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ksmbd: add AAPL kAAPL_SERVER_QUERY create context support

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macOS clients (Finder, and specifically Time Machine's backupd) send
an "AAPL" SMB2 create context on CREATE to negotiate AAPL-specific
server capabilities (server_caps/vol_caps/model string). Without a
response to this context, macOS Time Machine over SMB does not work
at all.

Add the AAPL create context structs (create_aapl_rsp,
aapl_server_query_req) and create_aapl_rsp_buf(), which builds the
kAAPL_SERVER_QUERY response mirroring the layout observed from macOS's
own smbd, including the model string workaround: omitting the model
string when the client requested it causes smbfs.kext to enter a
broken disconnect path requiring a full macOS reboot to recover from.
Command codes and bitmap values reuse the existing SMB2_CRTCTX_AAPL_*
constants in fs/smb/common/smb2pdu.h.

Wire format confirmed against AAPL's published public client kernel
source (public client behavior reference) -- every field
here and every SMB2_CRTCTX_AAPL_* constant matches exactly.

Hook the request parsing and response into smb2_open()'s existing
create-context handling, following the same DataOffset+DataLength
bounds-checking convention already used by every other context parser
in this file. The AAPL model string is configurable via the existing
netlink startup path (server_conf.aapl_model, default "Xserve").

This is scoped to shares with the new KSMBD_SHARE_FLAG_TIME_MACHINE
flag only, not enabled globally -- AAPL's AAPL extension is
undocumented, so containing its blast radius to shares that explicitly
opt in limits risk to ordinary SMB shares.

conn->aapl_readdir_attr is set here when the client also advertises
READDIR_ATTR support, but the actual inline-FinderInfo wire format
(the feature that flag gates) is not implemented yet -- follow-up
commit.

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Gael Blivet <gael.blivet@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Gael Blivet 2026-07-09 14:59:56 +09:00 • committed by Namjae Jeon
commit 8f1b796ff1
10 changed files with 212 additions and 2 deletions
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