April 2015 - tor-commits - lists.torproject.org

[tor/master] ... and if we do get multiple INTRODUCE1s on a circuit, kill the circuit
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit 8656cbcfc0cdce98d57e8f77d56bc8a69f5568b6 Author: George Kadianakis <desnacked(a)riseup.net> Date: Thu Apr 2 13:38:52 2015 +0100 ... and if we do get multiple INTRODUCE1s on a circuit, kill the circuit (Sending a nak would be pointless.) See ticket 15515 for discussion. --- src/or/rendmid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/or/rendmid.c b/src/or/rendmid.c index f85562e..2451acb 100644 --- a/src/or/rendmid.c +++ b/src/or/rendmid.c @@ -157,7 +157,8 @@ rend_mid_introduce(or_circuit_t *circ, const uint8_t *request, "Blocking multiple introductions on the same circuit. " "Someone might be trying to attack a hidden service through " "this relay."); - goto err; + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); + return -1; } circ->already_received_introduce1 = 1;

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[tor/master] Merge commit 'c1b36488e9c318fc414220e8549624b423560ad2'
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit c2462621ab0c6d74f5249c19b3c1bfccdb90a2c2 Merge: 38c8e0b c1b3648 Author: Nick Mathewson <nickm(a)torproject.org> Date: Fri Apr 3 09:40:16 2015 -0400 Merge commit 'c1b36488e9c318fc414220e8549624b423560ad2'

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[tor/master] Block multiple introductions on the same intro circuit.
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit 8dba8a088d7c1402831ab5a7211a4a347a60ff7a Author: George Kadianakis <desnacked(a)riseup.net> Date: Wed Apr 1 14:33:09 2015 +0100 Block multiple introductions on the same intro circuit. --- changes/bug15515 | 4 ++++ src/or/or.h | 3 +++ src/or/rendmid.c | 13 +++++++++++++ 3 files changed, 20 insertions(+) diff --git a/changes/bug15515 b/changes/bug15515 new file mode 100644 index 0000000..dda7c2f --- /dev/null +++ b/changes/bug15515 @@ -0,0 +1,4 @@ + o Minor features (DoS-resistance): + - Make it harder for attackers to overwhelm hidden services with + introductions, by blocking multiple introduction requests on the + same circuit. Resolves ticket #15515. diff --git a/src/or/or.h b/src/or/or.h index 34f055c..4459957 100644 --- a/src/or/or.h +++ b/src/or/or.h @@ -3157,6 +3157,9 @@ typedef struct or_circuit_t { * to the specification? */ unsigned int remaining_relay_early_cells : 4; + /* We have already received an INTRODUCE1 cell on this circuit. */ + unsigned int already_received_introduce1 : 1; + /** True iff this circuit was made with a CREATE_FAST cell. */ unsigned int is_first_hop : 1; diff --git a/src/or/rendmid.c b/src/or/rendmid.c index 1bd11f6..2f75ffb 100644 --- a/src/or/rendmid.c +++ b/src/or/rendmid.c @@ -149,6 +149,19 @@ rend_mid_introduce(or_circuit_t *circ, const uint8_t *request, goto err; } + /* We have already done an introduction on this circuit but we just + received a request for another one. We block it since this might + be an attempt to DoS a hidden service (#15515). */ + if (circ->already_received_introduce1) { + log_fn(LOG_PROTOCOL_WARN, LD_REND, + "Blocking multiple introductions on the same circuit. " + "Someone might be trying to attack a hidden service through " + "this relay."); + goto err; + } + + circ->already_received_introduce1 = 1; + /* We could change this to MAX_HEX_NICKNAME_LEN now that 0.0.9.x is * obsolete; however, there isn't much reason to do so, and we're going * to revise this protocol anyway.

