- add missing struct member @wait, drop @completion
- convert function comments to kernel-doc format
- for af_alg_readable(), change comments from "writable" to "readable"
Warning: include/crypto/if_alg.h:161 struct member 'wait' not described
in 'af_alg_ctx'
Warning: include/crypto/if_alg.h:161 Excess struct member 'completion'
description in 'af_alg_ctx'
Warning: include/crypto/if_alg.h:187 This comment starts with '/**', but
isn't a kernel-doc comment.
* Size of available buffer for sending data from user space to kernel.
Warning: include/crypto/if_alg.h:202 This comment starts with '/**', but
isn't a kernel-doc comment.
* Can the send buffer still be written to?
Warning: include/crypto/if_alg.h:213 This comment starts with '/**', but
isn't a kernel-doc comment.
* Size of available buffer used by kernel for the RX user space operation.
Warning: include/crypto/if_alg.h:228 This comment starts with '/**', but
isn't a kernel-doc comment.
* Can the RX buffer still be written to?
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add support for AES-CCM to the crypto library.
This will be used to provide a streamlined implementation of the
"ccm(aes)" crypto_aead algorithm. Most users of "ccm(aes)" will also be
able to switch to the library, which as usual will be faster and
simpler, e.g.:
- fs/smb/client/
- fs/smb/server/
- net/mac80211/
- net/mac802154/
(I've already written proof-of-concept patches for all the above, and
they helped inform the API design.)
As in the AES-GCM API, incremental operation is supported. It has to be
used carefully, especially when decrypting, but it makes the API general
enough to work well for all users.
The AES-CCM library code calls aes_cbcmac_blocks() directly, bypassing
the higher-level aes_cbcmac_init(), aes_cbcmac_update(), and
aes_cbcmac_final(). The latter set of functions is useful only for
AES-CCM, so they don't make sense to keep around and will be removed
once the "ccm(aes)" crypto_aead starts using the AES-CCM library.
Initial test coverage is provided by the crypto_aead support added in a
later commit. I'm planning a KUnit test suite as well.
Link: https://patch.msgid.link/20260715221153.246410-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Add support for AES-GCM to the crypto library.
This will be used to provide streamlined implementations of the
"gcm(aes)" and "rfc4106(gcm(aes))" crypto_aead algorithms. Most users
of these will also be able to switch to the library, which as usual will
be faster and simpler, e.g.:
- drivers/net/macsec.c
- fs/smb/client/
- fs/smb/server/
- net/ceph/messenger_v2.c
- net/mac80211/ (for both GMAC and GCMP)
- net/tipc/crypto.c
- security/keys/trusted-keys/trusted_dcp.c
(I've already written proof-of-concept patches for all the above, and
they helped inform the API design.)
As usual, the architecture-optimized AES-GCM code will be migrated into
the library as well (using the hooks provided in this commit as well as
the GHASH ones), eliminating lots of repetitive boilerplate code.
Incremental en/decryption is supported. Incremental operation is a bit
controversial in AEAD APIs because users have to be careful not to
consume any decrypted data that hasn't been authenticated yet. But I do
think it's the right choice here. It's not fundamentally different from
the existing incremental MAC APIs, and it's the only approach that's
general enough to work well for all users in the kernel:
- An array of virtually-addressed buffers (like that used by
BoringSSL's EVP_AEAD_CTX_sealv() and EVP_AEAD_CTX_openv()) doesn't
work in the kernel in general, since in some cases the data for a
single AES-GCM message is contained in a large number of highmem
pages that each need to be mapped into memory individually. That
can be done efficiently only by using CPU-local mappings, but there
is a limited number of those.
Ceph messenger v2 is a great example, as it can send or receive up
to 32 MiB in a single AES-GCM message. And it needs the
en/decrypted data to go into a (potentially large) number of bvecs
provided by a custom iterator, as well as into four
virtually-addressed buffers, two of which can be large buffers in
the vmalloc region.
Even just allocating an array big enough to store all the pointers
can be problematic in the kernel. There are cases in which
decryption runs in GFP_NOIO context or even in softirq context,
where memory allocations are not as reliable as they normally are.
