Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 519 insertions, 0 deletions

diff --git a/src/shared/rm-rf.c b/src/shared/rm-rf.c
new file mode 100644
index 0000000..4664215
--- /dev/null
+++ b/src/shared/rm-rf.c
@@ -0,0 +1,519 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "btrfs-util.h"
+#include "cgroup-util.h"
+#include "dirent-util.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "log.h"
+#include "macro.h"
+#include "mountpoint-util.h"
+#include "path-util.h"
+#include "rm-rf.h"
+#include "stat-util.h"
+#include "string-util.h"
+
+/* We treat tmpfs/ramfs + cgroupfs as non-physical file systems. cgroupfs is similar to tmpfs in a way
+ * after all: we can create arbitrary directory hierarchies in it, and hence can also use rm_rf() on it
+ * to remove those again. */
+static bool is_physical_fs(const struct statfs *sfs) {
+        return !is_temporary_fs(sfs) && !is_cgroup_fs(sfs);
+}
+
+static int patch_dirfd_mode(
+                int dfd,
+                bool refuse_already_set,
+                mode_t *ret_old_mode) {
+
+        struct stat st;
+        int r;
+
+        assert(dfd >= 0);
+        assert(ret_old_mode);
+
+        if (fstat(dfd, &st) < 0)
+                return -errno;
+        if (!S_ISDIR(st.st_mode))
+                return -ENOTDIR;
+
+        if (FLAGS_SET(st.st_mode, 0700)) { /* Already set? */
+                if (refuse_already_set)
+                        return -EACCES; /* original error */
+
+                *ret_old_mode = st.st_mode;
+                return 0;
+        }
+
+        if (st.st_uid != geteuid())  /* this only works if the UID matches ours */
+                return -EACCES;
+
+        r = fchmod_opath(dfd, (st.st_mode | 0700) & 07777);
+        if (r < 0)
+                return r;
+
+        *ret_old_mode = st.st_mode;
+        return 1;
+}
+
+int unlinkat_harder(int dfd, const char *filename, int unlink_flags, RemoveFlags remove_flags) {
+        mode_t old_mode;
+        int r;
+
+        /* Like unlinkat(), but tries harder: if we get EACCESS we'll try to set the r/w/x bits on the
+         * directory. This is useful if we run unprivileged and have some files where the w bit is
+         * missing. */
+
+        if (unlinkat(dfd, filename, unlink_flags) >= 0)
+                return 0;
+        if (errno != EACCES || !FLAGS_SET(remove_flags, REMOVE_CHMOD))
+                return -errno;
+
+        r = patch_dirfd_mode(dfd, /* refuse_already_set = */ true, &old_mode);
+        if (r < 0)
+                return r;
+
+        if (unlinkat(dfd, filename, unlink_flags) < 0) {
+                r = -errno;
+                /* Try to restore the original access mode if this didn't work */
+                (void) fchmod(dfd, old_mode & 07777);
+                return r;
+        }
+
+        if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode & 07777) < 0)
+                return -errno;
+
+        /* If this worked, we won't reset the old mode by default, since we'll need it for other entries too,
+         * and we should destroy the whole thing */
+        return 0;
+}
+
+int fstatat_harder(int dfd,
+                const char *filename,
+                struct stat *ret,
+                int fstatat_flags,
+                RemoveFlags remove_flags) {
+
+        mode_t old_mode;
+        int r;
+
+        /* Like unlink_harder() but does the same for fstatat() */
+
+        if (fstatat(dfd, filename, ret, fstatat_flags) >= 0)
+                return 0;
+        if (errno != EACCES || !FLAGS_SET(remove_flags, REMOVE_CHMOD))
+                return -errno;
+
+        r = patch_dirfd_mode(dfd, /* refuse_already_set = */ true, &old_mode);
+        if (r < 0)
+                return r;
+
+        if (fstatat(dfd, filename, ret, fstatat_flags) < 0) {
+                r = -errno;
+                (void) fchmod(dfd, old_mode & 07777);
+                return r;
+        }
+
+        if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode & 07777) < 0)
+                return -errno;
+
+        return 0;
+}
+
+static int openat_harder(int dfd, const char *path, int open_flags, RemoveFlags remove_flags, mode_t *ret_old_mode) {
+        _cleanup_close_ int pfd = -EBADF, fd = -EBADF;
+        bool chmod_done = false;
+        mode_t old_mode;
+        int r;
+
+        assert(dfd >= 0 || dfd == AT_FDCWD);
+        assert(path);
+
+        /* Unlike unlink_harder() and fstatat_harder(), this chmod the specified path. */
+
+        if (FLAGS_SET(open_flags, O_PATH) ||
+            !FLAGS_SET(open_flags, O_DIRECTORY) ||
+            !FLAGS_SET(remove_flags, REMOVE_CHMOD)) {
+
+                fd = RET_NERRNO(openat(dfd, path, open_flags));
+                if (fd < 0)
+                        return fd;
+
+                if (ret_old_mode) {
+                        struct stat st;
+
+                        if (fstat(fd, &st) < 0)
+                                return -errno;
+
+                        *ret_old_mode = st.st_mode;
+                }
+
