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gpu-screen-recorder/kms/client/kms_client.c

251 lines
8.7 KiB
C
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#include "kms_client.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <limits.h>
#include <stdbool.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <sys/capability.h>
static bool is_inside_flatpak(void) {
return getenv("FLATPAK_ID") != NULL;
}
static int send_msg_to_server(int server_fd, gsr_kms_request *request) {
struct iovec iov;
iov.iov_base = request;
iov.iov_len = sizeof(*request);
struct msghdr request_message = {0};
request_message.msg_iov = &iov;
request_message.msg_iovlen = 1;
return sendmsg(server_fd, &request_message, 0);
}
static int recv_msg_from_server(int server_fd, gsr_kms_response *response) {
struct iovec iov;
iov.iov_base = response;
iov.iov_len = sizeof(*response);
struct msghdr response_message = {0};
response_message.msg_iov = &iov;
response_message.msg_iovlen = 1;
char cmsgbuf[CMSG_SPACE(sizeof(int))];
memset(cmsgbuf, 0, sizeof(cmsgbuf));
response_message.msg_control = cmsgbuf;
response_message.msg_controllen = sizeof(cmsgbuf);
int res = recvmsg(server_fd, &response_message, MSG_WAITALL);
if(res <= 0)
return res;
if(response->result == KMS_RESULT_OK)
response->data.fd.fd = 0;
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&response_message);
if(cmsg) {
fprintf(stderr, "got cmsg, %d\n", cmsg->cmsg_type);
if(cmsg->cmsg_type == SCM_RIGHTS) {
int kms_fd = 0;
memcpy(&kms_fd, CMSG_DATA(cmsg), sizeof(int));
fprintf(stderr, "kms fd: %d\n", kms_fd);
response->data.fd.fd = kms_fd;
}
}
return res;
}
int gsr_kms_client_init(gsr_kms_client *self, const char *card_path) {
self->kms_server_pid = -1;
self->card_path = NULL;
self->socket_fd = -1;
self->client_fd = -1;
self->socket_path[0] = '\0';
struct sockaddr_un local_addr = {0};
struct sockaddr_un remote_addr = {0};
// This doesn't work on nixos, but we dont want to use $PATH because we want to make this as safe as possible by running pkexec
// on a path that only root can modify. If we use "gsr-kms-server" instead then $PATH can be modified in ~/.bashrc for example
// which will overwrite the path to gsr-kms-server and the user can end up running a malicious program that pretends to be gsr-kms-server.
// If there is a safe way to do this on nixos, then please tell me; or use gpu-screen-recorder flatpak instead.
const char *server_filepath = "/usr/bin/gsr-kms-server";
bool has_perm = 0;
bool inside_flatpak = is_inside_flatpak();
if(!inside_flatpak) {
if(access("/usr/bin/gsr-kms-server", F_OK) != 0) {
fprintf(stderr, "gsr error: gsr_kms_client_init: /usr/bin/gsr-kms-server not found, please install gpu-screen-recorder first\n");
return -1;
}
if(geteuid() == 0) {
has_perm = true;
} else {
cap_t kms_server_cap = cap_get_file(server_filepath);
if(kms_server_cap) {
cap_flag_value_t res = 0;
cap_get_flag(kms_server_cap, CAP_SYS_ADMIN, CAP_PERMITTED, &res);
if(res == CAP_SET) {
//fprintf(stderr, "has permission!\n");
has_perm = true;
} else {
//fprintf(stderr, "No permission:(\n");
}
cap_free(kms_server_cap);
} else {
if(errno == ENODATA)
fprintf(stderr, "gsr info: gsr_kms_client_init: gsr-kms-server is missing sys_admin cap and will require root authentication. To bypass this automatically, run: sudo setcap cap_sys_admin+ep '%s'\n", server_filepath);
else
fprintf(stderr, "gsr info: gsr_kms_client_init: failed to get cap\n");
}
}
}
self->card_path = strdup(card_path);
if(!self->card_path) {
fprintf(stderr, "gsr error: gsr_kms_client_init: failed to duplicate card_path\n");
goto err;
}
strcpy(self->socket_path, "/tmp/gsr-kms-socket-XXXXXX");
if(!tmpnam(self->socket_path)) {
fprintf(stderr, "gsr error: gsr_kms_client_init: mkstemp failed, error: %s\n", strerror(errno));
goto err;
}
