systemd/0465-user-util-be-stricter-in-parse_uid.patch

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From 87c22d3bb794118d25bc138108fd5bdd607365ef Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 1 Jun 2020 17:16:46 +0200
Subject: [PATCH] user-util: be stricter in parse_uid()
Let's refuse "+" and "-" prefixed UIDs. Let's refuse whitespace-prefixed
UIDS, Let's refuse zero-prefixed UIDs. Let's be safe than sorry.
(cherry picked from commit f5979b63cc305ba217dfd174b1bf0583bcf75a73)
Related: #1848373
---
src/basic/user-util.c | 10 +++++++++-
src/test/test-user-util.c | 26 +++++++++++++++++++++++---
2 files changed, 32 insertions(+), 4 deletions(-)
diff --git a/src/basic/user-util.c b/src/basic/user-util.c
index 10eeb256cd..40f4e45db6 100644
--- a/src/basic/user-util.c
+++ b/src/basic/user-util.c
@@ -49,7 +49,15 @@ int parse_uid(const char *s, uid_t *ret) {
assert(s);
assert_cc(sizeof(uid_t) == sizeof(uint32_t));
- r = safe_atou32_full(s, 10, &uid);
+
+ /* We are very strict when parsing UIDs, and prohibit +/- as prefix, leading zero as prefix, and
+ * whitespace. We do this, since this call is often used in a context where we parse things as UID
+ * first, and if that doesn't work we fall back to NSS. Thus we really want to make sure that UIDs
+ * are parsed as UIDs only if they really really look like UIDs. */
+ r = safe_atou32_full(s, 10
+ | SAFE_ATO_REFUSE_PLUS_MINUS
+ | SAFE_ATO_REFUSE_LEADING_ZERO
+ | SAFE_ATO_REFUSE_LEADING_WHITESPACE, &uid);
if (r < 0)
return r;
diff --git a/src/test/test-user-util.c b/src/test/test-user-util.c
index 8bf3dcd567..99203f7e48 100644
--- a/src/test/test-user-util.c
+++ b/src/test/test-user-util.c
@@ -52,13 +52,33 @@ static void test_parse_uid(void) {
assert_se(r == -EINVAL);
assert_se(uid == 100);
+ r = parse_uid("+1234", &uid);
+ assert_se(r == -EINVAL);
+ assert_se(uid == 100);
+
+ r = parse_uid("-1234", &uid);
+ assert_se(r == -EINVAL);
+ assert_se(uid == 100);
+
+ r = parse_uid(" 1234", &uid);
+ assert_se(r == -EINVAL);
+ assert_se(uid == 100);
+
r = parse_uid("01234", &uid);
- assert_se(r == 0);
- assert_se(uid == 1234);
+ assert_se(r == -EINVAL);
+ assert_se(uid == 100);
+
+ r = parse_uid("-0", &uid);
+ assert_se(r == -EINVAL);
+ assert_se(uid == 100);
+
+ r = parse_uid("+0", &uid);
+ assert_se(r == -EINVAL);
+ assert_se(uid == 100);
r = parse_uid("asdsdas", &uid);
assert_se(r == -EINVAL);
- assert_se(uid == 1234);
+ assert_se(uid == 100);
}
static void test_uid_ptr(void) {