- Meanwhile, 'struct scatterlist' (the choice of crypto_aead) has
turned out to be really inconvenient for anyone who *does* just have
virtually-addressed buffers. This is especially true if they can be
in the vmalloc region, including the stack, as in that case the
conversion to a scatterlist has to be done page-by-page.
And even for users who have all of their data in bare 'struct page',
none of them actually use 'struct scatterlist' as their native data
structure anyway. They actually use skbs, bvecs, or other formats.
- iov_iter is attractive, but ultimately not general enough either
(considering the Ceph case for example), but also too general in
some ways (like having support for userspace addresses). Additional
iter types like ITER_SKB would help a bit, but bloating iov_iter
with more types would reduce performance elsewhere in the kernel.
Initial test coverage is provided by the crypto_aead support added in a
later commit. I'm planning a KUnit test suite as well.
Link: https://patch.msgid.link/20260715221153.246410-7-ebiggers@kernel.org
Link: https://patch.msgid.link/20260722021730.16897-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Add support for AES-XTS to the crypto library.
This will be used to provide a streamlined implementation of the
"xts(aes)" crypto_skcipher algorithm. I'm also planning to use this
directly in fscrypt and blk-crypto-fallback.
As usual, the architecture-optimized AES-XTS code will be migrated into
the library as well (using the hooks provided in this commit),
eliminating lots of repetitive boilerplate code. Compared to direct
implementation of "xts(aes)", I've also eliminated the requirement for
architectures to implement ciphertext stealing, as the library just
handles it portably instead. That will simplify things considerably.
Initial test coverage is provided by the crypto_skcipher support added
in a later commit. I'm planning a KUnit test suite as well.
Link: https://patch.msgid.link/20260715221153.246410-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Add support for AES-CTR and AES-XCTR to the crypto library.
These will be used to provide streamlined implementations of the
"ctr(aes)" and "xctr(aes)" crypto_skcipher algorithms. Most users of
"ctr(aes)" will also be able to switch to the library, which as usual
will be simpler and faster, e.g.:
- net/mac80211/fils_aead.c
- net/mac802154/llsec.c
As usual, the architecture-optimized AES-CTR and AES-XCTR code will be
migrated into the library as well (using the hooks provided in this
commit), eliminating lots of repetitive boilerplate code.
This is also a prerequisite for supporting AES-GCM, AES-CCM, and
AES-HCTR2 in the crypto library.
Initial test coverage is provided by the crypto_skcipher support added
in a later commit. I'm planning a KUnit test suite as well.
Reviewed-by: Thomas Huth <thuth@redhat.com>
Link: https://patch.msgid.link/20260715221153.246410-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Add support for AES-CBC and AES-CBC-CTS to the crypto library.
These will be used to provide streamlined implementations of the
"cbc(aes)" and "cts(cbc(aes))" crypto_skcipher algorithms. Most users
of these crypto_skcipher algorithms will also be able to switch to the
library, which as usual will be simpler and faster, e.g.:
- block/blk-crypto-fallback.c (for AES-128-CBC-ESSIV)
- fs/crypto/crypto.c (for AES-128-CBC-ESSIV)
- fs/crypto/fname.c (for AES-256-CTS and AES-128-CBC)
- kernel/bpf/crypto.c
- net/ceph/crypto.c
- security/keys/encrypted-keys/encrypted.c
As usual, the architecture-optimized AES-CBC and AES-CBC-CTS code will
be migrated into the library as well (using the hooks provided in this
commit), eliminating lots of repetitive boilerplate code.
Initial test coverage is provided by the crypto_skcipher support added
in a later commit. I'm planning a KUnit test suite as well.
Reviewed-by: Thomas Huth <thuth@redhat.com>
Link: https://patch.msgid.link/20260715221153.246410-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Add support for AES-ECB to the crypto library.
This will be used to provide a streamlined implementation of the
"ecb(aes)" crypto_skcipher algorithm. fs/crypto/keysetup_v1.c will also
use aes_ecb_encrypt() directly.
