scsi: target: iscsi: CHAP: add support for SHA1, SHA256 and SHA3-256

This patch modifies the chap_server_compute_hash() function to make it
agnostic to the choice of hash algorithm that is used.  It also adds
support to three new hash algorithms: SHA1, SHA256 and SHA3-256.

The chap_got_response() function has been removed because the digest type
validity is already checked by chap_server_open()

Link: https://lore.kernel.org/r/20191028123822.5864-2-mlombard@redhat.com
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Tested-by: Chris Leech <cleech@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/target/iscsi/iscsi_target_auth.c b/drivers/target/iscsi/iscsi_target_auth.c
index 8fe9b12..b09f208 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_auth.c
+++ b/drivers/target/iscsi/iscsi_target_auth.c
@@ -18,6 +18,22 @@
 #include "iscsi_target_nego.h"
 #include "iscsi_target_auth.h"
 
+static char *chap_get_digest_name(const int digest_type)
+{
+       switch (digest_type) {
+       case CHAP_DIGEST_MD5:
+               return "md5";
+       case CHAP_DIGEST_SHA1:
+               return "sha1";
+       case CHAP_DIGEST_SHA256:
+               return "sha256";
+       case CHAP_DIGEST_SHA3_256:
+               return "sha3-256";
+       default:
+               return NULL;
+       }
+}
+
 static int chap_gen_challenge(
        struct iscsi_conn *conn,
        int caller,
@@ -46,9 +62,23 @@ static int chap_gen_challenge(
        return 0;
 }
 
+static int chap_test_algorithm(const char *name)
+{
+       struct crypto_shash *tfm;
+
+       tfm = crypto_alloc_shash(name, 0, 0);
+       if (IS_ERR(tfm))
+               return -1;
+
+       crypto_free_shash(tfm);
+       return 0;
+}
+
 static int chap_check_algorithm(const char *a_str)
 {
-       char *tmp, *orig, *token;
+       char *tmp, *orig, *token, *digest_name;
+       long digest_type;
+       int r = CHAP_DIGEST_UNKNOWN;
 
        tmp = kstrdup(a_str, GFP_KERNEL);
        if (!tmp) {
@@ -70,15 +100,24 @@ static int chap_check_algorithm(const char *a_str)
                if (!token)
                        goto out;
 
-               if (!strcmp(token, "5")) {
-                       pr_debug("Selected MD5 Algorithm\n");
-                       kfree(orig);
-                       return CHAP_DIGEST_MD5;
+               if (kstrtol(token, 10, &digest_type))
+                       continue;
+
+               digest_name = chap_get_digest_name(digest_type);
+               if (!digest_name)
+                       continue;
+
+               pr_debug("Selected %s Algorithm\n", digest_name);
+               if (chap_test_algorithm(digest_name) < 0) {
+                       pr_err("failed to allocate %s algo\n", digest_name);
+               } else {
+                       r = digest_type;
+                       goto out;
                }
        }
 out:
        kfree(orig);
-       return CHAP_DIGEST_UNKNOWN;
+       return r;
 }
 
 static void chap_close(struct iscsi_conn *conn)
@@ -94,7 +133,7 @@ static struct iscsi_chap *chap_server_open(
        char *aic_str,
        unsigned int *aic_len)
 {
-       int ret;
+       int digest_type;
        struct iscsi_chap *chap;
 
        if (!(auth->naf_flags & NAF_USERID_SET) ||
@@ -109,17 +148,19 @@ static struct iscsi_chap *chap_server_open(
                return NULL;
 
        chap = conn->auth_protocol;
-       ret = chap_check_algorithm(a_str);
-       switch (ret) {
+       digest_type = chap_check_algorithm(a_str);
+       switch (digest_type) {
        case CHAP_DIGEST_MD5:
-               pr_debug("[server] Got CHAP_A=5\n");
-               /*
-                * Send back CHAP_A set to MD5.
-               */
-               *aic_len = sprintf(aic_str, "CHAP_A=5");
-               *aic_len += 1;
-               chap->digest_type = CHAP_DIGEST_MD5;
-               pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
+               chap->digest_size = MD5_SIGNATURE_SIZE;
+               break;
+       case CHAP_DIGEST_SHA1:
+               chap->digest_size = SHA1_SIGNATURE_SIZE;
+               break;
+       case CHAP_DIGEST_SHA256:
+               chap->digest_size = SHA256_SIGNATURE_SIZE;
+               break;
+       case CHAP_DIGEST_SHA3_256:
+               chap->digest_size = SHA3_256_SIGNATURE_SIZE;
                break;
        case CHAP_DIGEST_UNKNOWN:
        default:
@@ -128,6 +169,13 @@ static struct iscsi_chap *chap_server_open(
                return NULL;
        }
 
