From 435ac6214e00eab191296cd6cfdc316aa07e7794 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Thu, 21 Jan 2021 14:19:41 +0100
Subject: [PATCH] would_dump: handle idmapped mounts
When determining whether or not to create a coredump the vfs will verify
that the caller is privileged over the inode. Make the would_dump()
helper handle idmapped mounts by passing down the mount's user namespace
of the exec file. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-23-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
fs/exec.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index a8ec371cd3cd1..d803227805f67 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1404,15 +1404,15 @@ EXPORT_SYMBOL(begin_new_exec);
void would_dump(struct linux_binprm *bprm, struct file *file)
{
struct inode *inode = file_inode(file);
- if (inode_permission(&init_user_ns, inode, MAY_READ) < 0) {
+ struct user_namespace *mnt_userns = file_mnt_user_ns(file);
+ if (inode_permission(mnt_userns, inode, MAY_READ) < 0) {
struct user_namespace *old, *user_ns;
bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
/* Ensure mm->user_ns contains the executable */
user_ns = old = bprm->mm->user_ns;
while ((user_ns != &init_user_ns) &&
- !privileged_wrt_inode_uidgid(user_ns, &init_user_ns,
- inode))
+ !privileged_wrt_inode_uidgid(user_ns, mnt_userns, inode))
user_ns = user_ns->parent;
if (old != user_ns) {
--
2.30.2