1. openvpn
  2. Commit cd5a74d0d7c6347b31e261e98ca8984819e594df
Browse code

Move create_temp_file() out of #ifdef ENABLE_CRYPTO

By using get_random() instead of prng_bytes(), we no longer have to place
create_temp_file() inside #ifdef ENABLE_CRYPTO.

The resulting filename now has 62 bits of entropy (2 * [0-INT_MAX])
instead of the previous 128 bits, but that should be plenty. Assuming an
int is 32 bits, we would need about 2**31 (2147483648) files to have a
(roughly) 0.5 chance of failing in one of the 6 attempts we do.

(This is preparing to move the function out of misc.c, where I'd prefer to
not have to add a #include "crypto.h".)

Signed-off-by: Steffan Karger <steffan.karger@fox-it.com>
Acked-by: David Sommerseth <davids@openvpn.net>
Message-Id: <20170725210234.5673-1-steffan@karger.me>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg15146.html
Signed-off-by: David Sommerseth <davids@openvpn.net>

Steffan Karger authored on 2017/07/26 06:02:34
Showing 1 changed files
src/openvpn/misc.c
History View file @ cd5a74d
... ... 
@@ -808,8 +808,6 @@ test_file(const char *filename)
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     return ret;
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 }
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-#ifdef ENABLE_CRYPTO
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-
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 /* create a temporary filename in directory */
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 const char *
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 create_temp_file(const char *directory, const char *prefix, struct gc_arena *gc)
... ... 
@@ -822,15 +820,11 @@ create_temp_file(const char *directory, const char *prefix, struct gc_arena *gc)
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     do
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     {
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-        uint8_t rndbytes[16];
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-        const char *rndstr;
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-
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         ++attempts;
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         ++counter;
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-        prng_bytes(rndbytes, sizeof rndbytes);
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-        rndstr = format_hex_ex(rndbytes, sizeof rndbytes, 40, 0, NULL, gc);
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-        buf_printf(&fname, PACKAGE "_%s_%s.tmp", prefix, rndstr);
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+        buf_printf(&fname, PACKAGE "_%s_%08lx%08lx.tmp", prefix,
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+                   (unsigned long) get_random(), (unsigned long) get_random());
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         retfname = gen_path(directory, BSTR(&fname), gc);
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         if (!retfname)
... ... 
@@ -861,6 +855,8 @@ create_temp_file(const char *directory, const char *prefix, struct gc_arena *gc)
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     return NULL;
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 }
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+#ifdef ENABLE_CRYPTO
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+
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 /*
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  * Prepend a random string to hostname to prevent DNS caching.
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  * For example, foo.bar.gov would be modified to <random-chars>.foo.bar.gov.