+       chap->digest_name = chap_get_digest_name(digest_type);
+
+       pr_debug("[server] Got CHAP_A=%d\n", digest_type);
+       *aic_len = sprintf(aic_str, "CHAP_A=%d", digest_type);
+       *aic_len += 1;
+       pr_debug("[server] Sending CHAP_A=%d\n", digest_type);
+
        /*
         * Set Identifier.
         */
@@ -146,7 +194,7 @@ static struct iscsi_chap *chap_server_open(
        return chap;
 }
 
-static int chap_server_compute_md5(
+static int chap_server_compute_hash(
        struct iscsi_conn *conn,
        struct iscsi_node_auth *auth,
        char *nr_in_ptr,
@@ -155,12 +203,13 @@ static int chap_server_compute_md5(
 {
        unsigned long id;
        unsigned char id_as_uchar;
-       unsigned char digest[MD5_SIGNATURE_SIZE];
-       unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2];
+       unsigned char type;
        unsigned char identifier[10], *challenge = NULL;
        unsigned char *challenge_binhex = NULL;
-       unsigned char client_digest[MD5_SIGNATURE_SIZE];
-       unsigned char server_digest[MD5_SIGNATURE_SIZE];
+       unsigned char *digest = NULL;
+       unsigned char *response = NULL;
+       unsigned char *client_digest = NULL;
+       unsigned char *server_digest = NULL;
        unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH];
        size_t compare_len;
        struct iscsi_chap *chap = conn->auth_protocol;
@@ -168,13 +217,33 @@ static int chap_server_compute_md5(
        struct shash_desc *desc = NULL;
        int auth_ret = -1, ret, challenge_len;
 
+       digest = kzalloc(chap->digest_size, GFP_KERNEL);
+       if (!digest) {
+               pr_err("Unable to allocate the digest buffer\n");
+               goto out;
+       }
+
+       response = kzalloc(chap->digest_size * 2 + 2, GFP_KERNEL);
+       if (!response) {
+               pr_err("Unable to allocate the response buffer\n");
+               goto out;
+       }
+
+       client_digest = kzalloc(chap->digest_size, GFP_KERNEL);
+       if (!client_digest) {
+               pr_err("Unable to allocate the client_digest buffer\n");
+               goto out;
+       }
+
+       server_digest = kzalloc(chap->digest_size, GFP_KERNEL);
+       if (!server_digest) {
+               pr_err("Unable to allocate the server_digest buffer\n");
+               goto out;
+       }
+
        memset(identifier, 0, 10);
        memset(chap_n, 0, MAX_CHAP_N_SIZE);
        memset(chap_r, 0, MAX_RESPONSE_LENGTH);
-       memset(digest, 0, MD5_SIGNATURE_SIZE);
-       memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2);
-       memset(client_digest, 0, MD5_SIGNATURE_SIZE);
-       memset(server_digest, 0, MD5_SIGNATURE_SIZE);
 
        challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
        if (!challenge) {
@@ -219,18 +288,18 @@ static int chap_server_compute_md5(
                pr_err("Could not find CHAP_R.\n");
                goto out;
        }
-       if (strlen(chap_r) != MD5_SIGNATURE_SIZE * 2) {
+       if (strlen(chap_r) != chap->digest_size * 2) {
                pr_err("Malformed CHAP_R\n");
                goto out;
        }
-       if (hex2bin(client_digest, chap_r, MD5_SIGNATURE_SIZE) < 0) {
+       if (hex2bin(client_digest, chap_r, chap->digest_size) < 0) {
                pr_err("Malformed CHAP_R\n");
                goto out;
        }
 
        pr_debug("[server] Got CHAP_R=%s\n", chap_r);
 
-       tfm = crypto_alloc_shash("md5", 0, 0);
+       tfm = crypto_alloc_shash(chap->digest_name, 0, 0);
        if (IS_ERR(tfm)) {
                tfm = NULL;
                pr_err("Unable to allocate struct crypto_shash\n");
@@ -271,15 +340,15 @@ static int chap_server_compute_md5(
                goto out;
        }
 
-       bin2hex(response, server_digest, MD5_SIGNATURE_SIZE);
-       pr_debug("[server] MD5 Server Digest: %s\n", response);
+       bin2hex(response, server_digest, chap->digest_size);
+       pr_debug("[server] %s Server Digest: %s\n", hash_name, response);
 
