FAILED: patch "[PATCH] memfd: do not -EACCES old memfd_create() users with" failed to apply to 6.5-stable tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



The patch below does not apply to the 6.5-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.5.y
git checkout FETCH_HEAD
git cherry-pick -x 202e14222fadb246dfdf182e67de1518e86a1e20
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023090745-depict-kinswoman-9083@gregkh' --subject-prefix 'PATCH 6.5.y' HEAD^..

Possible dependencies:

202e14222fad ("memfd: do not -EACCES old memfd_create() users with vm.memfd_noexec=2")
badbbcd76545 ("selftests/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED")
72de25913022 ("mm/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 202e14222fadb246dfdf182e67de1518e86a1e20 Mon Sep 17 00:00:00 2001
From: Aleksa Sarai <cyphar@xxxxxxxxxx>
Date: Mon, 14 Aug 2023 18:40:58 +1000
Subject: [PATCH] memfd: do not -EACCES old memfd_create() users with
 vm.memfd_noexec=2

Given the difficulty of auditing all of userspace to figure out whether
every memfd_create() user has switched to passing MFD_EXEC and
MFD_NOEXEC_SEAL flags, it seems far less distruptive to make it possible
for older programs that don't make use of executable memfds to run under
vm.memfd_noexec=2.  Otherwise, a small dependency change can result in
spurious errors.  For programs that don't use executable memfds, passing
MFD_NOEXEC_SEAL is functionally a no-op and thus having the same

In addition, every failure under vm.memfd_noexec=2 needs to print to the
kernel log so that userspace can figure out where the error came from.
The concerns about pr_warn_ratelimited() spam that caused the switch to
pr_warn_once()[1,2] do not apply to the vm.memfd_noexec=2 case.

This is a user-visible API change, but as it allows programs to do
something that would be blocked before, and the sysctl itself was broken
and recently released, it seems unlikely this will cause any issues.

[1]: https://lore.kernel.org/Y5yS8wCnuYGLHMj4@x1n/
[2]: https://lore.kernel.org/202212161233.85C9783FB@keescook/

Link: https://lkml.kernel.org/r/20230814-memfd-vm-noexec-uapi-fixes-v2-2-7ff9e3e10ba6@xxxxxxxxxx
Fixes: 105ff5339f49 ("mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC")
Signed-off-by: Aleksa Sarai <cyphar@xxxxxxxxxx>
Cc: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Daniel Verkamp <dverkamp@xxxxxxxxxxxx>
Cc: Jeff Xu <jeffxu@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index c758809d5bcf..53974d79d98e 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -17,18 +17,10 @@
 struct fs_pin;
 
 #if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
-/*
- * sysctl for vm.memfd_noexec
- * 0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL
- *	acts like MFD_EXEC was set.
- * 1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL
- *	acts like MFD_NOEXEC_SEAL was set.
- * 2: memfd_create() without MFD_NOEXEC_SEAL will be
- *	rejected.
- */
-#define MEMFD_NOEXEC_SCOPE_EXEC			0
-#define MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL		1
-#define MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED	2
+/* modes for vm.memfd_noexec sysctl */
+#define MEMFD_NOEXEC_SCOPE_EXEC			0 /* MFD_EXEC implied if unset */
+#define MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL		1 /* MFD_NOEXEC_SEAL implied if unset */
+#define MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED	2 /* same as 1, except MFD_EXEC rejected */
 #endif
 
 struct pid_namespace {
diff --git a/mm/memfd.c b/mm/memfd.c
index 0bdbd2335af7..d65485c762de 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -271,30 +271,22 @@ long memfd_fcntl(struct file *file, unsigned int cmd, unsigned int arg)
 static int check_sysctl_memfd_noexec(unsigned int *flags)
 {
 #ifdef CONFIG_SYSCTL
-	char comm[TASK_COMM_LEN];
-	int sysctl = MEMFD_NOEXEC_SCOPE_EXEC;
-	struct pid_namespace *ns;
-
-	ns = task_active_pid_ns(current);
-	if (ns)
-		sysctl = ns->memfd_noexec_scope;
+	int sysctl = task_active_pid_ns(current)->memfd_noexec_scope;
 
 	if (!(*flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
-		if (sysctl == MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL)
+		if (sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL)
 			*flags |= MFD_NOEXEC_SEAL;
 		else
 			*flags |= MFD_EXEC;
 	}
 
-	if (*flags & MFD_EXEC && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) {
-		pr_warn_once(
-			"memfd_create(): MFD_NOEXEC_SEAL is enforced, pid=%d '%s'\n",
-			task_pid_nr(current), get_task_comm(comm, current));
-
+	if (!(*flags & MFD_NOEXEC_SEAL) && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) {
+		pr_err_ratelimited(
+			"%s[%d]: memfd_create() requires MFD_NOEXEC_SEAL with vm.memfd_noexec=%d\n",
+			current->comm, task_pid_nr(current), sysctl);
 		return -EACCES;
 	}
 #endif
-
 	return 0;
 }
 
@@ -302,7 +294,6 @@ SYSCALL_DEFINE2(memfd_create,
 		const char __user *, uname,
 		unsigned int, flags)
 {
-	char comm[TASK_COMM_LEN];
 	unsigned int *file_seals;
 	struct file *file;
 	int fd, error;
@@ -325,12 +316,13 @@ SYSCALL_DEFINE2(memfd_create,
 
 	if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
 		pr_warn_once(
-			"memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
-			task_pid_nr(current), get_task_comm(comm, current));
+			"%s[%d]: memfd_create() called without MFD_EXEC or MFD_NOEXEC_SEAL set\n",
+			current->comm, task_pid_nr(current));
 	}
 
-	if (check_sysctl_memfd_noexec(&flags) < 0)
-		return -EACCES;
+	error = check_sysctl_memfd_noexec(&flags);
+	if (error < 0)
+		return error;
 
 	/* length includes terminating zero */
 	len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
index 8eb49204f9ea..8b7390ad81d1 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -1145,11 +1145,23 @@ static void test_sysctl_child(void)
 
 	printf("%s sysctl 2\n", memfd_str);
 	sysctl_assert_write("2");
-	mfd_fail_new("kern_memfd_sysctl_2",
-		MFD_CLOEXEC | MFD_ALLOW_SEALING);
-	mfd_fail_new("kern_memfd_sysctl_2_MFD_EXEC",
-		MFD_CLOEXEC | MFD_EXEC);
-	fd = mfd_assert_new("", 0, MFD_NOEXEC_SEAL);
+	mfd_fail_new("kern_memfd_sysctl_2_exec",
+		     MFD_EXEC | MFD_CLOEXEC | MFD_ALLOW_SEALING);
+
+	fd = mfd_assert_new("kern_memfd_sysctl_2_dfl",
+			    mfd_def_size,
+			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
+	mfd_assert_mode(fd, 0666);
+	mfd_assert_has_seals(fd, F_SEAL_EXEC);
+	mfd_fail_chmod(fd, 0777);
+	close(fd);
+
+	fd = mfd_assert_new("kern_memfd_sysctl_2_noexec_seal",
+			    mfd_def_size,
+			    MFD_NOEXEC_SEAL | MFD_CLOEXEC | MFD_ALLOW_SEALING);
+	mfd_assert_mode(fd, 0666);
+	mfd_assert_has_seals(fd, F_SEAL_EXEC);
+	mfd_fail_chmod(fd, 0777);
 	close(fd);
 
 	sysctl_fail_write("0");




[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux