From 7e3cf0843fe505491baa05e355e83e6997e089dd Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 5 Oct 2022 17:23:53 +0200 Subject: treewide: use get_random_{u8,u16}() when possible, part 1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Rather than truncate a 32-bit value to a 16-bit value or an 8-bit value, simply use the get_random_{u8,u16}() functions, which are faster than wasting the additional bytes from a 32-bit value. This was done mechanically with this coccinelle script: @@ expression E; identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; typedef u16; typedef __be16; typedef __le16; typedef u8; @@ ( - (get_random_u32() & 0xffff) + get_random_u16() | - (get_random_u32() & 0xff) + get_random_u8() | - (get_random_u32() % 65536) + get_random_u16() | - (get_random_u32() % 256) + get_random_u8() | - (get_random_u32() >> 16) + get_random_u16() | - (get_random_u32() >> 24) + get_random_u8() | - (u16)get_random_u32() + get_random_u16() | - (u8)get_random_u32() + get_random_u8() | - (__be16)get_random_u32() + (__be16)get_random_u16() | - (__le16)get_random_u32() + (__le16)get_random_u16() | - prandom_u32_max(65536) + get_random_u16() | - prandom_u32_max(256) + get_random_u8() | - E->inet_id = get_random_u32() + E->inet_id = get_random_u16() ) @@ identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; typedef u16; identifier v; @@ - u16 v = get_random_u32(); + u16 v = get_random_u16(); @@ identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; typedef u8; identifier v; @@ - u8 v = get_random_u32(); + u8 v = get_random_u8(); @@ identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; typedef u16; u16 v; @@ - v = get_random_u32(); + v = get_random_u16(); @@ identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; typedef u8; u8 v; @@ - v = get_random_u32(); + v = get_random_u8(); // 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)) // Examine limits @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 < 256: coccinelle.RESULT = cocci.make_ident("get_random_u8") elif value < 65536: coccinelle.RESULT = cocci.make_ident("get_random_u16") else: print("Skipping large mask of %s" % (literal)) cocci.include_match(False) // Replace the literal mask with the calculated result. @plus_one@ expression literal_mask.LITERAL; position literal_mask.p; identifier add_one.RESULT; identifier FUNC; @@ - (FUNC()@p & (LITERAL)) + (RESULT() & LITERAL) Reviewed-by: Greg Kroah-Hartman Reviewed-by: Kees Cook Reviewed-by: Yury Norov Acked-by: Jakub Kicinski Acked-by: Toke Høiland-Jørgensen # for sch_cake Signed-off-by: Jason A. Donenfeld --- crypto/testmgr.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'crypto/testmgr.c') diff --git a/crypto/testmgr.c b/crypto/testmgr.c index bff4833dbe7c..bcd059caa1c8 100644 --- a/crypto/testmgr.c +++ b/crypto/testmgr.c @@ -927,7 +927,7 @@ static void generate_random_bytes(u8 *buf, size_t count) b = 0xff; break; default: - b = (u8)prandom_u32(); + b = get_random_u8(); break; } memset(buf, b, count); @@ -935,8 +935,8 @@ static void generate_random_bytes(u8 *buf, size_t count) break; case 2: /* Ascending or descending bytes, plus optional mutations */ - increment = (u8)prandom_u32(); - b = (u8)prandom_u32(); + increment = get_random_u8(); + b = get_random_u8(); for (i = 0; i < count; i++, b += increment) buf[i] = b; mutate_buffer(buf, count); @@ -944,7 +944,7 @@ static void generate_random_bytes(u8 *buf, size_t count) default: /* Fully random bytes */ for (i = 0; i < count; i++) - buf[i] = (u8)prandom_u32(); + buf[i] = get_random_u8(); } } -- cgit v1.2.3-59-g8ed1b