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/20210112220124.837960-31-christian.brauner@xxxxxxxxxx Cc: Christoph Hellwig <hch@xxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: linux-fsdevel@xxxxxxxxxxxxxxx Reviewed-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx> --- /* v2 */ unchanged /* v3 */ unchanged /* v4 */ - Serge Hallyn <serge@xxxxxxxxxx>: - Use "mnt_userns" to refer to a vfsmount's userns everywhere to make terminology consistent. /* v5 */ unchanged base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837 - Christoph Hellwig <hch@xxxxxx>: - Use new file_mnt_user_ns() helper. /* v6 */ unchanged base-commit: 19c329f6808995b142b3966301f217c831e7cf31 --- fs/exec.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index a8ec371cd3cd..d803227805f6 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) { -- 2.30.0
