Mercurial > dropbear
annotate fuzz/fuzzer-kexdh.c @ 1855:35d504d59c05
Implement server-side support for sk-ecdsa U2F-backed keys (#142)
* Implement server-side support for sk-ecdsa U2F-backed keys
* Fix out-of-bounds read on normal ecdsa-sha2-[identifier] keys
* Fix one more potential out-of-bounds read
* Check if nistp256 curve is used in sk-ecdsa-sha2- key
It's the only allowed curve per PROTOCOL.u2f specification
* Implement server-side support for sk-ed25519 FIDO2-backed keys
* Keys with type sk-* make no sense as host keys, so they should be
disabled
* fix typo
* Make sk-ecdsa call buf_ecdsa_verify
This reduces code duplication, the SK code just handles the
different message format.
* Reduce sk specific code
The application id can be stored in signkey, then we don't need
to call sk-specific functions from svr-authpubkey
* Remove debugging output, which causes compilation errors with DEBUG_TRACE disabled
* Proper cleanup of sk_app
Co-authored-by: Matt Johnston <[email protected]>
| author | egor-duda <egor-duda@users.noreply.github.com> |
|---|---|
| date | Sat, 22 Jan 2022 16:53:04 +0300 |
| 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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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]; |
| 1589 | 12 |
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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(); |
| 1589 | 18 |
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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; |
| 1589 | 23 |
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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 } |
| 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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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 } |