From 6ebb1c680835aa85714f34d897621b65ac6fef5d Mon Sep 17 00:00:00 2001
From: Colin Walters <walters@verbum.org>
Date: Sat, 9 Jan 2021 20:42:43 +0000
Subject: [PATCH 1/3] main: Unconditionally set up mount namespace
I was being very conservative initially here, but I think it's
really safe to just unconditionally set up the mount namespace.
This avoids having to check twice for a read-only `/sysroot`
(once in the binary and once in the library).
---
src/ostree/ot-main.c | 22 +++-------------------
1 file changed, 3 insertions(+), 19 deletions(-)
diff --git a/src/ostree/ot-main.c b/src/ostree/ot-main.c
index bffa40c4d4..d153dcec5c 100644
--- a/src/ostree/ot-main.c
+++ b/src/ostree/ot-main.c
@@ -122,26 +122,10 @@ maybe_setup_mount_namespace (gboolean *out_ns,
if (errno == ENOENT)
return TRUE;
- glnx_autofd int sysroot_subdir_fd = glnx_opendirat_with_errno (AT_FDCWD, "/sysroot", TRUE);
- if (sysroot_subdir_fd < 0)
- {
- if (errno != ENOENT)
- return glnx_throw_errno_prefix (error, "opendirat");
- /* No /sysroot - nothing to do */
- return TRUE;
- }
-
- struct statvfs stvfs;
- if (fstatvfs (sysroot_subdir_fd, &stvfs) < 0)
- return glnx_throw_errno_prefix (error, "fstatvfs");
- if (stvfs.f_flag & ST_RDONLY)
- {
- if (unshare (CLONE_NEWNS) < 0)
- return glnx_throw_errno_prefix (error, "preparing writable sysroot: unshare (CLONE_NEWNS)");
-
- *out_ns = TRUE;
- }
+ if (unshare (CLONE_NEWNS) < 0)
+ return glnx_throw_errno_prefix (error, "setting up mount namespace: unshare(CLONE_NEWNS)");
+ *out_ns = TRUE;
return TRUE;
}
From efa2ecfa731b5d782987d9b495f397c502761eff Mon Sep 17 00:00:00 2001
From: Colin Walters <walters@verbum.org>
Date: Sat, 9 Jan 2021 20:40:55 +0000
Subject: [PATCH 2/3] sysroot: Also maintain canonical boot_fd
Just like we hold a fd for `/sysroot`, also do so for `/boot`
instead of opening and closing it in a few places.
This is a preparatory cleanup for further work.
---
src/libostree/ostree-sysroot-deploy.c | 32 ++++++++++++--------------
src/libostree/ostree-sysroot-private.h | 4 ++++
src/libostree/ostree-sysroot.c | 15 ++++++++++++
3 files changed, 34 insertions(+), 17 deletions(-)
diff --git a/src/libostree/ostree-sysroot-deploy.c b/src/libostree/ostree-sysroot-deploy.c
index 7b7ba5e92f..aa6c0e6f6f 100644
--- a/src/libostree/ostree-sysroot-deploy.c
+++ b/src/libostree/ostree-sysroot-deploy.c
@@ -1583,11 +1583,11 @@ full_system_sync (OstreeSysroot *self,
out_stats->root_syncfs_msec = (end_msec - start_msec);
- start_msec = g_get_monotonic_time () / 1000;
- glnx_autofd int boot_dfd = -1;
- if (!glnx_opendirat (self->sysroot_fd, "boot", TRUE, &boot_dfd, error))
+ if (!_ostree_sysroot_ensure_boot_fd (self, error))
return FALSE;
- if (!fsfreeze_thaw_cycle (self, boot_dfd, cancellable, error))
+
+ start_msec = g_get_monotonic_time () / 1000;
+ if (!fsfreeze_thaw_cycle (self, self->boot_fd, cancellable, error))
return FALSE;
end_msec = g_get_monotonic_time () / 1000;
out_stats->boot_syncfs_msec = (end_msec - start_msec);
@@ -1771,8 +1771,7 @@ install_deployment_kernel (OstreeSysroot *sysroot,
cancellable, error))
return FALSE;
- glnx_autofd int boot_dfd = -1;
- if (!glnx_opendirat (sysroot->sysroot_fd, "boot", TRUE, &boot_dfd, error))
+ if (!_ostree_sysroot_ensure_boot_fd (sysroot, error))
