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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Mon, 27 Jan 2020 19:01:21 +0000
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Subject: [PATCH] virtiofsd: add fuse_mbuf_iter API
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Introduce an API for consuming bytes from a buffer with size checks.
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All FUSE operations will be converted to use this safe API instead of
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void *inarg.
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit dad157e880416ab3a0e45beaa0e81977516568bc)
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---
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tools/virtiofsd/buffer.c | 28 ++++++++++++++++++++
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tools/virtiofsd/fuse_common.h | 49 ++++++++++++++++++++++++++++++++++-
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2 files changed, 76 insertions(+), 1 deletion(-)
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diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c
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index 772efa922d..42a608f6bd 100644
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--- a/tools/virtiofsd/buffer.c
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+++ b/tools/virtiofsd/buffer.c
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@@ -267,3 +267,31 @@ ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv)
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return copied;
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}
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+
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+void *fuse_mbuf_iter_advance(struct fuse_mbuf_iter *iter, size_t len)
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+{
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+ void *ptr;
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+
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+ if (len > iter->size - iter->pos) {
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+ return NULL;
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+ }
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+
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+ ptr = iter->mem + iter->pos;
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+ iter->pos += len;
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+ return ptr;
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+}
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+
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+const char *fuse_mbuf_iter_advance_str(struct fuse_mbuf_iter *iter)
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+{
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+ const char *str = iter->mem + iter->pos;
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+ size_t remaining = iter->size - iter->pos;
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+ size_t i;
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+
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+ for (i = 0; i < remaining; i++) {
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+ if (str[i] == '\0') {
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+ iter->pos += i + 1;
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+ return str;
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+ }
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+ }
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+ return NULL;
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+}
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diff --git a/tools/virtiofsd/fuse_common.h b/tools/virtiofsd/fuse_common.h
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index 0cb33acc2f..f8f6433743 100644
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--- a/tools/virtiofsd/fuse_common.h
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+++ b/tools/virtiofsd/fuse_common.h
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@@ -703,10 +703,57 @@ size_t fuse_buf_size(const struct fuse_bufvec *bufv);
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*/
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ssize_t fuse_buf_copy(struct fuse_bufvec *dst, struct fuse_bufvec *src);
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+/**
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+ * Memory buffer iterator
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+ *
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+ */
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+struct fuse_mbuf_iter {
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+ /**
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+ * Data pointer
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+ */
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+ void *mem;
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+
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+ /**
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+ * Total length, in bytes
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+ */
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+ size_t size;
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+
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+ /**
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+ * Offset from start of buffer
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+ */
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+ size_t pos;
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+};
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+
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+/* Initialize memory buffer iterator from a fuse_buf */
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+#define FUSE_MBUF_ITER_INIT(fbuf) \
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+ ((struct fuse_mbuf_iter){ \
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+ .mem = fbuf->mem, \
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+ .size = fbuf->size, \
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+ .pos = 0, \
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+ })
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+
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+/**
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+ * Consume bytes from a memory buffer iterator
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+ *
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+ * @param iter memory buffer iterator
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+ * @param len number of bytes to consume
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+ * @return pointer to start of consumed bytes or
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+ * NULL if advancing beyond end of buffer
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+ */
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+void *fuse_mbuf_iter_advance(struct fuse_mbuf_iter *iter, size_t len);
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+
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+/**
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+ * Consume a NUL-terminated string from a memory buffer iterator
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+ *
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+ * @param iter memory buffer iterator
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+ * @return pointer to the string or
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+ * NULL if advancing beyond end of buffer or there is no NUL-terminator
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+ */
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+const char *fuse_mbuf_iter_advance_str(struct fuse_mbuf_iter *iter);
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+
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/*
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* Signal handling
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*/
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-
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/**
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* Exit session on HUP, TERM and INT signals and ignore PIPE signal
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*
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