+static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash)
+{
+ struct crypto_ahash *tfm;
+ int rc;
+
+ tfm = ima_alloc_atfm(hash->algo);
+ if (IS_ERR(tfm))
+ return PTR_ERR(tfm);
+
+ rc = ima_calc_file_hash_atfm(file, hash, tfm);
+
+ ima_free_atfm(tfm);
+
+ return rc;
+}
+
static int ima_calc_file_hash_tfm(struct file *file,
struct ima_digest_data *hash,
struct crypto_shash *tfm)
@@ -156,7 +306,7 @@ out:
return rc;
}
-int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
+static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash)
{
struct crypto_shash *tfm;
int rc;
@@ -173,6 +323,35 @@ int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
}
/*
+ * ima_calc_file_hash - calculate file hash
+ *
+ * Asynchronous hash (ahash) allows using HW acceleration for calculating
+ * a hash. ahash performance varies for different data sizes on different
+ * crypto accelerators. shash performance might be better for smaller files.
+ * The 'ima.ahash_minsize' module parameter allows specifying the best
+ * minimum file size for using ahash on the system.
+ *
+ * If the ima.ahash_minsize parameter is not specified, this function uses
+ * shash for the hash calculation. If ahash fails, it falls back to using
+ * shash.
+ */
+int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
+{
+ loff_t i_size;
+ int rc;
+
+ i_size = i_size_read(file_inode(file));
+
+ if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
+ rc = ima_calc_file_ahash(file, hash);
+ if (!rc)
+ return 0;
+ }
+
+ return ima_calc_file_shash(file, hash);
+}
+
+/*
* Calculate the hash of template data
*/
static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,

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