wlroots/session/direct.c

421 lines
9.1 KiB
C

#define _POSIX_C_SOURCE 200809L
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <linux/kd.h>
#include <linux/major.h>
#include <linux/vt.h>
#include <wayland-server.h>
#include <xf86drm.h>
#include <wlr/session/interface.h>
#include <wlr/util/log.h>
#ifdef HAS_LIBCAP
#include <sys/capability.h>
#endif
enum { DRM_MAJOR = 226 };
const struct session_impl session_direct;
struct direct_session {
struct wlr_session base;
int tty_fd;
int old_kbmode;
int sock;
pid_t child;
struct wl_event_source *vt_source;
};
enum session_message_type {
SESSION_OPEN,
SESSION_SETMASTER,
SESSION_DROPMASTER,
SESSION_END,
};
struct session_message {
enum session_message_type type;
char path[60];
};
static int send_message(int sock, enum session_message_type type, const char *path) {
struct session_message msg = {
.type = type,
};
struct msghdr request = {
.msg_iov = &(struct iovec) {
.iov_base = &msg,
.iov_len = sizeof(msg),
},
.msg_iovlen = 1,
};
if (path) {
snprintf(msg.path, sizeof(msg.path), "%s", path);
}
sendmsg(sock, &request, 0);
int err = 0, fd = -1;
char control[CMSG_SPACE(sizeof(fd))] = {0};
struct msghdr reply = {
.msg_iov = &(struct iovec) {
.iov_base = &err,
.iov_len = sizeof(err),
},
.msg_iovlen = 1,
.msg_control = control,
.msg_controllen = sizeof(control),
};
recvmsg(sock, &reply, 0);
// The other types have no meaningful return value
if (type != SESSION_OPEN) {
return 0;
}
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&reply);
memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd));
return err ? -err : fd;
}
static int direct_session_open(struct wlr_session *base, const char *path) {
struct direct_session *session = wl_container_of(base, session, base);
struct stat st;
if (stat(path, &st)) {
return -errno;
}
uint32_t maj = major(st.st_rdev);
if (maj != DRM_MAJOR && maj != INPUT_MAJOR) {
return -EINVAL;
}
int fd = send_message(session->sock, SESSION_OPEN, path);
if (fd < 0) {
wlr_log(L_ERROR, "Failed to open %s: %s%s", path, strerror(-fd),
fd == -EINVAL ? "; is another display server running?" : "");
return fd;
}
if (maj == DRM_MAJOR) {
session->base.drm_fd = fd;
}
return fd;
}
static void direct_session_close(struct wlr_session *base, int fd) {
struct direct_session *session = wl_container_of(base, session, base);
if (fd == session->base.drm_fd) {
send_message(session->sock, SESSION_DROPMASTER, NULL);
session->base.drm_fd = -1;
}
close(fd);
}
static bool direct_change_vt(struct wlr_session *base, unsigned vt) {
struct direct_session *session = wl_container_of(base, session, base);
return ioctl(session->tty_fd, VT_ACTIVATE, (int)vt) == 0;
}
static void direct_session_finish(struct wlr_session *base) {
struct direct_session *session = wl_container_of(base, session, base);
struct vt_mode mode = {
.mode = VT_AUTO,
};
errno = 0;
ioctl(session->tty_fd, KDSKBMODE, session->old_kbmode);
ioctl(session->tty_fd, KDSETMODE, KD_TEXT);
ioctl(session->tty_fd, VT_SETMODE, &mode);
if (errno) {
wlr_log(L_ERROR, "Failed to restore tty");
}
send_message(session->sock, SESSION_END, NULL);
close(session->sock);
wait(NULL);
wl_event_source_remove(session->vt_source);
close(session->tty_fd);
free(session);
}
static int vt_handler(int signo, void *data) {
struct direct_session *session = data;
if (session->base.active) {
session->base.active = false;
wl_signal_emit(&session->base.session_signal, session);
send_message(session->sock, SESSION_DROPMASTER, NULL);
ioctl(session->tty_fd, VT_RELDISP, 1);
} else {
ioctl(session->tty_fd, VT_RELDISP, VT_ACKACQ);
send_message(session->sock, SESSION_SETMASTER, NULL);
session->base.active = true;
wl_signal_emit(&session->base.session_signal, session);
}
return 1;
}
static bool setup_tty(struct direct_session *session, struct wl_display *display) {
session->tty_fd = dup(STDIN_FILENO);
if (session->tty_fd == -1) {
wlr_log_errno(L_ERROR, "Cannot open tty");
return false;
}
struct stat st;
if (fstat(session->tty_fd, &st) == -1 || major(st.st_rdev) != TTY_MAJOR ||
minor(st.st_rdev) == 0) {
wlr_log(L_ERROR, "Not running from a virtual terminal");
goto error;
}
int tty = minor(st.st_rdev);
int ret, kd_mode;
session->base.vtnr = tty;
ret = ioctl(session->tty_fd, KDGETMODE, &kd_mode);
if (ret) {
wlr_log_errno(L_ERROR, "Failed to get tty mode");
