Mercurial > dropbear
annotate fuzz/fuzzer-kexdh.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
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parents:
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diff
changeset
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9 static struct key_context* keep_newkeys = NULL; |
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0cc85b4a4abb
Move fuzzer-kex initialisation into a constructor function
Matt Johnston <matt@ucc.asn.au>
parents:
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10 #define NUM_PARAMS 80 |
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0cc85b4a4abb
Move fuzzer-kex initialisation into a constructor function
Matt Johnston <matt@ucc.asn.au>
parents:
1756
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changeset
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11 static struct kex_dh_param *dh_params[NUM_PARAMS]; |
| 1589 | 12 |
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parents:
1756
diff
changeset
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13 static void setup() __attribute__((constructor)); |
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0cc85b4a4abb
Move fuzzer-kex initialisation into a constructor function
Matt Johnston <matt@ucc.asn.au>
parents:
1756
diff
changeset
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14 // Perform initial setup here to avoid hitting timeouts on first run |
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0cc85b4a4abb
Move fuzzer-kex initialisation into a constructor function
Matt Johnston <matt@ucc.asn.au>
parents:
1756
diff
changeset
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15 static void setup() { |
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0cc85b4a4abb
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Matt Johnston <matt@ucc.asn.au>
parents:
1756
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16 fuzz_common_setup(); |
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0cc85b4a4abb
Move fuzzer-kex initialisation into a constructor function
Matt Johnston <matt@ucc.asn.au>
parents:
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17 fuzz_svr_setup(); |
| 1589 | 18 |
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Matt Johnston <matt@ucc.asn.au>
parents:
1756
diff
changeset
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19 keep_newkeys = (struct key_context*)m_malloc(sizeof(struct key_context)); |
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Matt Johnston <matt@ucc.asn.au>
parents:
1756
diff
changeset
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20 keep_newkeys->algo_kex = fuzz_get_algo(sshkex, "diffie-hellman-group14-sha256"); |
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Matt Johnston <matt@ucc.asn.au>
parents:
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21 keep_newkeys->algo_hostkey = DROPBEAR_SIGNKEY_ECDSA_NISTP256; |
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parents:
1756
diff
changeset
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22 ses.newkeys = keep_newkeys; |
| 1589 | 23 |
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parents:
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diff
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24 /* Pre-generate parameters */ |
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parents:
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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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parents:
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28 } |
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parents:
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29 } |
| 1589 | 30 |
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31 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) { |
| 1589 | 32 if (fuzz_set_input(Data, Size) == DROPBEAR_FAILURE) { |
| 33 return 0; | |
| 34 } | |
| 35 | |
| 36 m_malloc_set_epoch(1); | |
| 37 | |
| 38 if (setjmp(fuzz.jmp) == 0) { | |
| 39 /* Based on recv_msg_kexdh_init()/send_msg_kexdh_reply() | |
| 40 with DROPBEAR_KEX_NORMAL_DH */ | |
| 41 ses.newkeys = keep_newkeys; | |
| 42 | |
| 43 /* Choose from the collection of ecdh params */ | |
| 44 unsigned int e = buf_getint(fuzz.input); | |
| 45 struct kex_dh_param * dh_param = dh_params[e % NUM_PARAMS]; | |
| 46 | |
| 47 DEF_MP_INT(dh_e); | |
| 48 m_mp_init(&dh_e); | |
| 49 if (buf_getmpint(fuzz.input, &dh_e) != DROPBEAR_SUCCESS) { | |
| 50 dropbear_exit("Bad kex value"); | |
| 51 } | |
| 52 | |
|
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kexhashbuf was much to small in kex fuzzers
Matt Johnston <matt@ucc.asn.au>
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53 ses.kexhashbuf = buf_new(KEXHASHBUF_MAX_INTS); |
| 1589 | 54 kexdh_comb_key(dh_param, &dh_e, svr_opts.hostkey); |
| 55 | |
| 1609 | 56 mp_clear(ses.dh_K); |
| 1589 | 57 m_free(ses.dh_K); |
| 58 mp_clear(&dh_e); | |
| 59 | |
| 1609 | 60 buf_free(ses.hash); |
| 61 buf_free(ses.session_id); | |
| 62 /* kexhashbuf is freed in kexdh_comb_key */ | |
| 63 | |
| 1589 | 64 m_malloc_free_epoch(1, 0); |
| 65 } else { | |
| 66 m_malloc_free_epoch(1, 1); | |
| 67 TRACE(("dropbear_exit longjmped")) | |
| 68 /* dropbear_exit jumped here */ | |
| 69 } | |
| 70 | |
| 71 return 0; | |
| 72 } |