wifi: rtw89: don't request partial firmware if SECURITY_LOADPIN_ENFORCE

Kernel logs on platform enabling SECURITY_LOADPIN_ENFORCE
------
```
LoadPin: firmware old-api-denied obj=<unknown> pid=810 cmdline="modprobe -q -- rtw89_8852ce"
rtw89_8852ce 0000:01:00.0: loading /lib/firmware/rtw89/rtw8852c_fw.bin failed with error -1
rtw89_8852ce 0000:01:00.0: Direct firmware load for rtw89/rtw8852c_fw.bin failed with error -1
rtw89_8852ce 0000:01:00.0: failed to early request firmware: -1
```

Trace
------
```
request_partial_firmware_into_buf()
> _request_firmware()
>> fw_get_filesystem_firmware()
>>> kernel_read_file_from_path_initns()
>>>> kernel_read_file()
>>>>> security_kernel_read_file()
// It will iterate enabled LSMs' hooks for kernel_read_file.
// With loadpin, it hooks loadpin_read_file.
```

If SECURITY_LOADPIN_ENFORCE is enabled, doing kernel_read_file() on partial
files will be denied and return -EPERM (-1). Then, the outer API based on it,
e.g. request_partial_firmware_into_buf(), will get the error.

In the case, we cannot get the firmware stuffs right, even though there might
be no error other than a permission issue on reading a partial file. So we have
to request full firmware if SECURITY_LOADPIN_ENFORCE is enabled. It makes us
still have a chance to do early firmware work on this kind of platforms.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20221202060521.501512-2-pkshih@realtek.com

diff --git a/drivers/net/wireless/realtek/rtw89/fw.c b/drivers/net/wireless/realtek/rtw89/fw.c
index 7e682709232d727eda1d8c0c9ee23dcf7cbf9a20..f5daea0d4f93ce7cf67f02d919405015a4958477 100644 (file)
--- a/drivers/net/wireless/realtek/rtw89/fw.c
+++ b/drivers/net/wireless/realtek/rtw89/fw.c
@@ -277,25 +277,37 @@ void rtw89_early_fw_feature_recognize(struct device *device,
                                      const struct rtw89_chip_info *chip,
                                      u32 *early_feat_map)
 {
-       union {
-               struct rtw89_mfw_hdr mfw_hdr;
-               u8 fw_hdr[RTW89_FW_HDR_SIZE];
-       } buf = {};
+       union rtw89_compat_fw_hdr buf = {};
        const struct firmware *firmware;
+       bool full_req = false;
        u32 ver_code;
        int ret;
        int i;
 
-       ret = request_partial_firmware_into_buf(&firmware, chip->fw_name,
-                                               device, &buf, sizeof(buf), 0);
+       /* If SECURITY_LOADPIN_ENFORCE is enabled, reading partial files will
+        * be denied (-EPERM). Then, we don't get right firmware things as
+        * expected. So, in this case, we have to request full firmware here.
+        */
+       if (IS_ENABLED(CONFIG_SECURITY_LOADPIN_ENFORCE))
+               full_req = true;
+
+       if (full_req)
+               ret = request_firmware(&firmware, chip->fw_name, device);
+       else
+               ret = request_partial_firmware_into_buf(&firmware, chip->fw_name,
+                                                       device, &buf, sizeof(buf),
+                                                       0);
+
        if (ret) {
                dev_err(device, "failed to early request firmware: %d\n", ret);
                return;
        }
 
-       ver_code = buf.mfw_hdr.sig != RTW89_MFW_SIG ?
-                  RTW89_FW_HDR_VER_CODE(&buf.fw_hdr) :
-                  RTW89_MFW_HDR_VER_CODE(&buf.mfw_hdr);
+       if (full_req)
+               ver_code = rtw89_compat_fw_hdr_ver_code(firmware->data);
+       else
+               ver_code = rtw89_compat_fw_hdr_ver_code(&buf);
+
        if (!ver_code)
                goto out;
 

diff --git a/drivers/net/wireless/realtek/rtw89/fw.h b/drivers/net/wireless/realtek/rtw89/fw.h
index 46d57414f24e21f8245050a95f7d37b93a1ed987..5c4c7de1b4f5de1de6be671c31f8bf0d530f0cc8 100644 (file)
--- a/drivers/net/wireless/realtek/rtw89/fw.h
+++ b/drivers/net/wireless/realtek/rtw89/fw.h
@@ -3291,6 +3291,21 @@ struct fwcmd_hdr {
        __le32 hdr1;
 };
 
+union rtw89_compat_fw_hdr {
+       struct rtw89_mfw_hdr mfw_hdr;
+       u8 fw_hdr[RTW89_FW_HDR_SIZE];
+};
+
+static inline u32 rtw89_compat_fw_hdr_ver_code(const void *fw_buf)
+{
+       const union rtw89_compat_fw_hdr *compat = (typeof(compat))fw_buf;
+
+       if (compat->mfw_hdr.sig == RTW89_MFW_SIG)
+               return RTW89_MFW_HDR_VER_CODE(&compat->mfw_hdr);
+       else
+               return RTW89_FW_HDR_VER_CODE(&compat->fw_hdr);
+}
+
 #define RTW89_H2C_RF_PAGE_SIZE 500
 #define RTW89_H2C_RF_PAGE_NUM 3
 struct rtw89_fw_h2c_rf_reg_info {