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Berrange" , Markus Armbruster , Steve Sistare Subject: [PATCH V5 12/23] migration: SCM_RIGHTS for QEMUFile Date: Tue, 24 Dec 2024 08:16:57 -0800 Message-Id: <1735057028-308595-13-git-send-email-steven.sistare@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1735057028-308595-1-git-send-email-steven.sistare@oracle.com> References: <1735057028-308595-1-git-send-email-steven.sistare@oracle.com> X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2024-12-24_06,2024-12-24_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxlogscore=999 mlxscore=0 suspectscore=0 malwarescore=0 adultscore=0 bulkscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2411120000 definitions=main-2412240141 X-Proofpoint-GUID: EQfl6miXtztAX_iZHex6ESOUV40A_vG7 X-Proofpoint-ORIG-GUID: EQfl6miXtztAX_iZHex6ESOUV40A_vG7 Received-SPF: pass client-ip=205.220.177.32; envelope-from=steven.sistare@oracle.com; helo=mx0b-00069f02.pphosted.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_MED=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Define functions to put/get file descriptors to/from a QEMUFile, for qio channels that support SCM_RIGHTS. Maintain ordering such that put(A), put(fd), put(B) followed by get(A), get(fd), get(B) always succeeds. Other get orderings may succeed but are not guaranteed. Signed-off-by: Steve Sistare Reviewed-by: Peter Xu --- migration/qemu-file.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++--- migration/qemu-file.h | 2 ++ migration/trace-events | 2 ++ 3 files changed, 83 insertions(+), 4 deletions(-) diff --git a/migration/qemu-file.c b/migration/qemu-file.c index b6d2f58..728c7dd 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -37,6 +37,11 @@ #define IO_BUF_SIZE 32768 #define MAX_IOV_SIZE MIN_CONST(IOV_MAX, 64) +typedef struct FdEntry { + QTAILQ_ENTRY(FdEntry) entry; + int fd; +} FdEntry; + struct QEMUFile { QIOChannel *ioc; bool is_writable; @@ -51,6 +56,9 @@ struct QEMUFile { int last_error; Error *last_error_obj; + + bool can_pass_fd; + QTAILQ_HEAD(, FdEntry) fds; }; /* @@ -109,6 +117,8 @@ static QEMUFile *qemu_file_new_impl(QIOChannel *ioc, bool is_writable) object_ref(ioc); f->ioc = ioc; f->is_writable = is_writable; + f->can_pass_fd = qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS); + QTAILQ_INIT(&f->fds); return f; } @@ -310,6 +320,10 @@ static ssize_t coroutine_mixed_fn qemu_fill_buffer(QEMUFile *f) int len; int pending; Error *local_error = NULL; + g_autofree int *fds = NULL; + size_t nfd = 0; + int **pfds = f->can_pass_fd ? &fds : NULL; + size_t *pnfd = f->can_pass_fd ? &nfd : NULL; assert(!qemu_file_is_writable(f)); @@ -325,10 +339,9 @@ static ssize_t coroutine_mixed_fn qemu_fill_buffer(QEMUFile *f) } do { - len = qio_channel_read(f->ioc, - (char *)f->buf + pending, - IO_BUF_SIZE - pending, - &local_error); + struct iovec iov = { f->buf + pending, IO_BUF_SIZE - pending }; + len = qio_channel_readv_full(f->ioc, &iov, 1, pfds, pnfd, 0, + &local_error); if (len == QIO_CHANNEL_ERR_BLOCK) { if (qemu_in_coroutine()) { qio_channel_yield(f->ioc, G_IO_IN); @@ -348,9 +361,65 @@ static ssize_t coroutine_mixed_fn qemu_fill_buffer(QEMUFile *f) qemu_file_set_error_obj(f, len, local_error); } + for (int i = 0; i < nfd; i++) { + FdEntry *fde = g_new0(FdEntry, 1); + fde->fd = fds[i]; + QTAILQ_INSERT_TAIL(&f->fds, fde, entry); + } + return len; } +int qemu_file_put_fd(QEMUFile *f, int fd) +{ + int ret = 0; + QIOChannel *ioc = qemu_file_get_ioc(f); + Error *err = NULL; + struct iovec iov = { (void *)" ", 1 }; + + /* + * Send a dummy byte so qemu_fill_buffer on the receiving side does not + * fail with a len=0 error. Flush first to maintain ordering wrt other + * data. + */ + + qemu_fflush(f); + if (qio_channel_writev_full(ioc, &iov, 1, &fd, 1, 0, &err) < 1) { + error_report_err(error_copy(err)); + qemu_file_set_error_obj(f, -EIO, err); + ret = -1; + } + trace_qemu_file_put_fd(f->ioc->name, fd, ret); + return ret; +} + +int qemu_file_get_fd(QEMUFile *f) +{ + int fd = -1; + FdEntry *fde; + + if (!f->can_pass_fd) { + Error *err = NULL; + error_setg(&err, "%s does not support fd passing", f->ioc->name); + error_report_err(error_copy(err)); + qemu_file_set_error_obj(f, -EIO, err); + goto out; + } + + /* Force the dummy byte and its fd passenger to appear. */ + qemu_peek_byte(f, 0); + + fde = QTAILQ_FIRST(&f->fds); + if (fde) { + qemu_get_byte(f); /* Drop the dummy byte */ + fd = fde->fd; + QTAILQ_REMOVE(&f->fds, fde, entry); + } +out: + trace_qemu_file_get_fd(f->ioc->name, fd); + return fd; +} + /** Closes the file * * Returns negative error value if any error happened on previous operations or @@ -361,11 +430,17 @@ static ssize_t coroutine_mixed_fn qemu_fill_buffer(QEMUFile *f) */ int qemu_fclose(QEMUFile *f) { + FdEntry *fde, *next; int ret = qemu_fflush(f); int ret2 = qio_channel_close(f->ioc, NULL); if (ret >= 0) { ret = ret2; } + QTAILQ_FOREACH_SAFE(fde, &f->fds, entry, next) { + warn_report("qemu_fclose: received fd %d was never claimed", fde->fd); + close(fde->fd); + g_free(fde); + } g_clear_pointer(&f->ioc, object_unref); error_free(f->last_error_obj); g_free(f); diff --git a/migration/qemu-file.h b/migration/qemu-file.h index 11c2120..3e47a20 100644 --- a/migration/qemu-file.h +++ b/migration/qemu-file.h @@ -79,5 +79,7 @@ size_t qemu_get_buffer_at(QEMUFile *f, const uint8_t *buf, size_t buflen, off_t pos); QIOChannel *qemu_file_get_ioc(QEMUFile *file); +int qemu_file_put_fd(QEMUFile *f, int fd); +int qemu_file_get_fd(QEMUFile *f); #endif diff --git a/migration/trace-events b/migration/trace-events index 89c0244..9388f81 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -88,6 +88,8 @@ put_qlist_end(const char *field_name, const char *vmsd_name) "%s(%s)" # qemu-file.c qemu_file_fclose(void) "" +qemu_file_put_fd(const char *name, int fd, int ret) "ioc %s, fd %d -> status %d" +qemu_file_get_fd(const char *name, int fd) "ioc %s -> fd %d" # ram.c get_queued_page(const char *block_name, uint64_t tmp_offset, unsigned long page_abs) "%s/0x%" PRIx64 " page_abs=0x%lx"