CODEWITHSUNDEEP
cfilelinux-kernelkernelproc
user1090944
user1090944

Reputation: 465

Can not create new file in the /proc filesystem from the user space in C. Is it even possible?

So, here is the function that should create and write string into a /proc/minifwdb:

int write_to_file(char* rule)
{
    FILE* fin;

    fin = fopen("/proc/minifwdb", "a");

    if (!fin)
    {
        printf("Could not open the file /proc/minifwdb, exiting...\n");
        return 1;
    }

    if (fprintf(fin, "%s\n", rule) < 0)
        return 1;

    fclose(fin);

    return 0;
}

When fopen() is called, it returns NULL. And there is no such file as /proc/minifwdb currently. Do I need to create it using LKM, and then use it to write the info? I am also trying to create it from the user that has no root access. Any suggestions?

Upvotes: 0

Views: 1646

Answers (1)

CL.
CL.

Reputation: 180010

Files in /proc are used as an interface between user space and the kernel.

It is possible to use such a file to pass a string from user space into the kernel, but the kernel code that wants to receive it is responsible for creating the file.

Upvotes: 2

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