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Qcom QMI fuzzing分享
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发表于: 2021-10-25 15:43
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在研究Qcom服务,发现一个潜在的fuzzing攻击面,分享出来供大家交流.
Qualcomm MSM Interface(QMI) is a messaging format used to communicate between software components in the modem and other peripheral subsystems.
QMI communication is based on a client-server model, where clients and servers exchange messages in QMI wire format.
0 - QMI Request
2 - QMI Response
4 - QMI Indication
更多信息可以参考以下文档
通过下面command来查看所有使用QMI接口的service
adb shell qmi-lookup
这些services分别分布在3个环境中
通过以下demo我们可以发送任意数据到这些对应的services.
注意此socket任然被selinux限制, normal app无法访问
radio 965 1 0 03:15:47 ? 00:00:34 imsqmidaemon
system 1020 1 0 03:15:47 ? 00:00:00 cnss-daemon -n -l
gps 1103 1040 0 03:15:47 ? 00:00:06 xtra-daemon
radio 1132 1 1 03:15:47 ? 00:42:36 imsdatadaemon
radio 1486 1 0 03:15:52 ? 00:21:12 ims_rtp_daemon
system 3182 1 0 03:42:01 ? 00:00:00 time_daemon
以下是kernel中用到的QMI接口的服务drivers/platform/msm/ipa/ipa_v3/ipa_qmi_service.csound/usb/usb_audio_qmi_svc.c drivers/char/diag/diagfwd_socket.c
我将以发现的oob来说明, 此issue位于Diag service
Root cause分析
函数diag_cntl_process_read_data()的buffer来自于用户可控的输入,这个buffer头部是diag_ctrl_pkt_header_t类型, 如果我们分配ctrl_pkt->pkt_id = 0x18 and ctrl_pkt->len = UINT_MAX;
当进入到函数process_ssid_range_report():
ptr指向struct diag_ctrl_ssid_range_report, header->count被赋值为UINT_MAX. ptr申请的大小只有16384 bytes. 当读取ptr content 循环UINT_MAX次, 就会导致OOB read issue.
socketFd = socket(AF_QIPCRTR, 524290, 0);
// Get socket address
uint8_t remote_addr[16] = {service_id, instance_id, node_id, port_id};
uint8_t *dest_addr = remote_addr;
addr->sa_family = AF_QIPCRTR;
memcpy((uint8_t *)&(addr->sa_data[2]), dest_addr+8, 8);
ssize_t ret = sendto(socketFd, buf, len, 64, addr, sizeof(struct sockaddr));
socketFd = socket(AF_QIPCRTR, 524290, 0);
// Get socket address
uint8_t remote_addr[16] = {service_id, instance_id, node_id, port_id};
uint8_t *dest_addr = remote_addr;
addr->sa_family = AF_QIPCRTR;
memcpy((uint8_t *)&(addr->sa_data[2]), dest_addr+8, 8);
ssize_t ret = sendto(socketFd, buf, len, 64, addr, sizeof(struct sockaddr));
int qmi_decode_message(const void *buf, size_t len,
struct qmi_elem_info *ei, void *c_struct)
{ if (!ei)
return -EINVAL;
if (!c_struct || !buf || !len)
return -EINVAL;
return qmi_decode(ei, c_struct, buf + sizeof(struct qmi_header),
len - sizeof(struct qmi_header), 1);
}int qmi_decode_message(const void *buf, size_t len,
struct qmi_elem_info *ei, void *c_struct)
{ if (!ei)
return -EINVAL;
if (!c_struct || !buf || !len)
return -EINVAL;
return qmi_decode(ei, c_struct, buf + sizeof(struct qmi_header),
len - sizeof(struct qmi_header), 1);
}void diag_cntl_process_read_data(struct diagfwd_info *p_info, void *buf,
int len)
{ uint8_t *ptr = buf;
struct diag_ctrl_pkt_header_t *ctrl_pkt = NULL;
if (!buf || len <= 0 || !p_info)
return;
while (read_len + header_len < len) {
ctrl_pkt = (struct diag_ctrl_pkt_header_t *)ptr;
switch (ctrl_pkt->pkt_id) {
case DIAG_CTRL_MSG_SSID_RANGE_REPORT:
process_ssid_range_report(ptr, ctrl_pkt->len,
....}void diag_cntl_process_read_data(struct diagfwd_info *p_info, void *buf,
int len)
{ uint8_t *ptr = buf;
struct diag_ctrl_pkt_header_t *ctrl_pkt = NULL;
if (!buf || len <= 0 || !p_info)
return;
while (read_len + header_len < len) {
ctrl_pkt = (struct diag_ctrl_pkt_header_t *)ptr;
switch (ctrl_pkt->pkt_id) {
case DIAG_CTRL_MSG_SSID_RANGE_REPORT:
process_ssid_range_report(ptr, ctrl_pkt->len,
....}static void process_ssid_range_report(uint8_t *buf, uint32_t len,
uint8_t peripheral)
{ header = (struct diag_ctrl_ssid_range_report *)ptr;
ptr += header_len;
/* Don't account for pkt_id and length */
read_len += header_len - (2 * sizeof(uint32_t));
driver->max_ssid_count[peripheral] = header->count;
for (i = 0; i < header->count && read_len < len; i++) {
ssid_range = (struct diag_ssid_range_t *)ptr;
ptr += sizeof(struct diag_ssid_range_t);
read_len += sizeof(struct diag_ssid_range_t);
mask_ptr = (struct diag_msg_mask_t *)msg_mask.ptr;
found = 0;
....
}
}static void process_ssid_range_report(uint8_t *buf, uint32_t len,
uint8_t peripheral)
{ header = (struct diag_ctrl_ssid_range_report *)ptr;
ptr += header_len;
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