As usual, the architecture-optimized AES-ECB code will be migrated into
the library as well (using the hooks provided in this commit),
eliminating lots of repetitive boilerplate code.
ECB is obsolete of course, but we need this for parity with the
traditional API and to support some odd users of ECB in the kernel.
Initial test coverage is provided by the crypto_skcipher support added
in a later commit. I'm planning a KUnit test suite as well.
Create a documentation file libcrypto-unauth-encryption.rst to hold the
documentation for this and other unauthenticated encryption modes.
Reviewed-by: Thomas Huth <thuth@redhat.com>
Link: https://patch.msgid.link/20260715221153.246410-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
AF_ALG is a frequent source of vulnerabilities and a maintenance
nightmare. It exposes far more functionality to userspace than ever
should have been exposed, especially to unprivileged processes. Recent
exploits have targeted kernel internal implementation details like
"authencesn" that have zero use case for userspace access.
Fortunately, AF_ALG is rarely used in practice, as userspace crypto
libraries exist. And when it is used, only some functionality is known
to be used, and many users are known to hold capabilities already.
iwd for example requires CAP_NET_ADMIN and has a known algorithm list
(https://lore.kernel.org/linux-crypto/bcbbef00-5881-421b-8892-7be6c04b832d@gmail.com/).
Thus, let's restrict the set of allowed algorithms by default, depending
on the capabilities held.
Add a sysctl /proc/sys/crypto/af_alg_restrict with meaning:
0: unrestricted
1: limited functionality
2: completely disabled
Set the default value to 1, which enables an algorithm allowlist for
unprivileged processes and a slightly longer allowlist for privileged
processes.
Note that the list may be tweaked in the future. However, the common
use cases such as iwd and bluez are taken into account already. I've
tested that iwd still works with the default value of 1.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Pull networking updates from Jakub Kicinski:
"Core & protocols:
- Work on removing rtnl_lock protection throughout the stack
continues. In this chapter:
- don't use rtnl_lock for IPv6 multicast routing configuration
- don't take rtnl_lock in ethtool for modern drivers
- prepare Qdisc dump callbacks for rtnl_lock removal
- Support dumping just ifindex + name of all interfaces, under RCU.
It's a common operation for Netlink CLI tools (when translating
names to ifindexes) and previously required full rtnl_lock.
- Support dumping qdiscs and page pools for a specific netdev. Even
tho user space wants a dump of all netdevs, most of the time, the
OOO programming model results in repeating the dump for each
netdev. Which, in absence of a cache, leads to a O(n^2) behavior.
- Flush nexthops once on multi-nexthop removal (e.g. when device goes
down), another O(n^2) -> O(n) improvement.
- Rehash locally generated traffic to a different nexthop on
retransmit timeout.
- Honor oif when choosing nexthop for locally generated IPv6 traffic.
- Convert TCP Auth Option to crypto library, and drop non-RFC algos.
- Increase subflow limits in MPTCP to 64 and endpoint limit to 256.
- Support MPTCP signaling of IPv6 address + port (ADD_ADDR). We need
to selectively skip reporting of the standard TCP Timestamp option,
because they won't fit into the header space together (12 + 30 >
40).
- Support using bridge neighbor suppression, Duplicate Address
Detection, Gratuitous ARP and unsolicited NA forwarding - in EVPN
deployments, e.g. VXLAN fabrics (IPv4 and IPv6).
- Improve link state reporting for upper netdevs (e.g. macvlan) over
tunnel devices (again, mostly for EVPN deployments).
- Support binding GENEVE tunnels to a local address.
- Speed up UDP tunnel destruction (remove one synchronize_rcu()).
- Support exponential field encoding in multicast (IGMPv3 and MLDv2).
- Support attaching PSP crypto offload to containers (veth, netkit).
- Add a new IPSec Netlink message XFRM_MSG_MIGRATE_STATE that allows
migrating individual IPsec SAs independently of their policies.
