Mercurial > dropbear

annotate fuzzer-kexcurve25519.c @ 1715:3974f087d9c0

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Disallow leading lines before the ident for server (#102) Per RFC4253 4.2 clients must be able to process other lines of data before the version string, server behavior is not defined neither with MUST/SHOULD nor with MAY. If server process up to 50 lines too - it may cause too long hanging session with invalid/evil client that consume host resources and potentially may lead to DDoS on poor embedded boxes. Let's require first line from client to be version string and fail early if it's not - matches both RFC and real OpenSSH behavior.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Mon, 15 Jun 2020 18:22:18 +0500
parents d32bcb5c557d
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1659
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Vladislav Grishenko <themiron@users.noreply.github.com>
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1 #include "fuzz.h"
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2 #include "session.h"
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3 #include "fuzz-wrapfd.h"
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4 #include "debug.h"
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5 #include "runopts.h"
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6 #include "algo.h"
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7 #include "bignum.h"
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8
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9 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
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10 static int once = 0;
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11 static struct key_context* keep_newkeys = NULL;
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12 /* number of generated parameters is limited by the timeout for the first run.
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13 TODO move this to the libfuzzer initialiser function instead if the timeout
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14 doesn't apply there */
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15 #define NUM_PARAMS 20
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16 static struct kex_curve25519_param *curve25519_params[NUM_PARAMS];
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17
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18 if (!once) {
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19 fuzz_common_setup();
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20 fuzz_svr_setup();
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21
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22 keep_newkeys = (struct key_context*)m_malloc(sizeof(struct key_context));
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23 keep_newkeys->algo_kex = fuzz_get_algo(sshkex, "curve25519-sha256");
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24 keep_newkeys->algo_hostkey = DROPBEAR_SIGNKEY_ED25519;
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25 ses.newkeys = keep_newkeys;
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26
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27 /* Pre-generate parameters */
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28 int i;
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29 for (i = 0; i < NUM_PARAMS; i++) {
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30 curve25519_params[i] = gen_kexcurve25519_param();
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31 }
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32
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33 once = 1;
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34 }
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35
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36 if (fuzz_set_input(Data, Size) == DROPBEAR_FAILURE) {
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37 return 0;
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38 }
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39
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40 m_malloc_set_epoch(1);
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41
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42 if (setjmp(fuzz.jmp) == 0) {
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43 /* Based on recv_msg_kexdh_init()/send_msg_kexdh_reply()
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44 with DROPBEAR_KEX_CURVE25519 */
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45 ses.newkeys = keep_newkeys;
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46
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47 /* Choose from the collection of curve25519 params */
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48 unsigned int e = buf_getint(fuzz.input);
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49 struct kex_curve25519_param *curve25519_param = curve25519_params[e % NUM_PARAMS];
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50
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51 buffer * ecdh_qs = buf_getstringbuf(fuzz.input);
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52
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53 ses.kexhashbuf = buf_new(KEXHASHBUF_MAX_INTS);
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54 kexcurve25519_comb_key(curve25519_param, ecdh_qs, svr_opts.hostkey);
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55
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56 mp_clear(ses.dh_K);
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57 m_free(ses.dh_K);
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58 buf_free(ecdh_qs);
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59
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60 buf_free(ses.hash);
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61 buf_free(ses.session_id);
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62 /* kexhashbuf is freed in kexdh_comb_key */
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63
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64 m_malloc_free_epoch(1, 0);
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65 } else {
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66 m_malloc_free_epoch(1, 1);
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67 TRACE(("dropbear_exit longjmped"))
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68 /* dropbear_exit jumped here */
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69 }
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70
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71 return 0;
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72 }