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David Hildenbrand
3c36b419b1
Patch series "fs/proc/kcore: don't read offline sections, logically offline pages and hwpoisoned pages", v3. Looking for places where the kernel might unconditionally read PageOffline() pages, I stumbled over /proc/kcore; turns out /proc/kcore needs some more love to not touch some other pages we really don't want to read -- i.e., hwpoisoned ones. Examples for PageOffline() pages are pages inflated in a balloon, memory unplugged via virtio-mem, and partially-present sections in memory added by the Hyper-V balloon. When reading pages inflated in a balloon, we essentially produce unnecessary load in the hypervisor; holes in partially present sections in case of Hyper-V are not accessible and already were a problem for /proc/vmcore, fixed in makedumpfile by detecting PageOffline() pages. In the future, virtio-mem might disallow reading unplugged memory -- marked as PageOffline() -- in some environments, resulting in undefined behavior when accessed; therefore, I'm trying to identify and rework all these (corner) cases. With this series, there is really only access via /dev/mem, /proc/vmcore and kdb left after I ripped out /dev/kmem. kdb is an advanced corner-case use case -- we won't care for now if someone explicitly tries to do nasty things by reading from/writing to physical addresses we better not touch. /dev/mem is a use case we won't support for virtio-mem, at least for now, so we'll simply disallow mapping any virtio-mem memory via /dev/mem next. /proc/vmcore is really only a problem when dumping the old kernel via something that's not makedumpfile (read: basically never), however, we'll try sanitizing that as well in the second kernel in the future. Tested via kcore_dump: https://github.com/schlafwandler/kcore_dump This patch (of 6): Commitdb779ef67f("proc/kcore: Remove unused kclist_add_remap()") removed the last user of KCORE_REMAP. Commit595dd46ebf("vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall user page") removed the last user of KCORE_OTHER. Let's drop both types. While at it, also drop vaddr in "struct kcore_list", used by KCORE_REMAP only. Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: David Hildenbrand <[email protected]> Reviewed-by: Mike Rapoport <[email protected]> Cc: "Michael S. Tsirkin" <[email protected]> Cc: Jason Wang <[email protected]> Cc: Alexey Dobriyan <[email protected]> Cc: "Matthew Wilcox (Oracle)" <[email protected]> Cc: Oscar Salvador <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Roman Gushchin <[email protected]> Cc: Alex Shi <[email protected]> Cc: Steven Price <[email protected]> Cc: Mike Kravetz <[email protected]> Cc: Aili Yao <[email protected]> Cc: Jiri Bohac <[email protected]> Cc: "K. Y. Srinivasan" <[email protected]> Cc: Haiyang Zhang <[email protected]> Cc: Stephen Hemminger <[email protected]> Cc: Wei Liu <[email protected]> Cc: Naoya Horiguchi <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
48 lines
891 B
C
48 lines
891 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* /proc/kcore definitions
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*/
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#ifndef _LINUX_KCORE_H
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#define _LINUX_KCORE_H
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enum kcore_type {
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KCORE_TEXT,
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KCORE_VMALLOC,
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KCORE_RAM,
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KCORE_VMEMMAP,
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KCORE_USER,
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};
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struct kcore_list {
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struct list_head list;
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unsigned long addr;
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size_t size;
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int type;
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};
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struct vmcore {
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struct list_head list;
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unsigned long long paddr;
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unsigned long long size;
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loff_t offset;
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};
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struct vmcoredd_node {
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struct list_head list; /* List of dumps */
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void *buf; /* Buffer containing device's dump */
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unsigned int size; /* Size of the buffer */
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};
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#ifdef CONFIG_PROC_KCORE
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void __init kclist_add(struct kcore_list *, void *, size_t, int type);
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extern int __init register_mem_pfn_is_ram(int (*fn)(unsigned long pfn));
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#else
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static inline
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void kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
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{
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}
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#endif
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#endif /* _LINUX_KCORE_H */
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