[Qemu-devel] [PATCH] linux-user: Let user specify random seed
This patch introduces the -seed command line option and the QEMU_RAND_SEED environment variable for setting the random seed, which is used for the AT_RANDOM ELF aux entry. Signed-off-by: Magnus Reftel --- linux-user/elfload.c | 1 - linux-user/main.c| 21 + 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 1c04fcf..f2e2197 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1539,7 +1539,6 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc, * Generate 16 random bytes for userspace PRNG seeding (not * cryptically secure but it's not the aim of QEMU). */ -srand((unsigned int) time(NULL)); for (i = 0; i < 16; i++) { k_rand_bytes[i] = rand(); } diff --git a/linux-user/main.c b/linux-user/main.c index 483eb3f..57cd721 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -46,6 +46,8 @@ unsigned long mmap_min_addr; #if defined(CONFIG_USE_GUEST_BASE) unsigned long guest_base; int have_guest_base; +static bool have_rand_seed = false; +static int rand_seed; #if (TARGET_LONG_BITS == 32) && (HOST_LONG_BITS == 64) /* * When running 32-on-64 we should make sure we can fit all of the possible @@ -3546,6 +3548,12 @@ static void handle_arg_pagesize(const char *arg) } } +static void handle_arg_randseed(const char *arg) +{ +have_rand_seed = true; +rand_seed = atoi(arg); +} + static void handle_arg_gdb(const char *arg) { gdbstub_port = atoi(arg); @@ -3674,6 +3682,8 @@ static const struct qemu_argument arg_table[] = { "", "run in singlestep mode"}, {"strace", "QEMU_STRACE", false, handle_arg_strace, "", "log system calls"}, +{"seed", "QEMU_RAND_SEED", true, handle_arg_randseed, + "", "Seed for pseudo-random number generator"}, {"version","QEMU_VERSION", false, handle_arg_version, "", "display version information and exit"}, {NULL, NULL, false, NULL, NULL, NULL} @@ -3926,6 +3936,17 @@ int main(int argc, char **argv, char **envp) do_strace = 1; } +if (getenv("QEMU_RAND_SEED")) { +have_rand_seed = true; +rand_seed = atoi(getenv("QEMU_RAND_SEED")); +} + +if (have_rand_seed) { +srand(rand_seed); +} else { +srand((int)time(NULL)); +} + target_environ = envlist_to_environ(envlist, NULL); envlist_free(envlist); -- 1.9.1
[Qemu-devel] [PATCH] linux-user: Let user specify random seed
This patch introduces the -seed command line option and the QEMU_RAND_SEED environment variable for setting the random seed, which is used for the AT_RANDOM ELF aux entry. Signed-off-by: Magnus Reftel --- linux-user/elfload.c | 1 - linux-user/main.c| 20 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 1c04fcf..f2e2197 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1539,7 +1539,6 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc, * Generate 16 random bytes for userspace PRNG seeding (not * cryptically secure but it's not the aim of QEMU). */ -srand((unsigned int) time(NULL)); for (i = 0; i < 16; i++) { k_rand_bytes[i] = rand(); } diff --git a/linux-user/main.c b/linux-user/main.c index 483eb3f..e80255c 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -3546,6 +3546,18 @@ static void handle_arg_pagesize(const char *arg) } } +static void handle_arg_randseed(const char *arg) +{ +unsigned long seed; +char* end; +seed = strtoul(arg, &end, 0); +if (end==arg || *end!='\0' || seed > UINT_MAX) { +fprintf(stderr, "Invalid seed number: %s\n", arg); +exit(1); +} +srand(seed); +} + static void handle_arg_gdb(const char *arg) { gdbstub_port = atoi(arg); @@ -3674,6 +3686,8 @@ static const struct qemu_argument arg_table[] = { "", "run in singlestep mode"}, {"strace", "QEMU_STRACE", false, handle_arg_strace, "", "log system calls"}, +{"seed", "QEMU_RAND_SEED", true, handle_arg_randseed, + "", "Seed for pseudo-random number generator"}, {"version","QEMU_VERSION", false, handle_arg_version, "", "display version information and exit"}, {NULL, NULL, false, NULL, NULL, NULL} @@ -3856,6 +3870,8 @@ int main(int argc, char **argv, char **envp) cpudef_setup(); /* parse cpu definitions in target config file (TBD) */ #endif +srand(time(NULL)); + optind = parse_args(argc, argv); /* Zero out regs */ @@ -3926,6 +3942,10 @@ int main(int argc, char **argv, char **envp) do_strace = 1; } +if (getenv("QEMU_RAND_SEED")) { +handle_arg_randseed(getenv("QEMU_RAND_SEED")); +} + target_environ = envlist_to_environ(envlist, NULL); envlist_free(envlist); -- 1.9.1