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[tor/maint-0.2.6] Block multiple introductions on the same intro circuit.
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit 8dba8a088d7c1402831ab5a7211a4a347a60ff7a Author: George Kadianakis <desnacked(a)riseup.net> Date: Wed Apr 1 14:33:09 2015 +0100 Block multiple introductions on the same intro circuit. --- changes/bug15515 | 4 ++++ src/or/or.h | 3 +++ src/or/rendmid.c | 13 +++++++++++++ 3 files changed, 20 insertions(+) diff --git a/changes/bug15515 b/changes/bug15515 new file mode 100644 index 0000000..dda7c2f --- /dev/null +++ b/changes/bug15515 @@ -0,0 +1,4 @@ + o Minor features (DoS-resistance): + - Make it harder for attackers to overwhelm hidden services with + introductions, by blocking multiple introduction requests on the + same circuit. Resolves ticket #15515. diff --git a/src/or/or.h b/src/or/or.h index 34f055c..4459957 100644 --- a/src/or/or.h +++ b/src/or/or.h @@ -3157,6 +3157,9 @@ typedef struct or_circuit_t { * to the specification? */ unsigned int remaining_relay_early_cells : 4; + /* We have already received an INTRODUCE1 cell on this circuit. */ + unsigned int already_received_introduce1 : 1; + /** True iff this circuit was made with a CREATE_FAST cell. */ unsigned int is_first_hop : 1; diff --git a/src/or/rendmid.c b/src/or/rendmid.c index 1bd11f6..2f75ffb 100644 --- a/src/or/rendmid.c +++ b/src/or/rendmid.c @@ -149,6 +149,19 @@ rend_mid_introduce(or_circuit_t *circ, const uint8_t *request, goto err; } + /* We have already done an introduction on this circuit but we just + received a request for another one. We block it since this might + be an attempt to DoS a hidden service (#15515). */ + if (circ->already_received_introduce1) { + log_fn(LOG_PROTOCOL_WARN, LD_REND, + "Blocking multiple introductions on the same circuit. " + "Someone might be trying to attack a hidden service through " + "this relay."); + goto err; + } + + circ->already_received_introduce1 = 1; + /* We could change this to MAX_HEX_NICKNAME_LEN now that 0.0.9.x is * obsolete; however, there isn't much reason to do so, and we're going * to revise this protocol anyway.

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[tor/maint-0.2.6] ... and if we do get multiple INTRODUCE1s on a circuit, kill the circuit
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit bcb839387ef65c0a87ca0a6b7957c3062188c601 Author: George Kadianakis <desnacked(a)riseup.net> Date: Thu Apr 2 13:38:52 2015 +0100 ... and if we do get multiple INTRODUCE1s on a circuit, kill the circuit (Sending a nak would be pointless.) See ticket 15515 for discussion. --- src/or/rendmid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/or/rendmid.c b/src/or/rendmid.c index 2f75ffb..0a005a6 100644 --- a/src/or/rendmid.c +++ b/src/or/rendmid.c @@ -157,7 +157,8 @@ rend_mid_introduce(or_circuit_t *circ, const uint8_t *request, "Blocking multiple introductions on the same circuit. " "Someone might be trying to attack a hidden service through " "this relay."); - goto err; + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); + return -1; } circ->already_received_introduce1 = 1;

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[tor/maint-0.2.6] Merge branch 'bug15515_024' into maint-0.2.4
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit 01e4bc80cd75bbf2a4ce3b18ff17550eed993bb0 Merge: 5f46a59 bcb8393 Author: Nick Mathewson <nickm(a)torproject.org> Date: Fri Apr 3 09:36:59 2015 -0400 Merge branch 'bug15515_024' into maint-0.2.4 changes/bug15515 | 4 ++++ src/or/or.h | 3 +++ src/or/rendmid.c | 14 ++++++++++++++ 3 files changed, 21 insertions(+)

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[tor/maint-0.2.6] Merge remote-tracking branch 'origin/maint-0.2.4' into maint-0.2.5
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit 3781955f079f25f8d6aa47cb746e339497076050 Merge: 9063f29 01e4bc8 Author: Nick Mathewson <nickm(a)torproject.org> Date: Fri Apr 3 09:38:54 2015 -0400 Merge remote-tracking branch 'origin/maint-0.2.4' into maint-0.2.5 changes/bug15515 | 4 ++++ src/or/or.h | 3 +++ src/or/rendmid.c | 14 ++++++++++++++ 3 files changed, 21 insertions(+)