goto error;
}
if (kd_mode != KD_TEXT) {
wlr_log(L_ERROR,
"tty already in graphics mode; is another display server running?");
goto error;
}
ioctl(session->tty_fd, VT_ACTIVATE, tty);
ioctl(session->tty_fd, VT_WAITACTIVE, tty);
if (ioctl(session->tty_fd, KDGKBMODE, &session->old_kbmode)) {
wlr_log_errno(L_ERROR, "Failed to read keyboard mode");
goto error;
}
if (ioctl(session->tty_fd, KDSKBMODE, K_OFF)) {
wlr_log_errno(L_ERROR, "Failed to set keyboard mode");
goto error;
}
if (ioctl(session->tty_fd, KDSETMODE, KD_GRAPHICS)) {
wlr_log_errno(L_ERROR, "Failed to set graphics mode on tty");
goto error;
}
struct vt_mode mode = {
.mode = VT_PROCESS,
.relsig = SIGUSR1,
.acqsig = SIGUSR1,
};
if (ioctl(session->tty_fd, VT_SETMODE, &mode) < 0) {
wlr_log(L_ERROR, "Failed to take control of tty");
goto error;
}
struct wl_event_loop *loop = wl_display_get_event_loop(display);
session->vt_source = wl_event_loop_add_signal(loop, SIGUSR1,
vt_handler, session);
if (!session->vt_source) {
goto error;
}
return true;
error:
close(session->tty_fd);
return false;
}
static void communicate(int sock) {
struct session_message msg;
struct msghdr hdr = {
.msg_iov = &(struct iovec) {
.iov_base = &msg,
.iov_len = sizeof(msg),
},
.msg_iovlen = 1,
};
int drm_fd = -1;
while (recvmsg(sock, &hdr, 0) >= 0 || errno == EINTR) {
switch (msg.type) {
case SESSION_OPEN:
errno = 0;
// These are the flags that logind use
int fd = open(msg.path, O_RDWR | O_CLOEXEC | O_NOCTTY | O_NONBLOCK);
int e = errno;
struct stat st;
if (fstat(fd, &st) >= 0 && major(st.st_rdev) == DRM_MAJOR) {
if (drmSetMaster(fd)) {
close(fd);
fd = -1;
e = errno;
}
drm_fd = fd;
}
char control[CMSG_SPACE(sizeof(fd))] = {0};
struct msghdr reply = {
.msg_iov = &(struct iovec) {
.iov_base = &e,
.iov_len = sizeof(e),
},
.msg_iovlen = 1,
.msg_control = &control,
.msg_controllen = sizeof(control),
};
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&reply);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
sendmsg(sock, &reply, 0);
break;
case SESSION_SETMASTER:
if (drm_fd != -1) {
drmSetMaster(drm_fd);
}
sendmsg(sock, &(struct msghdr){0}, 0);
break;
case SESSION_DROPMASTER:
if (drm_fd != -1) {
drmDropMaster(drm_fd);
}
sendmsg(sock, &(struct msghdr){0}, 0);
break;
case SESSION_END:
sendmsg(sock, &(struct msghdr){0}, 0);
return;
}
}
}
#ifdef HAS_LIBCAP
static bool have_permissions(void) {
cap_t cap = cap_get_proc();
cap_flag_value_t val;
if (!cap || cap_get_flag(cap, CAP_SYS_ADMIN, CAP_PERMITTED, &val) || val != CAP_SET) {
wlr_log(L_ERROR, "Do not have CAP_SYS_ADMIN; cannot become DRM master");
cap_free(cap);
return false;
}
cap_free(cap);
return true;
}
#else
static bool have_permissions(void) {
if (geteuid() != 0) {
wlr_log(L_ERROR, "Do not have root privileges; cannot become DRM master");
return false;
}
return true;
}
#endif
static struct wlr_session *direct_session_start(struct wl_display *disp) {
if (!have_permissions()) {
return NULL;
}
int sock[2];
if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sock) < 0) {
wlr_log_errno(L_ERROR, "Failed to create socket pair");
return NULL;
}
pid_t pid = fork();
if (pid < 0) {
wlr_log_errno(L_ERROR, "Fork failed");
goto error_sock;
} else if (pid == 0) {
close(sock[0]);
communicate(sock[1]);
_Exit(0);
}
close(sock[1]);
sock[1] = -1;
struct direct_session *session = calloc(1, sizeof(*session));
if (!session) {
wlr_log_errno(L_ERROR, "Allocation failed");
goto error_child;
}
session->child = pid;
session->sock = sock[0];
if (!setup_tty(session, disp)) {
goto error_session;
}
// XXX: Is it okay to trust the environment like this?
const char *seat = getenv("XDG_SEAT");
if (!seat) {
seat = "seat0";
}
wlr_log(L_INFO, "Successfully loaded direct session");
snprintf(session->base.seat, sizeof(session->base.seat), "%s", seat);
session->base.drm_fd = -1;
session->base.impl = &session_direct;
session->base.active = true;
wl_signal_init(&session->base.session_signal);
return &session->base;
error_session:
free(session);
error_child:
send_message(sock[0], SESSION_END, NULL);
wait(NULL);
error_sock:
close(sock[0]);
close(sock[1]);
return NULL;
}
const struct session_impl session_direct = {
.start = direct_session_start,
.finish = direct_session_finish,
.open = direct_session_open,
.close = direct_session_close,
.change_vt = direct_change_vt,
};