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[PATCH v3 2/4] util: introduce qemu_open and qemu_create with error repo
From: |
Daniel P . Berrangé |
Subject: |
[PATCH v3 2/4] util: introduce qemu_open and qemu_create with error reporting |
Date: |
Fri, 24 Jul 2020 14:25:08 +0100 |
This introduces two new helper metohds
int qemu_open(const char *name, int flags, Error **errp);
int qemu_create(const char *name, int flags, mode_t mode, Error **errp);
Note that with this design we no longer require or even accept the
O_CREAT flag. Avoiding overloading the two distinct operations
means we can avoid variable arguments which would prevent 'errp' from
being the last argument. It also gives us a guarantee that the 'mode' is
given when creating files, avoiding a latent security bug.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
include/qemu/osdep.h | 6 ++++
util/osdep.c | 78 ++++++++++++++++++++++++++++++++++++--------
2 files changed, 71 insertions(+), 13 deletions(-)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 3a16e58932..ca24ebe211 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -494,7 +494,13 @@ int qemu_madvise(void *addr, size_t len, int advice);
int qemu_mprotect_rwx(void *addr, size_t size);
int qemu_mprotect_none(void *addr, size_t size);
+/*
+ * Don't introduce new usage of this function, prefer the following
+ * qemu_open/qemu_create that take a "Error **errp"
+ */
int qemu_open_old(const char *name, int flags, ...);
+int qemu_open(const char *name, int flags, Error **errp);
+int qemu_create(const char *name, int flags, mode_t mode, Error **errp);
int qemu_close(int fd);
int qemu_unlink(const char *name);
#ifndef _WIN32
diff --git a/util/osdep.c b/util/osdep.c
index 9df1b6adec..5c0f4684b1 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -22,6 +22,7 @@
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
+#include "qapi/error.h"
/* Needed early for CONFIG_BSD etc. */
@@ -282,10 +283,10 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len,
bool exclusive)
/*
* Opens a file with FD_CLOEXEC set
*/
-int qemu_open_old(const char *name, int flags, ...)
+static int
+qemu_open_internal(const char *name, int flags, mode_t mode, Error **errp)
{
int ret;
- int mode = 0;
#ifndef _WIN32
const char *fdset_id_str;
@@ -297,24 +298,31 @@ int qemu_open_old(const char *name, int flags, ...)
fdset_id = qemu_parse_fdset(fdset_id_str);
if (fdset_id == -1) {
+ error_setg(errp, "Could not parse fdset %s", name);
errno = EINVAL;
return -1;
}
fd = monitor_fdset_get_fd(fdset_id, flags);
if (fd < 0) {
+ error_setg_errno(errp, -fd, "Could not acquire FD for %s flags %x",
+ name, flags);
errno = -fd;
return -1;
}
dupfd = qemu_dup_flags(fd, flags);
if (dupfd == -1) {
+ error_setg_errno(errp, errno, "Could not dup FD for %s flags %x",
+ name, flags);
return -1;
}
ret = monitor_fdset_dup_fd_add(fdset_id, dupfd);
if (ret == -1) {
close(dupfd);
+ error_setg(errp, "Could not save FD for %s flags %x",
+ name, flags);
errno = EINVAL;
return -1;
}
@@ -323,22 +331,66 @@ int qemu_open_old(const char *name, int flags, ...)
}
#endif
- if (flags & O_CREAT) {
- va_list ap;
-
- va_start(ap, flags);
- mode = va_arg(ap, int);
- va_end(ap);
- }
-
#ifdef O_CLOEXEC
- ret = open(name, flags | O_CLOEXEC, mode);
-#else
+ flags |= O_CLOEXEC;
+#endif /* O_CLOEXEC */
+
ret = open(name, flags, mode);
+
+#ifndef O_CLOEXEC
if (ret >= 0) {
qemu_set_cloexec(ret);
}
-#endif
+#endif /* ! O_CLOEXEC */
+
+ if (ret == -1) {
+ const char *action = "open";
+ if (flags & O_CREAT) {
+ action = "create";
+ }
+ error_setg_errno(errp, errno, "Could not %s '%s' flags 0x%x",
+ action, name, flags);
+ }
+
+
+ return ret;
+}
+
+
+int qemu_open(const char *name, int flags, Error **errp)
+{
+ if (flags & O_CREAT) {
+ error_setg(errp,
+ "Invalid O_CREAT flag passed to qemu_open, use
qemu_create");
+ return -1;
+ }
+ return qemu_open_internal(name, flags, 0, errp);
+}
+
+
+int qemu_create(const char *name, int flags, mode_t mode, Error **errp)
+{
+ if (flags & O_CREAT) {
+ error_setg(errp, "Redundant O_CREAT flag passed to qemu_create");
+ return -1;
+ }
+ return qemu_open_internal(name, flags | O_CREAT, mode, errp);
+}
+
+
+int qemu_open_old(const char *name, int flags, ...)
+{
+ va_list ap;
+ mode_t mode = 0;
+ int ret;
+
+ va_start(ap, flags);
+ if (flags & O_CREAT) {
+ mode = va_arg(ap, int);
+ }
+ va_end(ap);
+
+ ret = qemu_open_internal(name, flags, mode, NULL);
#ifdef O_DIRECT
if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) {
--
2.26.2