The existing XFRM_MSG_MIGRATE is tightly coupled to policy+SA
migration, lacks SPI for unique SA identification, and cannot
express reqid changes or migrate Transport mode selectors.
The new interface identifies the SA via SPI and mark, supports
reqid changes, address family changes, encap removal, and uses an
atomic create+install flow under x->lock to prevent SN/IV reuse
during AEAD SA migration.
- Implement GRO/GSO support for PPPoE.
- Convert sockopt callbacks in a number of protocols to iov_iter.
Cross-tree stuff:
- Remove support for Crypto TFM cloning (unblocked after the TCP Auth
Option rework). This feature regressed performance for all crypto
API users, since it changed crypto transformation objects into
reference-counted objects.
- Add FCrypt-PCBC implementation to rxrpc and remove it from the
global crypto API as obsolete and insecure.
Wireless:
- Major rework of station bandwidth handling, fixing issues with
lower capability than AP.
- Cleanups for EMLSR spec issues (drafts differed).
- More Neighbor Awareness Networking (Wi-Fi Aware) work (multicast,
schedule improvements, multi-station etc.)
- Some Ultra High Reliability (UHR) / IEEE 802.11bn (D1.4) work
(e.g. non-primary channel access, UHR DBE support).
- Fine Timing Measurement ranging (i.e. distance measurement) APIs.
Netfilter:
- Use per-rule hash initval in nf_conncount. This avoids unnecessary
lock contention with short keys (e.g. conntrack zones) in different
namespaces.
- Various safety improvements, both in packet parsing and object
lifetimes. Notably add refcounts to conntrack timeout policy.
Deletions:
- Remove TLS + sockmap integration. TLS wants to pin user pages to
avoid a copy, and sockmap wants to write to the input stream. More
work on this integration is clearly needed, and we can't find any
users (original author admitted that they never deployed it).
- Remove support for TLS offload with TCP Offload Engine (the far
more common opportunistic offload is retained). The locking looks
unfixable (driver sleeps under TCP spin locks) and people from the
vendor that added this are AWOL.
- Remove more ATM code, trying to leave behind only what PPPoATM
needs, AAL5 and br2684 with permanent circuits.
- Remove AppleTalk. Let it join hamradio in our out of tree protocol
graveyard, I mean, repository.
- Disable 32-bit x_tables compatibility (32bit binaries on 64bit
kernel) interface in user namespaces. To be deleted completely,
soon.
- Remove 5/10 MHz support from cfg80211/mac80211.
Drivers:
- Software:
- Support DEVMEM/DMABUF Tx over NETMEM_TX_NO_DMA devices (netkit)
- bonding: add knob to strictly follow 802.3ad for link state
- New drivers:
- Alibaba Elastic Ethernet Adaptor (cloud vNIC).
- NXP NETC switch within i.MX94.
- DPLL:
- Add operational state to pins (implement in zl3073x).
- Add generic DPLL type, for daisy-chaining DPLLs (implement in ice).
- Ethernet high-speed NICs:
- Huawei (hinic3):
- enhance tc flow offload support with queue selection,
tunnels
- nVidia/Mellanox:
- avoid over-copying payload to the skb's linear part (up to
60% win for LRO on slow CPUs like ARM64 V2)
- expose more per-queue stats over the standard API
- support additional, unprivileged PFs in the DPU
configuration
- support Socket Direct (multi-PF) with switchdev offloads
- add a pool / frag allocator for DMA mapped buffers for
control objects, save memory on systems with 64kB page size
- take advantage of the ability to dynamically change RSS
table size, even when table is configured by the user
- increase the max RSS table size for even traffic
distribution
- Ethernet NICs:
- Marvell/Aquantia:
- AQC113 PTP support
- Realtek USB (r8152):
- support 10Gbit Link Speeds and Energy-Efficient Ethernet
(EEE)
- support firmware loaded (for RTL8157/RTL8159)
- support for the RTL8159
- Intel (ixgbe):
- support Energy-Efficient Ethernet (EEE) on E610 devices
- Ethernet switches:
- Airoha:
- support multiple netdevs on a single GDM block / port
- Marvell (mv88e6xxx):
- support SERDES of mv88e6321
- Microchip (ksz8/9):
- rework the driver callbacks to remove one indirection layer
- Motorcomm (yt921x):
- support port rate policing
- support TBF qdisc offload
- support ACL/flower offload
- nVidia/Mellanox:
- expose per-PG rx_discards
- Realtek:
- rtl8365mb: bridge offloading and VLAN support
- Ethernet PHYs:
- Airoha:
- support Airoha AN8801R Gigabit PHYs.
