The patch titled
Subject: fs/coredump.c: log if a core dump is aborted due to changed file permissions
has been added to the -mm tree. Its filename is
log-if-a-core-dump-is-aborted-due-to-changed-file-permissions.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/log-if-a-core-dump-is-aborted-due-to-changed-file-permissions.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/log-if-a-core-dump-is-aborted-due-to-changed-file-permissions.patch
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------------------------------------------------------
From: David Oberhollenzer <david.oberhollenzer@xxxxxxxxxxxxx>
Subject: fs/coredump.c: log if a core dump is aborted due to changed file permissions
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.
Link: https://lkml.kernel.org/r/20210701233151.102720-1-david.oberhollenzer@xxxxxxxxxxxxx
Signed-off-by: David Oberhollenzer <david.oberhollenzer@xxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/coredump.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/fs/coredump.c~log-if-a-core-dump-is-aborted-due-to-changed-file-permissions
+++ a/fs/coredump.c
@@ -782,10 +782,17 @@ void do_coredump(const kernel_siginfo_t
* 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",
+ cn.corename);
goto close_fail;
- if ((inode->i_mode & 0677) != 0600)
+ }
+ if ((inode->i_mode & 0677) != 0600) {
+ pr_info_ratelimited("Core dump to |%s aborted: cannot preserve file permissions\n",
+ cn.corename);
goto close_fail;
+ }
if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
goto close_fail;
if (do_truncate(mnt_userns, cprm.file->f_path.dentry,
_
Patches currently in -mm which might be from david.oberhollenzer@xxxxxxxxxxxxx are
log-if-a-core-dump-is-aborted-due-to-changed-file-permissions.patch