-       if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
-               pr_debug("[server] MD5 Digests do not match!\n\n");
+       if (memcmp(server_digest, client_digest, chap->digest_size) != 0) {
+               pr_debug("[server] %s Digests do not match!\n\n", hash_name);
                goto out;
        } else
-               pr_debug("[server] MD5 Digests match, CHAP connection"
-                               " successful.\n\n");
+               pr_debug("[server] %s Digests match, CHAP connection"
+                               " successful.\n\n", hash_name);
        /*
         * One way authentication has succeeded, return now if mutual
         * authentication is not enabled.
@@ -393,7 +462,7 @@ static int chap_server_compute_md5(
        /*
         * Convert response from binary hex to ascii hext.
         */
-       bin2hex(response, digest, MD5_SIGNATURE_SIZE);
+       bin2hex(response, digest, chap->digest_size);
        *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
                        response);
        *nr_out_len += 1;
@@ -405,31 +474,13 @@ out:
                crypto_free_shash(tfm);
        kfree(challenge);
        kfree(challenge_binhex);
+       kfree(digest);
+       kfree(response);
+       kfree(server_digest);
+       kfree(client_digest);
        return auth_ret;
 }
 
-static int chap_got_response(
-       struct iscsi_conn *conn,
-       struct iscsi_node_auth *auth,
-       char *nr_in_ptr,
-       char *nr_out_ptr,
-       unsigned int *nr_out_len)
-{
-       struct iscsi_chap *chap = conn->auth_protocol;
-
-       switch (chap->digest_type) {
-       case CHAP_DIGEST_MD5:
-               if (chap_server_compute_md5(conn, auth, nr_in_ptr,
-                               nr_out_ptr, nr_out_len) < 0)
-                       return -1;
-               return 0;
-       default:
-               pr_err("Unknown CHAP digest type %d!\n",
-                               chap->digest_type);
-               return -1;
-       }
-}
-
 u32 chap_main_loop(
        struct iscsi_conn *conn,
        struct iscsi_node_auth *auth,
@@ -448,7 +499,7 @@ u32 chap_main_loop(
                return 0;
        } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
                convert_null_to_semi(in_text, *in_len);
-               if (chap_got_response(conn, auth, in_text, out_text,
+               if (chap_server_compute_hash(conn, auth, in_text, out_text,
                                out_len) < 0) {
                        chap_close(conn);
                        return 2;

diff --git a/drivers/target/iscsi/iscsi_target_auth.h b/drivers/target/iscsi/iscsi_target_auth.h
index d5600ac..93db1ab 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_auth.h
+++ b/drivers/target/iscsi/iscsi_target_auth.h
@@ -6,14 +6,19 @@
 
 #define CHAP_DIGEST_UNKNOWN    0
 #define CHAP_DIGEST_MD5                5
-#define CHAP_DIGEST_SHA                6
+#define CHAP_DIGEST_SHA1       6
+#define CHAP_DIGEST_SHA256     7
+#define CHAP_DIGEST_SHA3_256   8
 
 #define CHAP_CHALLENGE_LENGTH  16
 #define CHAP_CHALLENGE_STR_LEN 4096
-#define MAX_RESPONSE_LENGTH    64      /* sufficient for MD5 */
+#define MAX_RESPONSE_LENGTH    128     /* sufficient for SHA3 256 */
 #define        MAX_CHAP_N_SIZE         512
 
 #define MD5_SIGNATURE_SIZE     16      /* 16 bytes in a MD5 message digest */
+#define SHA1_SIGNATURE_SIZE    20      /* 20 bytes in a SHA1 message digest */
+#define SHA256_SIGNATURE_SIZE  32      /* 32 bytes in a SHA256 message digest */
+#define SHA3_256_SIGNATURE_SIZE        32      /* 32 bytes in a SHA3 256 message digest */
 
 #define CHAP_STAGE_CLIENT_A    1
 #define CHAP_STAGE_SERVER_AIC  2
@@ -28,9 +33,11 @@ extern u32 chap_main_loop(struct iscsi_conn *, struct iscsi_node_auth *, char *,
                                int *, int *);
 
 struct iscsi_chap {
-       unsigned char   digest_type;
        unsigned char   id;
        unsigned char   challenge[CHAP_CHALLENGE_LENGTH];
+       unsigned int    challenge_len;
+       unsigned char   *digest_name;
+       unsigned int    digest_size;
        unsigned int    authenticate_target;
        unsigned int    chap_state;
 } ____cacheline_aligned;