125 lines
6.0 KiB
Diff
125 lines
6.0 KiB
Diff
From 397aaad6da5c4bfb160adca7a68f865086f2ed0a Mon Sep 17 00:00:00 2001
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From: Franck Bui <fbui@suse.com>
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Date: Thu, 30 Sep 2021 14:05:36 +0200
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Subject: [PATCH] mount-util: fix fd_is_mount_point() when both the parent and
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directory are network fs
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The second call to name_to_handle_at_loop() didn't check for the specific
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errors that can happen when the parent dir is mounted by nfs and instead of
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falling back like it's done for the child dir, fd_is_mount_point() failed in
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this case.
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(cherry picked from commit 964ccab8286a7e75d7e9107f574f5cb23752bd5d)
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Resolves: #2015057
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---
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src/basic/mount-util.c | 71 ++++++++++++++++++++++++------------------
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1 file changed, 41 insertions(+), 30 deletions(-)
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diff --git a/src/basic/mount-util.c b/src/basic/mount-util.c
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index 45348bf878..0c709001be 100644
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--- a/src/basic/mount-util.c
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+++ b/src/basic/mount-util.c
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@@ -139,6 +139,19 @@ static int fd_fdinfo_mnt_id(int fd, const char *filename, int flags, int *mnt_id
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return safe_atoi(p, mnt_id);
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}
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+static bool is_name_to_handle_at_fatal_error(int err) {
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+ /* name_to_handle_at() can return "acceptable" errors that are due to the context. For
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+ * example the kernel does not support name_to_handle_at() at all (ENOSYS), or the syscall
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+ * was blocked (EACCES/EPERM; maybe through seccomp, because we are running inside of a
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+ * container), or the mount point is not triggered yet (EOVERFLOW, think nfs4), or some
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+ * general name_to_handle_at() flakiness (EINVAL). However other errors are not supposed to
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+ * happen and therefore are considered fatal ones. */
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+
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+ assert(err < 0);
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+
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+ return !IN_SET(err, -EOPNOTSUPP, -ENOSYS, -EACCES, -EPERM, -EOVERFLOW, -EINVAL);
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+}
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+
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int fd_is_mount_point(int fd, const char *filename, int flags) {
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_cleanup_free_ struct file_handle *h = NULL, *h_parent = NULL;
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int mount_id = -1, mount_id_parent = -1;
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@@ -173,42 +186,40 @@ int fd_is_mount_point(int fd, const char *filename, int flags) {
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* real mounts of their own. */
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r = name_to_handle_at_loop(fd, filename, &h, &mount_id, flags);
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- if (IN_SET(r, -ENOSYS, -EACCES, -EPERM, -EOVERFLOW, -EINVAL))
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- /* This kernel does not support name_to_handle_at() at all (ENOSYS), or the syscall was blocked
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- * (EACCES/EPERM; maybe through seccomp, because we are running inside of a container?), or the mount
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- * point is not triggered yet (EOVERFLOW, think nfs4), or some general name_to_handle_at() flakiness
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- * (EINVAL): fall back to simpler logic. */
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- goto fallback_fdinfo;
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- else if (r == -EOPNOTSUPP)
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- /* This kernel or file system does not support name_to_handle_at(), hence let's see if the upper fs
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- * supports it (in which case it is a mount point), otherwise fallback to the traditional stat()
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- * logic */
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+ if (r < 0) {
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+ if (is_name_to_handle_at_fatal_error(r))
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+ return r;
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+ if (r != -EOPNOTSUPP)
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+ goto fallback_fdinfo;
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+
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+ /* This kernel or file system does not support name_to_handle_at(), hence let's see
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+ * if the upper fs supports it (in which case it is a mount point), otherwise fall
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+ * back to the traditional stat() logic */
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nosupp = true;
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- else if (r < 0)
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- return r;
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+ }
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r = name_to_handle_at_loop(fd, "", &h_parent, &mount_id_parent, AT_EMPTY_PATH);
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- if (r == -EOPNOTSUPP) {
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+ if (r < 0) {
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+ if (is_name_to_handle_at_fatal_error(r))
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+ return r;
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+ if (r != -EOPNOTSUPP)
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+ goto fallback_fdinfo;
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if (nosupp)
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- /* Neither parent nor child do name_to_handle_at()? We have no choice but to fall back. */
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+ /* Both the parent and the directory can't do name_to_handle_at() */
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goto fallback_fdinfo;
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- else
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- /* The parent can't do name_to_handle_at() but the directory we are interested in can? If so,
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- * it must be a mount point. */
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- return 1;
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- } else if (r < 0)
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- return r;
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- /* The parent can do name_to_handle_at() but the
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- * directory we are interested in can't? If so, it
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- * must be a mount point. */
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+ /* The parent can't do name_to_handle_at() but the directory we are
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+ * interested in can? If so, it must be a mount point. */
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+ return 1;
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+ }
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+
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+ /* The parent can do name_to_handle_at() but the directory we are interested in can't? If
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+ * so, it must be a mount point. */
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if (nosupp)
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return 1;
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- /* If the file handle for the directory we are
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- * interested in and its parent are identical, we
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- * assume this is the root directory, which is a mount
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- * point. */
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+ /* If the file handle for the directory we are interested in and its parent are identical,
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+ * we assume this is the root directory, which is a mount point. */
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if (h->handle_bytes == h_parent->handle_bytes &&
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h->handle_type == h_parent->handle_type &&
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@@ -300,10 +311,10 @@ int path_get_mnt_id(const char *path, int *ret) {
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int r;
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r = name_to_handle_at_loop(AT_FDCWD, path, NULL, ret, 0);
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- if (IN_SET(r, -EOPNOTSUPP, -ENOSYS, -EACCES, -EPERM, -EOVERFLOW, -EINVAL)) /* kernel/fs don't support this, or seccomp blocks access, or untriggered mount, or name_to_handle_at() is flaky */
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- return fd_fdinfo_mnt_id(AT_FDCWD, path, 0, ret);
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+ if (r == 0 || is_name_to_handle_at_fatal_error(r))
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+ return r;
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- return r;
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+ return fd_fdinfo_mnt_id(AT_FDCWD, path, 0, ret);
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}
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int umount_recursive(const char *prefix, int flags) {
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