85 lines
3.0 KiB
Diff
85 lines
3.0 KiB
Diff
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Mon, 27 Jan 2020 19:02:20 +0000
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Subject: [PATCH] virtiofsd: prevent FUSE_INIT/FUSE_DESTROY races
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When running with multiple threads it can be tricky to handle
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FUSE_INIT/FUSE_DESTROY in parallel with other request types or in
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parallel with themselves. Serialize FUSE_INIT and FUSE_DESTROY so that
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malicious clients cannot trigger race conditions.
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit cdc497c6925be745bc895355bd4674a17a4b2a8b)
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---
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tools/virtiofsd/fuse_i.h | 1 +
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tools/virtiofsd/fuse_lowlevel.c | 18 ++++++++++++++++++
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2 files changed, 19 insertions(+)
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diff --git a/tools/virtiofsd/fuse_i.h b/tools/virtiofsd/fuse_i.h
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index a20854f1c4..1447d86866 100644
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--- a/tools/virtiofsd/fuse_i.h
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+++ b/tools/virtiofsd/fuse_i.h
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@@ -61,6 +61,7 @@ struct fuse_session {
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struct fuse_req list;
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struct fuse_req interrupts;
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pthread_mutex_t lock;
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+ pthread_rwlock_t init_rwlock;
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int got_destroy;
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int broken_splice_nonblock;
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uint64_t notify_ctr;
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diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
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index dab6a31e08..79a4031266 100644
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--- a/tools/virtiofsd/fuse_lowlevel.c
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+++ b/tools/virtiofsd/fuse_lowlevel.c
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@@ -2428,6 +2428,19 @@ void fuse_session_process_buf_int(struct fuse_session *se,
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req->ctx.pid = in->pid;
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req->ch = ch;
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+ /*
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+ * INIT and DESTROY requests are serialized, all other request types
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+ * run in parallel. This prevents races between FUSE_INIT and ordinary
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+ * requests, FUSE_INIT and FUSE_INIT, FUSE_INIT and FUSE_DESTROY, and
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+ * FUSE_DESTROY and FUSE_DESTROY.
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+ */
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+ if (in->opcode == FUSE_INIT || in->opcode == CUSE_INIT ||
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+ in->opcode == FUSE_DESTROY) {
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+ pthread_rwlock_wrlock(&se->init_rwlock);
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+ } else {
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+ pthread_rwlock_rdlock(&se->init_rwlock);
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+ }
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+
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err = EIO;
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if (!se->got_init) {
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enum fuse_opcode expected;
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@@ -2485,10 +2498,13 @@ void fuse_session_process_buf_int(struct fuse_session *se,
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} else {
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fuse_ll_ops[in->opcode].func(req, in->nodeid, &iter);
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}
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+
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+ pthread_rwlock_unlock(&se->init_rwlock);
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return;
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reply_err:
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fuse_reply_err(req, err);
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+ pthread_rwlock_unlock(&se->init_rwlock);
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}
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#define LL_OPTION(n, o, v) \
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@@ -2531,6 +2547,7 @@ void fuse_session_destroy(struct fuse_session *se)
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se->op.destroy(se->userdata);
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}
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}
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+ pthread_rwlock_destroy(&se->init_rwlock);
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pthread_mutex_destroy(&se->lock);
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free(se->cuse_data);
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if (se->fd != -1) {
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@@ -2610,6 +2627,7 @@ struct fuse_session *fuse_session_new(struct fuse_args *args,
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list_init_req(&se->list);
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list_init_req(&se->interrupts);
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fuse_mutex_init(&se->lock);
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+ pthread_rwlock_init(&se->init_rwlock, NULL);
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memcpy(&se->op, op, op_size);
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se->owner = getuid();
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