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| author | Luke Huang <huangluke@google.com> | 2020-07-07 23:11:05 +0800 |
|---|---|---|
| committer | mosimchah <mosimchah@gmail.com> | 2020-12-15 02:32:52 -0500 |
| commit | 4d5ab4290b20bcaa873aaaacc0264615e9e4f65d (patch) | |
| tree | 7f460d0e0b572abe0411d72aefbd735431201fcb /resolv/res_cache.cpp | |
| parent | b4939e066230e96fc0637b8f48c8c0ddef6a4ccc (diff) | |
Backport: Fix the side channel attack by using async DnsResolver API with FLAG_NO_CACHE_STOREq10.0
Before this CL, FLAG_NO_CACHE_STORE could be used to perform side
channel attack. Because this flag ensures the result is never
added to the cache, but will return a cached response if one exists.
So make FLAG_NO_CACHE_STORE imply FLAG_NO_CACHE_LOOKUP to block the
possibility of side channel attacking.
Bug: 150371903
Test: atest
Because DnsResolver had been moved to another git project in R,
use aosp/1302595 as Merged-In tag to avoid conflict.
Merged-In: I1ff2dc09f41f76973c5f066b07b15388e722b375
Change-Id: Ic0ef9b22bb5992b083bebc4f530acd63a02ac31c
(cherry picked from commit 91945c82ec4e8eda4cdd85b77029cceccfa11769)
Diffstat (limited to 'resolv/res_cache.cpp')
| -rw-r--r-- | resolv/res_cache.cpp | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/resolv/res_cache.cpp b/resolv/res_cache.cpp index d6f0cd80..879ddbb4 100644 --- a/resolv/res_cache.cpp +++ b/resolv/res_cache.cpp @@ -1423,7 +1423,9 @@ ResolvCacheStatus _resolv_cache_lookup(unsigned netid, const void* query, int qu // possible to cache the answer of this query. // If ANDROID_RESOLV_NO_CACHE_STORE is set, return RESOLV_CACHE_SKIP to skip possible cache // storing. - if (flags & ANDROID_RESOLV_NO_CACHE_LOOKUP) { + // (b/150371903): ANDROID_RESOLV_NO_CACHE_STORE should imply ANDROID_RESOLV_NO_CACHE_LOOKUP + // to avoid side channel attack. + if (flags & (ANDROID_RESOLV_NO_CACHE_LOOKUP | ANDROID_RESOLV_NO_CACHE_STORE)) { return flags & ANDROID_RESOLV_NO_CACHE_STORE ? RESOLV_CACHE_SKIP : RESOLV_CACHE_NOTFOUND; } Entry key; @@ -1456,11 +1458,6 @@ ResolvCacheStatus _resolv_cache_lookup(unsigned netid, const void* query, int qu if (e == NULL) { LOG(INFO) << __func__ << ": NOT IN CACHE"; - // If it is no-cache-store mode, we won't wait for possible query. - if (flags & ANDROID_RESOLV_NO_CACHE_STORE) { - return RESOLV_CACHE_SKIP; - } - if (!cache_has_pending_request_locked(cache, &key, true)) { return RESOLV_CACHE_NOTFOUND; |