cpp: model BDE bdlbb::Blob byte-buffer taint flow #22455
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| --- | ||
| category: minorAnalysis | ||
| --- | ||
| * Added flow summaries for the BDE `bdlbb::Blob` segmented byte buffer (`BloombergLP::bdlbb`). Taint now flows from a blob to its bytes through the `Blob::buffer`/`BlobBuffer::data` accessor chain and through the `bdlbb::BlobUtil::copy` and `getContiguousRangeOrCopy` helpers, so a blob populated from untrusted input (for example a BlazingMQ message body read via `bmqa::Message::getData`) is tracked into the payload bytes. | ||
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| # Model of the BDE bdlbb::Blob segmented byte buffer (BloombergLP::bdlbb). | ||||||||||
| # Lets taint reach a blob's payload bytes, e.g. a message body filled by bmqa::Message::getData. | ||||||||||
| extensions: | ||||||||||
| - addsTo: | ||||||||||
| pack: codeql/cpp-all | ||||||||||
| extensible: summaryModel | ||||||||||
| data: # namespace, type, subtypes, name, signature, ext, input, output, kind, provenance | ||||||||||
| # Accessor chain: a tainted blob taints its buffers, and a tainted buffer taints its bytes. | ||||||||||
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| - ["BloombergLP::bdlbb", "Blob", true, "buffer", "", "", "Argument[-1]", "ReturnValue[*]", "taint", "manual"] | ||||||||||
| - ["BloombergLP::bdlbb", "BlobBuffer", true, "data", "", "", "Argument[-1]", "ReturnValue[*]", "taint", "manual"] | ||||||||||
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There was a problem hiding this comment. I think we at least want to add |
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| # BlobUtil read-out: the source blob (Argument[*1]) taints the destination buffer (and the | ||||||||||
| # returned contiguous range). | ||||||||||
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| - ["BloombergLP::bdlbb", "BlobUtil", true, "copy", "(char *,const Blob &,int,int)", "", "Argument[*1]", "Argument[*0]", "taint", "manual"] | ||||||||||
| - ["BloombergLP::bdlbb", "BlobUtil", true, "getContiguousRangeOrCopy", "", "", "Argument[*1]", "Argument[*0]", "taint", "manual"] | ||||||||||
| - ["BloombergLP::bdlbb", "BlobUtil", true, "getContiguousRangeOrCopy", "", "", "Argument[*1]", "ReturnValue[*]", "taint", "manual"] | ||||||||||
| # BlobUtil write-in: the source (Argument[*2]) taints the destination blob. `copy` has two | ||||||||||
| # write-in overloads, one taking a raw byte buffer and one taking another blob as the source; | ||||||||||
| # each row pins the exact signature so the int offset/length arguments are never tainted. | ||||||||||
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| - ["BloombergLP::bdlbb", "BlobUtil", true, "copy", "(Blob *,int,const char *,int)", "", "Argument[*2]", "Argument[*0]", "taint", "manual"] | ||||||||||
| - ["BloombergLP::bdlbb", "BlobUtil", true, "copy", "(Blob *,int,const Blob &,int,int)", "", "Argument[*2]", "Argument[*0]", "taint", "manual"] | ||||||||||
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| // --- stub library headers --- | ||
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| namespace bsl { | ||
| typedef unsigned long size_t; | ||
| template <class T> class allocator {}; | ||
| template<class charT> struct char_traits {}; | ||
| template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> > | ||
| class basic_string { | ||
| public: | ||
| basic_string(const charT* s, const Allocator& a = Allocator()); | ||
| const charT* data() const; | ||
| size_t size() const; | ||
| }; | ||
| typedef basic_string<char> string; | ||
| } | ||
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| namespace BloombergLP { | ||
| namespace bdlbb { | ||
| class BlobBuffer { | ||
| public: | ||
| char *data() const; | ||
| }; | ||
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| class Blob { | ||
| public: | ||
| const BlobBuffer &buffer(int index) const; | ||
| }; | ||
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| struct BlobUtil { | ||
| static void copy(char *dstBuffer, const Blob &srcBlob, int position, int length); | ||
| static void copy(Blob *dstBlob, int dstOffset, const char *srcBuffer, int length); | ||
| static void copy(Blob *dstBlob, int dstOffset, const Blob &srcBlob, int srcOffset, | ||
| int length); | ||
| static char *getContiguousRangeOrCopy(char *dstBuffer, const Blob &srcBlob, int position, | ||
| int length, int alignment); | ||
| }; | ||
| } | ||
| } | ||
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| // --- test code --- | ||
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| char *source(); | ||
| void sink(char); | ||
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| // A blob populated from a tainted buffer taints the bytes read back out of it. | ||
| void test_BlobUtil_copy() { | ||
| bsl::string s(source()); | ||
| BloombergLP::bdlbb::Blob blob; | ||
| BloombergLP::bdlbb::BlobUtil::copy(&blob, 0, s.data(), s.size()); | ||
| char dst[16]; | ||
| BloombergLP::bdlbb::BlobUtil::copy(dst, blob, 0, 16); | ||
| sink(*dst); // $ ir | ||
| } | ||
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| void test_accessor_chain() { | ||
| bsl::string s(source()); | ||
| BloombergLP::bdlbb::Blob blob; | ||
| BloombergLP::bdlbb::BlobUtil::copy(&blob, 0, s.data(), s.size()); | ||
| const char *p = blob.buffer(0).data(); | ||
| sink(*p); // $ ir | ||
| } | ||
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| void test_getContiguousRangeOrCopy() { | ||
| bsl::string s(source()); | ||
| BloombergLP::bdlbb::Blob blob; | ||
| BloombergLP::bdlbb::BlobUtil::copy(&blob, 0, s.data(), s.size()); | ||
| char dst[16]; | ||
| char *r = BloombergLP::bdlbb::BlobUtil::getContiguousRangeOrCopy(dst, blob, 0, 16, 1); | ||
| sink(*r); // $ ir | ||
| } | ||
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| // A blob copied into another blob carries the taint across. | ||
| void test_BlobUtil_copy_blob_to_blob() { | ||
| bsl::string s(source()); | ||
| BloombergLP::bdlbb::Blob src; | ||
| BloombergLP::bdlbb::BlobUtil::copy(&src, 0, s.data(), s.size()); | ||
| BloombergLP::bdlbb::Blob dst; | ||
| BloombergLP::bdlbb::BlobUtil::copy(&dst, 0, src, 0, 16); | ||
| char out[16]; | ||
| BloombergLP::bdlbb::BlobUtil::copy(out, dst, 0, 16); | ||
| sink(*out); // $ ir | ||
| } |
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I would again shorten this.