linux/net/ceph
Jason A. Donenfeld 81895a65ec treewide: use prandom_u32_max() when possible, part 1
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)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((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>
2022-10-11 17:42:55 -06:00
..
crush libceph: use swap() macro instead of taking tmp variable 2022-05-25 20:45:13 +02:00
armor.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
auth_none.c libceph: kill ceph_none_authorizer::reply_buf 2021-06-28 23:49:25 +02:00
auth_none.h libceph: kill ceph_none_authorizer::reply_buf 2021-06-28 23:49:25 +02:00
auth_x_protocol.h libceph: fix some spelling mistakes 2021-06-28 23:49:25 +02:00
auth_x.c libceph: set global_id as soon as we get an auth ticket 2021-06-24 21:03:17 +02:00
auth_x.h ceph: fix whitespace 2018-08-02 21:33:21 +02:00
auth.c libceph: remove unnecessary ret variable in ceph_auth_init() 2021-06-28 23:49:25 +02:00
buffer.c mm: allow !GFP_KERNEL allocations for kvmalloc 2022-01-15 16:30:29 +02:00
ceph_common.c libceph: optionally use bounce buffer on recv path in crc mode 2022-02-02 18:50:36 +01:00
ceph_hash.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
ceph_strings.c libceph: introduce connection modes and ms_mode option 2020-12-14 23:21:50 +01:00
cls_lock_client.c libceph: fix doc warnings in cls_lock_client.c 2021-06-28 23:49:25 +02:00
crypto.c mm: allow !GFP_KERNEL allocations for kvmalloc 2022-01-15 16:30:29 +02:00
crypto.h libceph, ceph: incorporate nautilus cephx changes 2020-12-14 23:21:50 +01:00
debugfs.c libceph: dump class and method names on method calls 2020-08-03 11:03:01 +02:00
decode.c libceph: allow addrvecs with a single NONE/blank address 2021-05-04 16:06:15 +02:00
Kconfig libceph, ceph: implement msgr2.1 protocol (crc and secure modes) 2020-12-14 23:21:50 +01:00
Makefile libceph, ceph: implement msgr2.1 protocol (crc and secure modes) 2020-12-14 23:21:50 +01:00
messenger_v1.c libceph: optionally use bounce buffer on recv path in crc mode 2022-02-02 18:50:36 +01:00
messenger_v2.c libceph: drop else branches in prepare_read_data{,_cont} 2022-03-01 18:26:36 +01:00
messenger.c libceph: optionally use bounce buffer on recv path in crc mode 2022-02-02 18:50:36 +01:00
mon_client.c treewide: use prandom_u32_max() when possible, part 1 2022-10-11 17:42:55 -06:00
msgpool.c libceph: preallocate message data items 2018-10-22 10:28:22 +02:00
osd_client.c treewide: use prandom_u32_max() when possible, part 1 2022-10-11 17:42:55 -06:00
osdmap.c libceph: print fsid and epoch with osd id 2022-08-03 00:54:12 +02:00
pagelist.c libceph: fix ceph_pagelist_reserve() comment typo 2022-08-03 00:54:13 +02:00
pagevec.c libceph: remove ceph_get_direct_page_vector() 2019-07-08 14:01:40 +02:00
snapshot.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 268 2019-06-05 17:30:29 +02:00
string_table.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
striper.c rbd: support for object-map and fast-diff 2019-07-08 14:01:45 +02:00