[Qemu-devel] [PATCH] linux-user: Let user specify random seed
This patch introduces the -seed command line option and the QEMU_RAND_SEED environment variable for setting the random seed, which is used for the AT_RANDOM ELF aux entry. Signed-off-by: Magnus Reftel --- linux-user/elfload.c | 1 - linux-user/main.c| 20 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 1c04fcf..f2e2197 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1539,7 +1539,6 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc, * Generate 16 random bytes for userspace PRNG seeding (not * cryptically secure but it's not the aim of QEMU). */ -srand((unsigned int) time(NULL)); for (i = 0; i < 16; i++) { k_rand_bytes[i] = rand(); } diff --git a/linux-user/main.c b/linux-user/main.c index 483eb3f..56e0e28 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -3546,6 +3546,18 @@ static void handle_arg_pagesize(const char *arg) } } +static void handle_arg_randseed(const char *arg) +{ +unsigned long long seed; +char *end; + +if (parse_uint(arg, &seed, &end, 0) != 0 || *end != 0 || seed > UINT_MAX) { +fprintf(stderr, "Invalid seed number: %s\n", arg); +exit(1); +} +srand(seed); +} + static void handle_arg_gdb(const char *arg) { gdbstub_port = atoi(arg); @@ -3674,6 +3686,8 @@ static const struct qemu_argument arg_table[] = { "", "run in singlestep mode"}, {"strace", "QEMU_STRACE", false, handle_arg_strace, "", "log system calls"}, +{"seed", "QEMU_RAND_SEED", true, handle_arg_randseed, + "", "Seed for pseudo-random number generator"}, {"version","QEMU_VERSION", false, handle_arg_version, "", "display version information and exit"}, {NULL, NULL, false, NULL, NULL, NULL} @@ -3856,6 +3870,8 @@ int main(int argc, char **argv, char **envp) cpudef_setup(); /* parse cpu definitions in target config file (TBD) */ #endif +srand(time(NULL)); + optind = parse_args(argc, argv); /* Zero out regs */ @@ -3926,6 +3942,10 @@ int main(int argc, char **argv, char **envp) do_strace = 1; } +if (getenv("QEMU_RAND_SEED")) { +handle_arg_randseed(getenv("QEMU_RAND_SEED")); +} + target_environ = envlist_to_environ(envlist, NULL); envlist_free(envlist); -- 1.9.1
[Qemu-devel] [PATCH] linux-user: Let user specify random seed
This patch introduces the -seed command line option and the QEMU_RAND_SEED environment variable for setting the random seed, which is used for the AT_RANDOM ELF aux entry. Signed-off-by: Magnus Reftel --- linux-user/elfload.c | 1 - linux-user/main.c| 19 +++ 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 1c04fcf..f2e2197 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1539,7 +1539,6 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc, * Generate 16 random bytes for userspace PRNG seeding (not * cryptically secure but it's not the aim of QEMU). */ -srand((unsigned int) time(NULL)); for (i = 0; i < 16; i++) { k_rand_bytes[i] = rand(); } diff --git a/linux-user/main.c b/linux-user/main.c index 483eb3f..5887022 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -3546,6 +3546,17 @@ static void handle_arg_pagesize(const char *arg) } } +static void handle_arg_randseed(const char *arg) +{ +unsigned long long seed; + +if (parse_uint_full(arg, &seed, 0) != 0 || seed > UINT_MAX) { +fprintf(stderr, "Invalid seed number: %s\n", arg); +exit(1); +} +srand(seed); +} + static void handle_arg_gdb(const char *arg) { gdbstub_port = atoi(arg); @@ -3674,6 +3685,8 @@ static const struct qemu_argument arg_table[] = { "", "run in singlestep mode"}, {"strace", "QEMU_STRACE", false, handle_arg_strace, "", "log system calls"}, +{"seed", "QEMU_RAND_SEED", true, handle_arg_randseed, + "", "Seed for pseudo-random number generator"}, {"version","QEMU_VERSION", false, handle_arg_version, "", "display version information and exit"}, {NULL, NULL, false, NULL, NULL, NULL} @@ -3856,6 +3869,8 @@ int main(int argc, char **argv, char **envp) cpudef_setup(); /* parse cpu definitions in target config file (TBD) */ #endif +srand(time(NULL)); + optind = parse_args(argc, argv); /* Zero out regs */ @@ -3926,6 +3941,10 @@ int main(int argc, char **argv, char **envp) do_strace = 1; } +if (getenv("QEMU_RAND_SEED")) { +handle_arg_randseed(getenv("QEMU_RAND_SEED")); +} + target_environ = envlist_to_environ(envlist, NULL); envlist_free(envlist); -- 1.9.1
