From 655f2da0790d0f8670f7a4c7da1833786ce0137e Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 4 Sep 2017 23:35:07 +1000 Subject: [PATCH] tmpfiles: silently ignore any path that passes through autofs (#6506) If a path passes though an autofs filesystem, then accessing the path might trigger and automount. As systemd-tmpfiles is run before the network is up, and as automounts are often used for networked filesystems, this can cause a deadlock. So chase_symlinks is enhance to accept a new flag which tells it to check for autofs, and return -EREMOTE if autofs is found. tmpfiles is changed to check just before acting on a path so that it can avoid autofs even if a symlink was created earlier by tmpfiles that would send this path through an autofs. This fixes a deadlock that happens when /home is listed in /etc/fstab as x-systemd.automount for an NFS directory. --- src/basic/fs-util.c | 4 ++++ src/basic/fs-util.h | 1 + src/tmpfiles/tmpfiles.c | 3 +++ 3 files changed, 8 insertions(+) diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c index 5e1163c..fdedeff 100644 --- a/src/basic/fs-util.c +++ b/src/basic/fs-util.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include @@ -721,6 +722,9 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags, if (fstat(child, &st) < 0) return -errno; + if ((flags & CHASE_NO_AUTOFS) && + fd_check_fstype(child, AUTOFS_SUPER_MAGIC) > 0) + return -EREMOTE; if (S_ISLNK(st.st_mode)) { char *joined; diff --git a/src/basic/fs-util.h b/src/basic/fs-util.h index 094acf1..d3342d5 100644 --- a/src/basic/fs-util.h +++ b/src/basic/fs-util.h @@ -81,6 +81,7 @@ int inotify_add_watch_fd(int fd, int what, uint32_t mask); enum { CHASE_PREFIX_ROOT = 1, /* If set, the specified path will be prefixed by the specified root before beginning the iteration */ CHASE_NONEXISTENT = 2, /* If set, it's OK if the path doesn't actually exist. */ + CHASE_NO_AUTOFS = 4, /* If set, return -EREMOTE if autofs mount point found */ }; int chase_symlinks(const char *path_with_prefix, const char *root, unsigned flags, char **ret); diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c index 8f960cc..875a886 100644 --- a/src/tmpfiles/tmpfiles.c +++ b/src/tmpfiles/tmpfiles.c @@ -1664,6 +1664,9 @@ static int process_item(Item *i) { } } + if (chase_symlinks(i->path, NULL, CHASE_NO_AUTOFS, NULL) == -EREMOTE) + return t; + r = arg_create ? create_item(i) : 0; q = arg_remove ? remove_item(i) : 0; p = arg_clean ? clean_item(i) : 0; -- 2.7.4