From 2ae5cd6539253e03e065f3ecbf55179527bb5ea2 Mon Sep 17 00:00:00 2001 From: Scott Anderson Date: Tue, 11 Jul 2017 19:03:09 +1200 Subject: Moved session/ into backend/ --- backend/session/direct-ipc.c | 241 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 241 insertions(+) create mode 100644 backend/session/direct-ipc.c (limited to 'backend/session/direct-ipc.c') diff --git a/backend/session/direct-ipc.c b/backend/session/direct-ipc.c new file mode 100644 index 00000000..885662e0 --- /dev/null +++ b/backend/session/direct-ipc.c @@ -0,0 +1,241 @@ +#define _POSIX_C_SOURCE 200809L +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "session/direct-ipc.h" + +enum { DRM_MAJOR = 226 }; + +#ifdef HAS_LIBCAP +#include + +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 void send_msg(int sock, int fd, void *buf, size_t buf_len) { + char control[CMSG_SPACE(sizeof(fd))] = {0}; + struct iovec iovec = { .iov_base = buf, .iov_len = buf_len }; + struct msghdr msghdr = {0}; + + if (buf) { + msghdr.msg_iov = &iovec; + msghdr.msg_iovlen = 1; + } + + if (fd >= 0) { + msghdr.msg_control = &control; + msghdr.msg_controllen = sizeof(control); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msghdr); + *cmsg = (struct cmsghdr) { + .cmsg_level = SOL_SOCKET, + .cmsg_type = SCM_RIGHTS, + .cmsg_len = CMSG_LEN(sizeof(fd)), + }; + memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd)); + } + + ssize_t ret; + do { + ret = sendmsg(sock, &msghdr, 0); + } while (ret < 0 && errno == EINTR); +} + +static ssize_t recv_msg(int sock, int *fd_out, void *buf, size_t buf_len) { + char control[CMSG_SPACE(sizeof(*fd_out))] = {0}; + struct iovec iovec = { .iov_base = buf, .iov_len = buf_len }; + struct msghdr msghdr = {0}; + + if (buf) { + msghdr.msg_iov = &iovec; + msghdr.msg_iovlen = 1; + } + + if (fd_out) { + msghdr.msg_control = &control; + msghdr.msg_controllen = sizeof(control); + } + + ssize_t ret; + do { + ret = recvmsg(sock, &msghdr, MSG_CMSG_CLOEXEC); + } while (ret < 0 && errno == EINTR); + + if (fd_out) { + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msghdr); + if (cmsg) { + memcpy(fd_out, CMSG_DATA(cmsg), sizeof(*fd_out)); + } else { + *fd_out = -1; + } + } + + return ret; +} + +enum msg_type { + MSG_OPEN, + MSG_SETMASTER, + MSG_DROPMASTER, + MSG_END, +}; + +struct msg { + enum msg_type type; + char path[256]; +}; + +static void communicate(int sock) { + struct msg msg; + int drm_fd = -1; + bool running = true; + + while (running && recv_msg(sock, &drm_fd, &msg, sizeof(msg)) >= 0) { + switch (msg.type) { + case MSG_OPEN: + errno = 0; + + // These are the same flags that logind opens files with + int fd = open(msg.path, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK); + int ret = errno; + if (fd == -1) { + goto error; + } + + struct stat st; + if (fstat(fd, &st) < 0) { + ret = errno; + goto error; + } + + uint32_t maj = major(st.st_rdev); + if (maj != INPUT_MAJOR && maj != DRM_MAJOR) { + ret = ENOTSUP; + goto error; + } + + if (maj == DRM_MAJOR && drmSetMaster(fd)) { + ret = errno; + } +error: + send_msg(sock, ret ? -1 : fd, &ret, sizeof(ret)); + close(fd); + + break; + + case MSG_SETMASTER: + drmSetMaster(drm_fd); + close(drm_fd); + send_msg(sock, -1, NULL, 0); + break; + + case MSG_DROPMASTER: + drmDropMaster(drm_fd); + close(drm_fd); + send_msg(sock, -1, NULL, 0); + break; + + case MSG_END: + running = false; + send_msg(sock, -1, NULL, 0); + break; + } + } + + close(sock); +} + +int direct_ipc_open(int sock, const char *path) { + struct msg msg = { .type = MSG_OPEN }; + snprintf(msg.path, sizeof(msg.path), "%s", path); + + send_msg(sock, -1, &msg, sizeof(msg)); + + int fd, err; + recv_msg(sock, &fd, &err, sizeof(err)); + + return err ? -err : fd; +} + +void direct_ipc_setmaster(int sock, int fd) { + struct msg msg = { .type = MSG_SETMASTER }; + + send_msg(sock, fd, &msg, sizeof(msg)); + recv_msg(sock, NULL, NULL, 0); +} + +void direct_ipc_dropmaster(int sock, int fd) { + struct msg msg = { .type = MSG_DROPMASTER }; + + send_msg(sock, fd, &msg, sizeof(msg)); + recv_msg(sock, NULL, NULL, 0); +} + +void direct_ipc_finish(int sock, pid_t pid) { + struct msg msg = { .type = MSG_END }; + + send_msg(sock, -1, &msg, sizeof(msg)); + recv_msg(sock, NULL, NULL, 0); + + waitpid(pid, NULL, 0); +} + +int direct_ipc_start(pid_t *pid_out) { + if (!have_permissions()) { + return -1; + } + + int sock[2]; + if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sock) < 0) { + wlr_log_errno(L_ERROR, "Failed to create socket pair"); + return -1; + } + + pid_t pid = fork(); + if (pid < 0) { + wlr_log_errno(L_ERROR, "Fork failed"); + close(sock[0]); + close(sock[1]); + return -1; + } else if (pid == 0) { + close(sock[0]); + communicate(sock[1]); + _Exit(0); + } + + close(sock[1]); + *pid_out = pid; + return sock[0]; +} -- cgit v1.2.3