linux.git/fs/proc/kcore.c, branch v6.6

fs/proc/kcore: reinstate bounce buffer for KCORE_TEXT regions

2023-08-04T20:03:42+00:00

Some architectures do not populate the entire range categorised by
KCORE_TEXT, so we must ensure that the kernel address we read from is
valid.

Unfortunately there is no solution currently available to do so with a
purely iterator solution so reinstate the bounce buffer in this instance
so we can use copy_from_kernel_nofault() in order to avoid page faults
when regions are unmapped.

This change partly reverts commit 2e1c0170771e ("fs/proc/kcore: avoid
bounce buffer for ktext data"), reinstating the bounce buffer, but adapts
the code to continue to use an iterator.

[lstoakes@gmail.com: correct comment to be strictly correct about reasoning]
  Link: https://lkml.kernel.org/r/525a3f14-74fa-4c22-9fca-9dab4de8a0c3@lucifer.local
Link: https://lkml.kernel.org/r/20230731215021.70911-1-lstoakes@gmail.com
Fixes: 2e1c0170771e ("fs/proc/kcore: avoid bounce buffer for ktext data")
Signed-off-by: Lorenzo Stoakes 
Reported-by: Jiri Olsa 
Closes: https://lore.kernel.org/all/ZHc2fm+9daF6cgCE@krava
Tested-by: Jiri Olsa 
Tested-by: Will Deacon 
Cc: Alexander Viro 
Cc: Ard Biesheuvel 
Cc: Baoquan He 
Cc: Catalin Marinas 
Cc: David Hildenbrand 
Cc: Jens Axboe 
Cc: Kefeng Wang 
Cc: Liu Shixin 
Cc: Matthew Wilcox 
Cc: Mike Galbraith 
Cc: Thorsten Leemhuis 
Cc: Uladzislau Rezki (Sony) 
Cc: 
Signed-off-by: Andrew Morton

Merge tag 'asm-generic-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2023-07-06T17:06:04+00:00

Pull asm-generic updates from Arnd Bergmann:
 "These are cleanups for architecture specific header files:

   - the comments in include/linux/syscalls.h have gone out of sync and
     are really pointless, so these get removed

   - The asm/bitsperlong.h header no longer needs to be architecture
     specific on modern compilers, so use a generic version for newer
     architectures that use new enough userspace compilers

   - A cleanup for virt_to_pfn/virt_to_bus to have proper type checking,
     forcing the use of pointers"

* tag 'asm-generic-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  syscalls: Remove file path comments from headers
  tools arch: Remove uapi bitsperlong.h of hexagon and microblaze
  asm-generic: Unify uapi bitsperlong.h for arm64, riscv and loongarch
  m68k/mm: Make pfn accessors static inlines
  arm64: memory: Make virt_to_pfn() a static inline
  ARM: mm: Make virt_to_pfn() a static inline
  asm-generic/page.h: Make pfn accessors static inlines
  xen/netback: Pass (void *) to virt_to_page()
  netfs: Pass a pointer to virt_to_page()
  cifs: Pass a pointer to virt_to_page() in cifsglob
  cifs: Pass a pointer to virt_to_page()
  riscv: mm: init: Pass a pointer to virt_to_page()
  ARC: init: Pass a pointer to virt_to_pfn() in init
  m68k: Pass a pointer to virt_to_pfn() virt_to_page()
  fs/proc/kcore.c: Pass a pointer to virt_addr_valid()

procfs: replace all non-returning strlcpy with strscpy

2023-06-10T00:44:13+00:00

strlcpy() reads the entire source buffer first.  This read may exceed the
destination size limit.  This is both inefficient and can lead to linear
read overflows if a source string is not NUL-terminated [1].  In an effort
to remove strlcpy() completely [2], replace strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Link: https://lkml.kernel.org/r/20230510212457.3491385-1-azeemshaikh38@gmail.com
Signed-off-by: Azeem Shaikh 
Reviewed-by: Kees Cook 
Reviewed-by: Alexey Dobriyan 
Cc: Baoquan He 
Cc: David Hildenbrand 
Cc: Kefeng Wang 
Cc: Liu Shixin 
Cc: Lorenzo Stoakes 
Signed-off-by: Andrew Morton

fs/proc/kcore.c: Pass a pointer to virt_addr_valid()

2023-05-29T09:27:07+00:00

The virt_addr_valid() should be passed a pointer, the current
code passing a long unsigned int is just exploiting the
unintentional polymorphism of these calls being implemented
as preprocessor macros.

