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The arguments to list_splice_init() in handshake_net_exit() are
reversed. The call moves the local empty "requests" list onto
hn->hn_requests, leaving the local list empty, so the subsequent
drain loop runs zero iterations. Pending handshake requests that
had not yet been accepted are not torn down when the net namespace
is destroyed; each one keeps a reference on a socket file and on
the handshake_req allocation.
Pass the source and destination in the documented order
(list_splice_init(list, head) moves list onto head) so the pending
list is transferred to the local scratch list and drained through
handshake_complete().
Fixing the splice direction exposes a list-corruption race. After
the splice each req->hr_list still has non-empty link pointers,
threading the stack-local scratch list rather than hn_requests.
A concurrent handshake_req_cancel() -- for example, from sunrpc's
TLS timeout on a kernel socket whose netns reference was not
taken -- finds the request through the rhashtable, calls
remove_pending(), and sees !list_empty(&req->hr_list).
__remove_pending_locked() then list_del_init()s an entry off the
scratch list while the drain iterates, corrupting it. The same
call arriving after the drain loop has run list_del() on an
entry hits LIST_POISON instead.
Have remove_pending() check HANDSHAKE_F_NET_DRAINING under
hn_lock and report not-found when drain is in progress. The
drain has already taken ownership; handshake_complete()'s existing
test_and_set on HANDSHAKE_F_REQ_COMPLETED still arbitrates
between drain and cancel for who calls the consumer's hp_done. Use
list_del_init() rather than list_del() in the drain so req->hr_list
does not carry LIST_POISON after drain releases the entry.
The DRAINING guard in remove_pending() makes cancel return false,
but cancel still falls through to test_and_set_bit on
HANDSHAKE_F_REQ_COMPLETED and drops the request's hr_file reference.
Without another pin, if that is the last reference, sk_destruct frees
the request while it is still linked on the drain loop's local list.
Pin each request's hr_file under hn_lock before releasing the list,
and drop that drain pin after the loop finishes with the request.
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Link: https://patch.msgid.link/20260525-handshake-file-pin-v3-8-66c616906ead@oracle.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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handshake_req_submit() publishes the request via
handshake_req_hash_add() and __add_pending_locked(), drops
hn_lock, and calls handshake_genl_notify() (which can sleep)
before taking sock_hold() on req->hr_sk. A fast tlshd ACCEPT
followed by DONE can drive handshake_complete()'s sock_put()
into the window between the spin_unlock and the late
sock_hold(); on a system where the consumer's fd held the
only sk reference, the late sock_hold() then operates on an
sk whose refcount has reached zero.
The preceding two patches install an explicit file reference
on struct handshake_req. That file pins sock->file, which
pins the embedded struct socket, which defers inet_release()'s
sock_put(). As long as hr_file is held, sk cannot reach refcount
zero from the consumer side, and the submit-side sock_hold()
with its matching sock_put() calls in handshake_complete() and
handshake_req_cancel() is now redundant.
Drop all three. The file reference already keeps each request's
socket alive, and the lifetime story is contained in a single
get_file()/fput() pair.
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Link: https://patch.msgid.link/20260525-handshake-file-pin-v3-6-66c616906ead@oracle.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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handshake_req_next() removes the request from the per-net
pending list and drops hn_lock before handshake_nl_accept_doit()
reads req->hr_sk->sk_socket and dereferences sock->file (once in
FD_PREPARE() and again in get_file()). In that window a
consumer running tls_handshake_cancel() followed by sockfd_put()
(svc_sock_free) or __fput_sync() (xs_reset_transport) releases
sock->file. sock_release() then runs sock_orphan(), zeroing
sk_socket, and frees the struct socket. The accept-side code
either reads NULL through sk_socket or chases freed memory.
The submit-side sock_hold() does not prevent this. sk_refcnt
protects struct sock, but struct socket and sock->file are
independently refcounted via the file descriptor the consumer
owns. Pinning sk leaves sock and sock->file unprotected.
Retarget the accept-side dereferences at req->hr_file, which was
pinned at submit time, instead of req->hr_sk->sk_socket->file.
