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Hello Jenkins Builder, dexter, laforge,
I'd like you to reexamine a change. Please visit
https://gerrit.osmocom.org/c/pysim/+/43172?usp=email
to look at the new patch set (#2).
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Code-Review+1 by laforge, Code-Review+2 by dexter, Verified+1 by Jenkins
Builder, Verified+1 by dexter
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Change subject: GP: LOAD/STORE DATA chunk size from SCP overhead
......................................................................
GP: LOAD/STORE DATA chunk size from SCP overhead
SCP.overhead was so far set at construction time (SCP02: 8, SCP03:
s_mode), so the C-MAC length only.
Unfortunately sec lvl >= 3 pads the data field to the cipher block size
before encryption, so the real worst-case overhead is larger,
scc.max_cmd_len (255 - overhead) was too big, and ADF_SD.load()
used a hardcoded chunk_len=240.
Real world issue with a 286 byte CAP + SCP02 + sec lvl 3:
- 240-byte LOAD block is padded to 248,
- encrypted
- gets 8 byte C-MAC appended
-> Lc = 256
That dies with a weird "ValueError: bytes must be in range(0, 256)".
The only "fix" for that was to downgrade the seclevel.
STORE DATA has the same overflow with large max_cmd_len
(247 + padding + MAC = 256 as well).
Therefore the overhead must be properly calculated from the sec level.
While at it adjust the error in case I missed something to get a more
useful ValueError.
Change-Id: Ic208f3959a38896f64fb6ccefb24cc360a3ac3a2
---
M pySim/global_platform/__init__.py
M pySim/global_platform/scp.py
M tests/unittests/test_globalplatform.py
3 files changed, 224 insertions(+), 12 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/pysim refs/changes/72/43172/2
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Gerrit-MessageType: newpatchset
Gerrit-Project: pysim
Gerrit-Branch: master
Gerrit-Change-Id: Ic208f3959a38896f64fb6ccefb24cc360a3ac3a2
Gerrit-Change-Number: 43172
Gerrit-PatchSet: 2
Gerrit-Owner: Hoernchen <[email protected]>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: dexter <[email protected]>
Gerrit-Reviewer: laforge <[email protected]>
Gerrit-Attention: Hoernchen <[email protected]>
Gerrit-Attention: laforge <[email protected]>
Gerrit-Attention: dexter <[email protected]>
