nixos/nix
1
1
Fork 0
mirror of https://github.com/NixOS/nix.git synced 2025-12-23 17:31:08 +01:00
Code Activity

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

Browse source 
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.

(cherry picked from commit f1b4663805)
This commit is contained in:
Robert Hensing 2024-01-30 18:37:23 +01:00 • committed by github-actions[bot]
parent 60fb31a87d
commit b5947b55e2
4 changed files with 88 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

7
src/libstore/path-regex.hh
View file

@ -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\+\-\._\?=]+)";
}

13
src/libstore/path.cc
View file

@ -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')