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// SPDX-License-Identifier: GPL-3.0-or-later
#include "systemd-journal-helpers.h"
bool is_path_unix_socket(const char *path) {
// Check if the path is valid
if(!path || !*path)
return false;
struct stat statbuf;
// Use stat to check if the file exists and is a socket
if (stat(path, &statbuf) == -1)
// The file does not exist or cannot be accessed
return false;
// Check if the file is a socket
if (S_ISSOCK(statbuf.st_mode))
return true;
return false;
}
bool is_stderr_connected_to_journal(void) {
const char *journal_stream = getenv("JOURNAL_STREAM");
if (!journal_stream)
return false; // JOURNAL_STREAM is not set
struct stat stderr_stat;
if (fstat(STDERR_FILENO, &stderr_stat) < 0)
return false; // Error in getting stderr info
// Parse device and inode from JOURNAL_STREAM
char *endptr;
long journal_dev = strtol(journal_stream, &endptr, 10);
if (*endptr != ':')
return false; // Format error in JOURNAL_STREAM
long journal_ino = strtol(endptr + 1, NULL, 10);
return (stderr_stat.st_dev == (dev_t)journal_dev) && (stderr_stat.st_ino == (ino_t)journal_ino);
}
int journal_direct_fd(const char *path) {
if(!path || !*path)
path = JOURNAL_DIRECT_SOCKET;
if(!is_path_unix_socket(path))
return -1;
int fd = socket(AF_UNIX, SOCK_DGRAM| DEFAULT_SOCKET_FLAGS, 0);
if (fd < 0) return -1;
sock_setcloexec(fd);
struct sockaddr_un addr;
memset(&addr, 0, sizeof(struct sockaddr_un));
addr.sun_family = AF_UNIX;
strncpy(addr.sun_path, path, sizeof(addr.sun_path) - 1);
// Connect the socket (optional, but can simplify send operations)
if (connect(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
close(fd);
return -1;
}
return fd;
}
static inline bool journal_send_with_memfd(int fd __maybe_unused, const char *msg __maybe_unused, size_t msg_len __maybe_unused) {
#if defined(__NR_memfd_create) && defined(MFD_ALLOW_SEALING) && defined(F_ADD_SEALS) && defined(F_SEAL_SHRINK) && defined(F_SEAL_GROW) && defined(F_SEAL_WRITE)
// Create a memory file descriptor
int memfd = (int)syscall(__NR_memfd_create, "journald", MFD_ALLOW_SEALING);
if (memfd < 0) return false;
// Write data to the memfd
if (write(memfd, msg, msg_len) != (ssize_t)msg_len) {
close(memfd);
return false;
}
// Seal the memfd to make it immutable
if (fcntl(memfd, F_ADD_SEALS, F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE) < 0) {
close(memfd);
return false;
}
struct iovec iov = {0};
struct msghdr msghdr = {0};
struct cmsghdr *cmsghdr;
char cmsgbuf[CMSG_SPACE(sizeof(int))];
msghdr.msg_iov = &iov;
msghdr.msg_iovlen = 1;
msghdr.msg_control = cmsgbuf;
msghdr.msg_controllen = sizeof(cmsgbuf);
cmsghdr = CMSG_FIRSTHDR(&msghdr);
if(!cmsghdr) {
close(memfd);
return false;
}
cmsghdr->cmsg_level = SOL_SOCKET;
cmsghdr->cmsg_type = SCM_RIGHTS;
cmsghdr->cmsg_len = CMSG_LEN(sizeof(int));
memcpy(CMSG_DATA(cmsghdr), &memfd, sizeof(int));
ssize_t r = sendmsg(fd, &msghdr, 0);
close(memfd);
return r >= 0;
#else
return false;
#endif
}
bool journal_direct_send(int fd, const char *msg, size_t msg_len) {
// Send the datagram
if (send(fd, msg, msg_len, 0) < 0) {
if(errno != EMSGSIZE)
return false;
// datagram is too large, fallback to memfd
if(!journal_send_with_memfd(fd, msg, msg_len))
return false;
}
return true;
}
void journal_construct_path(char *dst, size_t dst_len, const char *host_prefix, const char *namespace_str) {
if(!host_prefix)
host_prefix = "";
if(namespace_str)
snprintfz(dst, dst_len, "%s/run/systemd/journal.%s/socket",
host_prefix, namespace_str);
else
snprintfz(dst, dst_len, "%s" JOURNAL_DIRECT_SOCKET,
host_prefix);
}
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