--- /dev/null
+/* scm.c - Socket level control messages processing.
+ *
+ * Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ * Alignment and value checking mods by Craig Metz
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/signal.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/kernel.h>
+#include <linux/stat.h>
+#include <linux/socket.h>
+#include <linux/file.h>
+#include <linux/fcntl.h>
+#include <linux/net.h>
+#include <linux/interrupt.h>
+#include <linux/netdevice.h>
+#include <linux/security.h>
+#include <linux/pid_namespace.h>
+#include <linux/pid.h>
+#include <linux/nsproxy.h>
+#include <linux/slab.h>
+
+#include <asm/uaccess.h>
+
+#include <net/protocol.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/compat.h>
+#include <net/scm.h>
+#include <net/cls_cgroup.h>
+
+
+/*
+ * Only allow a user to send credentials, that they could set with
+ * setu(g)id.
+ */
+
+static __inline__ int scm_check_creds(struct ucred *creds)
+{
+ const struct cred *cred = current_cred();
+ kuid_t uid = make_kuid(cred->user_ns, creds->uid);
+ kgid_t gid = make_kgid(cred->user_ns, creds->gid);
+
+ if (!uid_valid(uid) || !gid_valid(gid))
+ return -EINVAL;
+
+ if ((creds->pid == task_tgid_vnr(current) ||
+ ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) &&
+ ((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) ||
+ uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) &&
+ ((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) ||
+ gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) {
+ return 0;
+ }
+ return -EPERM;
+}
+
+static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
+{
+ int *fdp = (int*)CMSG_DATA(cmsg);
+ struct scm_fp_list *fpl = *fplp;
+ struct file **fpp;
+ int i, num;
+
+ num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
+
+ if (num <= 0)
+ return 0;
+
+ if (num > SCM_MAX_FD)
+ return -EINVAL;
+
+ if (!fpl)
+ {
+ fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
+ if (!fpl)
+ return -ENOMEM;
+ *fplp = fpl;
+ fpl->count = 0;
+ fpl->max = SCM_MAX_FD;
+ }
+ fpp = &fpl->fp[fpl->count];
+
+ if (fpl->count + num > fpl->max)
+ return -EINVAL;
+
+ /*
+ * Verify the descriptors and increment the usage count.
+ */
+
+ for (i=0; i< num; i++)
+ {
+ int fd = fdp[i];
+ struct file *file;
+
+ if (fd < 0 || !(file = fget_raw(fd)))
+ return -EBADF;
+ *fpp++ = file;
+ fpl->count++;
+ }
+ return num;
+}
+
+void __scm_destroy(struct scm_cookie *scm)
+{
+ struct scm_fp_list *fpl = scm->fp;
+ int i;
+
+ if (fpl) {
+ scm->fp = NULL;
+ for (i=fpl->count-1; i>=0; i--)
+ fput(fpl->fp[i]);
+ kfree(fpl);
+ }
+}
+EXPORT_SYMBOL(__scm_destroy);
+
+int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
+{
+ struct cmsghdr *cmsg;
+ int err;
+
+ for_each_cmsghdr(cmsg, msg) {
+ err = -EINVAL;
+
+ /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
+ /* The first check was omitted in <= 2.2.5. The reasoning was
+ that parser checks cmsg_len in any case, so that
+ additional check would be work duplication.
+ But if cmsg_level is not SOL_SOCKET, we do not check
+ for too short ancillary data object at all! Oops.
+ OK, let's add it...