return FALSE;
const char *osname = ostree_deployment_get_osname (deployment);
@@ -1782,14 +1781,14 @@ install_deployment_kernel (OstreeSysroot *sysroot,
g_autofree char *bootconf_name = g_strdup_printf ("ostree-%d-%s.conf",
n_deployments - ostree_deployment_get_index (deployment),
osname);
- if (!glnx_shutil_mkdir_p_at (boot_dfd, bootcsumdir, 0775, cancellable, error))
+ if (!glnx_shutil_mkdir_p_at (sysroot->boot_fd, bootcsumdir, 0775, cancellable, error))
return FALSE;
glnx_autofd int bootcsum_dfd = -1;
- if (!glnx_opendirat (boot_dfd, bootcsumdir, TRUE, &bootcsum_dfd, error))
+ if (!glnx_opendirat (sysroot->boot_fd, bootcsumdir, TRUE, &bootcsum_dfd, error))
return FALSE;
- if (!glnx_shutil_mkdir_p_at (boot_dfd, bootconfdir, 0775, cancellable, error))
+ if (!glnx_shutil_mkdir_p_at (sysroot->boot_fd, bootconfdir, 0775, cancellable, error))
return FALSE;
/* Install (hardlink/copy) the kernel into /boot/ostree/osname-${bootcsum} if
@@ -1880,18 +1879,18 @@ install_deployment_kernel (OstreeSysroot *sysroot,
{
overlay_initrds = g_ptr_array_new_with_free_func (g_free);
- if (!glnx_shutil_mkdir_p_at (boot_dfd, _OSTREE_SYSROOT_BOOT_INITRAMFS_OVERLAYS,
+ if (!glnx_shutil_mkdir_p_at (sysroot->boot_fd, _OSTREE_SYSROOT_BOOT_INITRAMFS_OVERLAYS,
0755, cancellable, error))
return FALSE;
}
- if (!glnx_fstatat_allow_noent (boot_dfd, rel_destpath, NULL, 0, error))
+ if (!glnx_fstatat_allow_noent (sysroot->boot_fd, rel_destpath, NULL, 0, error))
return FALSE;
if (errno == ENOENT)
{
g_autofree char *srcpath =
g_strdup_printf (_OSTREE_SYSROOT_RUNSTATE_STAGED_INITRDS_DIR "/%s", checksum);
- if (!install_into_boot (repo, sepolicy, AT_FDCWD, srcpath, boot_dfd, rel_destpath,
+ if (!install_into_boot (repo, sepolicy, AT_FDCWD, srcpath, sysroot->boot_fd, rel_destpath,
cancellable, error))
return FALSE;
}
@@ -2020,7 +2019,7 @@ install_deployment_kernel (OstreeSysroot *sysroot,
ostree_bootconfig_parser_set (bootconfig, "options", options_key);
glnx_autofd int bootconf_dfd = -1;
- if (!glnx_opendirat (boot_dfd, bootconfdir, TRUE, &bootconf_dfd, error))
+ if (!glnx_opendirat (sysroot->boot_fd, bootconfdir, TRUE, &bootconf_dfd, error))
return FALSE;
if (!ostree_bootconfig_parser_write_at (ostree_deployment_get_bootconfig (deployment),
@@ -2077,15 +2076,14 @@ swap_bootloader (OstreeSysroot *sysroot,
g_assert ((current_bootversion == 0 && new_bootversion == 1) ||
(current_bootversion == 1 && new_bootversion == 0));
- glnx_autofd int boot_dfd = -1;
- if (!glnx_opendirat (sysroot->sysroot_fd, "boot", TRUE, &boot_dfd, error))
+ if (!_ostree_sysroot_ensure_boot_fd (sysroot, error))
return FALSE;
/* The symlink was already written, and we used syncfs() to ensure
* its data is in place. Renaming now should give us atomic semantics;
* see https://bugzilla.gnome.org/show_bug.cgi?id=755595
*/
- if (!glnx_renameat (boot_dfd, "loader.tmp", boot_dfd, "loader", error))
+ if (!glnx_renameat (sysroot->boot_fd, "loader.tmp", sysroot->boot_fd, "loader", error))
return FALSE;
/* Now we explicitly fsync this directory, even though it
@@ -2097,7 +2095,7 @@ swap_bootloader (OstreeSysroot *sysroot,
* for whatever reason, and we wouldn't want to confuse the
* admin by going back to the previous session.
