[PATCH 24/34] would_dump: handle idmapped mounts

Christian Brauner
2020-10-29T00:39:39Z

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.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
fs/exec.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 8e75d7a33514..76de175eeba8 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1391,14 +1391,15 @@ EXPORT_SYMBOL(begin_new_exec);
void would_dump(struct linux_binprm *bprm, struct file *file)
{
struct inode *inode = file_inode(file);
- if (inode_permission(inode, MAY_READ) < 0) {
+ struct user_namespace *ns = mnt_user_ns(file->f_path.mnt);
+ if (mapped_inode_permission(ns, 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, ns, inode))
user_ns = user_ns->parent;

if (old != user_ns) {
--
2.29.0