Attributes may require encryption for certain operations. This commit
adds checks to the attribute server which verify whether the current
connection is encrypted (by checking the security level) and the
attribute being accessed requires authentication. If encryption
requirements are not satisfied, the "Insufficient Encryption" error is
returned by the server.
Note that currently there is no actual distinction between
authentication and encryption. Currently, if an attribute requires
authentication, it is only checked whether the link is encrypted. Core
Specification, as of version 4.0, does not specify an explicit
"encryption" permission (see Vol. 3, Part F, 3.2.5 "Attribute
Permissions").
---
src/attrib-server.c | 57 +++++++++++++++++++++++++++++++++++---------------
1 files changed, 40 insertions(+), 17 deletions(-)
diff --git a/src/attrib-server.c b/src/attrib-server.c
index 2ba21e9..f2df853 100644
--- a/src/attrib-server.c
+++ b/src/attrib-server.c
@@ -57,6 +57,7 @@ struct gatt_channel {
GAttrib *attrib;
guint mtu;
guint id;
+ gboolean encrypted;
};
struct group_elem {
@@ -138,8 +139,15 @@ static sdp_record_t *server_record_new(void)
return record;
}
-static uint8_t att_check_reqs(uint8_t opcode, int reqs)
+static uint8_t att_check_reqs(struct gatt_channel *channel, uint8_t opcode,
+ int reqs)
{
+ /* FIXME: currently, it is assumed an encrypted link is enough for
+ * authentication. This will allow to enable the SMP negotiation once
+ * it is on upstream kernel. */
+ if (reqs == ATT_AUTHENTICATION && !channel->encrypted)
+ return ATT_ECODE_INSUFF_ENC;
+
switch (opcode) {
case ATT_OP_READ_BY_GROUP_REQ:
case ATT_OP_READ_BY_TYPE_REQ:
@@ -160,8 +168,9 @@ static uint8_t att_check_reqs(uint8_t opcode, int reqs)
return 0;
}
-static uint16_t read_by_group(uint16_t start, uint16_t end, uuid_t *uuid,
- uint8_t *pdu, int len)
+static uint16_t read_by_group(struct gatt_channel *channel, uint16_t start,
+ uint16_t end, uuid_t *uuid,
+ uint8_t *pdu, int len)
{
struct att_data_list *adl;
struct attribute *a;
@@ -212,7 +221,8 @@ static uint16_t read_by_group(uint16_t start, uint16_t end, uuid_t *uuid,
if (last_size && (last_size != a->len))
break;
- status = att_check_reqs(ATT_OP_READ_BY_GROUP_REQ, a->read_reqs);
+ status = att_check_reqs(channel, ATT_OP_READ_BY_GROUP_REQ,
+ a->read_reqs);
if (status) {
g_slist_foreach(groups, (GFunc) g_free, NULL);
g_slist_free(groups);
@@ -271,8 +281,9 @@ static uint16_t read_by_group(uint16_t start, uint16_t end, uuid_t *uuid,
return length;
}
-static uint16_t read_by_type(uint16_t start, uint16_t end, uuid_t *uuid,
- uint8_t *pdu, int len)
+static uint16_t read_by_type(struct gatt_channel *channel, uint16_t start,
+ uint16_t end, uuid_t *uuid,
+ uint8_t *pdu, int len)
{
struct att_data_list *adl;
GSList *l, *types;
@@ -297,7 +308,8 @@ static uint16_t read_by_type(uint16_t start, uint16_t end, uuid_t *uuid,
if (sdp_uuid_cmp(&a->uuid, uuid) != 0)
continue;
- status = att_check_reqs(ATT_OP_READ_BY_TYPE_REQ, a->read_reqs);
+ status = att_check_reqs(channel, ATT_OP_READ_BY_TYPE_REQ,
+ a->read_reqs);
if (status) {
g_slist_free(types);
return enc_error_resp(ATT_OP_READ_BY_TYPE_REQ,
@@ -508,7 +520,8 @@ static int attribute_cmp(gconstpointer a1, gconstpointer a2)
return attrib1->handle - attrib2->handle;
}
-static uint16_t read_value(uint16_t handle, uint8_t *pdu, int len)
+static uint16_t read_value(struct gatt_channel *channel, uint16_t handle,
+ uint8_t *pdu, int len)
{
struct attribute *a;