- Micrel:
- implement 3 low-loss cable tunables
- Realtek:
- support MDI swapping for RTL8226-CG
- support MDIO for RTL931x
- Qualcomm:
- at803x: Rx and Tx clock management for IPQ5018 PHY
- Motorcomm:
- support YT8522 100M RMII PHY
- set drive strength in YT8531s RGMII
- TI:
- dp83822: add optional external PHY clock
- Bluetooth:
- hci_sync: add support for HCI_LE_Set_Host_Feature [v2]
- SMP: use AES-CMAC library API
- Intel:
- support Product level reset
- support smart trigger dump
- Mediatek:
- add event filter to filter specific event
- Realtek:
- fix RTL8761B/BU broken LE extended scan
- WiFi:
- Broadcom (b43):
- new support for a 11n device
- MediaTek (mt76):
- support mt7927
- mt792x: broken usb transport detection
- mt7921: regulatory improvements
- Qualcomm (ath9k):
- GPIO interface improvements
- Qualcomm (ath12k):
- WDS support
- replace dynamic memory allocation in WMI Rx path
- thermal throttling/cooling device support
- 6 GHz incumbent interference detection
- channel 177 in 5 GHz
- Realtek (rt89):
- RTL8922AU support
- USB 3 mode switch for performance
- better monitor radiotap support
- RTL8922DE preparations"
* tag 'net-next-7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1778 commits)
ipv4: fib_rule: Move fib4_rules_exit() to ->exit().
net: serialize netif_running() check in enqueue_to_backlog()
net: skmsg: preserve sg.copy across SG transforms
appletalk: move the protocol out of tree
appletalk: stop storing per-interface state in struct net_device
selftests/bpf: test that TLS crypto is rejected on a sockmap socket
selftests/bpf: drop the unused kTLS program from test_sockmap
selftests/bpf: remove sockmap + ktls tests
tls: remove dead sockmap (psock) handling from the SW path
tls: reject the combination of TLS and sockmap
atm: remove orphaned uAPI for deleted drivers, protocols and SVCs
atm: remove unused ATM PHY operations
atm: remove the unused pre_send and send_bh device operations
atm: remove the unused change_qos device operation
atm: remove SVC socket support and the signaling daemon interface
atm: remove the local ATM (NSAP) address registry
atm: remove dead SONET PHY ioctls
atm: remove the unused send_oam / push_oam callbacks
atm: remove AAL3/4 transport support
net: dsa: sja1105: fix lastused timestamp in flower stats
...