+                return TAKE_FD(fd);
+        }
+
+        pfd = RET_NERRNO(openat(dfd, path, (open_flags & (O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW)) | O_PATH));
+        if (pfd < 0)
+                return pfd;
+
+        if (FLAGS_SET(remove_flags, REMOVE_CHMOD)) {
+                r = patch_dirfd_mode(pfd, /* refuse_already_set = */ false, &old_mode);
+                if (r < 0)
+                        return r;
+
+                chmod_done = r;
+        }
+
+        fd = fd_reopen(pfd, open_flags & ~O_NOFOLLOW);
+        if (fd < 0) {
+                if (chmod_done)
+                        (void) fchmod_opath(pfd, old_mode & 07777);
+                return fd;
+        }
+
+        if (ret_old_mode)
+                *ret_old_mode = old_mode;
+
+        return TAKE_FD(fd);
+}
+
+static int rm_rf_children_impl(
+                int fd,
+                RemoveFlags flags,
+                const struct stat *root_dev,
+                mode_t old_mode);
+
+static int rm_rf_inner_child(
+                int fd,
+                const char *fname,
+                int is_dir,
+                RemoveFlags flags,
+                const struct stat *root_dev,
+                bool allow_recursion) {
+
+        struct stat st;
+        int r, q = 0;
+
+        assert(fd >= 0);
+        assert(fname);
+
+        if (is_dir < 0 ||
+            root_dev ||
+            (is_dir > 0 && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
+
+                r = fstatat_harder(fd, fname, &st, AT_SYMLINK_NOFOLLOW, flags);
+                if (r < 0)
+                        return r;
+
+                is_dir = S_ISDIR(st.st_mode);
+        }
+
+        if (is_dir) {
+                /* If root_dev is set, remove subdirectories only if device is same */
+                if (root_dev && st.st_dev != root_dev->st_dev)
+                        return 0;
+
+                /* Stop at mount points */
+                r = fd_is_mount_point(fd, fname, 0);
+                if (r < 0)
+                        return r;
+                if (r > 0)
+                        return 0;
+
+                if ((flags & REMOVE_SUBVOLUME) && btrfs_might_be_subvol(&st)) {
+                        /* This could be a subvolume, try to remove it */
+
+                        r = btrfs_subvol_remove_at(fd, fname, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
+                        if (r < 0) {
+                                if (!IN_SET(r, -ENOTTY, -EINVAL))
+                                        return r;
+
+                                /* ENOTTY, then it wasn't a btrfs subvolume, continue below. */
+                        } else
+                                /* It was a subvolume, done. */
+                                return 1;
+                }
+
+                if (!allow_recursion)
+                        return -EISDIR;
+
+                mode_t old_mode;
+                int subdir_fd = openat_harder(fd, fname,
+                                              O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME,
+                                              flags, &old_mode);
+                if (subdir_fd < 0)
+                        return subdir_fd;
+
+                /* We pass REMOVE_PHYSICAL here, to avoid doing the fstatfs() to check the file system type
+                 * again for each directory */
+                q = rm_rf_children_impl(subdir_fd, flags | REMOVE_PHYSICAL, root_dev, old_mode);
+
+        } else if (flags & REMOVE_ONLY_DIRECTORIES)
+                return 0;
+
+        r = unlinkat_harder(fd, fname, is_dir ? AT_REMOVEDIR : 0, flags);
+        if (r < 0)
+                return r;
+        if (q < 0)
+                return q;
+        return 1;
+}
+
+typedef struct TodoEntry {
+        DIR *dir;         /* A directory that we were operating on. */
+        char *dirname;    /* The filename of that directory itself. */
+        mode_t old_mode;  /* The original file mode. */
+} TodoEntry;
+
+static void free_todo_entries(TodoEntry **todos) {
+        for (TodoEntry *x = *todos; x && x->dir; x++) {
+                closedir(x->dir);
+                free(x->dirname);
+        }
+
+        freep(todos);
+}
+
+int rm_rf_children(
+                int fd,
+                RemoveFlags flags,
+                const struct stat *root_dev) {
+
+        struct stat st;
+
+        assert(fd >= 0);
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        return rm_rf_children_impl(fd, flags, root_dev, st.st_mode);
+}
+
+static int rm_rf_children_impl(
+                int fd,
+                RemoveFlags flags,
+                const struct stat *root_dev,
+                mode_t old_mode) {
+
+        _cleanup_(free_todo_entries) TodoEntry *todos = NULL;
+        size_t n_todo = 0;
+        _cleanup_free_ char *dirname = NULL; /* Set when we are recursing and want to delete ourselves */
+        int ret = 0, r;
+
+        /* Return the first error we run into, but nevertheless try to go on.