Signed-off-by: Linus Walleij

mm: vmalloc: convert vread() to vread_iter()

2023-04-06T02:42:57+00:00

Having previously laid the foundation for converting vread() to an
iterator function, pull the trigger and do so.

This patch attempts to provide minimal refactoring and to reflect the
existing logic as best we can, for example we continue to zero portions of
memory not read, as before.

Overall, there should be no functional difference other than a performance
improvement in /proc/kcore access to vmalloc regions.

Now we have eliminated the need for a bounce buffer in read_kcore_iter(),
we dispense with it, and try to write to user memory optimistically but
with faults disabled via copy_page_to_iter_nofault().  We already have
preemption disabled by holding a spin lock.  We continue faulting in until
the operation is complete.

Additionally, we must account for the fact that at any point a copy may
fail (most likely due to a fault not being able to occur), we exit
indicating fewer bytes retrieved than expected.

[sfr@canb.auug.org.au: fix sparc64 warning]
  Link: https://lkml.kernel.org/r/20230320144721.663280c3@canb.auug.org.au
[lstoakes@gmail.com: redo Stephen's sparc build fix]
  Link: https://lkml.kernel.org/r/8506cbc667c39205e65a323f750ff9c11a463798.1679566220.git.lstoakes@gmail.com
[akpm@linux-foundation.org: unbreak uio.h includes]
Link: https://lkml.kernel.org/r/941f88bc5ab928e6656e1e2593b91bf0f8c81e1b.1679511146.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes 
Signed-off-by: Stephen Rothwell 
Reviewed-by: Baoquan He 
Cc: Alexander Viro 
Cc: David Hildenbrand 
Cc: Jens Axboe 
Cc: Jiri Olsa 
Cc: Liu Shixin 
Cc: Matthew Wilcox (Oracle) 
Cc: Uladzislau Rezki (Sony) 
Signed-off-by: Andrew Morton

fs/proc/kcore: convert read_kcore() to read_kcore_iter()

2023-04-06T02:42:56+00:00

For the time being we still use a bounce buffer for vread(), however in
the next patch we will convert this to interact directly with the iterator
and eliminate the bounce buffer altogether.

Link: https://lkml.kernel.org/r/ebe12c8d70eebd71f487d80095605f3ad0d1489c.1679511146.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes 
Reviewed-by: David Hildenbrand 
Reviewed-by: Baoquan He 
Cc: Alexander Viro 
Cc: Jens Axboe 
Cc: Jiri Olsa 
Cc: Liu Shixin 
Cc: Matthew Wilcox (Oracle) 
Cc: Uladzislau Rezki (Sony) 
Signed-off-by: Andrew Morton

fs/proc/kcore: avoid bounce buffer for ktext data

2023-04-06T02:42:56+00:00

Patch series "convert read_kcore(), vread() to use iterators", v8.

While reviewing Baoquan's recent changes to permit vread() access to
vm_map_ram regions of vmalloc allocations, Willy pointed out [1] that it
would be nice to refactor vread() as a whole, since its only user is
read_kcore() and the existing form of vread() necessitates the use of a
bounce buffer.

This patch series does exactly that, as well as adjusting how we read the
kernel text section to avoid the use of a bounce buffer in this case as
well.

This has been tested against the test case which motivated Baoquan's
changes in the first place [2] which continues to function correctly, as
do the vmalloc self tests.


This patch (of 4):

Commit df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data")
introduced the use of a bounce buffer to retrieve kernel text data for
/proc/kcore in order to avoid failures arising from hardened user copies
enabled by CONFIG_HARDENED_USERCOPY in check_kernel_text_object().

We can avoid doing this if instead of copy_to_user() we use
_copy_to_user() which bypasses the hardening check.  This is more
efficient than using a bounce buffer and simplifies the code.