Pinning on its own is not sufficient: a consumer that cancels
between handshake_req_next() returning and accept_doit reaching
FD_PREPARE() takes the !remove_pending() branch in
handshake_req_cancel() and drops hr_file before the accept side
takes its own reference. Hand off an additional file reference
inside handshake_req_next(), under hn_lock, so the accept side
operates on a reference that no concurrent handshake_req_cancel()
can revoke. FD_PREPARE() consumes that handed-off reference,
either by transferring it to the new fd in fd_publish() or by
dropping it in the cleanup destructor on error; the explicit
get_file() that previously balanced FD_PREPARE() is therefore
redundant and goes away.
Update handshake_req_cancel_test2 and _test3 to simulate the
FD_PREPARE() consumption with an fput() so the kunit file-count
assertions stay balanced.
Reported-by: Chris Mason <clm@meta.com>
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Link: https://patch.msgid.link/20260525-handshake-file-pin-v3-5-66c616906ead@oracle.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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handshake_nl_accept_doit() needs the file pointer backing
req->hr_sk->sk_socket to survive the window between
handshake_req_next() and the subsequent FD_PREPARE() and get_file().
The submit-side sock_hold() does not provide that. sk_refcnt keeps
struct sock alive, but struct socket is owned by sock->file: when
the consumer fputs the last file reference, sock_release() tears
the socket down regardless of any sock_hold.
Add an hr_file pointer to struct handshake_req and acquire an
explicit reference on sock->file during handshake_req_submit().
handshake_complete() and handshake_req_cancel() release the
reference on the completion-bit-winning path.
The submit error path must also release the file reference, but
after rhashtable insertion a concurrent handshake_req_cancel() can
discover the request and race the error path. Gate the error-path
cleanup -- sk_destruct restoration, fput, and request destruction
-- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same
serialization handshake_complete() and handshake_req_cancel()
already use. When cancel has already claimed ownership, the submit
error path returns without touching the request; socket teardown
handles final destruction.
The accept-side dereferences are not yet retargeted; that change
comes in the next patch.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://patch.msgid.link/20260525-handshake-file-pin-v3-4-66c616906ead@oracle.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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handshake_complete() declares status as unsigned int and
tls_handshake_done() negates that value (-status) before handing
it to the TLS consumer. Consumers match on negative errno
constants -- xs_tls_handshake_done() has
switch (status) {
case 0:
case -EACCES:
case -ETIMEDOUT:
lower_transport->xprt_err = status;
break;
default:
lower_transport->xprt_err = -EACCES;
}
so the API as designed expects callers to pass positive errno
values that the tlshd shim then negates.
Three internal callers in handshake_nl_accept_doit(), the
net-exit drain, and a kunit test follow kernel convention and
pass negative errnos -- -EIO, -ETIMEDOUT, -ETIMEDOUT. The
implicit conversion to unsigned int turns -ETIMEDOUT into
0xFFFFFF92; the subsequent -status in tls_handshake_done()
wraps back to 110, the consumer's switch falls through, and
the xprt reports -EACCES on what should be -ETIMEDOUT or -EIO.
Fix the API rather than the call sites. The natural kernel
convention is negative errno in, negative errno out. Change
handshake_complete() and hp_done to take int status, drop the
negation in tls_handshake_done(), and negate once in
handshake_nl_done_doit() where status arrives from the wire
as an unsigned netlink attribute. The three internal callers
were already correct under that convention and need no change.
At the same wire boundary, declare MAX_ERRNO as the netlink
policy upper bound for HANDSHAKE_A_DONE_STATUS. Attribute
validation rejects out-of-range values before
handshake_nl_done_doit() runs, and negating a bounded u32 there
stays within int range -- closing the UBSAN-visible signed-
integer overflow that an unconstrained u32 would invoke.
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Link: https://patch.msgid.link/20260525-handshake-file-pin-v3-3-66c616906ead@oracle.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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nvmet_tcp_state_change(), a socket callback that runs in BH context,
can reach handshake_req_cancel() via nvmet_tcp_schedule_release_queue()
and tls_handshake_cancel(). handshake_req_cancel() acquires
hn->hn_lock with plain spin_lock(). If a process-context thread on
the same CPU holds hn->hn_lock when a softirq invokes the cancel path,
the lock attempt deadlocks. This is the only caller that invokes
tls_handshake_cancel() from BH context; every other consumer calls it
from process context.
Deferring the cancel to process context in the NVMe target is not
straightforward: nvmet_tcp_schedule_release_queue() must call
tls_handshake_cancel() atomically with its state transition to
DISCONNECTING. If the cancel were deferred, the handshake completion
callback could fire in the window before the cancel runs, observe the
unexpected state, and return without dropping its kref on the queue.