uint8_t status;
@@ -522,7 +535,7 @@ static uint16_t read_value(uint16_t handle, uint8_t *pdu, int len)
a = l->data;
- status = att_check_reqs(ATT_OP_READ_REQ, a->read_reqs);
+ status = att_check_reqs(channel, ATT_OP_READ_REQ, a->read_reqs);
if (status)
return enc_error_resp(ATT_OP_READ_REQ, handle, status, pdu,
len);
@@ -530,8 +543,9 @@ static uint16_t read_value(uint16_t handle, uint8_t *pdu, int len)
return enc_read_resp(a->data, a->len, pdu, len);
}
-static uint16_t write_value(uint16_t handle, const uint8_t *value, int vlen,
- uint8_t *pdu, int len)
+static uint16_t write_value(struct gatt_channel *channel, uint16_t handle,
+ const uint8_t *value, int vlen,
+ uint8_t *pdu, int len)
{
struct attribute *a;
uint8_t status;
@@ -546,7 +560,7 @@ static uint16_t write_value(uint16_t handle, const uint8_t *value, int vlen,
a = l->data;
- status = att_check_reqs(ATT_OP_WRITE_REQ, a->write_reqs);
+ status = att_check_reqs(channel, ATT_OP_WRITE_REQ, a->write_reqs);
if (status)
return enc_error_resp(ATT_OP_WRITE_REQ, handle, status, pdu,
len);
@@ -595,7 +609,8 @@ static void channel_handler(const uint8_t *ipdu, uint16_t len,
goto done;
}
- length = read_by_group(start, end, &uuid, opdu, channel->mtu);
+ length = read_by_group(channel, start, end, &uuid, opdu,
+ channel->mtu);
break;
case ATT_OP_READ_BY_TYPE_REQ:
length = dec_read_by_type_req(ipdu, len, &start, &end, &uuid);
@@ -604,7 +619,8 @@ static void channel_handler(const uint8_t *ipdu, uint16_t len,
goto done;
}
- length = read_by_type(start, end, &uuid, opdu, channel->mtu);
+ length = read_by_type(channel, start, end, &uuid, opdu,
+ channel->mtu);
break;
case ATT_OP_READ_REQ:
length = dec_read_req(ipdu, len, &start);
@@ -613,7 +629,7 @@ static void channel_handler(const uint8_t *ipdu, uint16_t len,
goto done;
}
- length = read_value(start, opdu, channel->mtu);
+ length = read_value(channel, start, opdu, channel->mtu);
break;
case ATT_OP_MTU_REQ:
length = dec_mtu_req(ipdu, len, &mtu);
@@ -640,12 +656,14 @@ static void channel_handler(const uint8_t *ipdu, uint16_t len,
goto done;
}
- length = write_value(start, value, vlen, opdu, channel->mtu);
+ length = write_value(channel, start, value, vlen, opdu,
+ channel->mtu);
break;
case ATT_OP_WRITE_CMD:
length = dec_write_cmd(ipdu, len, &start, value, &vlen);
if (length > 0)
- write_value(start, value, vlen, opdu, channel->mtu);
+ write_value(channel, start, value, vlen, opdu,
+ channel->mtu);
return;
case ATT_OP_FIND_BY_TYPE_REQ:
length = dec_find_by_type_req(ipdu, len, &start, &end,
@@ -682,6 +700,7 @@ static void connect_event(GIOChannel *io, GError *err, void *user_data)
{
struct gatt_channel *channel;
GError *gerr = NULL;
+ int sec_level;
if (err) {
error("%s", err->message);
@@ -693,6 +712,7 @@ static void connect_event(GIOChannel *io, GError *err, void *user_data)
bt_io_get(io, BT_IO_L2CAP, &gerr,
BT_IO_OPT_SOURCE_BDADDR, &channel->src,
BT_IO_OPT_DEST_BDADDR, &channel->dst,
+ BT_IO_OPT_SEC_LEVEL, &sec_level,
BT_IO_OPT_INVALID);
if (gerr) {
error("bt_io_get: %s", gerr->message);
@@ -705,6 +725,9 @@ static void connect_event(GIOChannel *io, GError *err, void *user_data)
channel->attrib = g_attrib_new(io);
channel->mtu = ATT_DEFAULT_MTU;
+ /* FIXME: the security level needs to checked on every request. */
+ channel->encrypted = sec_level > BT_IO_SEC_LOW;
+
channel->id = g_attrib_register(channel->attrib, GATTRIB_ALL_EVENTS,
channel_handler, channel, NULL);
--
1.7.0.4
--
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