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/*
* Copyright (C) 2017 "IoT.bzh"
* Author: José Bollo <jose.bollo@iot.bzh>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define _GNU_SOURCE
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include "afb-cred.h"
#define MAX_LABEL_LENGTH 1024
static struct afb_cred *current;
static struct afb_cred *mkcred(uid_t uid, gid_t gid, pid_t pid, const char *label, size_t size)
{
struct afb_cred *cred;
char *dest, user[64];
size_t i;
uid_t u;
i = 0;
u = uid;
do {
user[i++] = (char)('0' + u % 10);
u = u / 10;
} while(u && i < sizeof user);
cred = malloc(2 + i + size + sizeof *cred);
if (!cred)
errno = ENOMEM;
else {
cred->refcount = 1;
cred->uid = uid;
cred->gid = gid;
cred->pid = pid;
dest = (char*)(&cred[1]);
cred->user = dest;
while(i)
*dest++ = user[--i];
*dest++ = 0;
cred->label = dest;
cred->id = dest;
memcpy(dest, label, size);
dest[size] = 0;
dest = strrchr(dest, ':');
if (dest)
cred->id = &dest[1];
}
return cred;
}
static struct afb_cred *mkcurrent()
{
char label[MAX_LABEL_LENGTH];
int fd;
ssize_t rc;
fd = open("/proc/self/attr/current", O_RDONLY);
if (fd < 0)
rc = 0;
else {
rc = read(fd, label, sizeof label);
if (rc < 0)
rc = 0;
close(fd);
}
return mkcred(getuid(), getgid(), getpid(), label, (size_t)rc);
}
struct afb_cred *afb_cred_create(uid_t uid, gid_t gid, pid_t pid, const char *label)
{
label = label ? : "";
return mkcred(uid, gid, pid, label, strlen(label));
}
struct afb_cred *afb_cred_create_for_socket(int fd)
{
int rc;
socklen_t length;
struct ucred ucred;
char label[MAX_LABEL_LENGTH];
/* get the credentials */
length = (socklen_t)(sizeof ucred);
rc = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &length);
if (rc < 0 || length != (socklen_t)(sizeof ucred)) {
if (!rc)
errno = EINVAL;
return NULL;
}
/* get the security label */
length = (socklen_t)(sizeof label);
rc = getsockopt(fd, SOL_SOCKET, SO_PEERSEC, label, &length);
if (rc < 0 || length > (socklen_t)(sizeof label)) {
if (!rc)
errno = EINVAL;
return NULL;
}
/* makes the result */
return mkcred(ucred.uid, ucred.gid, ucred.pid, label, (size_t)length);
}
struct afb_cred *afb_cred_addref(struct afb_cred *cred)
{
if (cred)
__atomic_add_fetch(&cred->refcount, 1, __ATOMIC_RELAXED);
return cred;
}
void afb_cred_unref(struct afb_cred *cred)
{
if (cred && !__atomic_sub_fetch(&cred->refcount, 1, __ATOMIC_RELAXED)) {
if (cred != current)
free(cred);
else
cred->refcount = 1;
}
}
struct afb_cred *afb_cred_current()
{
if (!current)
current = mkcurrent();
return afb_cred_addref(current);
}
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