获取 avc：AOSP 6.0.1 中的被拒绝错误

问题描述

Getting avc: denied 错误（从 sdcard 目录复制到缓存/SH_DIR 时的 SEpolicy。

错误：

type=1400 audit(1623259119.150:7): avc: denied { search } for pid=2780 comm="xyz" name="default" dev="tmpfs" ino=7420 scontext=u:r:aaa_bbb:s0

代码逻辑：

    FILE *sourceFile; 
    FILE *destFile;
    char sourcePath[100]= "/storage/emulated/0/test.txt";
    char destPath[100]="/cache/SH_DIR/";
    char ch;


    printf("Enter source file path: %s",sourcePath);

    printf("Enter destination file path:%s ",destPath);


    sourceFile  = fopen(sourcePath,"r");
    destFile    = fopen(destPath,"w");
 
    if (sourceFile == NULL || destFile == NULL)
        {
    
    printf("\nUnable to open file.\n");
    printf("Please check if file exists and you have read/write privilege.\n");


    exit(EXIT_FAILURE);
        }
ch = fgetc(sourceFile);
while (ch != EOF)
{
    /* Write to destination file */
    fputc(ch,destFile);

    /* Read next character from source file */
    ch = fgetc(sourceFile);
}


printf("\nFiles copied successfully.\n");



/* Finally close files to release resources */
fclose(sourceFile);
fclose(destFile);

SEPOLICY 中的注册文件：

AOSP/vendor/.../sepolicy/file_contexts :

 /cache/SH_DIR(/.*)? u:object_r:ccc_downloaded_sw_file:s0

文件名.te：

allow filename ccc_downloaded_sw_file:dir { open search read write getattr add_name remove_name };
allow filename ccc_downloaded_sw_file:file { open read create write unlink append getattr setattr };

你能帮我吗，为什么我无法将文件从源复制到目标。

解决方法

如果/cache分区挂载为tmpfs，则需要添加：

allow filename tmpfs_t:dir { open search read write getattr add_name remove_name };

allow filename tmpfs_t:file {  open read create write unlink append getattr setattr }