爲什麼public_key_verify_signature（）會在文件範圍中定義簽名緩衝區時返回錯誤？ （linux內核加密）

Question

我使用的是linux內核4.8.0.26，並且編寫了一個驗證數字簽名的簡單模塊。

如果給予struct public_key_signature作爲簽名字節緩衝器中的文件範圍內被定義 - public_key_verify_signature()返回-EINVAL.

如果緩衝器被定義在函數內部 - public_key_verify_signature()成功。

下面的代碼返回錯誤。使它工作 - 只是移動signature_bytes聲明中rsa_verify()：

/* 
* rsa-verify.c - simple kernel module using crypto api to verify digital signature. 
*/ 
#include <linux/module.h> 
#include <linux/kernel.h> 
#include <crypto/public_key.h> 

MODULE_LICENSE("GPL"); 

//public key in der format 
u8 public_key_bytes[] = { 0x30,0x82,0x01,0x0a,0x02,0x82,0x01,0x01,0x00,0xe4,0xde,0x7c,0x12,0x6d,0xaa,0x6b,0xe9,0xb6,0x17,0x58,0x81,0x4e,0xad,0xfb,0x0e,0x21,0x39,0x4b,0x09,0x57,0xdd,0xa0,0xe1,0xfb,0x53,0x4b,0xc3,0xc3,0x0c,0x33,0xa7,0x37,0xfb,0xa8,0x47,0x26,0x2f,0xea,0x70,0x7c,0xbf,0x91,0x52,0xd8,0x2d,0x3a,0xd7,0xd9,0xba,0xa0,0x87,0x6d,0x8d,0x0c,0x7a,0xfe,0x7b,0x6c,0x7c,0x3d,0x57,0x73,0xb8,0xd1,0x55,0x2c,0x1e,0xc5,0x81,0xad,0x1a,0x59,0x71,0x12,0xa3,0x0b,0xee,0xe2,0x7b,0xf8,0x0c,0x8f,0xbf,0x68,0xbf,0x50,0x11,0x8b,0xa7,0xd7,0x00,0xb6,0xdc,0x65,0x4f,0xe3,0x75,0xdd,0xcc,0xa4,0x55,0x0c,0x70,0x27,0x23,0x9b,0x8d,0x1e,0x7d,0x66,0x33,0x06,0xad,0x62,0x37,0x1b,0xd4,0x68,0x50,0xcf,0x26,0x9d,0x60,0x6e,0xc0,0x3c,0xc7,0x15,0xcb,0x76,0x07,0x8a,0xc4,0xd3,0x84,0xf6,0xad,0x51,0xe0,0x63,0x31,0x55,0x4b,0x4a,0x96,0x4d,0x43,0xb7,0xd6,0x57,0xd6,0x6b,0x66,0x5c,0x60,0x35,0xf9,0x32,0x8d,0xe9,0x49,0x5c,0x3d,0x0f,0x77,0xfb,0x87,0x95,0xc2,0x57,0x8a,0xa2,0x9d,0xbe,0x42,0xc2,0x95,0x74,0x80,0xb1,0x10,0xd4,0x6c,0x37,0xb6,0xc5,0xed,0x73,0x2b,0xdd,0x44,0x87,0xf9,0xed,0x14,0xec,0x58,0x46,0x86,0xa4,0x0d,0x38,0x0f,0xcb,0x61,0xf9,0x39,0xf5,0x06,0xe6,0x20,0x0a,0x02,0xed,0x01,0xc7,0x77,0x9e,0x4e,0xaa,0x45,0xcf,0xc9,0xb2,0xa6,0xd1,0xf0,0x2c,0x6e,0x33,0xbb,0x49,0x18,0x7a,0x0a,0x55,0x06,0x7b,0xd8,0x6f,0x08,0xd6,0xc7,0xfd,0x41,0x2b,0x37,0x77,0x40,0x1e,0x63,0xf8,0x27,0x58,0x23,0x02,0x03,0x01,0x00,0x01 }; 

//SHA-256 digest for the data "asaf" 
u8 digest[] = { 0x6f,0x82,0xd3,0x9a,0x2c,0x53,0xaf,0xa5,0x00,0xd4,0x6e,0x0e,0xfb,0xe1,0xa8,0xd5,0x6c,0xc4,0x69,0x4d,0xde,0x94,0x66,0xde,0xb2,0xb7,0x76,0x30,0xd1,0xf7,0x53,0x57 }; 