[Qemu-devel] [PATCH] linux-user: Let user specify random seed
This patch introduces the -seed command line option and the QEMU_RAND_SEED environment variable for setting the random seed, which is used for the AT_RANDOM ELF aux entry. Signed-off-by: Magnus Reftel Reviewed-by: Eric Blake --- linux-user/elfload.c | 1 - linux-user/main.c| 19 +++ 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 1c04fcf..f2e2197 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1539,7 +1539,6 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc, * Generate 16 random bytes for userspace PRNG seeding (not * cryptically secure but it's not the aim of QEMU). */ -srand((unsigned int) time(NULL)); for (i = 0; i < 16; i++) { k_rand_bytes[i] = rand(); } diff --git a/linux-user/main.c b/linux-user/main.c index 483eb3f..5887022 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -3546,6 +3546,17 @@ static void handle_arg_pagesize(const char *arg) } } +static void handle_arg_randseed(const char *arg) +{ +unsigned long long seed; + +if (parse_uint_full(arg, &seed, 0) != 0 || seed > UINT_MAX) { +fprintf(stderr, "Invalid seed number: %s\n", arg); +exit(1); +} +srand(seed); +} + static void handle_arg_gdb(const char *arg) { gdbstub_port = atoi(arg); @@ -3674,6 +3685,8 @@ static const struct qemu_argument arg_table[] = { "", "run in singlestep mode"}, {"strace", "QEMU_STRACE", false, handle_arg_strace, "", "log system calls"}, +{"seed", "QEMU_RAND_SEED", true, handle_arg_randseed, + "", "Seed for pseudo-random number generator"}, {"version","QEMU_VERSION", false, handle_arg_version, "", "display version information and exit"}, {NULL, NULL, false, NULL, NULL, NULL} @@ -3856,6 +3869,8 @@ int main(int argc, char **argv, char **envp) cpudef_setup(); /* parse cpu definitions in target config file (TBD) */ #endif +srand(time(NULL)); + optind = parse_args(argc, argv); /* Zero out regs */ @@ -3926,6 +3941,10 @@ int main(int argc, char **argv, char **envp) do_strace = 1; } +if (getenv("QEMU_RAND_SEED")) { +handle_arg_randseed(getenv("QEMU_RAND_SEED")); +} + target_environ = envlist_to_environ(envlist, NULL); envlist_free(envlist); -- 1.9.1
Re: [Qemu-devel] [PATCH] linux-user: Let user specify random seed
On 10/08/2014 06:13 AM, Magnus Reftel wrote: > This patch introduces the -seed command line option and the > QEMU_RAND_SEED environment variable for setting the random seed, which > is used for the AT_RANDOM ELF aux entry. > > Signed-off-by: Magnus Reftel > --- > linux-user/elfload.c | 1 - > linux-user/main.c| 21 + > 2 files changed, 21 insertions(+), 1 deletion(-) > > +++ b/linux-user/main.c > @@ -46,6 +46,8 @@ unsigned long mmap_min_addr; > #if defined(CONFIG_USE_GUEST_BASE) > unsigned long guest_base; > int have_guest_base; > +static bool have_rand_seed = false; static variables are automatically 0-initialized without needing an explicit initializer. > +static int rand_seed; > #if (TARGET_LONG_BITS == 32) && (HOST_LONG_BITS == 64) > /* > * When running 32-on-64 we should make sure we can fit all of the possible > @@ -3546,6 +3548,12 @@ static void handle_arg_pagesize(const char *arg) > } > } > > +static void handle_arg_randseed(const char *arg) > +{ > +have_rand_seed = true; > +rand_seed = atoi(arg); > +} atoi() is trash when compared to strtol() - it doesn't diagnose overflow, trailing garbage, or empty input. > @@ -3926,6 +3936,17 @@ int main(int argc, char **argv, char **envp) > do_strace = 1; > } > > +if (getenv("QEMU_RAND_SEED")) { > +have_rand_seed = true; > +rand_seed = atoi(getenv("QEMU_RAND_SEED")); > +} why not call handle_arg_randseed(getenv("QEMU_RAND_SEED")) here? > + > +if (have_rand_seed) { > +srand(rand_seed); > +} else { > +srand((int)time(NULL)); The cast is pointless. This is C. > +} Do you even need have_rand_seed? Why not just pre-initialize rand_seed=time(NULL) and then overwrite rand_seed if the environment variable is present? -- Eric Blake eblake redhat com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature
