annotate fuzz/fuzzer-kexdh.c @ 1885:5d8dbb6fdab7

Fix SSH_PUBKEYINFO, limit characters, add tests We fix a bad_bufptr() failure from a previous commit. We now limit the allowed characters to those that will definitely be safe in a shell. Some scripts/programs may use arbitrary environment variables without escaping correctly - that could be a problem in a restricted environment. The current allowed set is a-z A-Z 0-9 .,_-+@ This also adds a test for SSH_PUBKEYINFO, by default it only runs under github actions (or "act -j build").
author Matt Johnston <matt@ucc.asn.au>
date Wed, 16 Mar 2022 17:17:23 +0800
parents 0cc85b4a4abb
children
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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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9 static struct key_context* keep_newkeys = NULL;
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10 #define NUM_PARAMS 80
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11 static struct kex_dh_param *dh_params[NUM_PARAMS];
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13 static void setup() __attribute__((constructor));
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14 // Perform initial setup here to avoid hitting timeouts on first run
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15 static void setup() {
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16 fuzz_common_setup();
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17 fuzz_svr_setup();
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19 keep_newkeys = (struct key_context*)m_malloc(sizeof(struct key_context));
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20 keep_newkeys->algo_kex = fuzz_get_algo(sshkex, "diffie-hellman-group14-sha256");
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21 keep_newkeys->algo_hostkey = DROPBEAR_SIGNKEY_ECDSA_NISTP256;
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22 ses.newkeys = keep_newkeys;
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24 /* Pre-generate parameters */
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25 int i;
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26 for (i = 0; i < NUM_PARAMS; i++) {
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27 dh_params[i] = gen_kexdh_param();
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28 }
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29 }
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31 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
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32 if (fuzz_set_input(Data, Size) == DROPBEAR_FAILURE) {
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33 return 0;
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34 }
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35
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36 m_malloc_set_epoch(1);
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37
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38 if (setjmp(fuzz.jmp) == 0) {
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39 /* Based on recv_msg_kexdh_init()/send_msg_kexdh_reply()
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40 with DROPBEAR_KEX_NORMAL_DH */
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41 ses.newkeys = keep_newkeys;
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42
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43 /* Choose from the collection of ecdh params */
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44 unsigned int e = buf_getint(fuzz.input);
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45 struct kex_dh_param * dh_param = dh_params[e % NUM_PARAMS];
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46
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47 DEF_MP_INT(dh_e);
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48 m_mp_init(&dh_e);
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49 if (buf_getmpint(fuzz.input, &dh_e) != DROPBEAR_SUCCESS) {
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50 dropbear_exit("Bad kex value");
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51 }
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52
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53 ses.kexhashbuf = buf_new(KEXHASHBUF_MAX_INTS);
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54 kexdh_comb_key(dh_param, &dh_e, 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 mp_clear(&dh_e);
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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 }