+ */
+ if (!CMSG_OK(msg, cmsg))
+ goto error;
+
+ if (cmsg->cmsg_level != SOL_SOCKET)
+ continue;
+
+ switch (cmsg->cmsg_type)
+ {
+ case SCM_RIGHTS:
+ if (!sock->ops || sock->ops->family != PF_UNIX)
+ goto error;
+ err=scm_fp_copy(cmsg, &p->fp);
+ if (err<0)
+ goto error;
+ break;
+ case SCM_CREDENTIALS:
+ {
+ struct ucred creds;
+ kuid_t uid;
+ kgid_t gid;
+ if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
+ goto error;
+ memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
+ err = scm_check_creds(&creds);
+ if (err)
+ goto error;
+
+ p->creds.pid = creds.pid;
+ if (!p->pid || pid_vnr(p->pid) != creds.pid) {
+ struct pid *pid;
+ err = -ESRCH;
+ pid = find_get_pid(creds.pid);
+ if (!pid)
+ goto error;
+ put_pid(p->pid);
+ p->pid = pid;
+ }
+
+ err = -EINVAL;
+ uid = make_kuid(current_user_ns(), creds.uid);
+ gid = make_kgid(current_user_ns(), creds.gid);
+ if (!uid_valid(uid) || !gid_valid(gid))
+ goto error;
+
+ p->creds.uid = uid;
+ p->creds.gid = gid;
+ break;
+ }
+ default:
+ goto error;
+ }
+ }
+
+ if (p->fp && !p->fp->count)
+ {
+ kfree(p->fp);
+ p->fp = NULL;
+ }
+ return 0;
+
+error:
+ scm_destroy(p);
+ return err;
+}
+EXPORT_SYMBOL(__scm_send);
+
+int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
+{
+ struct cmsghdr __user *cm
+ = (__force struct cmsghdr __user *)msg->msg_control;
+ struct cmsghdr cmhdr;
+ int cmlen = CMSG_LEN(len);
+ int err;
+
+ if (MSG_CMSG_COMPAT & msg->msg_flags)
+ return put_cmsg_compat(msg, level, type, len, data);
+
+ if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
+ msg->msg_flags |= MSG_CTRUNC;
+ return 0; /* XXX: return error? check spec. */
+ }
+ if (msg->msg_controllen < cmlen) {
+ msg->msg_flags |= MSG_CTRUNC;
+ cmlen = msg->msg_controllen;
+ }
+ cmhdr.cmsg_level = level;
+ cmhdr.cmsg_type = type;
+ cmhdr.cmsg_len = cmlen;
+
+ err = -EFAULT;
+ if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
+ goto out;
+ if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
+ goto out;
+ cmlen = CMSG_SPACE(len);
+ if (msg->msg_controllen < cmlen)
+ cmlen = msg->msg_controllen;
+ msg->msg_control += cmlen;
+ msg->msg_controllen -= cmlen;
+ err = 0;
+out:
+ return err;
+}
+EXPORT_SYMBOL(put_cmsg);
+
+void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
+{
+ struct cmsghdr __user *cm
+ = (__force struct cmsghdr __user*)msg->msg_control;
+
+ int fdmax = 0;
+ int fdnum = scm->fp->count;
+ struct file **fp = scm->fp->fp;
+ int __user *cmfptr;
+ int err = 0, i;
+
+ if (MSG_CMSG_COMPAT & msg->msg_flags) {
+ scm_detach_fds_compat(msg, scm);
+ return;
+ }
+
+ if (msg->msg_controllen > sizeof(struct cmsghdr))
+ fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
+ / sizeof(int));
+
+ if (fdnum < fdmax)
+ fdmax = fdnum;
+
+ for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
+ i++, cmfptr++)
+ {
+ struct socket *sock;
+ int new_fd;
+ err = security_file_receive(fp[i]);
+ if (err)
+ break;
+ err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
+ ? O_CLOEXEC : 0);
+ if (err < 0)
+ break;
+ new_fd = err;
+ err = put_user(new_fd, cmfptr);
+ if (err) {
+ put_unused_fd(new_fd);
+ break;
+ }
+ /* Bump the usage count and install the file. */
+ sock = sock_from_file(fp[i], &err);
+ if (sock) {
+ sock_update_netprioidx(sock->sk);
+ sock_update_classid(sock->sk);
+ }
+ fd_install(new_fd, get_file(fp[i]));
+ }
+
+ if (i > 0)
+ {
+ int cmlen = CMSG_LEN(i*sizeof(int));
+ err = put_user(SOL_SOCKET, &cm->cmsg_level);
+ if (!err)
+ err = put_user(SCM_RIGHTS, &cm->cmsg_type);
+ if (!err)
+ err = put_user(cmlen, &cm->cmsg_len);
+ if (!err) {
+ cmlen = CMSG_SPACE(i*sizeof(int));
+ msg->msg_control += cmlen;
+ msg->msg_controllen -= cmlen;
+ }
+ }
+ if (i < fdnum || (fdnum && fdmax <= 0))
+ msg->msg_flags |= MSG_CTRUNC;
+
+ /*
+ * All of the files that fit in the message have had their
+ * usage counts incremented, so we just free the list.
+ */
+ __scm_destroy(scm);
+}
+EXPORT_SYMBOL(scm_detach_fds);
+
+struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
+{
+ struct scm_fp_list *new_fpl;
+ int i;
+
+ if (!fpl)
+ return NULL;
+
+ new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
+ GFP_KERNEL);
+ if (new_fpl) {
+ for (i = 0; i < fpl->count; i++)
+ get_file(fpl->fp[i]);
+ new_fpl->max = new_fpl->count;
+ }
+ return new_fpl;
+}
+EXPORT_SYMBOL(scm_fp_dup);
Code Review / kvmfornfv.git / blobdiff