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Tue, 21 Jan 2020 12:32:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579609967; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cUeFPdME+vm3TzQVjRCoGIKY7xBnM50sNI8HRXdHPyI=; b=UNTRWwkrLwidvhvsfuKVFeuu5INBpLjFot2enxhHV/uWCf4LEb2ip0ZWzGMa/9w+VhK85i ei6cCFFqezUrYU+CCsxuj5MIHSIQfsgNRRLCB87ZHmNId6VUiP+ZudmdodVywJhRBWrEUC FdRo7LMPL2FIVgFFrFhrmOUouuYFE8o= From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com, vgoyal@redhat.com, berrange@redhat.com, slp@redhat.com, philmd@redhat.com Subject: [PATCH v2 103/109] virtiofsd: prevent FUSE_INIT/FUSE_DESTROY races Date: Tue, 21 Jan 2020 12:24:27 +0000 Message-Id: <20200121122433.50803-104-dgilbert@redhat.com> In-Reply-To: <20200121122433.50803-1-dgilbert@redhat.com> References: <20200121122433.50803-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: zXS8zYAHOOKGulwaHBVztA-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: m.mizuma@jp.fujitsu.com, misono.tomohiro@jp.fujitsu.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) Content-Type: text/plain; charset="utf-8" From: Stefan Hajnoczi 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 Reviewed-by: Masayoshi Mizuma --- 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 a20854f1c4..1447d86866 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_lowleve= l.c index fe332bcb90..8ae45d9c58 100644 --- a/tools/virtiofsd/fuse_lowlevel.c +++ b/tools/virtiofsd/fuse_lowlevel.c @@ -2430,6 +2430,19 @@ void fuse_session_process_buf_int(struct fuse_sessio= n *se, req->ctx.pid =3D in->pid; req->ch =3D ch; =20 + /* + * 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 =3D=3D FUSE_INIT || in->opcode =3D=3D CUSE_INIT || + in->opcode =3D=3D FUSE_DESTROY) { + pthread_rwlock_wrlock(&se->init_rwlock); + } else { + pthread_rwlock_rdlock(&se->init_rwlock); + } + err =3D EIO; if (!se->got_init) { enum fuse_opcode expected; @@ -2487,10 +2500,13 @@ void fuse_session_process_buf_int(struct fuse_sessi= on *se, } else { fuse_ll_ops[in->opcode].func(req, in->nodeid, &iter); } + + pthread_rwlock_unlock(&se->init_rwlock); return; =20 reply_err: fuse_reply_err(req, err); + pthread_rwlock_unlock(&se->init_rwlock); } =20 #define LL_OPTION(n, o, v) \ @@ -2535,6 +2551,7 @@ 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 !=3D -1) { @@ -2628,6 +2645,7 @@ struct fuse_session *fuse_session_new(struct fuse_arg= s *args, list_init_req(&se->list); list_init_req(&se->interrupts); fuse_mutex_init(&se->lock); + pthread_rwlock_init(&se->init_rwlock, NULL); =20 memcpy(&se->op, op, op_size); se->owner =3D getuid(); --=20 2.24.1