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contrib/dhcpcd/src/privsep-control.c
- This file was added.
/* SPDX-License-Identifier: BSD-2-Clause */ | |||||
/* | |||||
* Privilege Separation for dhcpcd, control proxy | |||||
* Copyright (c) 2006-2021 Roy Marples <roy@marples.name> | |||||
* All rights reserved | |||||
* Redistribution and use in source and binary forms, with or without | |||||
* modification, are permitted provided that the following conditions | |||||
* are met: | |||||
* 1. Redistributions of source code must retain the above copyright | |||||
* notice, this list of conditions and the following disclaimer. | |||||
* 2. Redistributions in binary form must reproduce the above copyright | |||||
* notice, this list of conditions and the following disclaimer in the | |||||
* documentation and/or other materials provided with the distribution. | |||||
* | |||||
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND | |||||
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |||||
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |||||
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | |||||
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |||||
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |||||
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |||||
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |||||
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |||||
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |||||
* SUCH DAMAGE. | |||||
*/ | |||||
#include <errno.h> | |||||
#include <stdlib.h> | |||||
#include <string.h> | |||||
#include "dhcpcd.h" | |||||
#include "control.h" | |||||
#include "eloop.h" | |||||
#include "logerr.h" | |||||
#include "privsep.h" | |||||
static int | |||||
ps_ctl_startcb(void *arg) | |||||
{ | |||||
struct dhcpcd_ctx *ctx = arg; | |||||
sa_family_t af; | |||||
if (ctx->options & DHCPCD_MANAGER) { | |||||
setproctitle("[control proxy]"); | |||||
af = AF_UNSPEC; | |||||
} else { | |||||
setproctitle("[control proxy] %s%s%s", | |||||
ctx->ifv[0], | |||||
ctx->options & DHCPCD_IPV4 ? " [ip4]" : "", | |||||
ctx->options & DHCPCD_IPV6 ? " [ip6]" : ""); | |||||
if ((ctx->options & | |||||
(DHCPCD_IPV4 | DHCPCD_IPV6)) == DHCPCD_IPV4) | |||||
af = AF_INET; | |||||
else if ((ctx->options & | |||||
(DHCPCD_IPV4 | DHCPCD_IPV6)) == DHCPCD_IPV6) | |||||
af = AF_INET6; | |||||
else | |||||
af = AF_UNSPEC; | |||||
} | |||||
ctx->ps_control_pid = getpid(); | |||||
return control_start(ctx, | |||||
ctx->options & DHCPCD_MANAGER ? NULL : *ctx->ifv, af); | |||||
} | |||||
static ssize_t | |||||
ps_ctl_recvmsgcb(void *arg, struct ps_msghdr *psm, __unused struct msghdr *msg) | |||||
{ | |||||
struct dhcpcd_ctx *ctx = arg; | |||||
if (psm->ps_cmd != PS_CTL_EOF) { | |||||
errno = ENOTSUP; | |||||
return -1; | |||||
} | |||||
if (ctx->ps_control_client != NULL) | |||||
ctx->ps_control_client = NULL; | |||||
return 0; | |||||
} | |||||
static void | |||||
ps_ctl_recvmsg(void *arg) | |||||
