There is a problem in the rand_unix.c code when the random seed fd is greater
than or equal to FD_SETSIZE and the FDSET overruns its limit and walks the
stack.
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/9686)
Improve handling of low entropy at start up from /dev/urandom by waiting for
a read(2) call on /dev/random to succeed. Once one such call has succeeded,
a shared memory segment is created and persisted as an indicator to other
processes that /dev/urandom is properly seeded.
This does not fully prevent against attacks weakening the entropy source.
An attacker who has control of the machine early in its boot sequence
could create the shared memory segment preventing detection of low entropy
conditions. However, this is no worse than the current situation.
An attacker would also be capable of removing the shared memory segment
and causing seeding to reoccur resulting in a denial of service attack.
This is partially mitigated by keeping the shared memory alive for the
duration of the process's existence. Thus, an attacker would not only need
to have called call shmctl(2) with the IPC_RMID command but the system
must subsequently enter a state where no instances of libcrypto exist in
any process. Even one long running process will prevent this attack.
The System V shared memory calls used here go back at least as far as
Linux kernel 2.0. Linux kernels 4.8 and later, don't have a reliable way
to detect that /dev/urandom has been properly seeded, so a failure is raised
for this case (i.e. the getentropy(2) call has already failed).
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/9595)
CLA: trivial
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/9149)
The DEVRANDOM_WAIT feature added a select() call to wait for the
`/dev/random` device to become readable before reading from the
`/dev/urandom` device. It was introduced in commit 38023b87f0
in order to mitigate the fact that the `/dev/urandom` device
does not block until the initial seeding of the kernel CSPRNG
has completed, contrary to the behaviour of the `getrandom()`
system call.
It turned out that this change had negative side effects on
performance which were not acceptable. After some discussion it
was decided to revert this feature and leave it up to the OS
resp. the platform maintainer to ensure a proper initialization
during early boot time.
Fixes#9078
This partially reverts commit 38023b87f0.
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9084)
If the structures have empty padding bytes, ensure they are zeroed.
These structures are added to seed pools as complete blocks including
any padding and alignment bytes.
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8610)
Use select to wait for /dev/random in readable state,
but do not actually read anything from /dev/random,
use /dev/urandom first.
Use linux define __NR_getrandom instead of the
glibc define SYS_getrandom, in case the kernel headers
are more current than the glibc headers.
Fixes#8215
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/8251)
Commit c7504aeb64 (pr #6432) fixed a regression for applications in
chroot environments, which compensated the fact that the new OpenSSL CSPRNG
(based on the NIST DRBG) now reseeds periodically, which the previous
one didn't. Now the reseeding could fail in the chroot environment if the
DEVRANDOM devices were not present anymore and no other entropy source
(e.g. getrandom()) was available.
The solution was to keep the file handles for the DEVRANDOM devices open
by default. In fact, the fix did more than this, it opened the DEVRANDOM
devices early and unconditionally in rand_pool_init(), which had the
unwanted side effect that the devices were opened (and kept open) even
in cases when they were not used at all, for example when the getrandom()
system call was available. Due to a bug (issue #7419) this even happened
when the feature was disabled by the application.
This commit removes the unconditional opening of all DEVRANDOM devices.
They will now only be opened (and kept open) on first use. In particular,
if getrandom() is available, the handles will not be opened unnecessarily.
This change does not introduce a regression for applications compiled for
libcrypto 1.1.0, because the SSLEAY RNG also seeds on first use. So in the
above constellation the CSPRNG will only be properly seeded if it is happens
before the forking and chrooting.
Fixes#7419
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7437)
In pull request #4328 the seeding of the DRBG via RAND_add()/RAND_seed()
was implemented by buffering the data in a random pool where it is
picked up later by the rand_drbg_get_entropy() callback. This buffer
was limited to the size of 4096 bytes.
When a larger input was added via RAND_add() or RAND_seed() to the DRBG,
the reseeding failed, but the error returned by the DRBG was ignored
by the two calling functions, which both don't return an error code.
As a consequence, the data provided by the application was effectively
ignored.
This commit fixes the problem by a more efficient implementation which
does not copy the data in memory and by raising the buffer the size limit
to INT32_MAX (2 gigabytes). This is less than the NIST limit of 2^35 bits
but it was chosen intentionally to avoid platform dependent problems
like integer sizes and/or signed/unsigned conversion.
Additionally, the DRBG is now less permissive on errors: In addition to
pushing a message to the openssl error stack, it enters the error state,
which forces a reinstantiation on next call.
Thanks go to Dr. Falko Strenzke for reporting this issue to the
openssl-security mailing list. After internal discussion the issue
has been categorized as not being security relevant, because the DRBG
reseeds automatically and is fully functional even without additional
randomness provided by the application.
Fixes#7381
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7382)
Fixes a compiler warning about an unused syscall_random()
and cleans up the OPENSSL_RAND_SEED preprocessor logic.
