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Changelog

Unreleased

Bug fixes

  • Unix: open_dir_at errors other than symlink-detection (ELOOP/EMLINK/ EFTYPE) that indicate a non-directory entry — specifically ENXIO (returned when opening an AF_UNIX socket) and ENOTDIR (returned when O_DIRECTORY is in effect) — are now treated as "not a directory" and the entry is removed with unlink_at rather than propagating an error. Fixes removal of directories containing Unix-domain sockets. (#82)

1.0.0

New features

  • New Builder and Remover structs provide a configurable API for controlling parallel deletion at runtime, exposed via the remove_dir_all crate root and the remove-dir-all CLI binary. (#80)

Other changes

  • macOS: parallel deletion is now disabled by default due to a global kernel lock in APFS that causes thrashing when readdir runs concurrently across threads. Parallelism can still be enabled explicitly via Builder. (#80)

0.8.4

Bug fixes

  • Unix: correctly detect symlinks on FreeBSD (EMLINK) and NetBSD (EFTYPE), which do not use ELOOP in response to O_NOFOLLOW. (#76)

0.8.3

Other changes

  • Windows: simplified implementation using fs_at's unified deletion path; removed significant internal dead code. (#72)

0.8.2

New features

  • RemoveDir trait is now public. (#59)
  • Added remove-dir-all CLI binary (opt-in via the cli Cargo feature). (#61)

Bug fixes

  • Windows: use fs_at's POSIX-deletion support to correctly handle in-use files on Windows, fixing #34. (#64)

Other changes

  • Improved crate documentation. (#58)

0.8.1

Other changes

  • Fix use of fcntl, missing undocumented extra argument.

0.8.0

Security changes

  • Fix TOCTOU race conditions both inside the implementation of functions and the contract: functions now only operate on directories. Callers wanting to process the contents of a symlink (e.g. for remove_dir_contents) should resolve the symlink themselves. This is an API break from 0.7.0, but the previous behaviour was insecure.

    This is due to the same code pattern as caused CVE-2022-21658 in Rust itself: it was possible to trick a privileged process doing a recursive delete in an attacker controlled directory into deleting privileged files, on all operating systems.

    For instance, consider deleting a tree called 'etc' in a parent directory called 'p'. Between calling remove_dir_all("a") and remove_dir_all("a") actually starting its work, the attacker can move 'p' to 'p-prime', and replace 'p' with a symlink to '/'. Then the privileged process deletes 'p/etc' which is actually /etc, and now your system is broken. There are some mitigations for this exact scenario, such as CWD relative file lookup, but they are not guaranteed - any code using absolute paths will not have that protection in place.

    The same attack could be performed at any point in the directory tree being deleted: if 'a' contains a child directory called 'etc', attacking the deletion by replacing 'a' with a link is possible.

    The new code in this release mitigates the attack within the directory tree being deleted by using file-handle relative operations: to open 'a/etc', the path 'etc' relative to 'a' is opened, where 'a' is represented by a file descriptor (Unix) or handle (Windows). With the exception of the entry points into the directory deletion logic, this is robust against manipulation of the directory hierarchy, and remove_dir_all will only delete files and directories contained in the tree it is deleting.

    The entry path however is a challenge - as described above, there are some potential mitigations, but since using them must be done by the calling code, it is hard to be confident about the security properties of the path based interface.

    The new extension trait RemoveDir provides an interface where it is much harder to get it wrong.

    somedir.remove_dir_contents("name-of-child").

    Callers can then make their own security evaluation about how to securely get a directory handle. That is still not particularly obvious, and we're going to follow up with a helper of some sort (probably in the fs_at crate). Once that is available, the path based entry points will get deprecated.

    In the interim, processes that might run with elevated privileges should figure out how to securely identify the directory they are going to delete, to avoid the initial race. Pragmatically, other processes should be fine with the path based entry points : this is the same interface std::fs::remove_dir_all offers, and an unprivileged process running in an attacker controlled directory can't do anything that the attacker can't already do.

    tl;dr: state shared with threat actors makes things dangerous; library functions cannot assume anything about the particular threat model of a program and must err on the side of caution.

Other changes

  • Made feature to control use of rayon off-by-default for easier integration by other crates.

0.7.0

  • add remove_dir_contents and ensure_empty_dir

0.6.1

  • update author
  • update README.md

0.6.0

  • Added threaded deletion on windows
  • requires edition 2018 to build

0.5.3

  • lints and doc fixes

0.5.2

  • Added support for aarch64-pc-windows-msvc.

0.5.1

  • Fixed deletion of readonly items.

0.5.0

  • Upgraded to winapi 0.3.