|author||Jann Horn <email@example.com>||2015-09-09 15:38:30 -0700|
|committer||Linus Torvalds <firstname.lastname@example.org>||2015-09-10 13:29:01 -0700|
fs: Don't dump core if the corefile would become world-readable.
On a filesystem like vfat, all files are created with the same owner and mode independent of who created the file. When a vfat filesystem is mounted with root as owner of all files and read access for everyone, root's processes left world-readable coredumps on it (but other users' processes only left empty corefiles when given write access because of the uid mismatch). Given that the old behavior was inconsistent and insecure, I don't see a problem with changing it. Now, all processes refuse to dump core unless the resulting corefile will only be readable by their owner. Signed-off-by: Jann Horn <email@example.com> Acked-by: Kees Cook <firstname.lastname@example.org> Cc: Al Viro <email@example.com> Signed-off-by: Andrew Morton <firstname.lastname@example.org> Signed-off-by: Linus Torvalds <email@example.com>
Diffstat (limited to 'fs')
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/coredump.c b/fs/coredump.c
index b696dc2c220d..a8f75640ac86 100644
@@ -685,11 +685,15 @@ void do_coredump(const siginfo_t *siginfo)
- * Dont allow local users get cute and trick others to coredump
- * into their pre-created files.
+ * Don't dump core if the filesystem changed owner or mode
+ * of the file during file creation. This is an issue when
+ * a process dumps core while its cwd is e.g. on a vfat
+ * filesystem.
if (!uid_eq(inode->i_uid, current_fsuid()))
+ if ((inode->i_mode & 0677) != 0600)
+ goto close_fail;
if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))