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authorDaniel P. Berrange <berrange@redhat.com>2013-03-19 11:20:20 +0000
committerAnthony Liguori <aliguori@us.ibm.com>2013-04-15 14:29:20 -0500
commite6b636779b51c97e67694be740ee972c52460c59 (patch)
tree132813125593e7128b06d88fc88f27530599a430 /qemu-nbd.c
parent0ca5aa4f4c4a8bcc73988dd52a536241d35e5223 (diff)
downloadqemu-arm-e6b636779b51c97e67694be740ee972c52460c59.tar.gz
Add -f FMT / --format FMT arg to qemu-nbd
Currently the qemu-nbd program will auto-detect the format of any disk it is given. This behaviour is known to be insecure. For example, if qemu-nbd initially exposes a 'raw' file to an unprivileged app, and that app runs 'qemu-img create -f qcow2 -o backing_file=/etc/shadow /dev/nbd0' then the next time the app is started, the qemu-nbd will now detect it as a 'qcow2' file and expose /etc/shadow to the unprivileged app. The only way to avoid this is to explicitly tell qemu-nbd what disk format to use on the command line, completely disabling auto-detection. This patch adds a '-f' / '--format' arg for this purpose, mirroring what is already available via qemu-img and qemu commands. qemu-nbd --format raw -p 9000 evil.img will now always use raw, regardless of what format 'evil.img' looks like it contains Signed-off-by: Daniel P. Berrange <berrange@redhat.com> [Use errx, not err. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'qemu-nbd.c')
-rw-r--r--qemu-nbd.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/qemu-nbd.c b/qemu-nbd.c
index ca722ed425..9c31d45706 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -306,6 +306,7 @@ static void nbd_accept(void *opaque)
int main(int argc, char **argv)
{
BlockDriverState *bs;
+ BlockDriver *drv;
off_t dev_offset = 0;
uint32_t nbdflags = 0;
bool disconnect = false;
@@ -313,7 +314,7 @@ int main(int argc, char **argv)
char *device = NULL;
int port = NBD_DEFAULT_PORT;
off_t fd_size;
- const char *sopt = "hVb:o:p:rsnP:c:dvk:e:t";
+ const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:t";
struct option lopt[] = {
{ "help", 0, NULL, 'h' },
{ "version", 0, NULL, 'V' },
@@ -333,6 +334,7 @@ int main(int argc, char **argv)
#endif
{ "discard", 1, NULL, QEMU_NBD_OPT_DISCARD },
{ "shared", 1, NULL, 'e' },
+ { "format", 1, NULL, 'f' },
{ "persistent", 0, NULL, 't' },
{ "verbose", 0, NULL, 'v' },
{ NULL, 0, NULL, 0 }
@@ -351,6 +353,7 @@ int main(int argc, char **argv)
bool seen_aio = false;
#endif
pthread_t client_thread;
+ const char *fmt = NULL;
/* The client thread uses SIGTERM to interrupt the server. A signal
* handler ensures that "qemu-nbd -v -c" exits with a nice status code.
@@ -454,6 +457,9 @@ int main(int argc, char **argv)
errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
}
break;
+ case 'f':
+ fmt = optarg;
+ break;
case 't':
persistent = 1;
break;
@@ -555,9 +561,19 @@ int main(int argc, char **argv)
bdrv_init();
atexit(bdrv_close_all);
+ if (fmt) {
+ drv = bdrv_find_format(fmt);
+ if (!drv) {
+ errx(EXIT_FAILURE, "Unknown file format '%s'", fmt);
+ }
+ } else {
+ drv = NULL;
+ }
+
bs = bdrv_new("hda");
srcpath = argv[optind];
- if ((ret = bdrv_open(bs, srcpath, NULL, flags, NULL)) < 0) {
+ ret = bdrv_open(bs, srcpath, NULL, flags, drv);
+ if (ret < 0) {
errno = -ret;
err(EXIT_FAILURE, "Failed to bdrv_open '%s'", argv[optind]);
}