self->socket_fd = socket(AF_UNIX, SOCK_STREAM, 0);
if(self->socket_fd == -1) {
fprintf(stderr, "gsr error: gsr_kms_client_init: socket failed, error: %s\n", strerror(errno));
goto err;
}
local_addr.sun_family = AF_UNIX;
strncpy(local_addr.sun_path, self->socket_path, sizeof(local_addr.sun_path));
if(bind(self->socket_fd, (struct sockaddr*)&local_addr, sizeof(local_addr.sun_family) + strlen(local_addr.sun_path)) == -1) {
fprintf(stderr, "gsr error: gsr_kms_client_init: failed to bind socket, error: %s\n", strerror(errno));
goto err;
}
if(listen(self->socket_fd, 1) == -1) {
fprintf(stderr, "gsr error: gsr_kms_client_init: failed to listen on socket, error: %s\n", strerror(errno));
goto err;
}
pid_t pid = fork();
if(pid == -1) {
fprintf(stderr, "gsr error: gsr_kms_client_init: fork failed, error: %s\n", strerror(errno));
goto err;
} else if(pid == 0) { /* child */
if(inside_flatpak) {
const char *args[] = { "flatpak-spawn", "--host", "pkexec", "flatpak", "run", "--command=gsr-kms-server", "com.dec05eba.gpu_screen_recorder", self->socket_path, NULL };
execvp(args[0], (char *const*)args);
} else if(has_perm) {
const char *args[] = { server_filepath, self->socket_path, NULL };
execvp(args[0], (char *const*)args);
} else {
const char *args[] = { "pkexec", server_filepath, self->socket_path, NULL };
execvp(args[0], (char *const*)args);
}
fprintf(stderr, "gsr error: gsr_kms_client_init: execvp failed, error: %s\n", strerror(errno));
_exit(127);
} else { /* parent */
self->kms_server_pid = pid;
}
fprintf(stderr, "gsr info: gsr_kms_client_init: waiting for client to connect\n");
for(;;) {
struct timeval tv;
fd_set rfds;
FD_ZERO(&rfds);
FD_SET(self->socket_fd, &rfds);
tv.tv_sec = 0;
tv.tv_usec = 100 * 1000; // 100 ms
int select_res = select(1 + self->socket_fd, &rfds, NULL, NULL, &tv);
if(select_res > 0) {
socklen_t sock_len = 0;
self->client_fd = accept(self->socket_fd, (struct sockaddr*)&remote_addr, &sock_len);
if(self->client_fd == -1) {
fprintf(stderr, "gsr error: gsr_kms_client_init: accept failed on socket, error: %s\n", strerror(errno));
goto err;
}
break;
} else {
int status;
int wait_result = waitpid(self->kms_server_pid, &status, WNOHANG);
if(wait_result != 0) {
fprintf(stderr, "gsr error: gsr_kms_client_init: kms server died or never started, error: %s\n", strerror(errno));
goto err;
}
}
}
fprintf(stderr, "gsr info: gsr_kms_client_init: client connected\n");
return 0;
err:
gsr_kms_client_deinit(self);
return -1;
}
void gsr_kms_client_deinit(gsr_kms_client *self) {
if(self->card_path) {
free(self->card_path);
self->card_path = NULL;
}
if(self->client_fd != -1) {
close(self->client_fd);
self->client_fd = -1;
}
if(self->socket_fd != -1) {
close(self->socket_fd);
self->socket_fd = -1;
}
if(self->kms_server_pid != -1) {
kill(self->kms_server_pid, SIGINT);
int status;
waitpid(self->kms_server_pid, &status, 0);
self->kms_server_pid = -1;
}
if(self->socket_path[0] != '\0') {
remove(self->socket_path);
self->socket_path[0] = '\0';
}
}
int gsr_kms_client_get_kms(gsr_kms_client *self, gsr_kms_response *response) {
response->result = KMS_RESULT_FAILED_TO_SEND;
strcpy(response->data.err_msg, "failed to send");
gsr_kms_request request;
request.type = KMS_REQUEST_TYPE_GET_KMS;
strcpy(request.data.card_path, self->card_path);
if(send_msg_to_server(self->client_fd, &request) == -1) {
fprintf(stderr, "gsr error: gsr_kms_client_get_kms: failed to send request message to server\n");
return -1;
}
const int recv_res = recv_msg_from_server(self->client_fd, response);
if(recv_res == 0) {
fprintf(stderr, "gsr warning: gsr_kms_client_get_kms: kms server shut down\n");
return -1;
} else if(recv_res == -1) {
fprintf(stderr, "gsr error: gsr_kms_client_get_kms: failed to receive response\n");
return -1;
}
return 0;
}
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