69 lines
2.4 KiB
Diff
69 lines
2.4 KiB
Diff
Description: fix race condition allowing attackers to access destination file
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This commit addresses https://github.com/facebook/zstd/issues/2491.
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.
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Note that a downside of this solution is that it is global: `umask()` affects
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all file creation calls in the process. I believe this is safe since
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`fileio.c` functions should only ever be used in the zstd binary, and these
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are (almost) the only files ever created by zstd, and AIUI they're only
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created in a single thread. So we can get away with messing with global state.
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.
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Note that this doesn't change the permissions of files created by `dibio.c`.
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I'm not sure what those should be...
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Author: W. Felix Handte <w@felixhandte.com>
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Origin: upstream
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Bug: https://github.com/facebook/zstd/issues/2491
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Bug-Debian: https://github.com/facebook/zstd/issues/2491
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Applied-Upstream: commit:a774c5797399040af62db21d8a9b9769e005430e
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Reviewed-by: Étienne Mollier <etienne.mollier@mailoo.org>
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Last-Update: 2021-03-03
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---
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This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
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--- a/programs/fileio.c
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+++ b/programs/fileio.c
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@@ -606,11 +606,11 @@ FIO_openDstFile(FIO_prefs_t* const prefs
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FIO_remove(dstFileName);
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} }
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- { FILE* const f = fopen( dstFileName, "wb" );
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+ { const int old_umask = UTIL_umask(0177); /* u-x,go-rwx */
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+ FILE* const f = fopen( dstFileName, "wb" );
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+ UTIL_umask(old_umask);
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if (f == NULL) {
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DISPLAYLEVEL(1, "zstd: %s: %s\n", dstFileName, strerror(errno));
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- } else if(srcFileName != NULL && strcmp (srcFileName, stdinmark)) {
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- chmod(dstFileName, 00600);
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}
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return f;
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}
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--- a/programs/util.c
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+++ b/programs/util.c
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@@ -54,6 +54,15 @@ int UTIL_getFileStat(const char* infilen
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return 1;
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}
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+int UTIL_umask(int mode) {
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+#if PLATFORM_POSIX_VERSION > 0
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+ return umask(mode);
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+#else
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+ /* do nothing, fake return value */
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+ return mode;
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+#endif
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+}
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+
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int UTIL_setFileStat(const char *filename, stat_t *statbuf)
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{
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int res = 0;
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--- a/programs/util.h
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+++ b/programs/util.h
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@@ -136,6 +136,10 @@ int UTIL_isSameFile(const char* file1, c
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int UTIL_compareStr(const void *p1, const void *p2);
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int UTIL_isCompressedFile(const char* infilename, const char *extensionList[]);
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const char* UTIL_getFileExtension(const char* infilename);
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+/**
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+ * Wraps umask(). Does nothing when the platform doesn't have that concept.
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+ */
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+int UTIL_umask(int mode);
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#ifndef _MSC_VER
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U32 UTIL_isFIFO(const char* infilename);
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