Add computation of credentials

[src/app-framework-binder.git] / src / afb-cred.c

diff --git a/src/afb-cred.c b/src/afb-cred.c
new file mode 100644 (file)
index 0000000..8a77700
--- /dev/null
+++ b/src/afb-cred.c
@@ -0,0 +1,136 @@
+/*
+ * 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;
+
+       cred = malloc(1 + size + sizeof *cred);
+       if (!cred)
+               errno = ENOMEM;
+       else {
+               cred->refcount = 1;
+               cred->uid = uid;
+               cred->gid = gid;
+               cred->pid = pid;
+               dest = (char*)(&cred[1]);
+               memcpy(dest, label, size);
+               dest[size] = 0;
+               cred->label = dest;
+               cred->id = dest;
+               dest = strrchr(dest, ':');
+               if (dest && dest[1])
+                       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);
+}
+