We do so as part an overall effort to eliminate bounce buffer usage in the
function with an eye to converting it an iterator read.

Link: https://lkml.kernel.org/r/cover.1679566220.git.lstoakes@gmail.com
Link: https://lore.kernel.org/all/Y8WfDSRkc%2FOHP3oD@casper.infradead.org/ [1]
Link: https://lore.kernel.org/all/87ilk6gos2.fsf@oracle.com/T/#u [2]
Link: https://lkml.kernel.org/r/fd39b0bfa7edc76d360def7d034baaee71d90158.1679511146.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes 
Reviewed-by: David Hildenbrand 
Reviewed-by: Baoquan He 
Cc: Alexander Viro 
Cc: Jens Axboe 
Cc: Jiri Olsa 
Cc: Liu Shixin 
Cc: Matthew Wilcox (Oracle) 
Cc: Uladzislau Rezki (Sony) 
Signed-off-by: Andrew Morton

mm: remove kern_addr_valid() completely

2022-11-09T01:37:18+00:00

Most architectures (except arm64/x86/sparc) simply return 1 for
kern_addr_valid(), which is only used in read_kcore(), and it calls
copy_from_kernel_nofault() which could check whether the address is a
valid kernel address.  So as there is no need for kern_addr_valid(), let's
remove it.

Link: https://lkml.kernel.org/r/20221018074014.185687-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Acked-by: Geert Uytterhoeven 	[m68k]
Acked-by: Heiko Carstens 		[s390]
Acked-by: Christoph Hellwig 
Acked-by: Helge Deller 			[parisc]
Acked-by: Michael Ellerman 		[powerpc]
Acked-by: Guo Ren 			[csky]
Acked-by: Catalin Marinas 	[arm64]
Cc: Alexander Gordeev 
Cc: Andy Lutomirski 
Cc: Anton Ivanov 
Cc: 
Cc: Borislav Petkov 
Cc: Christian Borntraeger 
Cc: Christophe Leroy 
Cc: Chris Zankel 
Cc: Dave Hansen 
Cc: David S. Miller 
Cc: Dinh Nguyen 
Cc: Greg Ungerer 
Cc: H. Peter Anvin 
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: Ivan Kokshaysky 
Cc: James Bottomley 
Cc: Johannes Berg 
Cc: Jonas Bonn 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michal Simek 
Cc: Nicholas Piggin 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Peter Zijlstra 
Cc: Richard Henderson 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Russell King 
Cc: Stafford Horne 
Cc: Stefan Kristiansson 
Cc: Sven Schnelle 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Cc: Vineet Gupta 
Cc: Will Deacon 
Cc: Xuerui Wang 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton

memory: move hotplug memory notifier priority to same file for easy sorting

2022-11-09T01:37:17+00:00

The priority of hotplug memory callback is defined in a different file. 
And there are some callers using numbers directly.  Collect them together
into include/linux/memory.h for easy reading.  This allows us to sort
their priorities more intuitively without additional comments.

Link: https://lkml.kernel.org/r/20220923033347.3935160-9-liushixin2@huawei.com
Signed-off-by: Liu Shixin 
Cc: Christoph Lameter 
Cc: David Hildenbrand 
Cc: Kefeng Wang 
Cc: Waiman Long 
Cc: zefan li 
Signed-off-by: Andrew Morton

fs/proc/kcore.c: use hotplug_memory_notifier() directly

2022-11-09T01:37:15+00:00

Commit 76ae847497bc52 ("Documentation: raise minimum supported version of
GCC to 5.1") updated the minimum gcc version to 5.1.  So the problem
mentioned in f02c69680088 ("include/linux/memory.h: implement
register_hotmemory_notifier()") no longer exist.  So we can now switch to
use hotplug_memory_notifier() directly rather than
register_hotmemory_notifier().

Link: https://lkml.kernel.org/r/20220923033347.3935160-3-liushixin2@huawei.com
Signed-off-by: Liu Shixin 
Reviewed-by: David Hildenbrand 
Cc: Christoph Lameter 
Cc: Kefeng Wang 
Cc: Waiman Long 
Cc: zefan li 
Signed-off-by: Andrew Morton