*/
- if (fsync (boot_dfd) != 0)
+ if (fsync (sysroot->boot_fd) != 0)
return glnx_throw_errno_prefix (error, "fsync(boot)");
/* TODO: In the future also execute this automatically via a systemd unit
diff --git a/src/libostree/ostree-sysroot-private.h b/src/libostree/ostree-sysroot-private.h
index 318b0b199e..641f053384 100644
--- a/src/libostree/ostree-sysroot-private.h
+++ b/src/libostree/ostree-sysroot-private.h
@@ -56,6 +56,7 @@ struct OstreeSysroot {
GFile *path;
int sysroot_fd;
+ int boot_fd;
GLnxLockFile lock;
OstreeSysrootLoadState loadstate;
@@ -160,6 +161,9 @@ char * _ostree_sysroot_get_runstate_path (OstreeDeployment *deployment, const ch
char *_ostree_sysroot_join_lines (GPtrArray *lines);
+gboolean
+_ostree_sysroot_ensure_boot_fd (OstreeSysroot *self, GError **error);
+
gboolean _ostree_sysroot_query_bootloader (OstreeSysroot *sysroot,
OstreeBootloader **out_bootloader,
GCancellable *cancellable,
diff --git a/src/libostree/ostree-sysroot.c b/src/libostree/ostree-sysroot.c
index e0813b5544..776572cc8d 100644
--- a/src/libostree/ostree-sysroot.c
+++ b/src/libostree/ostree-sysroot.c
@@ -197,6 +197,7 @@ ostree_sysroot_init (OstreeSysroot *self)
keys, G_N_ELEMENTS (keys));
self->sysroot_fd = -1;
+ self->boot_fd = -1;
}
/**
@@ -277,6 +278,19 @@ ensure_sysroot_fd (OstreeSysroot *self,
&self->sysroot_fd, error))
return FALSE;
}
+
+ return TRUE;
+}
+
+gboolean
+_ostree_sysroot_ensure_boot_fd (OstreeSysroot *self, GError **error)
+{
+ if (self->boot_fd == -1)
+ {
+ if (!glnx_opendirat (self->sysroot_fd, "boot", TRUE,
+ &self->boot_fd, error))
+ return FALSE;
+ }
return TRUE;
}
@@ -379,6 +393,7 @@ void
ostree_sysroot_unload (OstreeSysroot *self)
{
glnx_close_fd (&self->sysroot_fd);
+ glnx_close_fd (&self->boot_fd);
}
/**
From 518e5dc0eaad99ab44f905b7ccadda476338f5f8 Mon Sep 17 00:00:00 2001
From: Colin Walters <walters@verbum.org>
Date: Sat, 9 Jan 2021 18:34:27 +0000
Subject: [PATCH 3/3] sysroot: Handle ro /boot but rw /sysroot
The recent change in https://github.com/coreos/fedora-coreos-config/pull/659
broke some of our tests that do `mount -o remount,rw /sysroot` but
leave `/boot` read-only.
We had code for having `/boot` read-only before `/sysroot` but
in practice we had a file descriptor for `/sysroot` that we opened
before the remount that would happen later on.
Clean things up here so that in the library, we also remount
`/boot` at the same time we remount `/sysroot` if either are readonly.
Delete the legacy code for remounting `/boot` rw if we're not in
a mount namespace. I am fairly confident most users are either
using the `ostree` CLI, or they're using the mount namespace.
