9:08 a.m.
When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set. If the fd is found, a dup of the fd will be returned
from qemu_open.
Signed-off-by: Corey Bryant <coreyb(a)linux.vnet.ibm.com>
---
v2:
-Get rid of file_open and move dup code to qemu_open
(kwolf(a)redhat.com)
-Use strtol wrapper instead of atoi (kwolf(a)redhat.com)
v3:
-Add note about fd leakage (eblake(a)redhat.com)
v4
-Moved patch to be later in series (lcapitulino(a)redhat.com)
-Update qemu_open to check access mode flags and set flags that
can be set (eblake(a)redhat.com, kwolf(a)redhat.com)
v5:
-This patch was overhauled quite a bit in this version, with
the addition of fd set and refcount support.
-Use qemu_set_cloexec() on dup'd fd (eblake(a)redhat.com)
-Modify flags set by fcntl on dup'd fd (eblake(a)redhat.com)
-Reduce syscalls when setting flags for dup'd fd (eblake(a)redhat.com)
-Fix O_RDWR, O_RDONLY, O_WRONLY checks (eblake(a)redhat.com)
v6:
-Pass only the fd to qemu_close() and keep track of dup fds per fd
set. (kwolf(a)redhat.com, eblake(a)redhat.com)
-Handle refcount incr/decr in new dup_fd_add/remove fd functions.
-Use qemu_set_cloexec() appropriately in qemu_dup() (kwolf(a)redhat.com)
-Simplify setting of setfl_flags in qemu_dup() (kwolf(a)redhat.com)
-Add preprocessor checks for F_DUPFD_CLOEXEC (eblake(a)redhat.com)
-Simplify flag checking in monitor_fdset_get_fd() (kwolf(a)redhat.com)
v7:
-Minor updates to reference global mon_fdsets, and to remove
default_mon usage in osdep.c. (kwolf(a)redhat.com)
v8:
-Use camel case for structures. (stefanha(a)linux.vnet.ibm.com)
v9:
-Drop fdset refcount and check dup_fds instead. (eblake(a)redhat.com)
-Fix dupfd leak in qemu_dup(). (eblake(a)redhat.com)
-Always set O_CLOEXEC in qemu_dup(). (kwolf(a)redhat.com)
-Change name of qemu_dup() to qemu_dup_flags(). (kwolf(a)redhat.com)
v10:
-Don't use underscore prefix on functions. (blauwirbel(a)gmail.com)
-Set errno if monitor_fdset_dup_fd_add() fails. (eblake(a)redhat.com)
-Check dupfd for -1 on qemu_dup_flags() call. (eblake(a)redhat.com)
cutils.c | 5 +++
monitor.c | 83 ++++++++++++++++++++++++++++++++++++++++++-
monitor.h | 5 +++
osdep.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
qemu-common.h | 1 +
qemu-tool.c | 20 +++++++++++
6 files changed, 222 insertions(+), 1 deletion(-)
diff --git a/cutils.c b/cutils.c
index 9d4c570..8b0d2bb 100644
--- a/cutils.c
+++ b/cutils.c
@@ -382,3 +382,8 @@ int qemu_parse_fd(const char *param)
}
return fd;
}
+
+int qemu_parse_fdset(const char *param)
+{
+ return qemu_parse_fd(param);
+}
diff --git a/monitor.c b/monitor.c
index 6252d39..f56d6a1 100644
--- a/monitor.c
+++ b/monitor.c
@@ -154,6 +154,7 @@ typedef struct MonFdset MonFdset;
struct MonFdset {
int64_t id;
QLIST_HEAD(, MonFdsetFd) fds;
+ QLIST_HEAD(, MonFdsetFd) dup_fds;
QLIST_ENTRY(MonFdset) next;
};
@@ -2421,7 +2422,7 @@ static void monitor_fdset_cleanup(MonFdset *mon_fdset)
}
}
- if (QLIST_EMPTY(&mon_fdset->fds)) {
+ if (QLIST_EMPTY(&mon_fdset->fds) &&
QLIST_EMPTY(&mon_fdset->dup_fds)) {
QLIST_REMOVE(mon_fdset, next);
g_free(mon_fdset);
}
@@ -2578,6 +2579,86 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
return fdset_list;
}
+int monitor_fdset_get_fd(int64_t fdset_id, int flags)
+{
+ MonFdset *mon_fdset;
+ MonFdsetFd *mon_fdset_fd;
+ int mon_fd_flags;
+
+ QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
+ }
+
+ if ((flags & O_ACCMODE) == (mon_fd_flags & O_ACCMODE)) {
+ return mon_fdset_fd->fd;
+ }
+ }
+ errno = EACCES;
+ return -1;
+ }
+ errno = ENOENT;
+ return -1;
+}
+
+int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd)
+{
+ MonFdset *mon_fdset;
+ MonFdsetFd *mon_fdset_fd_dup;
+
+ QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {
+ if (mon_fdset_fd_dup->fd == dup_fd) {
+ return -1;
+ }
+ }
+ mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup));
+ mon_fdset_fd_dup->fd = dup_fd;
+ QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next);
+ return 0;
+ }
+ return -1;
+}
+
+static int monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
+{
+ MonFdset *mon_fdset;
+ MonFdsetFd *mon_fdset_fd_dup;
+
+ QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
+ QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {
+ if (mon_fdset_fd_dup->fd == dup_fd) {
+ if (remove) {
+ QLIST_REMOVE(mon_fdset_fd_dup, next);
