RE: [PATCH v5 3/6] fs: Enable to enforce noexec mounts or file exec through O_MAYEXEC

From: Kees Cook

Sent: 14 May 2020 04:05
On Wed, May 13, 2020 at 04:27:39PM -0700, Kees Cook wrote:

quoted

Like, couldn't just the entire thing just be:

diff --git a/fs/namei.c b/fs/namei.c
index a320371899cf..0ab18e19f5da 100644
--- a/fs/namei.c
+++ b/fs/namei.c

@@ -2849,6 +2849,13 @@ static int may_open(const struct path *path, int acc_mode, int flag)
 		break;
 	}

+	if (unlikely(mask & MAY_OPENEXEC)) {
+		if (sysctl_omayexec_enforce & OMAYEXEC_ENFORCE_MOUNT &&
+		    path_noexec(path))
+			return -EACCES;
+		if (sysctl_omayexec_enforce & OMAYEXEC_ENFORCE_FILE)
+			acc_mode |= MAY_EXEC;
+	}
 	error = inode_permission(inode, MAY_OPEN | acc_mode);
 	if (error)
 		return error;

FYI, I've confirmed this now. Effectively with patch 2 dropped, patch 3
reduced to this plus the Kconfig and sysctl changes, the self tests
pass.

I think this makes things much cleaner and correct.

And a summary of that would be right for the 0/n patch email.

	David

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