[PATCH v5 0/3] Replace invocations of prandom_u32() with get_random_u32()

[david.keisarschm@mail.huji.ac.il]

From: David Keisar Schmidt <david.keisarschm@mail.huji.ac.il>

Hi,

The security improvements for prandom_u32 done in commits c51f8f88d705
from October 2020 and d4150779e60f from May 2022 didn't handle the cases
when prandom_bytes_state() and prandom_u32_state() are used.

Specifically, this weak randomization takes place in three cases:
    1.	mm/slab.c
    2.	mm/slab_common.c
    3.	arch/x86/mm/kaslr.c

The first two invocations (mm/slab.c, mm/slab_common.c) are used to create
randomization in the slab allocator freelists.
This is done to make sure attackers can’t obtain information on the heap state.

The last invocation, inside arch/x86/mm/kaslr.c,
randomizes the virtual address space of kernel memory regions.
Hence, we have added the necessary changes to make those randomizations stronger,
switching  prandom_u32 instance to siphash.


Changes since v4:
* This fifth series changes only the arch/x86/mm/kaslr patch.
  In particular, we replaced the use of prandom_bytes_state and
  prandom_seed_state with siphash inside arch/x86/mm/kaslr.c.

Changes since v3:
* edited commit messages

Changes since v2:
* edited commit message.
* replaced instances of get_random_u32 with get_random_u32_below
      in mm/slab.c, mm/slab_common.c

Regards,


David Keisar Schmidt (3):
  Replace invocation of weak PRNG in mm/slab.c
  Replace invocation of weak PRNG inside mm/slab_common.c
  Replace invocation of weak PRNG in arch/x86/mm/kaslr.c


 arch/x86/mm/kaslr.c                           |  18 +-
 include/uapi/linux/netfilter/xt_connmark.h    |  40 +-
 include/uapi/linux/netfilter/xt_dscp.h        |  27 +-
 include/uapi/linux/netfilter/xt_mark.h        |  17 +-
 include/uapi/linux/netfilter/xt_rateest.h     |  38 +-
 include/uapi/linux/netfilter/xt_tcpmss.h      |  13 +-
 include/uapi/linux/netfilter_ipv4/ipt_ecn.h   |  40 +-
 include/uapi/linux/netfilter_ipv4/ipt_ttl.h   |  14 +-
 include/uapi/linux/netfilter_ipv6/ip6t_hl.h   |  14 +-
 mm/slab.c                                     |  25 +-
 mm/slab_common.c                              |  11 +-
 net/netfilter/xt_dscp.c                       | 149 ++++---
 net/netfilter/xt_hl.c                         | 164 +++++---
 net/netfilter/xt_rateest.c                    | 282 ++++++++-----
 net/netfilter/xt_tcpmss.c                     | 378 ++++++++++++++----
 ...Z6.0+pooncelock+pooncelock+pombonce.litmus |  12 +-
 16 files changed, 815 insertions(+), 427 deletions(-)

-- 
2.37.3