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#include <fcntl.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <uuid/uuid.h>
#include <json-c/json.h>
#define PAM_SM_AUTH
#define PAM_SM_ACCOUNT
#define PAM_SM_SESSION
#define PAM_SM_PASSWORD
#include <security/pam_modules.h>
#include <security/pam_appl.h>
#define DATABASE_FILE "/etc/agl/keys.json"
#define BLOCK_SIZE 4096
typedef struct header_
{
char mn[4];
size_t size;
} header;
int is_valid_mn(const char* v)
{
return v && v[0] == 'I' && v[1] == 'D' && v[2] == 'K' && v[3] == 'Y';
}
char* get_file_content(const char* path)
{
char* buffer;
long length;
FILE* f;
buffer = NULL;
length = 0;
f = fopen(path, "rb");
if (f)
{
fseek(f, 0, SEEK_END);
length = ftell(f);
fseek(f, 0, SEEK_SET);
buffer = malloc(length + 1);
if (buffer)
{
if (fread (buffer, 1, length, f) != length)
{
free(buffer);
buffer = NULL;
}
else buffer[length] = 0;
}
fclose (f);
}
return buffer;
}
int read_device(const char* device, char** idkey)
{
int fd;
ssize_t sz;
header h;
printf("[PAM DEBUG] check_device %s...\n", device);
fd = open(device, O_RDONLY);
if (fd == -1)
{
printf("[PAM DEBUG] Failed to open the device %s!\n", device);
return PAM_SERVICE_ERR;
}
sz = read(fd, &h, sizeof(header));
if (sz != sizeof(header) || !is_valid_mn(h.mn) || h.size < 1) { close(fd); printf("[PAM DEBUG]: bad header!\n"); return PAM_SERVICE_ERR; }
printf("[PAM DEBUG]: data size=%lu\n", h.size);
*idkey = (char*)malloc(h.size + 1);
if (!*idkey) { close(fd); printf("[PAM DEBUG] Bad alloc!\n"); return PAM_SERVICE_ERR; }
memset(*idkey, 0, h.size + 1);
sz = read(fd, *idkey, h.size);
close(fd);
if (sz != h.size) { free(idkey); printf("[PAM DEBUG] Bad data read!\n"); return PAM_SERVICE_ERR; }
return PAM_SUCCESS;
}
int authenticate(pam_handle_t* pamh, const char* uuid)
{
char* file_content;
struct json_object* database;
struct json_object* key;
file_content = get_file_content(DATABASE_FILE);
if (!file_content)
{
printf("[PAM DEBUG] Failed to read database file (%s)\n", DATABASE_FILE);
return PAM_SERVICE_ERR;
}
database = json_tokener_parse(file_content);
if (!database)
{
printf("[PAM DEBUG] Failed to parse the database\n");
return PAM_SERVICE_ERR;
}
if (json_object_object_get_ex(database, uuid, &key))
{
printf("[PAM] Key found!\n");
printf("[PAM DEBUG] pam_set_item(\"%s\")\n", uuid);
pam_set_item(pamh, PAM_USER, uuid);
const char* pam_authtok;
if (pam_get_item(pamh, PAM_AUTHTOK, (const void**)&pam_authtok) == PAM_SUCCESS && !pam_authtok)
pam_set_item(pamh, PAM_AUTHTOK, uuid);
json_object_put(database);
free(file_content);
return PAM_SUCCESS;
}
printf("[PAM] Key not found!\n");
free(file_content);
if (database) json_object_put(database);
return PAM_AUTH_ERR;
}
int check_device(pam_handle_t* pamh, const char* device)
{
char* idkey;
int ret;
ret = read_device(device, &idkey);
if (ret != PAM_SUCCESS) return ret;
printf("[PAM DEBUG] Data read:\n%s\n", idkey);
json_object* idkey_json = json_tokener_parse(idkey);
if (!idkey_json)
{
free(idkey);
printf("[PAM DEBUG] Failed to parse json data!\n");
return PAM_SERVICE_ERR;
}
json_object* uuid_json;
if(!json_object_object_get_ex(idkey_json, "uuid", &uuid_json))
{
free(idkey);
printf("[PAM DEBUG] The json does not contains a valid uuid\n");
return PAM_SERVICE_ERR;
}
const char* uuid = json_object_get_string(uuid_json);
printf("[PAM DEBUG] uuid: %s\n", uuid);
ret = authenticate(pamh, uuid);
free(idkey);
json_object_put(idkey_json);
return ret;
}
void log_pam(const char* fname, int flags, int argc, const char** argv, const char* device)
{
printf("[PAM DEBUG] ---------- %s ----------\n", fname);
printf("[PAM DEBUG] flags: %d\n", flags);
for(int i = 0; i < argc; ++i)
{
printf("[PAM DEBUG] argv[%d]: %s\n", i, argv[i]);
}
printf("[PAM DEBUG] device: %s\n", device);
printf("[PAM DEBUG] ----------------------------------------\n");
}
/*!
@brief The pam_sm_authenticate function is the service module's implementation
of the pam_authenticate(3) interface.
This function performs the task of authenticating the user.
@param[in] pamh Unknown.
@param[in] flags PAM_SILENT and/or PAM_DISALLOW_NULL_AUTHTOK.
@return PAM_SUCCESS if ok.
*/
PAM_EXTERN int pam_sm_authenticate(pam_handle_t* pamh, int flags, int argc, const char** argv)
{
const char* device = pam_getenv(pamh, "DEVICE");
log_pam("pam_sm_authenticate", flags, argc, argv, device);
return check_device(pamh, device);
}
PAM_EXTERN int pam_sm_setcred(pam_handle_t* pamh, int flags, int argc, const char** argv)
{
log_pam("pam_sm_setcred", flags, argc, argv, pam_getenv(pamh, "DEVICE"));
return PAM_SUCCESS;
}
PAM_EXTERN int pam_sm_acct_mgmt(pam_handle_t* pamh, int flags, int argc, const char** argv)
{
log_pam("pam_sm_acct_mgmt", flags, argc, argv, pam_getenv(pamh, "DEVICE"));
return PAM_SUCCESS;
}
PAM_EXTERN int pam_sm_open_session(pam_handle_t* pamh, int flags, int argc, const char** argv)
{
log_pam("pam_sm_open_session", flags, argc, argv, pam_getenv(pamh, "DEVICE"));
return PAM_SUCCESS;
}
PAM_EXTERN int pam_sm_close_session(pam_handle_t* pamh, int flags, int argc, const char** argv)
{
log_pam("pam_sm_close_session", flags, argc, argv, pam_getenv(pamh, "DEVICE"));
return PAM_SUCCESS;
}
PAM_EXTERN int pam_sm_chauthtok(pam_handle_t* pamh, int flags, int argc, const char** argv)
{
log_pam("pam_sm_chauthtok", flags, argc, argv, pam_getenv(pamh, "DEVICE"));
return PAM_SUCCESS;
}
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