Reworking that interlock is considerably more invasive than hardening
the handshake lock. Convert all hn->hn_lock acquisitions from
spin_lock/spin_unlock to spin_lock_bh/spin_unlock_bh so the lock is
never taken with softirqs enabled.
Fixes: 675b453e0241 ("nvmet-tcp: enable TLS handshake upcall")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Link: https://patch.msgid.link/20260525-handshake-file-pin-v3-1-66c616906ead@oracle.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
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When a handshake request is cancelled it is removed from the
handshake_net->hn_requests list, but it is still present in the
handshake_rhashtbl until it is destroyed.
If a second cancellation request arrives for the same handshake request,
then remove_pending() will return false... and assuming
HANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue
processing through the out_true label, where we put another reference on
the sock and a refcount underflow occurs.
This can happen for example if a handshake times out - particularly if
the SUNRPC client sends the AUTH_TLS probe to the server but doesn't
follow it up with the ClientHello due to a problem with tlshd. When the
timeout is hit on the server, the server will send a FIN, which triggers
a cancellation request via xs_reset_transport(). When the timeout is
hit on the client, another cancellation request happens via
xs_tls_handshake_sync().
Add a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel
path so duplicate cancels can be detected.
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Suggested-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://patch.msgid.link/20251209193015.3032058-1-smayhew@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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handshake_req_submit() replaces sk->sk_destruct but never restores it when
submission fails before the request is hashed. handshake_sk_destruct() then
returns early and the original destructor never runs, leaking the socket.
Restore sk_destruct on the error path.
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: caoping <caoping@cmss.chinamobile.com>
Link: https://patch.msgid.link/20251204091058.1545151-1-caoping@cmss.chinamobile.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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some of those used to be needed, some had been cargo-culted for
no reason...
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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A reference underflow is found in TLS handshake subsystem that causes a
direct use-after-free. Part of the crash log is like below:
[ 2.022114] ------------[ cut here ]------------
[ 2.022193] refcount_t: underflow; use-after-free.
[ 2.022288] WARNING: CPU: 0 PID: 60 at lib/refcount.c:28 refcount_warn_saturate+0xbe/0x110
[ 2.022432] Modules linked in:
[ 2.022848] RIP: 0010:refcount_warn_saturate+0xbe/0x110
[ 2.023231] RSP: 0018:ffffc900001bfe18 EFLAGS: 00000286
[ 2.023325] RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00000000ffffdfff
[ 2.023438] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[ 2.023555] RBP: ffff888004c20098 R08: ffffffff82b392c8 R09: 00000000ffffdfff
[ 2.023693] R10: ffffffff82a592e0 R11: ffffffff82b092e0 R12: ffff888004c200d8
[ 2.023813] R13: 0000000000000000 R14: ffff888004c20000 R15: ffffc90000013ca8
[ 2.023930] FS: 0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[ 2.024062] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2.024161] CR2: ffff888003601000 CR3: 0000000002a2e000 CR4: 00000000000006f0
[ 2.024275] Call Trace:
[ 2.024322] <TASK>
[ 2.024367] ? __warn+0x7f/0x130
[ 2.024430] ? refcount_warn_saturate+0xbe/0x110
[ 2.024513] ? report_bug+0x199/0x1b0
[ 2.024585] ? handle_bug+0x3c/0x70
[ 2.024676] ? exc_invalid_op+0x18/0x70
[ 2.024750] ? asm_exc_invalid_op+0x1a/0x20
[ 2.024830] ? refcount_warn_saturate+0xbe/0x110
[ 2.024916] ? refcount_warn_saturate+0xbe/0x110
[ 2.024998] __tcp_close+0x2f4/0x3d0
[ 2.025065] ? __pfx_kunit_generic_run_threadfn_adapter+0x10/0x10
[ 2.025168] tcp_close+0x1f/0x70
[ 2.025231] inet_release+0x33/0x60
[ 2.025297] sock_release+0x1f/0x80
[ 2.025361] handshake_req_cancel_test2+0x100/0x2d0
[ 2.025457] kunit_try_run_case+0x4c/0xa0
[ 2.025532] kunit_generic_run_threadfn_adapter+0x15/0x20
[ 2.025644] kthread+0xe1/0x110
[ 2.025708] ? __pfx_kthread+0x10/0x10
[ 2.025780] ret_from_fork+0x2c/0x50
One can enable CONFIG_NET_HANDSHAKE_KUNIT_TEST config to reproduce above
crash.
