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81895a65ec
Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:
@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
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- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
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- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
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- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)
@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@
- RAND = get_random_u32();
... when != RAND
- RAND %= (E);
+ RAND = prandom_u32_max(E);
// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@
((T)get_random_u32()@p & (LITERAL))
// Add one to the literal.
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@
value = None
if literal.startswith('0x'):
value = int(literal, 16)
elif literal[0] in '123456789':
value = int(literal, 10)
if value is None:
print("I don't know how to handle %s" % (literal))
cocci.include_match(False)
elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
print("Skipping 0x%x for cleanup elsewhere" % (value))
cocci.include_match(False)
elif value & (value + 1) != 0:
print("Skipping 0x%x because it's not a power of two minus one" % (value))
cocci.include_match(False)
elif literal.startswith('0x'):
coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))
// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@
- (FUNC()@p & (LITERAL))
+ prandom_u32_max(RESULT)
@collapse_ret@
type T;
identifier VAR;
expression E;
@@
{
- T VAR;
- VAR = (E);
- return VAR;
+ return E;
}
@drop_var@
type T;
identifier VAR;
@@
{
- T VAR;
... when != VAR
}
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
214 lines
5.4 KiB
C
214 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* SUCS NET3:
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*
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* Generic stream handling routines. These are generic for most
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* protocols. Even IP. Tonight 8-).
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* This is used because TCP, LLC (others too) layer all have mostly
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* identical sendmsg() and recvmsg() code.
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* So we (will) share it here.
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*
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* Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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* (from old tcp.c code)
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* Alan Cox <alan@lxorguk.ukuu.org.uk> (Borrowed comments 8-))
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*/
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#include <linux/module.h>
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#include <linux/sched/signal.h>
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#include <linux/net.h>
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#include <linux/signal.h>
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#include <linux/tcp.h>
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#include <linux/wait.h>
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#include <net/sock.h>
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/**
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* sk_stream_write_space - stream socket write_space callback.
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* @sk: socket
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*
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* FIXME: write proper description
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*/
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void sk_stream_write_space(struct sock *sk)
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{
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struct socket *sock = sk->sk_socket;
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struct socket_wq *wq;
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if (__sk_stream_is_writeable(sk, 1) && sock) {
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clear_bit(SOCK_NOSPACE, &sock->flags);
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rcu_read_lock();
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wq = rcu_dereference(sk->sk_wq);
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if (skwq_has_sleeper(wq))
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wake_up_interruptible_poll(&wq->wait, EPOLLOUT |
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EPOLLWRNORM | EPOLLWRBAND);
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if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
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sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
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rcu_read_unlock();
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}
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}
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/**
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* sk_stream_wait_connect - Wait for a socket to get into the connected state
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* @sk: sock to wait on
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* @timeo_p: for how long to wait
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*
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* Must be called with the socket locked.
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*/
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int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
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{
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DEFINE_WAIT_FUNC(wait, woken_wake_function);
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struct task_struct *tsk = current;
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int done;
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do {
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int err = sock_error(sk);
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if (err)
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return err;
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if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
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return -EPIPE;
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if (!*timeo_p)
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return -EAGAIN;
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if (signal_pending(tsk))
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return sock_intr_errno(*timeo_p);
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add_wait_queue(sk_sleep(sk), &wait);
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sk->sk_write_pending++;
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done = sk_wait_event(sk, timeo_p,
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!sk->sk_err &&
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!((1 << sk->sk_state) &
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~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)), &wait);
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remove_wait_queue(sk_sleep(sk), &wait);
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sk->sk_write_pending--;
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} while (!done);
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return 0;
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}
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EXPORT_SYMBOL(sk_stream_wait_connect);
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/**
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* sk_stream_closing - Return 1 if we still have things to send in our buffers.
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* @sk: socket to verify
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*/
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static inline int sk_stream_closing(struct sock *sk)
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{
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return (1 << sk->sk_state) &
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(TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
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}
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void sk_stream_wait_close(struct sock *sk, long timeout)
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{
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if (timeout) {
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DEFINE_WAIT_FUNC(wait, woken_wake_function);
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add_wait_queue(sk_sleep(sk), &wait);
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do {
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if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk), &wait))
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break;
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} while (!signal_pending(current) && timeout);
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remove_wait_queue(sk_sleep(sk), &wait);
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}
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}
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EXPORT_SYMBOL(sk_stream_wait_close);
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/**
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* sk_stream_wait_memory - Wait for more memory for a socket
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* @sk: socket to wait for memory
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* @timeo_p: for how long
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*/
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int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
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{
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int err = 0;
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long vm_wait = 0;
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long current_timeo = *timeo_p;
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DEFINE_WAIT_FUNC(wait, woken_wake_function);
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if (sk_stream_memory_free(sk))
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current_timeo = vm_wait = prandom_u32_max(HZ / 5) + 2;
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add_wait_queue(sk_sleep(sk), &wait);
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while (1) {
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sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
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if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
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goto do_error;
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if (!*timeo_p)
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goto do_eagain;
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if (signal_pending(current))
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goto do_interrupted;
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sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
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if (sk_stream_memory_free(sk) && !vm_wait)
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break;
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set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
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sk->sk_write_pending++;
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sk_wait_event(sk, ¤t_timeo, sk->sk_err ||
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(sk->sk_shutdown & SEND_SHUTDOWN) ||
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(sk_stream_memory_free(sk) &&
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!vm_wait), &wait);
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sk->sk_write_pending--;
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if (vm_wait) {
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vm_wait -= current_timeo;
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current_timeo = *timeo_p;
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if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
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(current_timeo -= vm_wait) < 0)
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current_timeo = 0;
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vm_wait = 0;
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}
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*timeo_p = current_timeo;
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}
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out:
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if (!sock_flag(sk, SOCK_DEAD))
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remove_wait_queue(sk_sleep(sk), &wait);
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return err;
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do_error:
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err = -EPIPE;
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goto out;
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do_eagain:
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/* Make sure that whenever EAGAIN is returned, EPOLLOUT event can
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* be generated later.
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* When TCP receives ACK packets that make room, tcp_check_space()
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* only calls tcp_new_space() if SOCK_NOSPACE is set.
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*/
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set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
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err = -EAGAIN;
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goto out;
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do_interrupted:
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err = sock_intr_errno(*timeo_p);
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goto out;
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}
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EXPORT_SYMBOL(sk_stream_wait_memory);
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int sk_stream_error(struct sock *sk, int flags, int err)
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{
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if (err == -EPIPE)
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err = sock_error(sk) ? : -EPIPE;
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if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
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send_sig(SIGPIPE, current, 0);
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return err;
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}
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EXPORT_SYMBOL(sk_stream_error);
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void sk_stream_kill_queues(struct sock *sk)
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{
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/* First the read buffer. */
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__skb_queue_purge(&sk->sk_receive_queue);
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/* Next, the write queue. */
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WARN_ON_ONCE(!skb_queue_empty(&sk->sk_write_queue));
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/* Account for returned memory. */
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sk_mem_reclaim_final(sk);
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WARN_ON_ONCE(sk->sk_wmem_queued);
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WARN_ON_ONCE(sk->sk_forward_alloc);
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/* It is _impossible_ for the backlog to contain anything
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* when we get here. All user references to this socket
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* have gone away, only the net layer knows can touch it.
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*/
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}
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EXPORT_SYMBOL(sk_stream_kill_queues);
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