[Devel] [PATCH hci-8.1 v7 1/2] selftests: ve: grant the directories the files sit in

[Eva Kurchatova <eva.kurchatova@virtuozzo.com>]

The sysfs variant names nested leaves, kernel/vmcoreinfo and
kernel/notes, while the proc one names files at the top of the
filesystem. Both enforcement tests grant the leaves and nothing else,
so in the sysfs case the lookup stops at /sys/kernel, which a fresh VE
cannot traverse, and every open answers ENOENT.

Grant x on each directory along the way, taken from the path the
variant already gives. set_entry() gets a PATH_MAX buffer and fails on
truncation instead of writing a cut entry, as ve_open_rel() does.

Fixes: 303ce49b7446 ("selftests/ve: add ve_perms test for proc and sysfs")

https://virtuozzo.atlassian.net/browse/VSTOR-144955

Feature: fix selftests
Signed-off-by: Eva Kurchatova <eva.kurchatova@virtuozzo.com>
---
 tools/testing/selftests/ve/ve_perms_test.c | 34 ++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/ve/ve_perms_test.c b/tools/testing/selftests/ve/ve_perms_test.c
index 25ffbd42c380..8096b1fa3b43 100644
--- a/tools/testing/selftests/ve/ve_perms_test.c
+++ b/tools/testing/selftests/ve/ve_perms_test.c
@@ -114,9 +114,11 @@ static int ve_open_rel(int cgv2_fd, int ctid, const char *prefix,
 static int set_entry(int cgv2_fd, const char *path, const char *entry,
 		     const char *mask)
 {
-	char line[256];
+	char line[PATH_MAX];
 
-	snprintf(line, sizeof(line), "%s %s", entry, mask);
+	if (snprintf(line, sizeof(line), "%s %s", entry, mask) >=
+	    (int)sizeof(line))
+		return -1;
 	return write_file_at(cgv2_fd, path, line);
 }
 
@@ -343,6 +345,32 @@ TEST_F(ve_perms, write_parser)
 	EXPECT_LT(write_file_at(self->cgv2_fd, path, file), 0);
 }
 
+/* A leaf is reachable only once every directory above it can be traversed */
+static int allow_path(int cgv2_fd, const char *path, const char *file)
+{
+	char dir[PATH_MAX];
+	const char *sep;
+
+	for (sep = strchr(file, '/'); sep; sep = strchr(sep + 1, '/')) {
+		if (snprintf(dir, sizeof(dir), "%.*s", (int)(sep - file),
+			     file) >= (int)sizeof(dir))
+			return -1;
+		if (set_entry(cgv2_fd, path, dir, "x") < 0)
+			return -1;
+	}
+	return 0;
+}
+
+static int allow_paths(int cgv2_fd, const char *path, const char *const files[])
+{
+	int i;
+
+	for (i = 0; i < NR_FILES; i++)
+		if (allow_path(cgv2_fd, path, files[i]) < 0)
+			return -1;
+	return 0;
+}
+
 /*
  * Enforcement, allowed side: from inside a VE, granting r lets each file be
  * read, and granting x on the directory lets it be traversed (the lookup then
@@ -358,6 +386,7 @@ TEST_F(ve_perms, enforce_allows)
 
 	ve_file(path, sizeof(path), self->ctid_a, variant->fs);
 
+	ASSERT_EQ(allow_paths(self->cgv2_fd, path, variant->files), 0);
 	ASSERT_EQ(set_entries(self->cgv2_fd, path, variant->files, "r"), 0);
 	for (i = 0; i < NR_FILES; i++)
 		EXPECT_EQ(ve_open_rel(self->cgv2_fd, self->ctid_a,
@@ -400,6 +429,7 @@ TEST_F(ve_perms, enforce_denies)
 				      O_RDONLY), 0);
 
 	/* Granted w only: visible but not readable. */
+	ASSERT_EQ(allow_paths(self->cgv2_fd, path, variant->files), 0);
 	ASSERT_EQ(set_entries(self->cgv2_fd, path, variant->files, "w"), 0);
 	for (i = 0; i < NR_FILES; i++)
 		EXPECT_EQ(ve_open_rel(self->cgv2_fd, self->ctid_a,
-- 
2.56.0

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