[LibOS] Allow stat() and chmod() on encrypted-files dirs

Commit "[LibOS] Allow `unlink()` on corrupted encrypted files" introduced checks `if (!dent->inode->data) return -EACCES` for all encrypted-files callbacks. However, these callbacks are also used for directories of encrypted files (FS mounts in manifest file and their sub-dirs), and directories never have `inode->data` anyway. Therefore, that commit introduced a bug that encrypted-files dirs returned EACCES error on `stat()` and `chmod()`. This commit fixes this bug by additionally checking that the inode is of "regular file" type. A sub-test is added in `sealed_file` LibOS test. Signed-off-by: Dmitrii Kuvaiskii <[email protected]>
gramineproject · Apr 10, 2024 · fa241d4 · fa241d4
1 parent a9f7d1c
commit fa241d4
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Showing 2 changed files with 14 additions and 2 deletions.
diff --git a/libos/src/fs/chroot/encrypted.c b/libos/src/fs/chroot/encrypted.c
@@ -359,7 +359,7 @@ static int chroot_encrypted_chmod(struct libos_dentry* dent, mode_t perm) {
     assert(locked(&g_dcache_lock));
     assert(dent->inode);
 
-    if (!dent->inode->data)
+    if (dent->inode->type == S_IFREG && !dent->inode->data)
         return -EACCES;
 
     char* uri = NULL;
@@ -528,7 +528,7 @@ static int chroot_encrypted_stat(struct libos_dentry* dent, struct stat* buf) {
     assert(locked(&g_dcache_lock));
     assert(dent->inode);
 
-    if (!dent->inode->data)
+    if (dent->inode->type == S_IFREG && !dent->inode->data)
         return -EACCES;
 
     return generic_inode_stat(dent, buf);

diff --git a/libos/test/regression/sealed_file.c b/libos/test/regression/sealed_file.c
@@ -1,17 +1,22 @@
 /* SPDX-License-Identifier: LGPL-3.0-or-later */
 /* Copyright (C) 2021 Intel Corporation */
 
+#define _GNU_SOURCE
 #include <assert.h>
 #include <err.h>
 #include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 #include <unistd.h>
 
 #include "rw_file.h"
 
+#define ENC_FILES_MOUNT "tmp_enc/mrenclaves/"
+
 #define SECRETSTRING "Secret string\n"
 #define SECRETSTRING_LEN (sizeof(SECRETSTRING) - 1)
 
@@ -24,6 +29,13 @@ int main(int argc, char** argv) {
              argv[0]);
     }
 
+    /* test that the encrypted-files mount is stat-able (there was a bug in Gramine) */
+    struct stat st;
+    if (stat(ENC_FILES_MOUNT, &st) < 0)
+        err(EXIT_FAILURE, "stat on encrypted-files mount");
+    if ((st.st_mode & S_IFMT) != S_IFDIR)
+        errx(EXIT_FAILURE, "stat on encrypted-files mount didn't return S_IFDIR");
+
     ret = access(argv[1], F_OK);
     if (ret < 0) {
         if (errno == ENOENT) {