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CVS log for src/lib/libc/gen/getentropy.3

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Revision 1.4.2.1 / (download) - annotate - [select for diffs], Fri Aug 11 14:35:24 2023 UTC (6 months, 2 weeks ago) by martin
Branch: netbsd-10
CVS Tags: netbsd-10-0-RC5, netbsd-10-0-RC4, netbsd-10-0-RC3, netbsd-10-0-RC2, netbsd-10-0-RC1
Changes since 1.4: +48 -23 lines
Diff to previous 1.4 (colored) next main 1.5 (colored)

Pull up following revision(s) (requested by riastradh in ticket #319):

	sys/dev/pci/ubsec.c: revision 1.64
	sys/dev/pci/hifn7751.c: revision 1.82
	lib/libc/gen/getentropy.3: revision 1.5
	lib/libc/gen/getentropy.3: revision 1.6
	share/man/man4/rnd.4: revision 1.41
	lib/libc/sys/getrandom.2: revision 1.2
	lib/libc/sys/getrandom.2: revision 1.3
	share/man/man5/rc.conf.5: revision 1.193
	share/man/man7/entropy.7: revision 1.5
	share/man/man7/entropy.7: revision 1.6
	share/man/man7/entropy.7: revision 1.7
	share/man/man7/entropy.7: revision 1.8
	etc/security: revision 1.130
	share/man/man7/entropy.7: revision 1.9
	etc/security: revision 1.131
	sys/crypto/cprng_fast/cprng_fast.c: revision 1.19
	sys/sys/rndio.h: revision 1.3
	tests/lib/libc/sys/t_getrandom.c: revision 1.5
	etc/defaults/rc.conf: revision 1.164
	etc/defaults/rc.conf: revision 1.165
	sys/sys/rndsource.h: revision 1.10
	sys/kern/kern_entropy.c: revision 1.62
	sys/kern/kern_entropy.c: revision 1.63
	sys/kern/kern_entropy.c: revision 1.64
	sys/kern/subr_cprng.c: revision 1.44
	sys/kern/kern_entropy.c: revision 1.65
	sys/kern/kern_clock.c: revision 1.149
	sys/dev/pci/viornd.c: revision 1.22
	share/man/man9/rnd.9: revision 1.32
	sys/kern/subr_prf.c: revision 1.202
	sys/sys/rndsource.h: revision 1.8
	sys/sys/rndsource.h: revision 1.9
	share/man/man7/entropy.7: revision 1.10

1. Reinstate netbsd<=9 entropy estimator to unblock /dev/random, in
   parallel with assessment of only confident entropy sources (seed,
   HWRNG) for security warnings like sshd keys in motd and daily
   insecurity report.

2. Make multiuser boot wait for first /dev/random output soon after
   loading a seed and configuring rndctl, so that getentropy(3) meets
   its contract starting early at boot without introducing blocking
   paths that could cause hangs in init(8) or single-user mode.
   Operators can choose to disable this wait in rc.conf.

3. Fix some bugs left over from reducing the global entropy lock from
   a spin lock at IPL_VM to an adaptive lock at IPL_SOFTSERIAL.

4. Update man pages.

Revision 1.6 / (download) - annotate - [select for diffs], Fri Jun 30 22:15:14 2023 UTC (8 months ago) by uwe
Branch: MAIN
CVS Tags: HEAD
Changes since 1.5: +4 -2 lines
Diff to previous 1.5 (colored)

getentropy(3): use .Sx to xref CAVEATS

Revision 1.5 / (download) - annotate - [select for diffs], Fri Jun 30 21:44:22 2023 UTC (8 months ago) by riastradh
Branch: MAIN
Changes since 1.4: +46 -23 lines
Diff to previous 1.4 (colored)

getrandom(2), getentropy(3): Rework man pages.

Make supportable promises.  Omit needless verbiage.  Give caveats
with cross-references to entropy(7).  Emphasize that security is
necessarily relative to system configuration.

XXX pullup-10

Revision 1.4 / (download) - annotate - [select for diffs], Tue May 31 13:42:59 2022 UTC (21 months ago) by riastradh
Branch: MAIN
CVS Tags: netbsd-10-base
Branch point for: netbsd-10
Changes since 1.3: +9 -8 lines
Diff to previous 1.3 (colored)

libc: Reintroduce getentropy.

