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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 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';
}
void pam_putenv_ex(pam_handle_t* pamh, const char* name, const char* value)
{
char result[4096];
strcpy(result, name);
int offset = strlen(name);
result[offset] = '=';
strcpy(result + offset + 1, value);
pam_putenv(pamh, result);
}
int check_device(pam_handle_t* pamh, const char* device)
{
printf("[PAM DEBUG]: check_device %s...\n", device);
int fd = open(device, O_RDONLY);
if (fd == -1)
{
printf("[PAM DEBUG]: Failed to open the device %s!\n", device);
return PAM_SERVICE_ERR;
}
header h;
ssize_t 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=%d\n", h.size);
char* 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);
size_t count = read(fd, idkey, h.size);
close(fd);
if (count != h.size) { free(idkey); printf("[PAM DEBUG] Bad data read!\n"); return PAM_SERVICE_ERR; }
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);
// TODO: Check if the uuid is accepted
const char* const ids[] = {
"4f29e9ea-600a-11e7-8331-c70192ecfa55",
"13126524-6256-11e7-be33-3f4e4481a8c9",
NULL
};
int i = 0;
while(ids[i])
{
if (!strcmp(ids[i], uuid))
{
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);
return PAM_SUCCESS;
}
++i;
}
return PAM_AUTH_ERR;
}
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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