From 709b55ee0281bc2d587dff6f60ec189b010800f6 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 29 Oct 2008 15:34:48 +0000 Subject: [PATCH] * Put the chroots under /nix/var/nix/chroots to reduce the risk of disasters involving `rm -rf' on bind mounts. Will try the definitive fix (per-process mounts, apparently possible via the CLONE_NEWNS flag in clone()) some other time. --- src/libmain/shared.cc | 1 + src/libstore/build.cc | 17 +++++++---------- src/libstore/globals.cc | 1 + src/libstore/globals.hh | 6 ++++++ 4 files changed, 15 insertions(+), 10 deletions(-) diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc index fd16dece7..4725d1ed1 100644 --- a/src/libmain/shared.cc +++ b/src/libmain/shared.cc @@ -138,6 +138,7 @@ static void initAndRun(int argc, char * * argv) nixConfDir = canonPath(getEnv("NIX_CONF_DIR", NIX_CONF_DIR)); nixLibexecDir = canonPath(getEnv("NIX_LIBEXEC_DIR", NIX_LIBEXEC_DIR)); nixBinDir = canonPath(getEnv("NIX_BIN_DIR", NIX_BIN_DIR)); + nixChrootsDir = canonPath(getEnv("NIX_CHROOTS_DIR", nixStateDir + "/chroots")); string subs = getEnv("NIX_SUBSTITUTERS", "default"); if (subs == "default") { diff --git a/src/libstore/build.cc b/src/libstore/build.cc index 2a8ddd491..586e44922 100644 --- a/src/libstore/build.cc +++ b/src/libstore/build.cc @@ -1710,16 +1710,13 @@ void DerivationGoal::startBuilder() /* Create a temporary directory in which we set up the chroot environment using bind-mounts. - !!! Big danger here: since we're doing this in /tmp, there - is a risk that the admin does something like "rm -rf - /tmp/chroot-nix-*" to clean up aborted builds, and if some - of the bind-mounts are still active, then "rm -rf" will - happily recurse into those mount points (thereby deleting, - say, /nix/store). Ideally, chrootRootDir should be created in - some special location (maybe in /nix/var/nix) where Nix - takes care of unmounting / deleting old chroots - automatically. */ - chrootRootDir = createTempDir("", "chroot-nix"); + !!! Bind mounts are potentially dangerous: if the user + cleans up his system by doing "rm -rf + /nix/var/nix/chroots/*", this will recurse into /nix/store + via the bind mounts (and potentially other parts of the + filesystem, depending on the setting of the + `build-chroot-dirs' option). */ + chrootRootDir = createTempDir(nixChrootsDir, "chroot-nix"); /* Clean up the chroot directory automatically, but don't recurse; that would be very very bad if the unmount of a diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc index eaea4b707..7228fc193 100644 --- a/src/libstore/globals.cc +++ b/src/libstore/globals.cc @@ -16,6 +16,7 @@ string nixDBPath = "/UNINIT"; string nixConfDir = "/UNINIT"; string nixLibexecDir = "/UNINIT"; string nixBinDir = "/UNINIT"; +string nixChrootsDir = "/UNINIT"; bool keepFailed = false; bool keepGoing = false; diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh index f650cd1b7..a97aa6d8b 100644 --- a/src/libstore/globals.hh +++ b/src/libstore/globals.hh @@ -35,6 +35,12 @@ extern string nixLibexecDir; /* nixBinDir is the directory where the main programs are stored. */ extern string nixBinDir; +/* nixChrootsDir is the directory where we create chroot environments + (when chroot builds are enabled). We don't put these under /tmp to + prevent "rm -rf /tmp" from recursing into /nix/store via the bind + mounts in the chroots. */ +extern string nixChrootsDir; + /* Misc. global flags. */