+         * The passed fd is closed in all cases, including on failure. */
+
+        for (;;) {  /* This loop corresponds to the directory nesting level. */
+                _cleanup_closedir_ DIR *d = NULL;
+
+                if (n_todo > 0) {
+                        /* We know that we are in recursion here, because n_todo is set.
+                         * We need to remove the inner directory we were operating on. */
+                        assert(dirname);
+                        r = unlinkat_harder(dirfd(todos[n_todo-1].dir), dirname, AT_REMOVEDIR, flags);
+                        if (r < 0 && r != -ENOENT) {
+                                if (ret == 0)
+                                        ret = r;
+
+                                if (FLAGS_SET(flags, REMOVE_CHMOD_RESTORE))
+                                        (void) fchmodat(dirfd(todos[n_todo-1].dir), dirname, old_mode & 07777, 0);
+                        }
+                        dirname = mfree(dirname);
+
+                        /* And now let's back out one level up */
+                        n_todo --;
+                        d = TAKE_PTR(todos[n_todo].dir);
+                        dirname = TAKE_PTR(todos[n_todo].dirname);
+                        old_mode = todos[n_todo].old_mode;
+
+                        assert(d);
+                        fd = dirfd(d); /* Retrieve the file descriptor from the DIR object */
+                        assert(fd >= 0);
+                } else {
+        next_fd:
+                        assert(fd >= 0);
+                        d = fdopendir(fd);
+                        if (!d) {
+                                safe_close(fd);
+                                return -errno;
+                        }
+                        fd = dirfd(d); /* We donated the fd to fdopendir(). Let's make sure we sure we have
+                                        * the right descriptor even if it were to internally invalidate the
+                                        * one we passed. */
+
+                        if (!(flags & REMOVE_PHYSICAL)) {
+                                struct statfs sfs;
+
+                                if (fstatfs(fd, &sfs) < 0)
+                                        return -errno;
+
+                                if (is_physical_fs(&sfs)) {
+                                        /* We refuse to clean physical file systems with this call, unless
+                                         * explicitly requested. This is extra paranoia just to be sure we
+                                         * never ever remove non-state data. */
+
+                                        _cleanup_free_ char *path = NULL;
+
+                                        (void) fd_get_path(fd, &path);
+                                        return log_error_errno(SYNTHETIC_ERRNO(EPERM),
+                                                               "Attempted to remove disk file system under \"%s\", and we can't allow that.",
+                                                               strna(path));
+                                }
+                        }
+                }
+
+                FOREACH_DIRENT_ALL(de, d, return -errno) {
+                        int is_dir;
+
+                        if (dot_or_dot_dot(de->d_name))
+                                continue;
+
+                        is_dir = de->d_type == DT_UNKNOWN ? -1 : de->d_type == DT_DIR;
+
+                        r = rm_rf_inner_child(fd, de->d_name, is_dir, flags, root_dev, false);
+                        if (r == -EISDIR) {
+                                /* Push the current working state onto the todo list */
+
+                                 if (!GREEDY_REALLOC0(todos, n_todo + 2))
+                                         return log_oom();
+
+                                 _cleanup_free_ char *newdirname = strdup(de->d_name);
+                                 if (!newdirname)
+                                         return log_oom();
+
+                                 mode_t mode;
+                                 int newfd = openat_harder(fd, de->d_name,
+                                                           O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME,
+                                                           flags, &mode);
+                                 if (newfd >= 0) {
+                                         todos[n_todo++] = (TodoEntry) {
+                                                 .dir = TAKE_PTR(d),
+                                                 .dirname = TAKE_PTR(dirname),
+                                                 .old_mode = old_mode
