From 01573e231f18eb2d99162747186f59511f56b64d Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 08 Dec 2023 10:40:48 +0000
Subject: [PATCH] 移去rt
---
kernel/lib/strncpy_from_user.c | 27 +++++++++++++++++++++++----
1 files changed, 23 insertions(+), 4 deletions(-)
diff --git a/kernel/lib/strncpy_from_user.c b/kernel/lib/strncpy_from_user.c
index 56a5981..122d8d0 100644
--- a/kernel/lib/strncpy_from_user.c
+++ b/kernel/lib/strncpy_from_user.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
#include <linux/export.h>
+#include <linux/fault-inject-usercopy.h>
#include <linux/kasan-checks.h>
#include <linux/thread_info.h>
#include <linux/uaccess.h>
@@ -34,17 +35,32 @@
goto byte_at_a_time;
while (max >= sizeof(unsigned long)) {
- unsigned long c, data;
+ unsigned long c, data, mask;
/* Fall back to byte-at-a-time if we get a page fault */
unsafe_get_user(c, (unsigned long __user *)(src+res), byte_at_a_time);
- *(unsigned long *)(dst+res) = c;
+ /*
+ * Note that we mask out the bytes following the NUL. This is
+ * important to do because string oblivious code may read past
+ * the NUL. For those routines, we don't want to give them
+ * potentially random bytes after the NUL in `src`.
+ *
+ * One example of such code is BPF map keys. BPF treats map keys
+ * as an opaque set of bytes. Without the post-NUL mask, any BPF
+ * maps keyed by strings returned from strncpy_from_user() may
+ * have multiple entries for semantically identical strings.
+ */
if (has_zero(c, &data, &constants)) {
data = prep_zero_mask(c, data, &constants);
data = create_zero_mask(data);
+ mask = zero_bytemask(data);
+ *(unsigned long *)(dst+res) = c & mask;
return res + find_zero(data);
}
+
+ *(unsigned long *)(dst+res) = c;
+
res += sizeof(unsigned long);
max -= sizeof(unsigned long);
}
@@ -98,6 +114,9 @@
{
unsigned long max_addr, src_addr;
+ might_fault();
+ if (should_fail_usercopy())
+ return -EFAULT;
if (unlikely(count <= 0))
return 0;
@@ -116,9 +135,9 @@
kasan_check_write(dst, count);
check_object_size(dst, count, false);
- if (user_access_begin(VERIFY_READ, src, max)) {
+ if (user_read_access_begin(src, max)) {
retval = do_strncpy_from_user(dst, src, count, max);
- user_access_end();
+ user_read_access_end();
return retval;
}
}
--
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