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Disallow store path names that are . or .. (plus opt. -)

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As discussed in the maintainer meeting on 2024-01-29.

Mainly this is to avoid a situation where the name is parsed and
treated as a file name, mostly to protect users.
.-* and ..-* are also considered invalid because they might strip
on that separator to remove versions. Doesn't really work, but that's
what we decided, and I won't argue with it, because .-* probably
doesn't seem to have a real world application anyway.
We do still permit a 1-character name that's just "-", which still
poses a similar risk in such a situation. We can't start disallowing
trailing -, because a non-zero number of users will need it and we've
seen how annoying and painful such a change is.

What matters most is preventing a situation where . or .. can be
injected, and to just get this done.
This commit is contained in:
Robert Hensing 2024-01-30 18:37:23 +01:00 • committed by Théophane Hufschmitt
parent 80ea2dcc25
commit 6e3548f866
4 changed files with 88 additions and 2 deletions
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7
src/libstore/path-regex.hh
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@ -3,6 +3,11 @@
namespace nix {
static constexpr std::string_view nameRegexStr = R"([0-9a-zA-Z\+\-\._\?=]+)";
static constexpr std::string_view nameRegexStr =
// This uses a negative lookahead: (?!\.\.?(-|$))
// - deny ".", "..", or those strings followed by '-'
// - when it's not those, start again at the start of the input and apply the next regex, which is [0-9a-zA-Z\+\-\._\?=]+
R"((?!\.\.?(-|$))[0-9a-zA-Z\+\-\._\?=]+)";
}