+                                         };
+
+                                         fd = newfd;
+                                         dirname = TAKE_PTR(newdirname);
+                                         old_mode = mode;
+
+                                         goto next_fd;
+
+                                 } else if (newfd != -ENOENT && ret == 0)
+                                         ret = newfd;
+
+                        } else if (r < 0 && r != -ENOENT && ret == 0)
+                                ret = r;
+                }
+
+                if (FLAGS_SET(flags, REMOVE_SYNCFS) && syncfs(fd) < 0 && ret >= 0)
+                        ret = -errno;
+
+                if (n_todo == 0) {
+                        if (FLAGS_SET(flags, REMOVE_CHMOD_RESTORE) &&
+                            fchmod(fd, old_mode & 07777) < 0 && ret >= 0)
+                                ret = -errno;
+
+                        break;
+                }
+        }
+
+        return ret;
+}
+
+int rm_rf_at(int dir_fd, const char *path, RemoveFlags flags) {
+        mode_t old_mode;
+        int fd, r, q = 0;
+
+        assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
+        assert(path);
+
+        /* For now, don't support dropping subvols when also only dropping directories, since we can't do
+         * this race-freely. */
+        if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES|REMOVE_SUBVOLUME))
+                return -EINVAL;
+
+        /* We refuse to clean the root file system with this call. This is extra paranoia to never cause a
+         * really seriously broken system. */
+        if (path_is_root_at(dir_fd, path) > 0)
+                return log_error_errno(SYNTHETIC_ERRNO(EPERM),
+                                       "Attempted to remove entire root file system, and we can't allow that.");
+
+        if (FLAGS_SET(flags, REMOVE_SUBVOLUME | REMOVE_ROOT | REMOVE_PHYSICAL)) {
+                /* Try to remove as subvolume first */
+                r = btrfs_subvol_remove_at(dir_fd, path, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
+                if (r >= 0)
+                        return r;
+
+                if (FLAGS_SET(flags, REMOVE_MISSING_OK) && r == -ENOENT)
+                        return 0;
+
+                if (!IN_SET(r, -ENOTTY, -EINVAL, -ENOTDIR))
+                        return r;
+
+                /* Not btrfs or not a subvolume */
+        }
+
+        fd = openat_harder(dir_fd, path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME, flags, &old_mode);
+        if (fd >= 0) {
+                /* We have a dir */
+                r = rm_rf_children_impl(fd, flags, NULL, old_mode);
+
+                if (FLAGS_SET(flags, REMOVE_ROOT))
+                        q = RET_NERRNO(unlinkat(dir_fd, path, AT_REMOVEDIR));
+        } else {
+                r = fd;
+                if (FLAGS_SET(flags, REMOVE_MISSING_OK) && r == -ENOENT)
+                        return 0;
+
+                if (!IN_SET(r, -ENOTDIR, -ELOOP))
+                        return r;
+
+                if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES) || !FLAGS_SET(flags, REMOVE_ROOT))
+                        return 0;
+
+                if (!FLAGS_SET(flags, REMOVE_PHYSICAL)) {
+                        struct statfs s;
+
+                        r = xstatfsat(dir_fd, path, &s);
+                        if (r < 0)
+                                return r;
+                        if (is_physical_fs(&s))
+                                return log_error_errno(SYNTHETIC_ERRNO(EPERM),
+                                                       "Attempted to remove files from a disk file system under \"%s\", refusing.",
+                                                       path);
+                }
+
+                r = 0;
+                q = RET_NERRNO(unlinkat(dir_fd, path, 0));
+        }
+
+        if (r < 0)
+                return r;
+        if (q < 0 && (q != -ENOENT || !FLAGS_SET(flags, REMOVE_MISSING_OK)))
+                return q;
+        return 0;
+}
+
+int rm_rf_child(int fd, const char *name, RemoveFlags flags) {
+
+        /* Removes one specific child of the specified directory */
+
+        if (fd < 0)
+                return -EBADF;
+
+        if (!filename_is_valid(name))
+                return -EINVAL;
+
+        if ((flags & (REMOVE_ROOT|REMOVE_MISSING_OK)) != 0) /* Doesn't really make sense here, we are not supposed to remove 'fd' anyway */
+                return -EINVAL;
+
+        if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES|REMOVE_SUBVOLUME))
+                return -EINVAL;
+
+        return rm_rf_inner_child(fd, name, -1, flags, NULL, true);
+}