//given signature of data "asaf" using a private key 
u8 signature_bytes[] = { 0xb7,0xa8,0x48,0x1c,0x31,0x80,0xab,0xa3,0x16,0x23,0xc8,0xb8,0x2b,0xf6,0x99,0x5b,0x90,0x64,0xe1,0x4f,0xda,0xe4,0xfc,0x4c,0xa4,0xbe,0x58,0x9c,0xec,0xef,0x9c,0x92,0x56,0x05,0x3e,0xa3,0xcc,0x00,0xd3,0x7e,0xa3,0xab,0x09,0xd7,0xc9,0x3f,0x2b,0x28,0x4f,0x14,0x57,0x2a,0x24,0x56,0x07,0x55,0xc1,0xbe,0xf8,0xbe,0x41,0x8d,0xa3,0xa4,0x79,0xdd,0x27,0x3e,0xc6,0x32,0xe1,0x80,0xe3,0x40,0x27,0x48,0x9f,0xe8,0xb6,0x87,0xee,0x4e,0x8a,0x82,0x6c,0x6c,0x32,0x50,0x7a,0x28,0x63,0xbc,0xb2,0xd4,0x59,0x50,0x66,0x07,0xb9,0x93,0x27,0x1b,0x45,0x35,0x00,0x15,0xe2,0x6e,0x7d,0xf8,0xb6,0x75,0x9b,0x3a,0xb8,0xc5,0xe5,0x1d,0xda,0x4c,0xdc,0x01,0xb2,0x69,0x7f,0x87,0x08,0x6e,0x11,0xb7,0xcd,0x1f,0x9f,0xaa,0xb4,0xe4,0x13,0x4e,0x67,0x1f,0x60,0x9c,0x30,0x7d,0xec,0xf1,0xf4,0x0d,0x72,0x62,0x39,0x51,0x82,0x9f,0x5f,0x25,0x1f,0x4a,0xff,0x73,0x88,0xf1,0x8e,0x2d,0x6e,0xec,0xa9,0x2a,0xea,0xca,0x49,0x39,0x6d,0x00,0xeb,0xb8,0x25,0x2b,0x02,0x06,0xcf,0xf3,0xa7,0xe2,0x14,0xcd,0xd6,0x5c,0xfa,0xd0,0x87,0x6b,0x29,0xc5,0xc4,0xe0,0x97,0x76,0x6b,0xd8,0x7c,0x49,0x63,0x2e,0xc9,0x96,0xf6,0xb2,0x3b,0x2d,0x35,0x77,0x3c,0x33,0x09,0x39,0xa6,0xff,0xb2,0x98,0x27,0x61,0x32,0x5b,0x30,0x30,0xd5,0xee,0xa0,0xcb,0x0a,0xb1,0xc7,0x6d,0x7b,0xf5,0x1a,0x12,0x25,0xe1,0xf0,0x78,0x4f,0xd9,0x54,0x32,0xb7,0x3b,0x6f,0xf3,0x33,0x9e,0xa8,0x58,0x7c,0xa3 };  

int rsa_verify(void) 
{  
    // u8 signature_bytes[]... if it was here - it would work 

    struct public_key rsa_pub_key = { 
     .key = public_key_bytes, 
     .keylen = (u32)(sizeof(public_key_bytes)), 
     .pkey_algo = "rsa", 
     .id_type = "X509" 
    }; 

    struct public_key_signature sig = { 
     .s = signature_bytes, 
     .s_size = (u32)(sizeof(signature_bytes)), 
     .digest = digest, 
     .digest_size = (u8)(sizeof(digest)), 
     .pkey_algo = "rsa", 
     .hash_algo = "sha256" 
    }; 

    int error = public_key_verify_signature(&rsa_pub_key, &sig); 
    if (error) { 
     pr_info("error verifying. error %d\n", error); 
     return -1; 
    } 

    pr_info("verified successfuly!!!\n"); 
    return 0; 
} 

int init_module(void) 
{ 
    printk(KERN_INFO "Hello rsa-verify\n"); 
    return rsa_verify(); 
} 

void cleanup_module(void) 
{ 
    printk(KERN_INFO "Goodbye rsa-verify\n"); 
} 

的Makefile：

obj-m += rsa-verify.o 

all: 
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules EXTRA_CFLAGS="$(EXTRA_CFLAGS)" 

clean: 
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean 

（gcc版本6.1.1）

Answer 1

的原因是，當你跟隨的代碼，你可以看到以下呼叫：

public_key_verify_signature();    // will call: 
sg_init_one(&sig_sg, sig->s, sig->s_size);` //will call: 
sg_set_buf(sg, buf, buflen); 

sg_set_buf代碼：

#ifdef CONFIG_DEBUG_SG 
    BUG_ON(!virt_addr_valid(buf)); 
#endif 
    sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); 

和virt_to_page將無法​​正常工作，因爲ELF節被加載到與vmalloc分配頁。