daemon: Bypass authentication when importing content-addressed store items.

This puts ‘importPaths’ on par with ‘addToStore’ and ‘addTextToStore’: since
the two latter RPCs let anyone add content-addressed items in the store,
there’s no reason for ‘importPaths’ to require signatures by authorized keys
on these content-addressed items.

This will allow for things like ‘guix copy’ of .drv items without
authorization, or ‘guix deploy’ with (build-locally? #f) without
authorization.

* nix/libstore/store-api.hh (isContentAddressedPath): New prototype.
* nix/libstore/store-api.cc (isContentAddressedPath): New function.
* nix/libutil/util.hh (isPlainFile): New prototype.
* nix/libutil/util.cc (isPlainFile): New function.
* nix/libstore/local-store.cc (LocalStore::importPath): Define ‘narHash’ and
‘contentAddressed’.  Allow unsigned imports when ‘contentAddressed’ is true;
bypass signature verification when ‘contentAddressed’ is true.
* tests/store.scm ("import not signed"): Rewrite to not use a
content-addressed store item.
("import signed by unauthorized key"): Likewise.
("import not signed but content-addressed tree"): New test.
("import not signed but content-addressed regular file"): New test.
("import signed by unauthorized key but content-addressed"): New test.
("import with corrupt signature"): New test.
("import signed by authorized key but hash doesn't match"): New test.
("import with corrupt signature but content-addressed"): New test.
("import signed by authorized key, hash doesn't match, but content-addressed"):
New test.
* doc/guix.texi (Invoking guix archive): Document the exception for
content-addressed store items.  Add anchor for ‘--authorize’.
(Invoking guix deploy): Document the benefit of (build-locally? #f).
Add cross-reference for ‘authorize?’.

Co-authored-by: Reepca Russelstein <reepca@russelstein.xyz>
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
Merges: #8979

1 files changed, 7 insertions, 0 deletions

diff --git a/nix/libutil/util.cc b/nix/libutil/util.cc
index 95f293ff10f..72c8d38bd50 100644
--- a/nix/libutil/util.cc
+++ b/nix/libutil/util.cc
@@ -287,6 +287,13 @@ unsigned char getFileType(const Path & path)
     return DT_UNKNOWN;
 }
 
+bool isPlainFile(const Path & path)
+{
+    struct stat st = lstat(path);
+    return S_ISREG(st.st_mode)
+      && ((st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0);
+}
+
 
 string readFile(int fd)
 {