9pfs: fix qemu_mknodat(S_IFSOCK) on macOS

mknod() on macOS does not support creating sockets, so divert to
call sequence socket(), bind() and fchmodat() respectively if S_IFSOCK
was passed with mode argument.

Link: https://lore.kernel.org/qemu-devel/17933734.zYzKuhC07K@silver/
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Message-Id: <2e7b5ecd7a6d83a538db4e8a22d8fb03e9e0f06e.1651228001.git.qemu_oss@crudebyte.com>
[C.S. - Use AT_SYMLINK_NOFOLLOW instead of AT_SYMLINK_NOFOLLOW_ANY. ]
Link: https://lore.kernel.org/qemu-devel/3704033.BMyLRrx2Jx@silver/
This commit is contained in:
Christian Schoenebeck 2022-04-29 12:25:11 +02:00
parent 096af17127
commit 055ab89327

View File

@ -74,6 +74,42 @@ int fsetxattrat_nofollow(int dirfd, const char *filename, const char *name,
*/
#if defined CONFIG_PTHREAD_FCHDIR_NP
static int create_socket_file_at_cwd(const char *filename, mode_t mode) {
int fd, err;
struct sockaddr_un addr = {
.sun_family = AF_UNIX
};
err = snprintf(addr.sun_path, sizeof(addr.sun_path), "./%s", filename);
if (err < 0 || err >= sizeof(addr.sun_path)) {
errno = ENAMETOOLONG;
return -1;
}
fd = socket(PF_UNIX, SOCK_DGRAM, 0);
if (fd == -1) {
return fd;
}
err = bind(fd, (struct sockaddr *) &addr, sizeof(addr));
if (err == -1) {
goto out;
}
/*
* FIXME: Should rather be using descriptor-based fchmod() on the
* socket file descriptor above (preferably before bind() call),
* instead of path-based fchmodat(), to prevent concurrent transient
* state issues between creating the named FIFO file at bind() and
* delayed adjustment of permissions at fchmodat(). However currently
* macOS (12.x) does not support such operations on socket file
* descriptors yet.
*
* Filed report with Apple: FB9997731
*/
err = fchmodat(AT_FDCWD, filename, mode, AT_SYMLINK_NOFOLLOW);
out:
close_preserve_errno(fd);
return err;
}
int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev)
{
int preserved_errno, err;
@ -93,7 +129,11 @@ int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev)
if (pthread_fchdir_np(dirfd) < 0) {
return -1;
}
err = mknod(filename, mode, dev);
if (S_ISSOCK(mode)) {
err = create_socket_file_at_cwd(filename, mode);
} else {
err = mknod(filename, mode, dev);
}
preserved_errno = errno;
/* Stop using the thread-local cwd */
pthread_fchdir_np(-1);