linux-kernel - [PATCH v2 4/6] Wire UFFD up to SELinux

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Message-Id: <20200211225547.235083-5-dancol@google.com>
Date:   Tue, 11 Feb 2020 14:55:45 -0800
From:   Daniel Colascione <dancol@...gle.com>
To:     dancol@...gle.com, timmurray@...gle.com, nosh@...gle.com,
        nnk@...gle.com, lokeshgidra@...gle.com,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        selinux@...r.kernel.org
Subject: [PATCH v2 4/6] Wire UFFD up to SELinux

This change gives userfaultfd file descriptors a real security
context, allowing policy to act on them.

Signed-off-by: Daniel Colascione <dancol@...gle.com>
---
 fs/userfaultfd.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 07b0f6e03849..11227b94a5a7 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1020,6 +1020,8 @@ static int resolve_userfault_fork(struct userfaultfd_ctx *ctx,
 {
 	int fd;
 
+	/* Regular inode here is okay: only CAP_SYS_PTRACE callers
+	 * can monitor forks.  */
 	fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, new,
 			      O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS));
 	if (fd < 0)
@@ -1972,8 +1974,9 @@ SYSCALL_DEFINE1(userfaultfd, int, flags)
 	/* prevent the mm struct to be freed */
 	mmgrab(ctx->mm);
 
-	fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, ctx,
-			      O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS));
+	fd = anon_inode_getfd2("[userfaultfd]", &userfaultfd_fops, ctx,
+			       O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS),
+			       ANON_INODE_SECURE);
 	if (fd < 0) {
 		mmdrop(ctx->mm);
 		kmem_cache_free(userfaultfd_ctx_cachep, ctx);
-- 
2.25.0.225.g125e21ebc7-goog