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Iu: add UEA encryption

Add vty 'encryption uea 0 1 2', defaults to 'encryption uea 0' to yield
previous behavior.

If any UEA above 0 is enabled, include the UEA key in the Iu Security
Mode Command.

I noticed that only the code bit in st_iu_security_cmd_on_enter()
affects the test. The same code in gsm48_gmm_authorize() seems to be
dead code? But applying the patch there as well just to be safe.

We cannot yet verify the chosen UEA to match a configured UEA level,
because the iu_client.c does not send us message details with the
RANAP_IU_EVENT_SECURITY_MODE_COMPLETE.
Also we cannot yet send the set of configured UEA to the hNodeB, since,
again, iu_client.c does not provide the proper API for it.
The proper solution here is to completely dissolve iu_client.c and do
all Iu handling in osmo-sgsn itself -- see OS#5487.

Related: SYS#5516
Related: I1a7c3b156830058c43f15f55883ea301d2d01d5f (osmo-ttcn3-hacks)
Change-Id: I27e8e0078c45426bf227bb44aac82a4875d18d0f
changes/27/27427/4
Neels Hofmeyr 5 months ago
parent
commit
3c7656a481
  1. 1
      include/osmocom/sgsn/sgsn.h
  2. 9
      src/sgsn/gprs_gmm.c
  3. 11
      src/sgsn/gprs_gmm_attach.c
  4. 5
      src/sgsn/gprs_ranap.c
  5. 24
      src/sgsn/sgsn_vty.c
  6. 1
      tests/osmo-sgsn_test-nodes.vty

1
include/osmocom/sgsn/sgsn.h

@ -77,6 +77,7 @@ struct sgsn_config {
enum sgsn_auth_policy auth_policy;
uint8_t gea_encryption_mask;
uint8_t uea_encryption_mask;
struct llist_head imsi_acl;
struct sockaddr_in gsup_server_addr;

9
src/sgsn/gprs_gmm.c

@ -41,6 +41,7 @@
#include <osmocom/core/utils.h>
#include <osmocom/core/tdef.h>
#include <osmocom/crypt/auth.h>
#include <osmocom/crypt/utran_cipher.h>
#include <osmocom/gsm/protocol/gsm_04_08_gprs.h>
#include <osmocom/gprs/gprs_bssgp.h>
@ -916,7 +917,13 @@ int gsm48_gmm_authorize(struct sgsn_mm_ctx *ctx)
/* The MS is authorized */
#ifdef BUILD_IU
if (ctx->ran_type == MM_CTX_T_UTRAN_Iu && !ctx->iu.ue_ctx->integrity_active) {
rc = ranap_iu_tx_sec_mode_cmd(ctx->iu.ue_ctx, &ctx->auth_triplet.vec, 0, ctx->iu.new_key);
/* Is any encryption above UEA0 enabled? */
bool send_ck = sgsn->cfg.uea_encryption_mask > (1 << OSMO_UTRAN_UEA0);
LOGMMCTXP(LOGL_DEBUG, ctx, "Iu Security Mode Command: %s encryption key (UEA encryption mask = 0x%x)\n",
send_ck ? "sending" : "not sending", sgsn->cfg.uea_encryption_mask);
/* FIXME: we should send the set of allowed UEA, as in ranap_new_msg_sec_mod_cmd2(). However, this
* is not possible in the iu_client API. See OS#5487. */
rc = ranap_iu_tx_sec_mode_cmd(ctx->iu.ue_ctx, &ctx->auth_triplet.vec, send_ck, ctx->iu.new_key);
ctx->iu.new_key = 0;
return rc;
}

11
src/sgsn/gprs_gmm_attach.c

@ -1,4 +1,5 @@
#include <osmocom/core/tdef.h>
#include <osmocom/crypt/utran_cipher.h>
#include <osmocom/sgsn/gprs_gmm_attach.h>
@ -257,6 +258,7 @@ static void st_iu_security_cmd_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_
{
#ifdef BUILD_IU
struct sgsn_mm_ctx *ctx = fi->priv;
bool send_ck;
/* TODO: shouldn't this set always? not only when the integrity_active? */
if (ctx->iu.ue_ctx->integrity_active) {
@ -264,7 +266,14 @@ static void st_iu_security_cmd_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_
return;
}
ranap_iu_tx_sec_mode_cmd(ctx->iu.ue_ctx, &ctx->auth_triplet.vec, 0, ctx->iu.new_key);
/* Is any encryption above UEA0 enabled? */
send_ck = sgsn->cfg.uea_encryption_mask > (1 << OSMO_UTRAN_UEA0);
LOGMMCTXP(LOGL_DEBUG, ctx, "Iu Security Mode Command: %s encryption key (UEA encryption mask = 0x%x)\n",
send_ck ? "sending" : "not sending", sgsn->cfg.uea_encryption_mask);
/* FIXME: we should send the set of allowed UEA, as in ranap_new_msg_sec_mod_cmd2(). However, this
* is not possible in the iu_client API. See OS#5487. */
ranap_iu_tx_sec_mode_cmd(ctx->iu.ue_ctx, &ctx->auth_triplet.vec, send_ck, ctx->iu.new_key);
ctx->iu.new_key = 0;
#endif
}

