CAN_HARDLINK_SYMLINK and CAN_HARDLINK_SPECIAL are decided by configure running
linkat() on whatever filesystem the build tree happened to sit on. The
destination is free to disagree, and one host can hold both answers: macOS
builds on APFS, which can hard-link a symlink, and backs up to HFS+, which
returns ENOTSUP.
A build that said yes had no fallback left. try_dests_non() reported the
refusal as a transfer error and returned a matched basis, so the caller created
the entry anyway -- correctly -- and the run still exited 23. Every
neighbouring case copes: a regular file whose link() fails goes to try_a_copy,
and a build compiled without either macro resorts to --copy-dest behaviour.
This was the same situation, discovered a little later, and the only one
treated as fatal.
Take the existing fallback on any refusal. Singling out the "cannot" errnos is
not possible: link(2) documents EPERM both for a filesystem with no hard-link
support and for an ordinary permission refusal, and FUSE reports ENOSYS for the
same thing. It is also what the regular-file path next door has always done
(try_dests_reg -> hard_link_one -> try_a_copy), and consistency between the two
was the point. Where the errno does matter the surrounding transfer says so
anyway: ENOSPC, EDQUOT and EROFS fail the creation independently, EMLINK and
EXDEV mean the link was never possible. EIO alone goes unremarked; reporting
it would put a line into --link-dest's itemised output, so it is left out on
purpose.
Returning -3 rather than -2 keeps the caller out of the "already up to date,
skip it" arm, which under --link-dest would drop the entry entirely. Both
callers give -3 the treatment the compile-time fallback already gets -- clearing
itemizing and code -- because try_dests_non() has itemised the match itself and
would otherwise report the entry twice.
The fallback is silent, matching a build that cannot link these at compile
time; documented under --link-dest instead.
(cherry picked from commit d09edb85e6)
The ownership walk that resolves operator-supplied paths asks who planted a
symlink, not where the path came out, so a symlink owned by uid 0 or the euid
is followed wherever it points. A daemon already narrows that with the served
module root; nothing else has a root to narrow it with.
That leaves a wrapper serving a restricted directory over a remote shell with
no way to bound the resolution. rrsync can vet the argv it is handed, but
filter rules travel over the protocol instead: a dir-merge rule can name a
merge file outside the restricted dir and the server reads it in as rules.
Redacting the resulting diagnostics does not close it, because an exclude-only
merge produces none -- every line becomes a pattern, so nothing fails to parse,
and the client reads the file's contents off which of its own names went
missing from the file list.
--confine-root gives that wrapper the root the daemon has. The existing module
check becomes a root check that takes its root from module_dir when we are a
daemon and from the option otherwise, so daemon behaviour is unchanged; a
daemon ignores the option outright, since it arrives in a peer-supplied argv
and could only widen the module.
The tracker is seeded from getcwd() rather than curr_dir, which is only the
lexical name change_dir() was given: descend into a source argument through a
trusted symlink and the two sit at different depths, so a ".." that really
escapes looks like it landed inside. When the cwd cannot be read there is
nothing to measure against and the open is refused -- an empty tracker does not
deny by itself, because a leading ".." pops nothing from it and an empty path
reads as an ancestor of the root.
An fd pin (/proc/self/fd/N, which rrsync uses so no later symlink can redirect
a validated option path) is spelled outside the root by construction, so the
walk transits the pin namespace and the pin is judged by what it points at.
Only a bare ".../fd/<digits>" is resolved that way, and one that will not
readlink to an absolute path is refused; rrsync's ".../fd/N/<leaf>" spelling
resolves through the magic link and has its remaining components checked
normally.
--insecure-links is refused alongside it: that opt-out returns the legacy open
before the walk that enforces the root runs, so the pair would have quietly
meant no confinement at all.
(cherry picked from commit 3113011218)
-D and --no-D do two jobs at once: they decide whether devices and
special files are created, and they decide whether those entries carry
their rdev fields on the wire. send_file_entry() and recv_file_entry()
frame those fields with the same condition, but each end evaluates its
own preserve_devices/preserve_specials, so the two only agree because
both normally parse the same command line.
That makes --no-D unusable for a wrapper that controls one end of a
connection and wants to deny creation. Give it to the receiver alone
and the client's -D sender writes rdev the receiver never reads: the
file list desynchronises from that entry on. A FIFO or socket breaks
below protocol 31 -- a hang at 29, "File-list index 0 not in 0 - -1" at
30 -- and a device node breaks at EVERY protocol, current ones included,
because its arm of the condition has no protocol clause at all.
--drop-D separates the two jobs: it refuses the creation and leaves the
encoding alone. The entry is skipped through the existing non-regular
fall-through, so the visible result matches --no-D, and because it
touches no wire state it can be applied to one end by itself.
It has no effect on a sending rsync, which creates nothing.
(cherry picked from commit b607369f5f)
Move the uid/gid/acls/xattrs *_ndx assignments past check_batch_flags():
a mismatched-flag batch otherwise wrote F_XATTR(file) at offset 0 of
every file_struct, clobbering file->dirname. parse_negotiate_str() no
longer short-circuits on am_server, so each side picks its own #1 mutual
digest/checksum/compress choice rather than deferring to the peer's
order; man pages updated to match.
Co-authored-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Document --insecure-links, clarify in rsyncd.conf(5) that exclude=/filter is a
name-based filter and not a symlink boundary, and record the backported fixes.
The main purpose of the SHA checksums are to allow the daemon auth code
to pick a stonger digest method when negotiating the auth digest to use.
However, the SHA digests are also available for use in file checksums,
should someon really want to use one of them.
The new digests are listed from strongest to weakest at the start of the
daemon auth list, giving them the highest priority.
The new digests are listed from weakest to strongest near the end of the
checksum list, giving them the lowest priority of use for file
checksums.
A local_server copy now includes the dev+ino info from the destination
file so that the sender can make sure that it is not going to delete
the destination file. Fixes mistakes such as:
rsync -aiv --remove-source-files dir .
Zen Dodd