Re: [Qemu-devel] [PATCH] linux-user: Let user specify random seed
On 10/09/2014 02:36 AM, Magnus Reftel wrote: > This patch introduces the -seed command line option and the > QEMU_RAND_SEED environment variable for setting the random seed, which > is used for the AT_RANDOM ELF aux entry. > > Signed-off-by: Magnus Reftel > --- > > +static void handle_arg_randseed(const char *arg) > +{ > +unsigned long seed; > +char* end; Style: we prefer: char *end; > +seed = strtoul(arg, &end, 0); > +if (end==arg || *end!='\0' || seed > UINT_MAX) { Style: spaces around operators: if (end == arg || *end || seed > UINT_MAX) { Bug: strtoul() sometimes reports error via errno; the only safe way to use it is to first prime errno = 0, then do strtoul, then check if errno was changed. Reimplementation: util/cutils.c already provides parse_uint() that takes care of calling strtoul safely (hmm, that version only parses 64-bit numbers; maybe we should expand it to also parse 32-bit numbers?) Surprising behavior: your code behaves differently on 32-bit hosts than it does on 64-bit hosts. Seriously. strotoul() has the annoying specification of requiring twos-complement wraparound according to the size of long, which means "-1" on a 32-bit platform parses as 0x (accepted), while on a 64-bit platform parses it as 0x (which you reject as > UINT_MAX); conversely "-18446744073709551615" fails to parse due to overflow on a 32-bit platform, while successfully being parsed as 1 on 64-bit. > +fprintf(stderr, "Invalid seed number: %s\n", arg); > +exit(1); > +} > +srand(seed); > +} > + > static void handle_arg_gdb(const char *arg) > { > gdbstub_port = atoi(arg); > @@ -3674,6 +3686,8 @@ static const struct qemu_argument arg_table[] = { > "", "run in singlestep mode"}, > {"strace", "QEMU_STRACE", false, handle_arg_strace, > "", "log system calls"}, > +{"seed", "QEMU_RAND_SEED", true, handle_arg_randseed, > + "", "Seed for pseudo-random number generator"}, > {"version","QEMU_VERSION", false, handle_arg_version, > "", "display version information and exit"}, > {NULL, NULL, false, NULL, NULL, NULL} > @@ -3856,6 +3870,8 @@ int main(int argc, char **argv, char **envp) > cpudef_setup(); /* parse cpu definitions in target config file (TBD) */ > #endif > > +srand(time(NULL)); > + > optind = parse_args(argc, argv); > > /* Zero out regs */ > @@ -3926,6 +3942,10 @@ int main(int argc, char **argv, char **envp) > do_strace = 1; > } > > +if (getenv("QEMU_RAND_SEED")) { > +handle_arg_randseed(getenv("QEMU_RAND_SEED")); > +} Now that you have exactly one caller of the static function, it might make sense to just inline the body of that function here. > + > target_environ = envlist_to_environ(envlist, NULL); > envlist_free(envlist); > > -- Eric Blake eblake redhat com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature
Re: [Qemu-devel] [PATCH] linux-user: Let user specify random seed
Hi, Thank you for your patience! I will send a third version. On Thu, Oct 9, 2014 at 5:27 PM, Eric Blake wrote: > On 10/09/2014 02:36 AM, Magnus Reftel wrote: >> +char* end; > Style: we prefer: > char *end; Done. >> +if (end==arg || *end!='\0' || seed > UINT_MAX) { > Style: spaces around operators: Done. > Bug: strtoul() sometimes reports error via errno; the only safe way to > use it is to first prime errno = 0, then do strtoul, then check if errno > was changed. > > Reimplementation: util/cutils.c already provides parse_uint() that takes > care of calling strtoul safely (hmm, that version only parses 64-bit > numbers; maybe we should expand it to also parse 32-bit numbers?) Solved both by switching to parse_uint. >> +{"seed", "QEMU_RAND_SEED", true, handle_arg_randseed, >> + "", "Seed for pseudo-random number generator"}, ... >> +if (getenv("QEMU_RAND_SEED")) { >> +handle_arg_randseed(getenv("QEMU_RAND_SEED")); >> +} > > Now that you have exactly one caller of the static function, it might > make sense to just inline the body of that function here. No, it may be called using the function pointer in the argument table, above. Best Regards Magnus reftel
