linux-hardening - [PATCH v1 3/6] PKEY: Apply PKEY_ENFORCE

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Date:   Fri, 19 May 2023 01:19:11 +0000
From:   jeffxu@...omium.org
To:     dave.hansen@...el.com, luto@...nel.org, jorgelo@...omium.org,
        keescook@...omium.org, groeck@...omium.org, jannh@...gle.com,
        sroettger@...gle.com
Cc:     akpm@...ux-foundation.org, jeffxu@...gle.com,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-mm@...ck.org, linux-hardening@...r.kernel.org
Subject: [PATCH v1 3/6] PKEY: Apply PKEY_ENFORCE_API to mprotect

From: Jeff Xu <jeffxu@...gle.com>

This patch enables PKEY_ENFORCE_API for the mprotect and
mprotect_pkey syscalls.

Signed-off-by: Jeff Xu<jeffxu@...gle.com>
---
 mm/mprotect.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 8a68fdca8487..1db30b8baac3 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -794,6 +794,17 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 		}
 	}
 
+	/*
+	 * arch_check_pkey_enforce_api checks if current thread
+	 * has the PKEY permission to modify the memory mapping.
+	 * Note: this should only apply to the cases that do_mprotect_pkey
+	 * is called from syscall entry. Ref. to munmap for other cases.
+	 */
+	if (arch_check_pkey_enforce_api(current->mm, start, end) < 0) {
+		error = -EACCES;
+		goto out;
+	}
+
 	prev = vma_prev(&vmi);
 	if (start > vma->vm_start)
 		prev = vma;
-- 
2.40.1.606.ga4b1b128d6-goog