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[tor/maint-0.2.6] Merge remote-tracking branch 'origin/maint-0.2.5' into maint-0.2.6
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit c1b36488e9c318fc414220e8549624b423560ad2 Merge: b117a06 3781955 Author: Nick Mathewson <nickm(a)torproject.org> Date: Fri Apr 3 09:39:19 2015 -0400 Merge remote-tracking branch 'origin/maint-0.2.5' into maint-0.2.6 changes/bug15515 | 4 ++++ src/or/or.h | 3 +++ src/or/rendmid.c | 14 ++++++++++++++ 3 files changed, 21 insertions(+)

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[tor/maint-0.2.5] Block multiple introductions on the same intro circuit.
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit 8dba8a088d7c1402831ab5a7211a4a347a60ff7a Author: George Kadianakis <desnacked(a)riseup.net> Date: Wed Apr 1 14:33:09 2015 +0100 Block multiple introductions on the same intro circuit. --- changes/bug15515 | 4 ++++ src/or/or.h | 3 +++ src/or/rendmid.c | 13 +++++++++++++ 3 files changed, 20 insertions(+) diff --git a/changes/bug15515 b/changes/bug15515 new file mode 100644 index 0000000..dda7c2f --- /dev/null +++ b/changes/bug15515 @@ -0,0 +1,4 @@ + o Minor features (DoS-resistance): + - Make it harder for attackers to overwhelm hidden services with + introductions, by blocking multiple introduction requests on the + same circuit. Resolves ticket #15515. diff --git a/src/or/or.h b/src/or/or.h index 34f055c..4459957 100644 --- a/src/or/or.h +++ b/src/or/or.h @@ -3157,6 +3157,9 @@ typedef struct or_circuit_t { * to the specification? */ unsigned int remaining_relay_early_cells : 4; + /* We have already received an INTRODUCE1 cell on this circuit. */ + unsigned int already_received_introduce1 : 1; + /** True iff this circuit was made with a CREATE_FAST cell. */ unsigned int is_first_hop : 1; diff --git a/src/or/rendmid.c b/src/or/rendmid.c index 1bd11f6..2f75ffb 100644 --- a/src/or/rendmid.c +++ b/src/or/rendmid.c @@ -149,6 +149,19 @@ rend_mid_introduce(or_circuit_t *circ, const uint8_t *request, goto err; } + /* We have already done an introduction on this circuit but we just + received a request for another one. We block it since this might + be an attempt to DoS a hidden service (#15515). */ + if (circ->already_received_introduce1) { + log_fn(LOG_PROTOCOL_WARN, LD_REND, + "Blocking multiple introductions on the same circuit. " + "Someone might be trying to attack a hidden service through " + "this relay."); + goto err; + } + + circ->already_received_introduce1 = 1; + /* We could change this to MAX_HEX_NICKNAME_LEN now that 0.0.9.x is * obsolete; however, there isn't much reason to do so, and we're going * to revise this protocol anyway.

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[tor/maint-0.2.5] ... and if we do get multiple INTRODUCE1s on a circuit, kill the circuit
by nickm＠torproject.org 03 Apr '15

03 Apr '15

commit bcb839387ef65c0a87ca0a6b7957c3062188c601 Author: George Kadianakis <desnacked(a)riseup.net> Date: Thu Apr 2 13:38:52 2015 +0100 ... and if we do get multiple INTRODUCE1s on a circuit, kill the circuit (Sending a nak would be pointless.) See ticket 15515 for discussion. --- src/or/rendmid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/or/rendmid.c b/src/or/rendmid.c index 2f75ffb..0a005a6 100644 --- a/src/or/rendmid.c +++ b/src/or/rendmid.c @@ -157,7 +157,8 @@ rend_mid_introduce(or_circuit_t *circ, const uint8_t *request, "Blocking multiple introductions on the same circuit. " "Someone might be trying to attack a hidden service through " "this relay."); - goto err; + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); + return -1; } circ->already_received_introduce1 = 1;

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