On Fri, 2 Jul 2021 01:31:51 +0200 David Oberhollenzer <david.oberhollenzer@xxxxxxxxxxxxx> wrote:
> For obvious security reasons, a core dump is aborted if the
> filesystem cannot preserve ownership or permissions of the
> dump file.
>
> This affects filesystems like e.g. vfat, but also something like
> a 9pfs share in a Qemu test setup, running as a regular user,
> depending on the security model used. In those cases, the result
> is an empty core file and a confused user.
>
> To hopefully safe other people a lot of time figuring out the
> cause, this patch adds a simple log message for those specific
> cases.
Seems sane.
> --- a/fs/coredump.c
> +++ b/fs/coredump.c
> @@ -782,10 +777,17 @@ void do_coredump(const kernel_siginfo_t *siginfo)
> * filesystem.
> */
> mnt_userns = file_mnt_user_ns(cprm.file);
> - if (!uid_eq(i_uid_into_mnt(mnt_userns, inode), current_fsuid()))
> + if (!uid_eq(i_uid_into_mnt(mnt_userns, inode),
> + current_fsuid())) {
> + pr_info_ratelimited("Core dump to |%s aborted: cannot preserve file owner\n",
But why the "|%s"? This signifies dump-to-pipe, yes? Don't we need
the below?
--- a/fs/coredump.c~log-if-a-core-dump-is-aborted-due-to-changed-file-permissions-fix
+++ a/fs/coredump.c
@@ -784,12 +784,12 @@ void do_coredump(const kernel_siginfo_t
mnt_userns = file_mnt_user_ns(cprm.file);
if (!uid_eq(i_uid_into_mnt(mnt_userns, inode),
current_fsuid())) {
- pr_info_ratelimited("Core dump to |%s aborted: cannot preserve file owner\n",
+ pr_info_ratelimited("Core dump to %s aborted: cannot preserve file owner\n",
cn.corename);
goto close_fail;
}
if ((inode->i_mode & 0677) != 0600) {
- pr_info_ratelimited("Core dump to |%s aborted: cannot preserve file permissions\n",
+ pr_info_ratelimited("Core dump to %s aborted: cannot preserve file permissions\n",
cn.corename);
goto close_fail;
}
_