{ | |||||
struct dhcpcd_ctx *ctx = arg; | |||||
if (ps_recvpsmsg(ctx, ctx->ps_control_fd, ps_ctl_recvmsgcb, ctx) == -1) | |||||
logerr(__func__); | |||||
} | |||||
ssize_t | |||||
ps_ctl_handleargs(struct fd_list *fd, char *data, size_t len) | |||||
{ | |||||
/* Make any change here in dhcpcd.c as well. */ | |||||
if (strncmp(data, "--version", | |||||
MIN(strlen("--version"), len)) == 0) { | |||||
return control_queue(fd, UNCONST(VERSION), | |||||
strlen(VERSION) + 1); | |||||
} else if (strncmp(data, "--getconfigfile", | |||||
MIN(strlen("--getconfigfile"), len)) == 0) { | |||||
return control_queue(fd, UNCONST(fd->ctx->cffile), | |||||
strlen(fd->ctx->cffile) + 1); | |||||
} else if (strncmp(data, "--listen", | |||||
MIN(strlen("--listen"), len)) == 0) { | |||||
fd->flags |= FD_LISTEN; | |||||
return 0; | |||||
} | |||||
if (fd->ctx->ps_control_client != NULL && | |||||
fd->ctx->ps_control_client != fd) | |||||
{ | |||||
logerrx("%s: cannot handle another client", __func__); | |||||
return 0; | |||||
} | |||||
return 1; | |||||
} | |||||
static ssize_t | |||||
ps_ctl_dispatch(void *arg, struct ps_msghdr *psm, struct msghdr *msg) | |||||
{ | |||||
struct dhcpcd_ctx *ctx = arg; | |||||
struct iovec *iov = msg->msg_iov; | |||||
struct fd_list *fd; | |||||
unsigned int fd_flags = FD_SENDLEN; | |||||
switch (psm->ps_flags) { | |||||
case PS_CTL_PRIV: | |||||
break; | |||||
case PS_CTL_UNPRIV: | |||||
fd_flags |= FD_UNPRIV; | |||||
break; | |||||
} | |||||
switch (psm->ps_cmd) { | |||||
case PS_CTL: | |||||
if (msg->msg_iovlen != 1) { | |||||
errno = EINVAL; | |||||
return -1; | |||||
} | |||||
if (ctx->ps_control_client != NULL) { | |||||
logerrx("%s: cannot handle another client", __func__); | |||||
return 0; | |||||
} | |||||
fd = control_new(ctx, ctx->ps_control_data_fd, fd_flags); | |||||
if (fd == NULL) | |||||
return -1; | |||||
ctx->ps_control_client = fd; | |||||
control_recvdata(fd, iov->iov_base, iov->iov_len); | |||||
break; | |||||
case PS_CTL_EOF: | |||||
control_free(ctx->ps_control_client); | |||||
break; | |||||
default: | |||||
errno = ENOTSUP; | |||||
return -1; | |||||
} | |||||
return 0; | |||||
} | |||||
static void | |||||
ps_ctl_dodispatch(void *arg) | |||||
{ | |||||
struct dhcpcd_ctx *ctx = arg; | |||||
if (ps_recvpsmsg(ctx, ctx->ps_control_fd, ps_ctl_dispatch, ctx) == -1) | |||||
logerr(__func__); | |||||
} | |||||
static void | |||||
ps_ctl_recv(void *arg) | |||||
{ | |||||
struct dhcpcd_ctx *ctx = arg; | |||||
char buf[BUFSIZ]; | |||||
ssize_t len; | |||||
errno = 0; | |||||
len = read(ctx->ps_control_data_fd, buf, sizeof(buf)); | |||||
if (len == -1 || len == 0) { | |||||
logerr("%s: read", __func__); | |||||
eloop_exit(ctx->eloop, EXIT_FAILURE); | |||||
return; | |||||
} | |||||
if (ctx->ps_control_client == NULL) /* client disconnected */ | |||||
return; | |||||
errno = 0; | |||||
if (control_queue(ctx->ps_control_client, buf, (size_t)len) == -1) | |||||
logerr("%s: control_queue", __func__); | |||||
} | |||||