Pull crypto updates from Herbert Xu:
"API:
- Drop support for off-CPU cryptography in af_alg
- Document that af_alg is *always* slower
- Document the deprecation of af_alg
- Remove zero-copy support from skcipher and aead in af_alg
- Cap AEAD AD length to 0x80000000 in af_alg
- Free default RNG on module exit
Algorithms:
- Fix vli multiplication carry overflow in ecc
- Drop unused cipher_null crypto_alg
- Remove unused variants of drbg
- Use lib/crypto in drbg
- Use memcpy_from/to_sglist in authencesn
- Allow authenc(hmac(sha{256,384}),cts(cbc(aes))) in FIPS mode
- Disallow RSA PKCS#1 SHA-1 sig algs in FIPS mode
- Filter out async aead implementations at alloc in krb5
- Fix non-parallel fallback by rstoring callback in pcrypt
- Validate poly1305 template argument in chacha20poly1305
Drivers:
- Add sysfs PCI reset support to qat
- Add KPT support for GEN6 devices to qat
- Remove unused character device and ioctls from qat
- Add support for hw access via SMCC to mtk
- Remove prng support from crypto4xx
- Remove prng support from hisi-trng
- Remove prng support from sun4i-ss
- Remove prng support from xilinx-trng
- Remove loongson-rng
- Remove exynos-rng
Others:
- Remove support for AIO on sockets"
* tag 'v7.2-p1' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (196 commits)
crypto: tegra - fix refcount leak in tegra_se_host1x_submit()
crypto: rng - Free default RNG on module exit
crypto: testmgr - allow authenc(hmac(sha{256,384}),cts(cbc(aes))) in FIPS mode
hwrng: jh7110 - fix refcount leak in starfive_trng_read()
crypto: atmel-ecc - drop dead code in atmel_ecdh_max_size
crypto: cavium/cpt - fix DMA cleanup using wrong loop index
crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
MAINTAINERS: make myself the maintainer of the Qualcomm QCE driver
crypto: amcc - convert irq_of_parse_and_map to platform_get_irq
crypto: sun4i-ss - Remove insecure and unused rng_alg
hwrng: xilinx - Move xilinx-rng into drivers/char/hw_random/
crypto: xilinx-trng - Replace crypto_drbg_ctr_df() with HMAC-SHA512
crypto: xilinx-trng - Fix return value of xtrng_hwrng_trng_read()
crypto: xilinx-trng - Remove crypto_rng interface
crypto: exynos-rng - Remove exynos-rng driver
hwrng: hisi-trng - Move hisi-trng into drivers/char/hw_random/
crypto: hisi-trng - Remove crypto_rng interface
crypto: loongson - Remove broken and unused loongson-rng
crypto: crypto4xx - Remove insecure and unused rng_alg
crypto: qat - validate RSA CRT component lengths
...
This code is just trying to condition 48 bytes of random data. This can
be done easily using HKDF-SHA512-Extract, saving 300 lines of code.
This commit also fixes forward security (in this particular case) by
clearing the entropy from memory after it's used.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
AF_ALG is deprecated and exposed to unprivileged userspace. Only
use the least buggy algorithm implementations: the pure software ones.
This removes one of the main advantages of AF_ALG, which is the
ability to use it with off-CPU accelerators. However, using off-CPU
accelerators has huge overheads, both in performance and attack surface.
I have yet to see real-world, performance-critical workloads where using
an accelerator via AF_ALG is actually a win over doing cryptography in
userspace.
If using an off-CPU accelerator really does turn out to be a win, a new
API should be developed that is actually a good fit for it.
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The only user of msg->msg_iocb was AF_ALG, but that's deprecated.
It can be removed entirely at the cost of only supporting synchronous
operations. This doesn't break userspace, which will silently block
(for a bounded amount of time) in io_submit instead of operating
asynchronously.
This also makes struct msghdr smaller, helping every other caller of
sendmsg().
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use straightforward (buffer, len) parameters instead of struct
drbg_string or lists of strings. This simplifies the code considerably.
For now struct drbg_string is still used in crypto_drbg_ctr_df(), so
move its definition to crypto/df_sp80090a.h.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Remove the support for CTR_DRBG. It's likely unused code, seeing as
HMAC_DRBG is always enabled and prioritized over it unless
NETLINK_CRYPTO is used to change the algorithm priorities.
There's also no compelling reason to support more than one of
[HMAC_DRBG, HASH_DRBG, CTR_DRBG]. By definition, callers cannot tell
any difference in their outputs. And all are FIPS-certifiable, which is
the only point of the kernel's NIST DRBGs anyway.
Switching to CTR_DRBG doesn't seem all that compelling, either. While
it's often the fastest NIST DRBG, it has several disadvantages:
- CTR_DRBG uses AES. Some platforms don't have AES acceleration at all,
causing a fallback to the table-based AES code which is very slow and
can be vulnerable to cache-timing attacks. In contrast, HMAC_DRBG
uses primitives that are consistently constant-time.