This was introduced two years ago when the getrandom/getentropy API
question was still open, and removed because the discussion was
ongoing.  Now getentropy is more widely adopted and soon to be in
POSIX.  So reintroduce the symbol into libc since we'll be keeping it
anyway.  Discussion of details of the semantics, as interpreted by
NetBSD, is ongoing, but the symbol needs to get in before the
netbsd-10 branch.  The draft POSIX text is
(https://www.opengroup.org/austin/docs/austin_1110.pdf):

    SYNOPSIS
        #include <unistd.h>

        int getentropy(void *buffer, size_t length);

    DESCRIPTION
        The getentropy() function shall write length bytes of data
        starting at the location pointed to by buffer. The output
        shall be unpredictable high quality random data, generated by
        a cryptographically secure pseudo-random number
        generator. The maximum permitted value for the length
        argument is given by the {GETENTROPY_MAX} symbolic constant
        defined in <limits.h>.

    RETURN VALUES
        Upon successful completion, getentropy() shall return 0;
        otherwise, -1 shall be retunred and errno set to indicate the
        error.

    ERRORS
        The getentropy() function shall fail if:

        [EINVAL]        The value of length is greater than
                        {GETENTROPY_MAX}.

        The getentropy() function may fail if:

        [ENOSYS]        The system does not provide the necessary
                        source of entropy.

    RATIONALE
        The getentropy() function is not a cancellation point.

Minor changes from the previous introduction of getentropy into libc:

- Return EINVAL, not EIO, on buflen > 256.
- Define GETENTROPY_MAX in limits.h.

The declaration of getentropy in unistd.h and definition of
GETENTROPY_MAX in limits.h are currently conditional on
_NETBSD_SOURCE.  When the next revision of POSIX is finalized, we can
expose them also under _POSIX_C_SOURCE > 20yymmL as usual -- and this
can be done as a pullup without breaking existing compiled programs.

Revision 1.3, Tue Sep 22 21:37:47 2020 UTC (3 years, 5 months ago) by nia
Branch: MAIN
CVS Tags: cjep_sun2x-base, cjep_sun2x, cjep_staticlib_x-base1, cjep_staticlib_x-base, cjep_staticlib_x
Changes since 1.2: +1 -1 lines
FILE REMOVED

remove getentropy bits

Revision 1.2 / (download) - annotate - [select for diffs], Thu May 7 12:55:06 2020 UTC (3 years, 9 months ago) by wiz
Branch: MAIN
Changes since 1.1: +6 -6 lines
Diff to previous 1.1 (colored)

Fix macro usage. Fix typo. New sentence, new line.

Revision 1.1 / (download) - annotate - [select for diffs], Wed May 6 16:17:36 2020 UTC (3 years, 9 months ago) by nia
Branch: MAIN

Add getentropy() to libc - a simple wrapper to access the kernel CSPRNG.

Posted to tech-userlevel@ a week ago and reviewed by riastradh@.

GETENTROPY(3)		   Library Functions Manual		 GETENTROPY(3)

NAME
     getentropy - fill a buffer with high quality random data

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     getentropy(void *buf, size_t buflen);

DESCRIPTION
     The getentropy() function fills a buffer with high quality random data,
     suitable for seeding cryptographically secure psuedorandom number
     generators.

     getentropy() is only intended for seeding random number generators and is
     not intended for use by regular code which simply needs secure random
     data.  For this purpose, please use arc4random(3).

     The maximum value for buflen is 256 bytes.

IMPLEMENTATION NOTES
     getentropy() reads from the sysctl(7) variable kern.arandom.

RETURN VALUES
     The getentropy() function returns 0 on success, and -1 if an error
     occurred.

ERRORS
     getentropy() will succeed unless:

     [EFAULT]		The buf argument points to an invalid memory address.

     [EIO]		Too many bytes were requested.

SEE ALSO
     arc4random(3), rnd(4)

STANDARDS
     The getentropy() function is non-standard.

HISTORY
     The getentropy() function first appeared in OpenBSD 5.6, then in
     FreeBSD 12.0, and NetBSD 10.

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