static void | |||||
ps_ctl_listen(void *arg) | |||||
{ | |||||
struct dhcpcd_ctx *ctx = arg; | |||||
char buf[BUFSIZ]; | |||||
ssize_t len; | |||||
struct fd_list *fd; | |||||
errno = 0; | |||||
len = read(ctx->ps_control->fd, buf, sizeof(buf)); | |||||
if (len == -1 || len == 0) { | |||||
logerr("%s: read", __func__); | |||||
eloop_exit(ctx->eloop, EXIT_FAILURE); | |||||
return; | |||||
} | |||||
/* Send to our listeners */ | |||||
TAILQ_FOREACH(fd, &ctx->control_fds, next) { | |||||
if (!(fd->flags & FD_LISTEN)) | |||||
continue; | |||||
if (control_queue(fd, buf, (size_t)len)== -1) | |||||
logerr("%s: control_queue", __func__); | |||||
} | |||||
} | |||||
pid_t | |||||
ps_ctl_start(struct dhcpcd_ctx *ctx) | |||||
{ | |||||
int data_fd[2], listen_fd[2]; | |||||
pid_t pid; | |||||
if (xsocketpair(AF_UNIX, SOCK_STREAM | SOCK_CXNB, 0, data_fd) == -1 || | |||||
xsocketpair(AF_UNIX, SOCK_STREAM | SOCK_CXNB, 0, listen_fd) == -1) | |||||
return -1; | |||||
#ifdef PRIVSEP_RIGHTS | |||||
if (ps_rights_limit_fdpair(data_fd) == -1 || | |||||
ps_rights_limit_fdpair(listen_fd) == -1) | |||||
return -1; | |||||
#endif | |||||
pid = ps_dostart(ctx, &ctx->ps_control_pid, &ctx->ps_control_fd, | |||||
ps_ctl_recvmsg, ps_ctl_dodispatch, ctx, | |||||
ps_ctl_startcb, NULL, | |||||
PSF_DROPPRIVS); | |||||
if (pid == -1) | |||||
return -1; | |||||
else if (pid != 0) { | |||||
ctx->ps_control_data_fd = data_fd[1]; | |||||
close(data_fd[0]); | |||||
ctx->ps_control = control_new(ctx, | |||||
listen_fd[1], FD_SENDLEN | FD_LISTEN); | |||||
if (ctx->ps_control == NULL) | |||||
return -1; | |||||
close(listen_fd[0]); | |||||
return pid; | |||||
} | |||||
ctx->ps_control_data_fd = data_fd[0]; | |||||
close(data_fd[1]); | |||||
if (eloop_event_add(ctx->eloop, ctx->ps_control_data_fd, | |||||
ps_ctl_recv, ctx) == -1) | |||||
return -1; | |||||
ctx->ps_control = control_new(ctx, | |||||
listen_fd[0], 0); | |||||
close(listen_fd[1]); | |||||
if (ctx->ps_control == NULL) | |||||
return -1; | |||||
if (eloop_event_add(ctx->eloop, ctx->ps_control->fd, | |||||
ps_ctl_listen, ctx) == -1) | |||||
return -1; | |||||
ps_entersandbox("stdio inet", NULL); | |||||
return 0; | |||||
} | |||||
int | |||||
ps_ctl_stop(struct dhcpcd_ctx *ctx) | |||||
{ | |||||
return ps_dostop(ctx, &ctx->ps_control_pid, &ctx->ps_control_fd); | |||||
} | |||||
ssize_t | |||||
ps_ctl_sendargs(struct fd_list *fd, void *data, size_t len) | |||||
{ | |||||
struct dhcpcd_ctx *ctx = fd->ctx; | |||||
if (ctx->ps_control_client != NULL && ctx->ps_control_client != fd) | |||||
logerrx("%s: cannot deal with another client", __func__); | |||||
ctx->ps_control_client = fd; | |||||
return ps_sendcmd(ctx, ctx->ps_control_fd, PS_CTL, | |||||
fd->flags & FD_UNPRIV ? PS_CTL_UNPRIV : PS_CTL_PRIV, | |||||
data, len); | |||||
} | |||||
ssize_t | |||||
ps_ctl_sendeof(struct fd_list *fd) | |||||
{ | |||||
struct dhcpcd_ctx *ctx = fd->ctx; | |||||
return ps_sendcmd(ctx, ctx->ps_control_fd, PS_CTL_EOF, 0, NULL, 0); | |||||
} |