qemu-kvm/SOURCES/kvm-virtiofsd-prevent-FUSE_INIT-FUSE_DESTROY-races.patch

104 lines
3.6 KiB
Diff

From 249c02ae54739dc5894ee1b2905bbe8f1e79e909 Mon Sep 17 00:00:00 2001
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Date: Mon, 27 Jan 2020 19:02:20 +0100
Subject: [PATCH 109/116] virtiofsd: prevent FUSE_INIT/FUSE_DESTROY races
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-id: <20200127190227.40942-106-dgilbert@redhat.com>
Patchwork-id: 93562
O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 105/112] virtiofsd: prevent FUSE_INIT/FUSE_DESTROY races
Bugzilla: 1694164
RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>
From: Stefan Hajnoczi <stefanha@redhat.com>
When running with multiple threads it can be tricky to handle
FUSE_INIT/FUSE_DESTROY in parallel with other request types or in
parallel with themselves. Serialize FUSE_INIT and FUSE_DESTROY so that
malicious clients cannot trigger race conditions.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
(cherry picked from commit cdc497c6925be745bc895355bd4674a17a4b2a8b)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
tools/virtiofsd/fuse_i.h | 1 +
tools/virtiofsd/fuse_lowlevel.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+)
diff --git a/tools/virtiofsd/fuse_i.h b/tools/virtiofsd/fuse_i.h
index a20854f..1447d86 100644
--- a/tools/virtiofsd/fuse_i.h
+++ b/tools/virtiofsd/fuse_i.h
@@ -61,6 +61,7 @@ struct fuse_session {
struct fuse_req list;
struct fuse_req interrupts;
pthread_mutex_t lock;
+ pthread_rwlock_t init_rwlock;
int got_destroy;
int broken_splice_nonblock;
uint64_t notify_ctr;
diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
index dab6a31..79a4031 100644
--- a/tools/virtiofsd/fuse_lowlevel.c
+++ b/tools/virtiofsd/fuse_lowlevel.c
@@ -2428,6 +2428,19 @@ void fuse_session_process_buf_int(struct fuse_session *se,
req->ctx.pid = in->pid;
req->ch = ch;
+ /*
+ * INIT and DESTROY requests are serialized, all other request types
+ * run in parallel. This prevents races between FUSE_INIT and ordinary
+ * requests, FUSE_INIT and FUSE_INIT, FUSE_INIT and FUSE_DESTROY, and
+ * FUSE_DESTROY and FUSE_DESTROY.
+ */
+ if (in->opcode == FUSE_INIT || in->opcode == CUSE_INIT ||
+ in->opcode == FUSE_DESTROY) {
+ pthread_rwlock_wrlock(&se->init_rwlock);
+ } else {
+ pthread_rwlock_rdlock(&se->init_rwlock);
+ }
+
err = EIO;
if (!se->got_init) {
enum fuse_opcode expected;
@@ -2485,10 +2498,13 @@ void fuse_session_process_buf_int(struct fuse_session *se,
} else {
fuse_ll_ops[in->opcode].func(req, in->nodeid, &iter);
}
+
+ pthread_rwlock_unlock(&se->init_rwlock);
return;
reply_err:
fuse_reply_err(req, err);
+ pthread_rwlock_unlock(&se->init_rwlock);
}
#define LL_OPTION(n, o, v) \
@@ -2531,6 +2547,7 @@ void fuse_session_destroy(struct fuse_session *se)
se->op.destroy(se->userdata);
}
}
+ pthread_rwlock_destroy(&se->init_rwlock);
pthread_mutex_destroy(&se->lock);
free(se->cuse_data);
if (se->fd != -1) {
@@ -2610,6 +2627,7 @@ struct fuse_session *fuse_session_new(struct fuse_args *args,
list_init_req(&se->list);
list_init_req(&se->interrupts);
fuse_mutex_init(&se->lock);
+ pthread_rwlock_init(&se->init_rwlock, NULL);
memcpy(&se->op, op, op_size);
se->owner = getuid();
--
1.8.3.1