5
src/sgsn/gprs_ranap.c

@ -145,6 +145,11 @@ int sgsn_ranap_iu_event(struct ranap_ue_conn_ctx *ctx, enum ranap_iu_event_type
rc = 0;
break;
case RANAP_IU_EVENT_SECURITY_MODE_COMPLETE:
/* FIXME: verify that a permitted UEA level was chosen. Compare how osmo-msc does it in
* msc_a_ran_dec_from_msc_i(), case RAN_MSG_CIPHER_MODE_COMPLETE.
* We should dissolve iu_client.c, it was a design mistake when first implementing Iu support. osmo-msc
* has moved away from it a long time ago.
*/
/* Continue authentication here */
mm->iu.ue_ctx->integrity_active = 1;
ranap_iu_tx_common_id(mm->iu.ue_ctx, mm->imsi);

24
src/sgsn/sgsn_vty.c

@ -47,6 +47,7 @@
#include <osmocom/vty/vty.h>
#include <osmocom/vty/misc.h>
#include <osmocom/crypt/gprs_cipher.h>
#include <osmocom/crypt/utran_cipher.h>
#include <osmocom/abis/ipa.h>
#include <osmocom/gprs/gprs_bssgp.h>
@ -775,9 +776,11 @@ DEFUN_DEPRECATED(cfg_encrypt, cfg_encrypt_cmd,
return CMD_SUCCESS;
}
#define ENCRYPTION_STR "Set encryption algorithms for SGSN\n"
DEFUN(cfg_encrypt2, cfg_encrypt2_cmd,
"encryption gea <0-4> [<0-4>] [<0-4>] [<0-4>] [<0-4>]",
"Set encryption algorithms for SGSN\n"
ENCRYPTION_STR
"GPRS Encryption Algorithm\n"
"GEAn Algorithm Number\n"
"GEAn Algorithm Number\n"
@ -835,6 +838,23 @@ DEFUN(cfg_authentication, cfg_authentication_cmd,
return CMD_SUCCESS;
}
DEFUN(cfg_encryption_uea, cfg_encryption_uea_cmd,
"encryption uea <0-2> [<0-2>] [<0-2>]",
ENCRYPTION_STR
"UTRAN (3G) encryption algorithms to allow: 0 = UEA0 (no encryption), 1 = UEA1, 2 = UEA2.\n"
"UEAn Algorithm Number\n"
"UEAn Algorithm Number\n"
"UEAn Algorithm Number\n")
{
unsigned int i;
g_cfg->uea_encryption_mask = 0;
for (i = 0; i < argc; i++)
g_cfg->uea_encryption_mask |= (1 << atoi(argv[i]));
return CMD_SUCCESS;
}
DEFUN(cfg_auth_policy, cfg_auth_policy_cmd,
"auth-policy (accept-all|closed|acl-only|remote)",
"Configure the Authorization policy of the SGSN. This setting determines which subscribers are"
@ -1732,6 +1752,7 @@ int sgsn_vty_init(struct sgsn_config *cfg)
/* order matters here: ensure we attempt to parse our new command first! */
install_element(SGSN_NODE, &cfg_encrypt2_cmd);
install_element(SGSN_NODE, &cfg_encrypt_cmd);
install_element(SGSN_NODE, &cfg_encryption_uea_cmd);
install_element(SGSN_NODE, &cfg_gsup_ipa_name_cmd);
install_element(SGSN_NODE, &cfg_gsup_remote_ip_cmd);
@ -1784,6 +1805,7 @@ int sgsn_parse_config(const char *config_file)
OSMO_ASSERT(g_cfg);
g_cfg->gea_encryption_mask = 0x1; /* support GEA0 by default unless specific encryption config exists */
g_cfg->uea_encryption_mask = (1 << OSMO_UTRAN_UEA0); /* support UEA0 by default unless specific encryption config exists */
rc = vty_read_config_file(config_file, NULL);
if (rc < 0) {

1
tests/osmo-sgsn_test-nodes.vty

@ -36,6 +36,7 @@ OsmoSGSN(config-sgsn)# list
auth-policy (accept-all|closed|acl-only|remote)
authentication (optional|required)
encryption gea <0-4> [<0-4>] [<0-4>] [<0-4>] [<0-4>]
encryption uea <0-2> [<0-2>] [<0-2>]
gsup ipa-name NAME
gsup remote-ip A.B.C.D
gsup remote-port <0-65535>

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