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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
parent 8406da2877
commit f1b4663805
4 changed files with 88 additions and 2 deletions
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13
src/libstore/path.cc
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@ -10,6 +10,19 @@ static void checkName(std::string_view path, std::string_view name)
throw BadStorePath("store path '%s' has a name longer than %d characters",
path, StorePath::MaxPathLen);
// See nameRegexStr for the definition
if (name[0] == '.') {
// check against "." and "..", followed by end or dash
if (name.size() == 1)
throw BadStorePath("store path '%s' has invalid name '%s'", path, name);
if (name[1] == '-')
throw BadStorePath("store path '%s' has invalid name '%s': first dash-separated component must not be '%s'", path, name, ".");
if (name[1] == '.') {
if (name.size() == 2)
throw BadStorePath("store path '%s' has invalid name '%s'", path, name);
if (name[2] == '-')
throw BadStorePath("store path '%s' has invalid name '%s': first dash-separated component must not be '%s'", path, name, "..");
}
}
for (auto c : name)
if (!((c >= '0' && c <= '9')
|| (c >= 'a' && c <= 'z')