From f8278798a32ca169157f2f7b96be6b3a48cd61c8 Mon Sep 17 00:00:00 2001 From: Misaki Kasumi Date: Thu, 19 Dec 2024 15:04:55 +0800 Subject: [PATCH] sysroot: _ostree_sysroot_invisible & _ostree_in_root_mount_namespace --- src/libostree/ostree-sysroot-private.h | 3 +- src/libostree/ostree-sysroot.c | 58 +++++++++++++++++--------- src/libotutil/ot-fs-utils.c | 23 ++++++++++ src/libotutil/ot-fs-utils.h | 2 + 4 files changed, 64 insertions(+), 22 deletions(-) diff --git a/src/libostree/ostree-sysroot-private.h b/src/libostree/ostree-sysroot-private.h index 35cc8535e5..4cf8414ad4 100644 --- a/src/libostree/ostree-sysroot-private.h +++ b/src/libostree/ostree-sysroot-private.h @@ -124,8 +124,7 @@ gboolean _ostree_sysroot_ensure_visible (OstreeSysroot *self, GError **error); gboolean _ostree_sysroot_ensure_writable (OstreeSysroot *self, GError **error); gboolean -_ostree_sysroot_enter_mount_namespace (OstreeSysroot *self, GCancellable *cancellable, - GError **error); +_ostree_sysroot_enter_mount_namespace (OstreeSysroot *self, GError **error); void _ostree_sysroot_emit_journal_msg (OstreeSysroot *self, const char *msg); diff --git a/src/libostree/ostree-sysroot.c b/src/libostree/ostree-sysroot.c index 51e441b2d3..bdd1e583b6 100644 --- a/src/libostree/ostree-sysroot.c +++ b/src/libostree/ostree-sysroot.c @@ -228,20 +228,22 @@ ostree_sysroot_new_default (void) } static gboolean -is_in_root_mount_namespace (GCancellable *cancellable, GError **error) +_ostree_in_root_mount_namespace (gboolean *out_val, GError **error) { + /* glnx_readlinkat_malloc does not use cancellable acually. */ g_autofree char *mntns_pid1 - = glnx_readlinkat_malloc (AT_FDCWD, "/proc/1/ns/mnt", cancellable, error); + = glnx_readlinkat_malloc (AT_FDCWD, "/proc/1/ns/mnt", NULL, error); if (!mntns_pid1) return glnx_prefix_error (error, "Reading /proc/1/ns/mnt"); /* mount namespace is per-thread, not per-process */ g_autofree char *cur_thread = g_strdup_printf ("/proc/%d/ns/mnt", gettid ()); g_autofree char *mntns_cur - = glnx_readlinkat_malloc (AT_FDCWD, cur_thread, cancellable, error); + = glnx_readlinkat_malloc (AT_FDCWD, cur_thread, NULL, error); if (!mntns_cur) return glnx_prefix_error (error, "Reading %s", cur_thread); - return g_str_equal (mntns_pid1, mntns_cur); + *out_val = g_str_equal (mntns_pid1, mntns_cur); + return TRUE; } /** @@ -268,15 +270,14 @@ ostree_sysroot_set_mount_namespace_in_use (OstreeSysroot *self) /* Must be before we're loaded, as otherwise we'd have to close/reopen all our fds, e.g. the repo */ g_return_if_fail (self->loadstate < OSTREE_SYSROOT_LOAD_STATE_LOADED); + gboolean in_root; g_autoptr (GError) local_error = NULL; - g_assert (!is_in_root_mount_namespace (NULL, &local_error)); - g_assert (local_error == NULL); + g_assert (_ostree_in_root_mount_namespace (&in_root, &local_error) && !in_root); self->mount_namespace_in_use = TRUE; } gboolean -_ostree_sysroot_enter_mount_namespace (OstreeSysroot *self, GCancellable *cancellable, - GError **error) +_ostree_sysroot_enter_mount_namespace (OstreeSysroot *self, GError **error) { /* Do nothing if we're not privileged */ if (!ot_util_process_privileged ()) @@ -287,7 +288,9 @@ _ostree_sysroot_enter_mount_namespace (OstreeSysroot *self, GCancellable *cancel return TRUE; // If the mount namespaces are the same, we need to unshare(). - if (is_in_root_mount_namespace (cancellable, error)) + gboolean in_root; + g_return_val_if_fail (_ostree_in_root_mount_namespace (&in_root, error), FALSE); + if (in_root) { if (unshare (CLONE_NEWNS) < 0) return glnx_throw_errno_prefix (error, "Failed to invoke unshare(CLONE_NEWNS)"); @@ -296,8 +299,6 @@ _ostree_sysroot_enter_mount_namespace (OstreeSysroot *self, GCancellable *cancel if (mount (NULL, "/", NULL, MS_PRIVATE | MS_REC | MS_SILENT, NULL) < 0) return glnx_throw_errno_prefix (error, "Failed to set the mount propagation to private"); } - else - g_return_val_if_fail (error == NULL || *error == NULL, FALSE); ostree_sysroot_set_mount_namespace_in_use (self); @@ -334,7 +335,7 @@ ostree_sysroot_initialize_with_mount_namespace (OstreeSysroot *self, GCancellabl if (!ostree_sysroot_initialize (self, error)) return FALSE; - return _ostree_sysroot_enter_mount_namespace (self, cancellable, error); + return _ostree_sysroot_enter_mount_namespace (self, error); } /** @@ -400,20 +401,33 @@ remount_writable (const char *path, gboolean *did_remount, GError **error) } static gboolean -is_sysroot_invisible (void) +_ostree_sysroot_invisible (gboolean *out_val, GError **error) { - struct stat stbuf; + gboolean exists; - if (lstat (OTCORE_RUN_OSTREE_PRIVATE "/sysroot-ns", &stbuf) < 0) + if (!ot_path_exists (OTCORE_RUN_OSTREE_PRIVATE "/sysroot-ns", &exists, error)) return FALSE; - if (lstat ("/sysroot/ostree", &stbuf) == 0) + if (!exists) + { + *out_val = FALSE; + return TRUE; + } + + if (!ot_path_exists ("/sysroot/ostree", &exists, error)) return FALSE; + if (exists) + { + *out_val = FALSE; + return TRUE; + } + + *out_val = TRUE; return TRUE; } -/* Unmount covering tmpfs to make /sysroot visible */ +/* Make /sysroot visible */ gboolean _ostree_sysroot_ensure_visible (OstreeSysroot *self, GError **error) { @@ -430,8 +444,10 @@ _ostree_sysroot_ensure_visible (OstreeSysroot *self, GError **error) if (!self->root_is_ostree_booted) return TRUE; + gboolean invisible; + g_return_val_if_fail (_ostree_sysroot_invisible (&invisible, error), FALSE); /* Handle invisible sysroot */ - if (is_sysroot_invisible ()) + if (invisible) { glnx_autofd int sysroot_ns_fd = open (OTCORE_RUN_OSTREE_PRIVATE "/sysroot-ns", O_RDONLY); if (sysroot_ns_fd < 0) @@ -1158,9 +1174,11 @@ ostree_sysroot_initialize (OstreeSysroot *self, GError **error) return TRUE; } - if (is_sysroot_invisible ()) + gboolean invisible; + g_return_val_if_fail (_ostree_sysroot_invisible (&invisible, error), FALSE); + if (invisible) { - if (!_ostree_sysroot_enter_mount_namespace (self, NULL, error)) + if (!_ostree_sysroot_enter_mount_namespace (self, error)) return FALSE; if (!_ostree_sysroot_ensure_visible (self, error)) return FALSE; diff --git a/src/libotutil/ot-fs-utils.c b/src/libotutil/ot-fs-utils.c index 1e961a986c..31097a5b08 100644 --- a/src/libotutil/ot-fs-utils.c +++ b/src/libotutil/ot-fs-utils.c @@ -277,3 +277,26 @@ ot_get_dir_size (int dfd, const char *path, guint64 blocksize, guint64 *out_size return TRUE; } + +/* Check whether a path exists */ +gboolean +ot_path_exists (const char *path, gboolean *out_val, GError **error) +{ + g_autoptr (GError) local_error = NULL; + + struct stat stbuf; + if (glnx_fstatat (AT_FDCWD, path, &stbuf, 0, &local_error)) + { + *out_val = TRUE; + return TRUE; + } + + if (g_error_matches (local_error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND)) + { + *out_val = FALSE; + return TRUE; + } + + g_propagate_error (error, local_error); + return FALSE; +} diff --git a/src/libotutil/ot-fs-utils.h b/src/libotutil/ot-fs-utils.h index 7df79ba2a6..671988177a 100644 --- a/src/libotutil/ot-fs-utils.h +++ b/src/libotutil/ot-fs-utils.h @@ -78,4 +78,6 @@ gboolean ot_parse_file_by_line (const char *path, gboolean (*cb) (const char *, gboolean ot_get_dir_size (int dfd, const char *path, guint64 blocksize, guint64 *out_size, GCancellable *cancellable, GError **error); +gboolean ot_path_exists (const char *path, gboolean *out_val, GError **error); + G_END_DECLS