60 lines
2.0 KiB
Diff
60 lines
2.0 KiB
Diff
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https://github.com/distropatches/syslinux/tree/isohybrid
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Author: Bernhard M. Wiedemann <bwiedemann@suse.de>
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Date: Wed Feb 3 09:30:53 2021 +0100
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isohybrid: Use SOURCE_DATE_EPOCH for deterministic results
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without this patch, iso output contained 4 random bytes
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at offset 440 for MBR ID
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See https://reproducible-builds.org/ for why this matters.
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isohybrid: Keep entropy for srand
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without this patch, the seed would often be 0 or 0x70000000
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The <<2 is added so that pid and ppid do not cancel out each other.
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Index: syslinux-4.04/utils/isohybrid.pl
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===================================================================
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--- syslinux-4.04.orig/utils/isohybrid.pl
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+++ syslinux-4.04/utils/isohybrid.pl
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@@ -199,7 +199,7 @@ if (defined($opt{'id'})) {
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seek(FILE, 440, SEEK_SET) or die "$0: $file: $!\n";
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read(FILE, $id, 4);
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if ($id eq "\x00\x00\x00\x00") {
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- $id = pack("V", get_random());
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+ $id = pack("V", $ENV{SOURCE_DATE_EPOCH} || get_random());
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}
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}
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Index: syslinux-4.04/utils/isohybrid.c
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===================================================================
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--- syslinux-4.04.orig/utils/isohybrid.c
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+++ syslinux-4.04/utils/isohybrid.c
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@@ -927,6 +927,8 @@ main(int argc, char *argv[])
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uint8_t *buf = NULL, *bufz = NULL;
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int cylsize = 0, frac = 0;
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unsigned padding = 0;
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+ int randseed;
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+ char *source_date_epoch;
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size_t orig_gpt_size, free_space, gpt_size;
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struct iso_primary_descriptor descriptor;
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struct stat isostat;
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@@ -956,7 +958,11 @@ main(int argc, char *argv[])
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if(entry != part_efi && entry != part_mac) part_data = entry;
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}
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- srand(time(NULL) << (getppid() << getpid()));
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+
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+ if((source_date_epoch = getenv("SOURCE_DATE_EPOCH")) == NULL ||
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+ (randseed = strtol(source_date_epoch, NULL, 10)) <= 0)
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+ randseed = time(NULL) ^ (getppid()<<2) ^ getpid();
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+ srand(randseed);
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if (!(fp = fopen(argv[0], "r+"))) // #####
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err(1, "could not open file `%s'", argv[0]);
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