100 lines
4.0 KiB
Diff
100 lines
4.0 KiB
Diff
From 99ca5b681fceedd010b2616b1248a483f4bfbd97 Mon Sep 17 00:00:00 2001
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From: Kairui Song <kasong@redhat.com>
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Date: Wed, 13 Jan 2021 00:04:53 +0800
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Subject: [PATCH] initrd: extend SYSTEMD_IN_INITRD to accept non-ramfs rootfs
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Sometimes, non-ramfs initrd root are useful. Eg, for kdump, because
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initramfs is memory consuming, so mount a compressed image in earlier
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initrd, chroot into it then let systemd do the rest of job is a good
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solution.
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But systemd doesn't recognize the initrd environment if rootfs is not a
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temporary fs. This is a reasonable check, because switch-root in initrd
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will wipe the whole rootfs, will be a disaster if there are any
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misdetect.
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So extend SYSTEMD_IN_INITRD environment variable, now it accepts boolean
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value and two extra keyword, "auto" and "lenient". "auto" is same as
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before, and it's the default value. "lenient" will let systemd bypass
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the rootfs check.
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(cherry picked from commit db4c45cf4f10ca094b9e9570b758abd445d65381)
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Related: #1959339
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---
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doc/ENVIRONMENT.md | 8 ++++++++
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src/basic/util.c | 28 +++++++++++++++++++++++++---
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2 files changed, 33 insertions(+), 3 deletions(-)
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diff --git a/doc/ENVIRONMENT.md b/doc/ENVIRONMENT.md
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index 36b649afe1..8d7ce6ae2c 100644
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--- a/doc/ENVIRONMENT.md
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+++ b/doc/ENVIRONMENT.md
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@@ -37,6 +37,14 @@ All tools:
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useful for debugging, in order to test generators and other code against
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specific kernel command lines.
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+* `$SYSTEMD_IN_INITRD=[auto|lenient|0|1]` — if set, specifies initrd detection
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+ method. Defaults to `auto`. Behavior is defined as follows:
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+ `auto`: Checks if `/etc/initrd-release` exists, and a temporary fs is mounted
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+ on `/`. If both conditions meet, then it's in initrd.
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+ `lenient`: Similiar to `auto`, but the rootfs check is skipped.
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+ `0|1`: Simply overrides initrd detection. This is useful for debugging and
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+ testing initrd-only programs in the main system.
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+
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* `$SYSTEMD_EMOJI=0` — if set, tools such as "systemd-analyze security" will
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not output graphical smiley emojis, but ASCII alternatives instead. Note that
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this only controls use of Unicode emoji glyphs, and has no effect on other
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diff --git a/src/basic/util.c b/src/basic/util.c
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index b443e639f3..59bcf7b00c 100644
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--- a/src/basic/util.c
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+++ b/src/basic/util.c
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@@ -130,11 +130,14 @@ int prot_from_flags(int flags) {
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}
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bool in_initrd(void) {
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+ int r;
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+ const char *e;
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+ bool lenient = false;
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if (saved_in_initrd >= 0)
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return saved_in_initrd;
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- /* We make two checks here:
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+ /* We have two checks here:
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*
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* 1. the flag file /etc/initrd-release must exist
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* 2. the root file system must be a memory file system
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@@ -142,10 +145,29 @@ bool in_initrd(void) {
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* The second check is extra paranoia, since misdetecting an
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* initrd can have bad consequences due the initrd
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* emptying when transititioning to the main systemd.
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+ *
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+ * If env var $SYSTEMD_IN_INITRD is not set or set to "auto",
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+ * both checks are used. If it's set to "lenient", only check
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+ * 1 is used. If set to a booleen value, then the boolean
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+ * value is returned.
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*/
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- saved_in_initrd = access("/etc/initrd-release", F_OK) >= 0 &&
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- path_is_temporary_fs("/") > 0;
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+ e = secure_getenv("SYSTEMD_IN_INITRD");
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+ if (e) {
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+ if (streq(e, "lenient"))
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+ lenient = true;
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+ else if (!streq(e, "auto")) {
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+ r = parse_boolean(e);
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+ if (r >= 0) {
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+ saved_in_initrd = r > 0;
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+ return saved_in_initrd;
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+ }
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+ log_debug_errno(r, "Failed to parse $SYSTEMD_IN_INITRD, ignoring: %m");
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+ }
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+ }
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+
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+ saved_in_initrd = (lenient || path_is_temporary_fs("/") > 0) &&
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+ access("/etc/initrd-release", F_OK) >= 0;
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return saved_in_initrd;
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}
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