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/779)
Don't discard partial reads from /dev/*random and retry instead.
Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6990)
Fixes#6978
Don't discard partial reads from syscall_random() and retry instead.
Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6990)
Change return value type to ssize_t and ensure that a negative value
is returned only if a corresponding errno is set.
Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6990)
Occasionally, e.g. when compiling for elderly glibc, you end up passing
-D_GNU_SOURCE on command line, and doing so triggered warning...
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6616)
This allows operation inside a chroot environment without having the
random device present.
A new call, RAND_keep_random_devices_open(), has been introduced that can
be used to control file descriptor use by the random seed sources. Some
seed sources maintain open file descriptors by default, which allows
such sources to operate in a chroot(2) jail without the associated device
nodes being available.
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/6432)
Unlike other ELF systems, HP-UX run-time linker fails to detect symbol
availability through weak declaration.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6583)
Calling the functions rand_pool_add_{additional,nonce}_data()
in crypto/rand/rand_lib.c with no implementation for djgpp/MSDOS
causees unresolved symbols when linking with djgpp.
Reported and fixed by Gisle Vanem
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6421)
If built with no-dso, syscall_random remains "blind" to getentropy.
Since it's possible to detect symbol availability on ELF-based systems
without involving DSO module, bypass it.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/6436)
If built with no-dso, DSO_global_lookup leaves "unsupported" message
in error queue. Since there is a fall-back code, it's unnecessary
distraction.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/6436)
Only Linux and FreeBSD provide getrandom(), but they both also provide
getentropy() since the same version and we already tried to call that.
Reviewed-by: Andy Polyakov <appro@openssl.org>
GH: #6405
This will actually support most OSs, and at least adds support for
Solaris and OSX
Fixes: #6403
Reviewed-by: Andy Polyakov <appro@openssl.org>
GH: #6405
rand_pool_bytes_needed() was constructed in such a way that the
smallest acceptable entropy factor was 1 entropy bits per 8 bits of
data. At the same time, we have a DRBG_MINMAX_FACTOR that allows
weaker source, as small as 1 bit of entropy per 128 bits of data.
The conclusion is that rand_pool_bytes_needed() needs to change to
support weaker entropy sources. We therefore change the input of
entropy per byte to be an entropy factor instead. This entropy factor
expresses how many bits of data it takes (on average) to get 1 bit of
entropy.
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/6150)
Fixes#5849
In pull request #5503 a fallback was added which adds a random nonce of
security_strength/2 bits if no nonce callback is provided. This change raised
the entropy requirements form 256 to 384 bit, which can cause problems on some
platforms (e.g. VMS, see issue #5849).
The requirements for the nonce are given in section 8.6.7 of NIST SP 800-90Ar1:
A nonce may be required in the construction of a seed during instantiation
in order to provide a security cushion to block certain attacks.
The nonce shall be either:
a) A value with at least (security_strength/2) bits of entropy, or
b) A value that is expected to repeat no more often than a
(security_strength/2)-bit random string would be expected to repeat.
Each nonce shall be unique to the cryptographic module in which instantiation
is performed, but need not be secret. When used, the nonce shall be considered
to be a critical security parameter.
This commit implements a nonce of type b) in order to lower the entropy
requirements during instantiation back to 256 bits.
The formulation "shall be unique to the cryptographic module" above implies
that the nonce needs to be unique among (with high probability) among all
DRBG instances in "space" and "time". We try to achieve this goal by creating a
nonce of the following form
nonce = app-specific-data || high-resolution-utc-timestamp || counter
Where || denotes concatenation. The application specific data can be something
like the process or group id of the application. A utc timestamp is used because
it increases monotonically, provided the system time is synchronized. This approach
may not be perfect yet for a FIPS evaluation, but it should be good enough for the
moment.
This commit also harmonizes the implementation of the get_nonce() and the
get_additional_data() callbacks and moves the platform specific parts from
rand_lib.c into rand_unix.c, rand_win.c, and rand_vms.c.
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5920)
When these two functions returned zero, it could mean:
1. that an error occured. In their case, the error is an overflow of
the pool, i.e. the correct response from the caller would be to
stop trying to fill the pool.
2. that there isn't enought entropy acquired yet, i.e. the correct
response from the caller would be to try and add more entropy to
the pool.
Because of this ambiguity, the returned zero turns out to be useless.
This change makes the returned value more consistent. 1 means the
addition of new entropy was successful, 0 means it wasn't. To know if
the pool has been filled enough, the caller will have to call some
other function, such as rand_pool_entropy_available().
Fixes#5846
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/5876)
Fixes#4403
This commit moves the internal header file "internal/rand.h" to
<openssl/rand_drbg.h>, making the RAND_DRBG API public.
The RAND_POOL API remains private, its function prototypes were
moved to "internal/rand_int.h" and converted to lowercase.
Documentation for the new API is work in progress on GitHub #5461.
