nested mounts

[aep]

nesting a protected file inside a tmpfs doesnt work.
writes to the nested protected file do not make it to the host.

fs.mounts = [
  { path = "/lib",              uri = "file:{{ gramine.runtimedir() }}" },
  { path = "{{ arch_libdir }}", uri = "file:{{ arch_libdir }}" },
  { path = "/usr/lib",          uri = "file:/usr/lib" },
  { path = "/app",              uri = "file:/app" },
  { path = "/app/wordpress",    uri = "file:/app/wordpress",  type="tmpfs"},
]

sgx.protected_files = [
  "file:/app/wordpress/wp-config.php",
]

background:

the tmpfs is needed here to preload php code into the enclave memory, since we are required to use gramines fs implementation. but the code expects the directory to be persisted, so i tried making individual file exceptions

[dimakuv]

Yes, I think the complex combinations of fs.mounts and sgx.protected_files (like yours) do not work currently in Gramine.

However, we are close to finishing the rework of the whole FS subsystem: #371

After this rework, sgx.protected_files and sgx.trusted_files and sgx.allowed_files will become deprecated, and all FS hierarchy will be set up only through fs.mounts array. This will make nesting possible (the mounts will overlay each over), and your app will work as expected.

In fact, you can already try the latest Gramine with the encrypted FS mount. See also my reply here: #371 (comment)

[aep]

wait are you saying this should already work?

fs.mounts = [
 { path = "/app/wordpress",    uri = "file:/app/wordpress",  type="tmpfs"},
 { path = "/app/wordpress/wp-config.php", uri = "file:/app/persisted/wp-config.php", type = "encrypted", key_name = "default" },
]

it doesnt for me

warning: Disallowing access to file '/app/persisted/wp-config.php'; file is not protected, trusted or allowed.

[dimakuv]

Do you have the "default" key specified in your manifest? Like here:

gramine/LibOS/shim/test/regression/manifest.template

Line 48 in 9774ce1

fs.insecure__keys.default = "ffeeddccbbaa99887766554433221100"

Also, what is the Gramine version/commit you're running? (You can find it when you enable loader.log_level = "debug", it will be one of the first lines printed.)

This feature was merged in Gramine very recently, on 20. April.

[aep]

yes key is specified, debug doesnt show more info

however, adding it to allowed confusingly makes it work

sgx.allowed_files = [
    "file:/app/persisted/wp-config.php"
] 

is this intentional? i was assuming allowed means unencrypted write, but it actually looks encrypted on the host

gramine is git from last week, let me make sure to pull todays head instead.

[dimakuv]

gramine is git from last week, let me make sure to pull todays head instead.

Please do. There was a small bug exactly as you describe (adding the file to sgx.allowed_files allows to use the file in an encrypted way). We fixed it on 20. April, see this PR: #534

[aep]

going to close because the new feature does what we need. thanks!