---
src/libostree/ostree-sysroot-deploy.c | 87 +--------------------------
src/libostree/ostree-sysroot.c | 47 +++++++++++----
src/libotutil/otutil.h | 6 ++
3 files changed, 44 insertions(+), 96 deletions(-)
diff --git a/src/libostree/ostree-sysroot-deploy.c b/src/libostree/ostree-sysroot-deploy.c
index aa6c0e6f6f..326e0b7cf5 100644
--- a/src/libostree/ostree-sysroot-deploy.c
+++ b/src/libostree/ostree-sysroot-deploy.c
@@ -57,9 +57,6 @@
#define OSTREE_DEPLOYMENT_FINALIZING_ID SD_ID128_MAKE(e8,64,6c,d6,3d,ff,46,25,b7,79,09,a8,e7,a4,09,94)
#endif
-static gboolean
-is_ro_mount (const char *path);
-
/*
* Like symlinkat() but overwrites (atomically) an existing
* symlink.
@@ -2226,57 +2223,6 @@ cleanup_legacy_current_symlinks (OstreeSysroot *self,
return TRUE;
}
-/* Detect whether or not @path refers to a read-only mountpoint. This is
- * currently just used to handle a potentially read-only /boot by transiently
- * remounting it read-write. In the future we might also do this for e.g.
- * /sysroot.
- */
-static gboolean
-is_ro_mount (const char *path)
-{
-#ifdef HAVE_LIBMOUNT
- /* Dragging in all of this crud is apparently necessary just to determine
- * whether something is a mount point.
- *
- * Systemd has a totally different implementation in
- * src/basic/mount-util.c.
- */
- struct libmnt_table *tb = mnt_new_table_from_file ("/proc/self/mountinfo");
- struct libmnt_fs *fs;
- struct libmnt_cache *cache;
- gboolean is_mount = FALSE;
- struct statvfs stvfsbuf;
-
- if (!tb)
- return FALSE;
-
- /* to canonicalize all necessary paths */
- cache = mnt_new_cache ();
- mnt_table_set_cache (tb, cache);
-
- fs = mnt_table_find_target(tb, path, MNT_ITER_BACKWARD);
- is_mount = fs && mnt_fs_get_target (fs);
-#ifdef HAVE_MNT_UNREF_CACHE
- mnt_unref_table (tb);
- mnt_unref_cache (cache);
-#else
- mnt_free_table (tb);
- mnt_free_cache (cache);
-#endif
-
- if (!is_mount)
- return FALSE;
-
- /* We *could* parse the options, but it seems more reliable to
- * introspect the actual mount at runtime.
- */
- if (statvfs (path, &stvfsbuf) == 0)
- return (stvfsbuf.f_flag & ST_RDONLY) != 0;
-
-#endif
- return FALSE;
-}
-
/**
* ostree_sysroot_write_deployments:
* @self: Sysroot
@@ -2579,18 +2525,6 @@ ostree_sysroot_write_deployments_with_options (OstreeSysroot *self,
}
else
{
- gboolean boot_was_ro_mount = FALSE;
- if (self->booted_deployment)
- boot_was_ro_mount = is_ro_mount ("/boot");
-
- g_debug ("boot is ro: %s", boot_was_ro_mount ? "yes" : "no");
-
- if (boot_was_ro_mount)
- {
- if (mount ("/boot", "/boot", NULL, MS_REMOUNT | MS_SILENT, NULL) < 0)
- return glnx_throw_errno_prefix (error, "Remounting /boot read-write");
- }
-
OstreeRepo *repo = ostree_sysroot_repo (self);
bootloader_config = ostree_repo_get_bootloader (repo);
@@ -2617,25 +2551,8 @@ ostree_sysroot_write_deployments_with_options (OstreeSysroot *self,
bootloader_is_atomic = bootloader != NULL && _ostree_bootloader_is_atomic (bootloader);
- /* Note equivalent of try/finally here */
- gboolean success = write_deployments_bootswap (self, new_deployments, opts, bootloader,
- &syncstats, cancellable, error);
- /* Below here don't set GError until the if (!success) check.
- * Note we only bother remounting if a mount namespace isn't in use.