+ if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
+ monitor_fdset_cleanup(mon_fdset);
+ }
+ }
+ return mon_fdset->id;
+ }
+ }
+ }
+ return -1;
+}
+
+int monitor_fdset_dup_fd_find(int dup_fd)
+{
+ return monitor_fdset_dup_fd_find_remove(dup_fd, false);
+}
+
+int monitor_fdset_dup_fd_remove(int dup_fd)
+{
+ return monitor_fdset_dup_fd_find_remove(dup_fd, true);
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
diff --git a/monitor.h b/monitor.h
index 5f4de1b..30b660f 100644
--- a/monitor.h
+++ b/monitor.h
@@ -86,4 +86,9 @@ int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret);
int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret);
+int monitor_fdset_get_fd(int64_t fdset_id, int flags);
+int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd);
+int monitor_fdset_dup_fd_remove(int dup_fd);
+int monitor_fdset_dup_fd_find(int dup_fd);
+
#endif /* !MONITOR_H */
diff --git a/osdep.c b/osdep.c
index 7f876ae..2688af5 100644
--- a/osdep.c
+++ b/osdep.c
@@ -48,6 +48,7 @@ extern int madvise(caddr_t, size_t, int);
#include "qemu-common.h"
#include "trace.h"
#include "qemu_socket.h"
+#include "monitor.h"
static bool fips_enabled = false;
@@ -78,6 +79,64 @@ int qemu_madvise(void *addr, size_t len, int advice)
#endif
}
+/*
+ * Dups an fd and sets the flags
+ */
+static int qemu_dup_flags(int fd, int flags)
+{
+ int ret;
+ int serrno;
+ int dup_flags;
+ int setfl_flags;
+
+#ifdef F_DUPFD_CLOEXEC
+ ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
+#else
+ ret = dup(fd);
+ if (ret != -1) {
+ qemu_set_cloexec(ret);
+ }
+#endif
+ if (ret == -1) {
+ goto fail;
+ }
+
+ dup_flags = fcntl(ret, F_GETFL);
+ if (dup_flags == -1) {
+ goto fail;
+ }
+
+ if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
+ errno = EINVAL;
+ goto fail;
+ }
+
+ /* Set/unset flags that we can with fcntl */
+ setfl_flags = O_APPEND | O_ASYNC | O_DIRECT | O_NOATIME | O_NONBLOCK;
+ dup_flags &= ~setfl_flags;
+ dup_flags |= (flags & setfl_flags);
+ if (fcntl(ret, F_SETFL, dup_flags) == -1) {
+ goto fail;
+ }
+
+ /* Truncate the file in the cases that open() would truncate it */
+ if (flags & O_TRUNC ||
+ ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {
+ if (ftruncate(ret, 0) == -1) {
+ goto fail;
+ }
+ }
+
+ return ret;
+
+fail:
+ serrno = errno;
+ if (ret != -1) {
+ close(ret);
+ }
+ errno = serrno;
+ return -1;
+}
/*
* Opens a file with FD_CLOEXEC set
@@ -87,6 +146,41 @@ int qemu_open(const char *name, int flags, ...)
int ret;
int mode = 0;
+#ifndef _WIN32
+ const char *fdset_id_str;
+
+ /* Attempt dup of fd from fd set */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int64_t fdset_id;
+ int fd, dupfd;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ fd = monitor_fdset_get_fd(fdset_id, flags);
+ if (fd == -1) {
+ return -1;
+ }
+
+ dupfd = qemu_dup_flags(fd, flags);
+ if (dupfd == -1) {
+ return -1;
+ }
+
+ ret = monitor_fdset_dup_fd_add(fdset_id, dupfd);
+ if (ret == -1) {
+ close(dupfd);
+ errno = EINVAL;
+ return -1;
+ }
+
+ return dupfd;
+ }
+#endif
+
if (flags & O_CREAT) {
va_list ap;
@@ -109,6 +203,21 @@ int qemu_open(const char *name, int flags, ...)
int qemu_close(int fd)
{
+ int64_t fdset_id;
+
+ /* Close fd that was dup'd from an fdset */
+ fdset_id = monitor_fdset_dup_fd_find(fd);
+ if (fdset_id != -1) {
+ int ret;
+
+ ret = close(fd);
+ if (ret == 0) {
+ monitor_fdset_dup_fd_remove(fd);
+ }
+
+ return ret;
+ }
+
return close(fd);
}
diff --git a/qemu-common.h b/qemu-common.h
index 90ddacd..efaefba 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -166,6 +166,7 @@ int qemu_fls(int i);
int qemu_fdatasync(int fd);
int fcntl_setfl(int fd, int flag);
int qemu_parse_fd(const char *param);
+int qemu_parse_fdset(const char *param);
/*
* strtosz() suffixes used to specify the default treatment of an
diff --git a/qemu-tool.c b/qemu-tool.c
index 64b5e88..18205ba 100644
--- a/qemu-tool.c
+++ b/qemu-tool.c
@@ -62,6 +62,26 @@ void monitor_protocol_event(MonitorEvent event, QObject *data)
{
}
+int monitor_fdset_get_fd(int64_t fdset_id, int flags)
+{
+ return -1;
+}
+
+int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd)
+{
+ return -1;
+}
+
+int monitor_fdset_dup_fd_remove(int dup_fd)
+{
+ return -1;
+}
+
+int monitor_fdset_dup_fd_find(int dup_fd)
+{
+ return -1;
+}
+
int64_t cpu_get_clock(void)
{
return qemu_get_clock_ns(rt_clock);
--
1.7.10.4