如何使用不具有root特权的PAM验证用户名/密码 [英] How to authenticate username/password using PAM w/o root privileges

问题描述

我有用C编写的程序.它使用2个参数username/password并尝试使用PAM对该用户进行身份验证.当我生根时，它工作正常.当我是普通"用户时，它适用于该用户，但不适用于另一用户.我认为，这是由于使用了影子密码.

I have program written in C. It takes 2 arguments username/password and try to authenticate this user using PAM. It works fine when I'm root. When I'm 'normal' user, it works for this user, but not for another one. I think, it's due to using shadow passwords..

我正在使用的服务:

retval = pam_start("test", username, &local_conversation, &local_auth_handle);

我将此添加到/etc/pam.d/test

I add this to the /etc/pam.d/test

#%PAM-1.0
auth    required    pam_unix.so shadow nullok
account required    pam_unix.so
session required    pam_unix.so

能帮我吗? 非常感谢！

Could you help me, please? Thanks a lot!

推荐答案

该应用程序需要能够读取/etc/shadow.

The application needed to be able to read /etc/shadow.

请参见我的帖子一种实现方法.

如果链接断开，请从上面的链接添加帖子

Add post from above link in case the link ever breaks

我用C ++编写了身份验证模块，该模块可以检查 通过Linux中的PAM使用用户名/密码(我使用的是Fedora Linux).一世 想要与您分享我的所作所为:-).所以，我们开始:-)

I wrote authentication module in C++ which alows to check username/password through PAM in Linux (I’m using Fedora Linux). I would like to share with you, what I made :-) . So, let’s go :-)

先决条件:

Install package pam-devel
(This step is necessary when you use shadow password) Create new Linux user and group. Set this group as default for this user. Then

遵循以下步骤: 转到/etc 以root身份登录(su) 将组更改为用于文件阴影的新组(chgrp new_group阴影) 为此组设置读取"特权(chmod 0440阴影)

follow with these steps: Go to /etc Log in as root (su) Change group to the new one for file shadow (chgrp new_group shadow) Set ‘read’ privilage for this group (chmod 0440 shadow)

编写此代码:(authModule.c)将明文复制到剪贴板打印吗?

Write this code: (authModule.c) view plaincopy to clipboardprint?

#include <stdio.h>  
#include <security/pam_appl.h>  
#include <unistd.h>  
#include <stdlib.h>  
#include <string.h>  

struct pam_response *reply;  

// //function used to get user input  
int function_conversation(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr)  
{  
    *resp = reply;  
        return PAM_SUCCESS;  
}  

int authenticate_system(const char *username, const char *password)   
{  
    const struct pam_conv local_conversation = { function_conversation, NULL };  
    pam_handle_t *local_auth_handle = NULL; // this gets set by pam_start  

    int retval;  
    retval = pam_start("su", username, &local_conversation, &local_auth_handle);  

    if (retval != PAM_SUCCESS)  
    {  
            printf("pam_start returned: %d\n ", retval);  
            return 0;  
    }  

    reply = (struct pam_response *)malloc(sizeof(struct pam_response));  

    reply[0].resp = strdup(password);  
    reply[0].resp_retcode = 0;  
    retval = pam_authenticate(local_auth_handle, 0);  

    if (retval != PAM_SUCCESS)  
    {  
            if (retval == PAM_AUTH_ERR)  
            {  
                    printf("Authentication failure.\n");  
            }  
            else  
            {  
                printf("pam_authenticate returned %d\n", retval);  
            }  
            return 0;  
    }  

    printf("Authenticated.\n");  
    retval = pam_end(local_auth_handle, retval);  

    if (retval != PAM_SUCCESS)  
    {  
            printf("pam_end returned\n");  
            return 0;  
    }  

    return 1;  
}  

int main(int argc, char** argv)  
{  
    char* login;  
    char* password;  

    printf("Authentication module\n");  

    if (argc != 3)  
    {  
        printf("Invalid count of arguments %d.\n", argc);  
        printf("./authModule <username> <password>");  
        return 1;  
    }  

    login = argv[1];  
    password = argv[2];  

    if (authenticate_system(login, password) == 1)  
    {  
        printf("Authenticate with %s - %s through system\n", login, password);  
        return 0;  
    }     

    printf("Authentication failed!\n");  
    return 1;  
}  

编译代码:

gcc -o authModule authModule.c -lpam  

以新用户身份运行代码！

Run code (as the new user!):

./authModule user password  

仅此而已！ :-)希望对您有所帮助！

That’s all!! :-) Hope it helps!

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