The root cause of this bug is that the commit 1ce77c998f04
("net/handshake: Unpin sock->file if a handshake is cancelled") adds one
additional fput() function. That patch claims that the fput() is used to
enable sock->file to be freed even when user space never calls DONE.
However, it seems that the intended DONE routine will never give an
additional fput() of ths sock->file. The existing two of them are just
used to balance the reference added in sockfd_lookup().
This patch revert the mentioned commit to avoid the use-after-free. The
patched kernel could successfully pass the KUNIT test and boot to shell.
[ 0.733613] # Subtest: Handshake API tests
[ 0.734029] 1..11
[ 0.734255] KTAP version 1
[ 0.734542] # Subtest: req_alloc API fuzzing
[ 0.736104] ok 1 handshake_req_alloc NULL proto
[ 0.736114] ok 2 handshake_req_alloc CLASS_NONE
[ 0.736559] ok 3 handshake_req_alloc CLASS_MAX
[ 0.737020] ok 4 handshake_req_alloc no callbacks
[ 0.737488] ok 5 handshake_req_alloc no done callback
[ 0.737988] ok 6 handshake_req_alloc excessive privsize
[ 0.738529] ok 7 handshake_req_alloc all good
[ 0.739036] # req_alloc API fuzzing: pass:7 fail:0 skip:0 total:7
[ 0.739444] ok 1 req_alloc API fuzzing
[ 0.740065] ok 2 req_submit NULL req arg
[ 0.740436] ok 3 req_submit NULL sock arg
[ 0.740834] ok 4 req_submit NULL sock->file
[ 0.741236] ok 5 req_lookup works
[ 0.741621] ok 6 req_submit max pending
[ 0.741974] ok 7 req_submit multiple
[ 0.742382] ok 8 req_cancel before accept
[ 0.742764] ok 9 req_cancel after accept
[ 0.743151] ok 10 req_cancel after done
[ 0.743510] ok 11 req_destroy works
[ 0.743882] # Handshake API tests: pass:11 fail:0 skip:0 total:11
[ 0.744205] # Totals: pass:17 fail:0 skip:0 total:17
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Fixes: 1ce77c998f04 ("net/handshake: Unpin sock->file if a handshake is cancelled")
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Link: https://lore.kernel.org/r/20230613083204.633896-1-linma@zju.edu.cn
Link: https://lore.kernel.org/r/20230614015249.987448-1-linma@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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If user space never calls DONE, sock->file's reference count remains
elevated. Enable sock->file to be freed eventually in this case.
Reported-by: Jakub Kacinski <kuba@kernel.org>
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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These verify the API contracts and help exercise lifetime rules for
consumer sockets and handshake_req structures.
One way to run these tests:
./tools/testing/kunit/kunit.py run --kunitconfig ./net/handshake/.kunitconfig
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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When a kernel consumer needs a transport layer security session, it
first needs a handshake to negotiate and establish a session. This
negotiation can be done in user space via one of the several
existing library implementations, or it can be done in the kernel.
No in-kernel handshake implementations yet exist. In their absence,
we add a netlink service that can:
a. Notify a user space daemon that a handshake is needed.
b. Once notified, the daemon calls the kernel back via this
netlink service to get the handshake parameters, including an
open socket on which to establish the session.
c. Once the handshake is complete, the daemon reports the
session status and other information via a second netlink
operation. This operation marks that it is safe for the
kernel to use the open socket and the security session
established there.
The notification service uses a multicast group. Each handshake
mechanism (eg, tlshd) adopts its own group number so that the
handshake services are completely independent of one another. The
kernel can then tell via netlink_has_listeners() whether a handshake
service is active and prepared to handle a handshake request.
A new netlink operation, ACCEPT, acts like accept(2) in that it
instantiates a file descriptor in the user space daemon's fd table.
If this operation is successful, the reply carries the fd number,
which can be treated as an open and ready file descriptor.
While user space is performing the handshake, the kernel keeps its
muddy paws off the open socket. A second new netlink operation,
DONE, indicates that the user space daemon is finished with the
socket and it is safe for the kernel to use again. The operation
also indicates whether a session was established successfully.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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