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authorJason A. Donenfeld <Jason@zx2c4.com>2022-10-05 17:43:38 +0300
committerJason A. Donenfeld <Jason@zx2c4.com>2022-10-12 02:42:55 +0300
commit81895a65ec63ee1daec3255dc1a06675d2fbe915 (patch)
tree03703a64413a07bd4e6a171a449a8f18c760e21c /net/core
parentd465bff130bf4ca17b6980abe51164ace1e0cba4 (diff)
downloadlinux-81895a65ec63ee1daec3255dc1a06675d2fbe915.tar.xz
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>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/neighbour.c2
-rw-r--r--net/core/pktgen.c43
-rw-r--r--net/core/stream.c2
3 files changed, 23 insertions, 24 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index e93edb810103..3c4786b99907 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -111,7 +111,7 @@ static void neigh_cleanup_and_release(struct neighbour *neigh)
unsigned long neigh_rand_reach_time(unsigned long base)
{
- return base ? (prandom_u32() % base) + (base >> 1) : 0;
+ return base ? prandom_u32_max(base) + (base >> 1) : 0;
}
EXPORT_SYMBOL(neigh_rand_reach_time);
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 88906ba6d9a7..5ca4f953034c 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2324,7 +2324,7 @@ static inline int f_pick(struct pktgen_dev *pkt_dev)
pkt_dev->curfl = 0; /*reset */
}
} else {
- flow = prandom_u32() % pkt_dev->cflows;
+ flow = prandom_u32_max(pkt_dev->cflows);
pkt_dev->curfl = flow;
if (pkt_dev->flows[flow].count > pkt_dev->lflow) {
@@ -2380,10 +2380,9 @@ static void set_cur_queue_map(struct pktgen_dev *pkt_dev)
else if (pkt_dev->queue_map_min <= pkt_dev->queue_map_max) {
__u16 t;
if (pkt_dev->flags & F_QUEUE_MAP_RND) {
- t = prandom_u32() %
- (pkt_dev->queue_map_max -
- pkt_dev->queue_map_min + 1)
- + pkt_dev->queue_map_min;
+ t = prandom_u32_max(pkt_dev->queue_map_max -
+ pkt_dev->queue_map_min + 1) +
+ pkt_dev->queue_map_min;
} else {
t = pkt_dev->cur_queue_map + 1;
if (t > pkt_dev->queue_map_max)
@@ -2412,7 +2411,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
__u32 tmp;
if (pkt_dev->flags & F_MACSRC_RND)
- mc = prandom_u32() % pkt_dev->src_mac_count;
+ mc = prandom_u32_max(pkt_dev->src_mac_count);
else {
mc = pkt_dev->cur_src_mac_offset++;
if (pkt_dev->cur_src_mac_offset >=
@@ -2438,7 +2437,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
__u32 tmp;
if (pkt_dev->flags & F_MACDST_RND)
- mc = prandom_u32() % pkt_dev->dst_mac_count;
+ mc = prandom_u32_max(pkt_dev->dst_mac_count);
else {
mc = pkt_dev->cur_dst_mac_offset++;
@@ -2470,18 +2469,18 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
}
if ((pkt_dev->flags & F_VID_RND) && (pkt_dev->vlan_id != 0xffff)) {
- pkt_dev->vlan_id = prandom_u32() & (4096 - 1);
+ pkt_dev->vlan_id = prandom_u32_max(4096);
}
if ((pkt_dev->flags & F_SVID_RND) && (pkt_dev->svlan_id != 0xffff)) {
- pkt_dev->svlan_id = prandom_u32() & (4096 - 1);
+ pkt_dev->svlan_id = prandom_u32_max(4096);
}
if (pkt_dev->udp_src_min < pkt_dev->udp_src_max) {
if (pkt_dev->flags & F_UDPSRC_RND)
- pkt_dev->cur_udp_src = prandom_u32() %
- (pkt_dev->udp_src_max - pkt_dev->udp_src_min)
- + pkt_dev->udp_src_min;
+ pkt_dev->cur_udp_src = prandom_u32_max(
+ pkt_dev->udp_src_max - pkt_dev->udp_src_min) +
+ pkt_dev->udp_src_min;
else {
pkt_dev->cur_udp_src++;
@@ -2492,9 +2491,9 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
if (pkt_dev->udp_dst_min < pkt_dev->udp_dst_max) {
if (pkt_dev->flags & F_UDPDST_RND) {
- pkt_dev->cur_udp_dst = prandom_u32() %
- (pkt_dev->udp_dst_max - pkt_dev->udp_dst_min)
- + pkt_dev->udp_dst_min;
+ pkt_dev->cur_udp_dst = prandom_u32_max(
+ pkt_dev->udp_dst_max - pkt_dev->udp_dst_min) +
+ pkt_dev->udp_dst_min;
} else {
pkt_dev->cur_udp_dst++;
if (pkt_dev->cur_udp_dst >= pkt_dev->udp_dst_max)
@@ -2509,7 +2508,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
if (imn < imx) {
__u32 t;
if (pkt_dev->flags & F_IPSRC_RND)
- t = prandom_u32() % (imx - imn) + imn;
+ t = prandom_u32_max(imx - imn) + imn;
else {
t = ntohl(pkt_dev->cur_saddr);
t++;
@@ -2531,8 +2530,8 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
if (pkt_dev->flags & F_IPDST_RND) {
do {
- t = prandom_u32() %
- (imx - imn) + imn;
+ t = prandom_u32_max(imx - imn) +
+ imn;
s = htonl(t);
} while (ipv4_is_loopback(s) ||
ipv4_is_multicast(s) ||
@@ -2579,9 +2578,9 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
if (pkt_dev->min_pkt_size < pkt_dev->max_pkt_size) {
__u32 t;
if (pkt_dev->flags & F_TXSIZE_RND) {
- t = prandom_u32() %
- (pkt_dev->max_pkt_size - pkt_dev->min_pkt_size)
- + pkt_dev->min_pkt_size;
+ t = prandom_u32_max(pkt_dev->max_pkt_size -
+ pkt_dev->min_pkt_size) +
+ pkt_dev->min_pkt_size;
} else {
t = pkt_dev->cur_pkt_size + 1;
if (t > pkt_dev->max_pkt_size)
@@ -2590,7 +2589,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
pkt_dev->cur_pkt_size = t;
} else if (pkt_dev->n_imix_entries > 0) {
struct imix_pkt *entry;
- __u32 t = prandom_u32() % IMIX_PRECISION;
+ __u32 t = prandom_u32_max(IMIX_PRECISION);
__u8 entry_index = pkt_dev->imix_distribution[t];
entry = &pkt_dev->imix_entries[entry_index];
diff --git a/net/core/stream.c b/net/core/stream.c
index 1105057ce00a..75fded8495f5 100644
--- a/net/core/stream.c
+++ b/net/core/stream.c
@@ -123,7 +123,7 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
DEFINE_WAIT_FUNC(wait, woken_wake_function);
if (sk_stream_memory_free(sk))
- current_timeo = vm_wait = (prandom_u32() % (HZ / 5)) + 2;
+ current_timeo = vm_wait = prandom_u32_max(HZ / 5) + 2;
add_wait_queue(sk_sleep(sk), &wait);