Re: [Qemu-devel] [PATCH] linux-user: Let user specify random seed
On 10/09/2014 01:12 PM, Magnus Reftel wrote: > This patch introduces the -seed command line option and the > QEMU_RAND_SEED environment variable for setting the random seed, which > is used for the AT_RANDOM ELF aux entry. > > Signed-off-by: Magnus Reftel > --- > linux-user/elfload.c | 1 - > linux-user/main.c| 20 > 2 files changed, 20 insertions(+), 1 deletion(-) > > > +static void handle_arg_randseed(const char *arg) > +{ > +unsigned long long seed; > +char *end; > + > +if (parse_uint(arg, &seed, &end, 0) != 0 || *end != 0 || seed > > UINT_MAX) { Slightly shorter as: if (parse_uint_full(arg, &seed, 0) < 0 || seed > UINT_MAX) { but that's not a functional difference. Reviewed-by: Eric Blake -- Eric Blake eblake redhat com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature
Re: [Qemu-devel] [PATCH] linux-user: Let user specify random seed
On Thu, Oct 9, 2014 at 11:30 PM, Eric Blake wrote: > On 10/09/2014 01:12 PM, Magnus Reftel wrote: >> +if (parse_uint(arg, &seed, &end, 0) != 0 || *end != 0 || seed > >> UINT_MAX) { > > Slightly shorter as: > > if (parse_uint_full(arg, &seed, 0) < 0 || seed > UINT_MAX) { > > but that's not a functional difference. That would silently truncate and accept strings containing illegal characters at the end, e.g. 123a would be treated at 123 (decimal) while it was likely intended to be 0x123a. Therefore, I suggest to keep the code as proposed in version 3 of the patch. BR Magnus
Re: [Qemu-devel] [PATCH] linux-user: Let user specify random seed
On 10/10/2014 02:16 AM, Magnus Reftel wrote: > On Thu, Oct 9, 2014 at 11:30 PM, Eric Blake wrote: >> On 10/09/2014 01:12 PM, Magnus Reftel wrote: >>> +if (parse_uint(arg, &seed, &end, 0) != 0 || *end != 0 || seed > >>> UINT_MAX) { >> >> Slightly shorter as: >> >> if (parse_uint_full(arg, &seed, 0) < 0 || seed > UINT_MAX) { >> >> but that's not a functional difference. > > That would silently truncate and accept strings containing illegal > characters at the end, e.g. 123a would be treated at 123 (decimal) No, the whole point of using parse_uint_full() instead of parse_uint() is that parse_uint_full() has one less parameter and enforces no trailing garbage on your behalf. -- Eric Blake eblake redhat com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature
Re: [Qemu-devel] [PATCH] linux-user: Let user specify random seed
On Fri, Oct 10, 2014 at 6:20 PM, Eric Blake wrote: > On 10/10/2014 02:16 AM, Magnus Reftel wrote: >> On Thu, Oct 9, 2014 at 11:30 PM, Eric Blake wrote: >>> On 10/09/2014 01:12 PM, Magnus Reftel wrote: +if (parse_uint(arg, &seed, &end, 0) != 0 || *end != 0 || seed > UINT_MAX) { >>> >>> Slightly shorter as: >>> >>> if (parse_uint_full(arg, &seed, 0) < 0 || seed > UINT_MAX) { >>> >>> but that's not a functional difference. >> >> That would silently truncate and accept strings containing illegal >> characters at the end, e.g. 123a would be treated at 123 (decimal) > > No, the whole point of using parse_uint_full() instead of parse_uint() > is that parse_uint_full() has one less parameter and enforces no > trailing garbage on your behalf. Right, missed the "_full". Sending an updated patch. BR Magnus Reftel
Re: [Qemu-devel] [PATCH] linux-user: Let user specify random seed
On 10/14/2014 03:50 AM, Magnus Reftel wrote: > This patch introduces the -seed command line option and the > QEMU_RAND_SEED environment variable for setting the random seed, which > is used for the AT_RANDOM ELF aux entry. > > Signed-off-by: Magnus Reftel > --- > linux-user/elfload.c | 1 - > linux-user/main.c| 19 +++ > 2 files changed, 19 insertions(+), 1 deletion(-) Reviewed-by: Eric Blake -- Eric Blake eblake redhat com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature