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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:43:11 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:43:11 +0000 |
commit | fc22b3d6507c6745911b9dfcc68f1e665ae13dbc (patch) | |
tree | ce1e3bce06471410239a6f41282e328770aa404a /upstream/fedora-40/man8/systemd-boot-random-seed.service.8 | |
parent | Initial commit. (diff) | |
download | manpages-l10n-fc22b3d6507c6745911b9dfcc68f1e665ae13dbc.tar.xz manpages-l10n-fc22b3d6507c6745911b9dfcc68f1e665ae13dbc.zip |
Adding upstream version 4.22.0.upstream/4.22.0
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'upstream/fedora-40/man8/systemd-boot-random-seed.service.8')
-rw-r--r-- | upstream/fedora-40/man8/systemd-boot-random-seed.service.8 | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/upstream/fedora-40/man8/systemd-boot-random-seed.service.8 b/upstream/fedora-40/man8/systemd-boot-random-seed.service.8 new file mode 100644 index 00000000..8fb4d033 --- /dev/null +++ b/upstream/fedora-40/man8/systemd-boot-random-seed.service.8 @@ -0,0 +1,114 @@ +'\" t +.TH "SYSTEMD\-BOOT\-RANDOM\-SEED\&.SERVICE" "8" "" "systemd 255" "systemd-boot-random-seed.service" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +systemd-boot-random-seed.service \- Refresh boot loader random seed at boot +.SH "SYNOPSIS" +.PP +systemd\-boot\-random\-seed\&.service +.SH "DESCRIPTION" +.PP +systemd\-boot\-random\-seed\&.service +is a system service that automatically refreshes the boot loader random seed stored in the EFI System Partition (ESP), from the Linux kernel entropy pool\&. The boot loader random seed is primarily consumed and updated by +\fBsystemd-boot\fR(7) +from the UEFI environment (or +\fBsystemd-stub\fR(7) +if the former is not used, but the latter is), and passed as initial RNG seed to the OS\&. It is an effective way to ensure the OS comes up with a random pool that is fully initialized\&. +.PP +The service also automatically generates a \*(Aqsystem token\*(Aq to store in an EFI variable in the system\*(Aqs NVRAM\&. The boot loader may then combine the on\-disk random seed and the system token by cryptographic hashing, and pass it to the OS it boots as initialization seed for its entropy pool\&. Note: the random seed stored in the ESP is refreshed on +\fIevery\fR +reboot ensuring that multiple subsequent boots will boot with different seeds\&. On the other hand, the system token is generated randomly +\fIonce\fR, and then persistently stored in the system\*(Aqs EFI variable storage, ensuring the same disk image won\*(Aqt result in the same series of boot loader seed values if used on multiple systems in parallel\&. +.PP +The +systemd\-boot\-random\-seed\&.service +unit invokes the +\fBbootctl random\-seed\fR +command, which updates the random seed in the ESP, and initializes the system token if it\*(Aqs not initialized yet\&. The service is conditionalized so that it is run only when a boot loader is used that implements the +\m[blue]\fBBoot Loader Interface\fR\m[]\&\s-2\u[1]\d\s+2\&. +.PP +For further details see +\fBbootctl\fR(1), regarding the command this service invokes\&. +.PP +Note the relationship between +systemd\-boot\-random\-seed\&.service +and +\fBsystemd-random-seed\fR(8)\&. The former maintains the random seed consumed and updated by the boot environment (i\&.e\&. by +\fBsystemd-boot\fR(7) +or +\fBsystemd-stub\fR(7)), the latter maintains a random seed consumed and updated by the OS itself\&. The former ensures that the OS has a filled entropy pool already during earliest boot when regular disk access is not available yet (i\&.e\&. when the OS random seed cannot be loaded yet)\&. The latter is processed much later, once writable disk access is available\&. Thus it cannot be used to seed the initial boot phase, but typically has much higher quality of entropy\&. Both files are consumed and updated at boot, but at different times\&. Specifically: +.sp +.RS 4 +.ie n \{\ +\h'-04' 1.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 1." 4.2 +.\} +In UEFI mode, the +\fBsystemd-boot\fR(7) +or +\fBsystemd-stub\fR(7) +components load the boot loader random seed from the ESP, hash it with available entropy and the system token, and then update it on disk\&. A derived seed is passed to the kernel which writes it to its entropy pool\&. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 2.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 2." 4.2 +.\} +In userspace the +systemd\-random\-seed\&.service +service loads the OS random seed, writes it to the kernel entropy pool, and then updates it on disk with a new value derived from the kernel entropy pool\&. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 3.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 3." 4.2 +.\} +In userspace the +systemd\-boot\-random\-seed\&.service +service updates the boot loader random seed with a new value derived from the kernel entropy pool\&. +.RE +.PP +This logic should ensure that the kernel\*(Aqs entropy pool is seeded during earliest bool already, if possible, but the highest quality entropy is propagated back to both on\-disk seeds\&. +.SH "SEE ALSO" +.PP +\fBsystemd\fR(1), +\fBrandom\fR(4), +\fBbootctl\fR(1), +\fBsystemd-boot\fR(7), +\fBsystemd-stub\fR(7), +\fBsystemd-random-seed.service\fR(8) +.SH "NOTES" +.IP " 1." 4 +Boot Loader Interface +.RS 4 +\%https://systemd.io/BOOT_LOADER_INTERFACE +.RE |