- CTR_DRBG is usually considered to be somewhat less cryptographically
robust than HMAC_DRBG. Granted, HMAC_DRBG isn't all that great
either, e.g. given the negative result from Woodage & Shumow (2018)
(https://eprint.iacr.org/2018/349.pdf), but that can be worked around.
- CTR_DRBG is more complex than HMAC_DRBG, risking bugs. Indeed, while
reviewing the CTR_DRBG code, I found two bugs, including one where it
can return success while leaving the output buffer uninitialized.
- The kernel's implementation of CTR_DRBG uses an "ctr(aes)"
crypto_skcipher and relies on it returning the next counter value.
That's fragile, and indeed historically many "ctr(aes)"
crypto_skcipher implementations haven't done that. E.g. see
commit 511306b2d0 ("crypto: arm/aes-ce - update IV after partial final CTR block"),
commit fa5fd3afc7 ("crypto: arm64/aes-blk - update IV after partial final CTR block"),
commit 371731ec21 ("crypto: atmel-aes - Fix saving of IV for CTR mode"),
commit 25baaf8e2c ("crypto: crypto4xx - fix ctr-aes missing output IV"),
commit 334d37c9e2 ("crypto: caam - update IV using HW support"),
commit 0a4491d3fe ("crypto: chelsio - count incomplete block in IV"),
commit e8e3c1ca57 ("crypto: s5p - update iv after AES-CBC op end").
I.e., there were many years where the kernel's CTR_DRBG code (if it
were to have actually been used) repeated outputs on some platforms.
AES-CTR also uses a 128-bit counter, which creates overflow edge cases
that are sometimes gotten wrong. E.g. see commit 009b30ac74
("crypto: vmx - CTR: always increment IV as quadword").
So, while switching to CTR_DRBG for performance reasons isn't completely
out of the question (notably BoringSSL uses it), it would take quite a
bit more work to create a solid implementation of it in the kernel,
including a more solid implementation of AES-CTR itself (in lib/crypto/,
with a scalar bit-sliced fallback, etc). Since HMAC_DRBG has always
been the default NIST DRBG variant in the kernel and is in a better
state, let's just standardize on it for now.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
include/crypto/drbg.h no longer contains anything that is used
externally to crypto/drbg.c. Therefore, fold it into crypto/drbg.c.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
FIPS 140-2 required that a continuous test for repeated outputs be done
on both "Approved RNGs" and "Non-Approved RNGs".
That's apparently why crypto/drbg.c does such a test on the bytes it
pulls from get_random_bytes(), despite get_random_bytes() being a
"Non-Approved RNG" that is credited with zero entropy for FIPS purposes.
(From FIPS's point of view, the "Approved RNG" is jitterentropy.)
FIPS 140-3 "modernized" the continuous RNG test requirements. They're
now a bit more sophisticated, requiring both an "Adaptive Proportion
Test" and a "Repetition Count Test".
At the same time, FIPS 140-3 doesn't require continuous RNG tests on
"Non-Approved RNGs" if a "vetted conditioning component" is used. The
SP800-90A DRBGs are exactly such a vetted conditioning component, by
their design. (In the case of HASH_DRBG and CTR_DRBG, the derivation
function does have to be implemented. But the kernel does that.)
In other words: from FIPS 140-3's point of view, get_random_bytes()
still produces zero entropy, but the way the DRBG combines those bytes
with the jitterentropy bytes preserves all the "approved" entropy from
jitterentropy. Thus no test for get_random_bytes() is required.
Seeing as FIPS 140-2 certificates stopped being issued in 2021 in favor
of FIPS 140-3, this means this code is obsolete. Remove it.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Fold the contents of the inline functions crypto_drbg_get_bytes_addtl(),
crypto_drbg_get_bytes_addtl_test(), and crypto_drbg_reset_test() into
their only caller in drbg_cavs_test(). It ends up being much simpler.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Mark Brown
Randy DunlapandHerbert Xu
Eric Biggers
Thorsten BlumandHerbert Xu
Linus Torvalds
Demi Marie ObenourandHerbert Xu
David HowellsandJakub Kicinski