- * */
- if (boot_was_ro_mount && !self->mount_namespace_in_use)
- {
- if (mount ("/boot", "/boot", NULL, MS_REMOUNT | MS_RDONLY | MS_SILENT, NULL) < 0)
- {
- /* Only make this a warning because we don't want to
- * completely bomb out if some other process happened to
- * jump in and open a file there. See above TODO
- * around doing this in a new mount namespace.
- */
- g_printerr ("warning: Failed to remount /boot read-only: %s\n", strerror (errno));
- }
- }
- if (!success)
+ if (!write_deployments_bootswap (self, new_deployments, opts, bootloader,
+ &syncstats, cancellable, error))
return FALSE;
}
diff --git a/src/libostree/ostree-sysroot.c b/src/libostree/ostree-sysroot.c
index 776572cc8d..9f54e6667c 100644
--- a/src/libostree/ostree-sysroot.c
+++ b/src/libostree/ostree-sysroot.c
@@ -294,6 +294,31 @@ _ostree_sysroot_ensure_boot_fd (OstreeSysroot *self, GError **error)
return TRUE;
}
+static gboolean
+remount_writable (const char *path, gboolean *did_remount, GError **error)
+{
+ *did_remount = FALSE;
+ struct statvfs stvfsbuf;
+ if (statvfs (path, &stvfsbuf) < 0)
+ {
+ if (errno != ENOENT)
+ return glnx_throw_errno_prefix (error, "statvfs(%s)", path);
+ else
+ return TRUE;
+ }
+
+ if ((stvfsbuf.f_flag & ST_RDONLY) != 0)
+ {
+ /* OK, let's remount writable. */
+ if (mount (path, path, NULL, MS_REMOUNT | MS_RELATIME, "") < 0)
+ return glnx_throw_errno_prefix (error, "Remounting %s read-write", path);
+ *did_remount = TRUE;
+ g_debug ("remounted %s writable", path);
+ }
+
+ return TRUE;
+}
+
/* Remount /sysroot read-write if necessary */
gboolean
_ostree_sysroot_ensure_writable (OstreeSysroot *self,
@@ -313,19 +338,19 @@ _ostree_sysroot_ensure_writable (OstreeSysroot *self,
if (!self->root_is_ostree_booted)
return TRUE;
- /* Check if /sysroot is a read-only mountpoint */
- struct statvfs stvfsbuf;
- if (statvfs ("/sysroot", &stvfsbuf) < 0)
- return glnx_throw_errno_prefix (error, "fstatvfs(/sysroot)");
- if ((stvfsbuf.f_flag & ST_RDONLY) == 0)
- return TRUE;
+ /* In these cases we also require /boot */
+ if (!_ostree_sysroot_ensure_boot_fd (self, error))
+ return FALSE;
- /* OK, let's remount writable. */
- if (mount ("/sysroot", "/sysroot", NULL, MS_REMOUNT | MS_RELATIME, "") < 0)
- return glnx_throw_errno_prefix (error, "Remounting /sysroot read-write");
+ gboolean did_remount_sysroot = FALSE;
+ if (!remount_writable ("/sysroot", &did_remount_sysroot, error))
+ return FALSE;
+ gboolean did_remount_boot = FALSE;
+ if (!remount_writable ("/boot", &did_remount_boot, error))
+ return FALSE;
- /* Reopen our fd */
- glnx_close_fd (&self->sysroot_fd);
+ /* Now close and reopen our file descriptors */
+ ostree_sysroot_unload (self);
if (!ensure_sysroot_fd (self, error))
return FALSE;
diff --git a/src/libotutil/otutil.h b/src/libotutil/otutil.h
index 7db7270da0..4cc5cd9f17 100644
--- a/src/libotutil/otutil.h
+++ b/src/libotutil/otutil.h
@@ -34,6 +34,12 @@
#define OT_VARIANT_BUILDER_INITIALIZER {{{0,}}}
#endif
+static inline const char *
+ot_booltostr (int b)
+{
+ return b ? "true" : "false";
+}
+
#define ot_gobject_refz(o) (o ? g_object_ref (o) : o)
#define ot_transfer_out_value(outp, srcp) G_STMT_START { \