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5462)
Reseeding is handled very differently by the classic RAND_METHOD API
and the new RAND_DRBG api. These differences led to some problems when
the new RAND_DRBG was made the default OpenSSL RNG. In particular,
RAND_add() did not work as expected anymore. These issues are discussed
on the thread '[openssl-dev] Plea for a new public OpenSSL RNG API'
and in Pull Request #4328. This commit fixes the mentioned issues,
introducing the following changes:
- Replace the fixed size RAND_BYTES_BUFFER by a new RAND_POOL API which
facilitates collecting entropy by the get_entropy() callback.
- Don't use RAND_poll()/RAND_add() for collecting entropy from the
get_entropy() callback anymore. Instead, replace RAND_poll() by
RAND_POOL_acquire_entropy().
- Add a new function rand_drbg_restart() which tries to get the DRBG
in an instantiated state by all means, regardless of the current
state (uninstantiated, error, ...) the DRBG is in. If the caller
provides entropy or additional input, it will be used for reseeding.
- Restore the original documented behaviour of RAND_add() and RAND_poll()
(namely to reseed the DRBG immediately) by a new implementation based
on rand_drbg_restart().
- Add automatic error recovery from temporary failures of the entropy
source to RAND_DRBG_generate() using the rand_drbg_restart() function.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4328)
cryptilib.h is the second.
Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4188)
The DRBG callbacks 'get_entropy()' and 'cleanup_entropy()' are designed
in such a way that the randomness buffer does not have to be allocated
by the calling function. It receives the address of a dynamically
allocated buffer from get_entropy() and returns this address to
cleanup_entropy(), where it is freed. If these two calls are properly
paired, the address can be stored in a stack local variable of the
calling function, so there is no need for having a 'randomness' member
(and a 'filled' member) in 'RAND_DRBG'.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4266)
With the introduction of RAND_poll_ex(), the `RAND_add()` calls were
replaced by meaningless cb(...). This commit changes the 'cb(...)'
calls back to 'rand_add(...)' calls by changing the signature as follows:
-int RAND_poll_ex(RAND_poll_fn cb, void *arg);
+int RAND_poll_ex(RAND_poll_cb rand_add, void *arg);
Changed the function typedef name to 'RAND_poll_cb' to emphasize the fact
that the function type represents a callback function.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4266)
If RAND_add wraps around, XOR with existing. Add test to drbgtest that
does the wrap-around.
Re-order seeding and stop after first success.
Add RAND_poll_ex()
Use the DF and therefore lower RANDOMNESS_NEEDED. Also, for child DRBG's,
mix in the address as the personalization bits.
Centralize the entropy callbacks, from drbg_lib to rand_lib.
(Conceptually, entropy is part of the enclosing application.)
Thanks to Dr. Matthias St Pierre for the suggestion.
Various code cleanups:
-Make state an enum; inline RANDerr calls.
-Add RAND_POLL_RETRIES (thanks Pauli for the idea)
-Remove most RAND_seed calls from rest of library
-Rename DRBG_CTX to RAND_DRBG, etc.
-Move some code from drbg_lib to drbg_rand; drbg_lib is now only the
implementation of NIST DRBG.
-Remove blocklength
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/4019)
Add a new config param to specify how the CSPRNG should be seeded.
Illegal values or nonsensical combinations (e.g., anything other
than "os" on VMS or HP VOS etc) result in build failures.
Add RDSEED support.
Add RDTSC but leave it disabled for now pending more investigation.
Refactor and reorganization all seeding files (rand_unix/win/vms) so
that they are simpler.
Only require 128 bits of seeding material.
Many document improvements, including why to not use RAND_add() and the
limitations around using load_file/write_file.
Document RAND_poll().
Cleanup Windows RAND_poll and return correct status
More completely initialize the default DRBG.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/3965)
Remove unused rand_hw_xor, MD/EVP indirection
Make rand_pseudo same as rand.
Cleanup formatting and ifdef control
Rename some things:
- rand_meth to openssl_rand_meth; make it global
- source file
- lock/init functions, start per-thread state
- ossl_meth_init to ossl_rand_init
Put state into RAND_STATE structure
And put OSSL_RAND_STATE into ossl_typ.h
Use "randomness" instead of "entropy"
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/3758)
Original text:
Check if a random "file" is really a device file, and treat it
specially if it is.
Add a few OpenBSD-specific cases.
This is part of a large change submitted by Markus Friedl <markus@openbsd.or
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3700)
This was done by the following
find . -name '*.[ch]' | /tmp/pl
where /tmp/pl is the following three-line script:
print unless $. == 1 && m@/\* .*\.[ch] \*/@;
close ARGV if eof; # Close file to reset $.
And then some hand-editing of other files.
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
The entropy-gathering daemon is used only on a small number of machines.
Provide a configure knob so that EGD support can be disabled by default
but re-enabled on those systems that do need it.
Reviewed-by: Dr. Stephen Henson <steve@openssl.org>
