Mercurial > dropbear
annotate fuzz/fuzzer-kexecdh.c @ 1861:2b3a8026a6ce
Add re-exec for server
This allows ASLR to re-randomize the address
space for every connection, preventing some
vulnerabilities from being exploitable by
repeated probing.
Overhead (memory and time) is yet to be confirmed.
At present this is only enabled on Linux. Other BSD platforms
with fexecve() would probably also work though have not been tested.
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Sun, 30 Jan 2022 10:14:56 +0800 |
| parents | 0cc85b4a4abb |
| children |
| rev | line source |
|---|---|
| 1589 | 1 #include "fuzz.h" |
| 2 #include "session.h" | |
| 3 #include "fuzz-wrapfd.h" | |
| 4 #include "debug.h" | |
| 5 #include "runopts.h" | |
| 6 #include "algo.h" | |
| 7 #include "bignum.h" | |
| 8 | |
|
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0cc85b4a4abb
Move fuzzer-kex initialisation into a constructor function
Matt Johnston <matt@ucc.asn.au>
parents:
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9 static const struct dropbear_kex *ecdh[3]; /* 256, 384, 521 */ |
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parents:
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10 static struct key_context* keep_newkeys = NULL; |
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parents:
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11 /* number of generated parameters. An arbitrary limit, but will delay startup */ |
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parents:
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12 #define NUM_PARAMS 80 |
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Matt Johnston <matt@ucc.asn.au>
parents:
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13 static struct kex_ecdh_param *ecdh_params[NUM_PARAMS]; |
| 1589 | 14 |
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15 static void setup() __attribute__((constructor)); |
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0cc85b4a4abb
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Matt Johnston <matt@ucc.asn.au>
parents:
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16 // Perform initial setup here to avoid hitting timeouts on first run |
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Matt Johnston <matt@ucc.asn.au>
parents:
1756
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changeset
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17 static void setup() { |
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parents:
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18 fuzz_common_setup(); |
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19 fuzz_svr_setup(); |
| 1589 | 20 |
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21 /* ses gets zeroed by fuzz_set_input */ |
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parents:
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changeset
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22 keep_newkeys = (struct key_context*)m_malloc(sizeof(struct key_context)); |
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Matt Johnston <matt@ucc.asn.au>
parents:
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23 ecdh[0] = fuzz_get_algo(sshkex, "ecdh-sha2-nistp256"); |
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parents:
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24 ecdh[1] = fuzz_get_algo(sshkex, "ecdh-sha2-nistp384"); |
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parents:
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25 ecdh[2] = fuzz_get_algo(sshkex, "ecdh-sha2-nistp521"); |
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26 assert(ecdh[0]); |
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parents:
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27 assert(ecdh[1]); |
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parents:
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28 assert(ecdh[2]); |
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29 keep_newkeys->algo_hostkey = DROPBEAR_SIGNKEY_ECDSA_NISTP256; |
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30 ses.newkeys = keep_newkeys; |
| 1589 | 31 |
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parents:
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32 /* Pre-generate parameters */ |
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33 int i; |
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34 for (i = 0; i < NUM_PARAMS; i++) { |
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35 ses.newkeys->algo_kex = ecdh[i % 3]; |
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parents:
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36 ecdh_params[i] = gen_kexecdh_param(); |
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parents:
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37 } |
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parents:
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38 } |
| 1589 | 39 |
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parents:
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40 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) { |
| 1589 | 41 |
| 42 if (fuzz_set_input(Data, Size) == DROPBEAR_FAILURE) { | |
| 43 return 0; | |
| 44 } | |
| 45 | |
| 46 m_malloc_set_epoch(1); | |
| 47 | |
| 48 if (setjmp(fuzz.jmp) == 0) { | |
| 49 /* Based on recv_msg_kexdh_init()/send_msg_kexdh_reply() | |
| 50 with DROPBEAR_KEX_ECDH */ | |
| 51 ses.newkeys = keep_newkeys; | |
| 52 | |
| 53 /* random choice of ecdh 256, 384, 521 */ | |
| 54 unsigned char b = buf_getbyte(fuzz.input); | |
| 55 ses.newkeys->algo_kex = ecdh[b % 3]; | |
| 56 | |
| 57 /* Choose from the collection of ecdh params */ | |
| 58 unsigned int e = buf_getint(fuzz.input); | |
| 59 struct kex_ecdh_param *ecdh_param = ecdh_params[e % NUM_PARAMS]; | |
| 60 | |
| 61 buffer * ecdh_qs = buf_getstringbuf(fuzz.input); | |
| 62 | |
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kexhashbuf was much to small in kex fuzzers
Matt Johnston <matt@ucc.asn.au>
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63 ses.kexhashbuf = buf_new(KEXHASHBUF_MAX_INTS); |
| 1589 | 64 kexecdh_comb_key(ecdh_param, ecdh_qs, svr_opts.hostkey); |
| 65 | |
| 1609 | 66 mp_clear(ses.dh_K); |
| 1589 | 67 m_free(ses.dh_K); |
| 68 buf_free(ecdh_qs); | |
| 69 | |
| 1609 | 70 buf_free(ses.hash); |
| 71 buf_free(ses.session_id); | |
| 72 /* kexhashbuf is freed in kexdh_comb_key */ | |
| 73 | |
| 1589 | 74 m_malloc_free_epoch(1, 0); |
| 75 } else { | |
| 76 m_malloc_free_epoch(1, 1); | |
| 77 TRACE(("dropbear_exit longjmped")) | |
| 78 /* dropbear_exit jumped here */ | |
| 79 } | |
| 80 | |
| 81 return 0; | |
| 82 } |