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https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
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6a98bc4614
Nodes that are written to flash can only be authenticated through the index after the next commit. When a journal replay is necessary the nodes are not yet referenced by the index and thus can't be authenticated. This patch overcomes this situation by creating a hash over all nodes beginning from the commit start node over the reference node(s) and the buds themselves. From time to time we insert authentication nodes. Authentication nodes contain a HMAC from the current hash state, so that they can be used to authenticate a journal replay up to the point where the authentication node is. The hash is continued afterwards so that theoretically we would only have to check the HMAC of the last authentication node we find. Overall we get this picture: ,,,,,,,, ,......,........................................... ,. CS , hash1.----. hash2.----. ,. | , . |hmac . |hmac ,. v , . v . v ,.REF#0,-> bud -> bud -> bud.-> auth -> bud -> bud.-> auth ... ,..|...,........................................... , | , , | ,,,,,,,,,,,,,,, . | hash3,----. , | , |hmac , v , v , REF#1 -> bud -> bud,-> auth ... ,,,|,,,,,,,,,,,,,,,,,, v REF#2 -> ... | V ... Note how hash3 covers CS, REF#0 and REF#1 so that it is not possible to exchange or skip any reference nodes. Unlike the picture suggests the auth nodes themselves are not hashed. With this it is possible for an offline attacker to cut each journal head or to drop the last reference node(s), but not to skip any journal heads or to reorder any operations. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Richard Weinberger <richard@nod.at> |
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| .. | ||
| auth.c | ||
| budget.c | ||
| commit.c | ||
| compress.c | ||
| crypto.c | ||
| debug.c | ||
| debug.h | ||
| dir.c | ||
| file.c | ||
| find.c | ||
| gc.c | ||
| io.c | ||
| ioctl.c | ||
| journal.c | ||
| Kconfig | ||
| key.h | ||
| log.c | ||
| lprops.c | ||
| lpt_commit.c | ||
| lpt.c | ||
| Makefile | ||
| master.c | ||
| misc.c | ||
| misc.h | ||
| orphan.c | ||
| recovery.c | ||
| replay.c | ||
| sb.c | ||
| scan.c | ||
| shrinker.c | ||
| super.c | ||
| tnc_commit.c | ||
| tnc_misc.c | ||
| tnc.c | ||
| ubifs-media.h | ||
| ubifs.h | ||
| xattr.c | ||