diff options
| author | David Howells <dhowells@redhat.com> | 2026-06-22 10:08:53 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2026-07-01 15:26:22 +0200 |
| commit | 26f17ce6fa3f05cb5965790499c1839094260de4 (patch) | |
| tree | 9fdf6bca2824620aae2243f91fc9c75a1c535572 /fs | |
| parent | 55e841836c6f4646490f7b0347192b7a92d431ba (diff) | |
afs: Fix premature cell exposure through /afs
AFS cell records are prematurely exposured through the /afs dynamic root by
virtue of adding them immediately to the net->cells_dyn_ino IDR when the
cell is allocated rather than when it is added to the lookup tree. This
allows a candidate record to be accessed, even if it's actually a duplicate
or not published yet.
Fix this by not adding the cell to cells_dyn_ino until it's confirmed
non-duplicate and is being published. A flag is then used to record
whether it is added to the IDR to make removal from the IDR conditional.
Closes: https://sashiko.dev/#/patchset/20260618155141.2513212-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260622090856.2746629-20-dhowells@redhat.com
Fixes: 1d0b929fc070 ("afs: Change dynroot to create contents on demand")
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/afs/cell.c | 27 | ||||
| -rw-r--r-- | fs/afs/internal.h | 1 |
2 files changed, 18 insertions, 10 deletions
diff --git a/fs/afs/cell.c b/fs/afs/cell.c index 9d8937ae24e2..47a2645768d7 100644 --- a/fs/afs/cell.c +++ b/fs/afs/cell.c @@ -205,14 +205,7 @@ static struct afs_cell *afs_alloc_cell(struct afs_net *net, cell->dns_source = vllist->source; cell->dns_status = vllist->status; smp_store_release(&cell->dns_lookup_count, 1); /* vs source/status */ - down_write(&net->cells_lock); - ret = idr_alloc_cyclic(&net->cells_dyn_ino, cell, - 2, INT_MAX / 2, GFP_KERNEL); - up_write(&net->cells_lock); - if (ret < 0) - goto error; atomic_inc(&net->cells_outstanding); - cell->dynroot_ino = ret; cell->debug_id = atomic_inc_return(&cell_debug_id); trace_afs_cell(cell->debug_id, 1, 0, afs_cell_trace_alloc); @@ -306,6 +299,13 @@ struct afs_cell *afs_lookup_cell(struct afs_net *net, goto cell_already_exists; } + ret = idr_alloc_cyclic(&net->cells_dyn_ino, candidate, + 2, INT_MAX / 2, GFP_KERNEL); + if (ret < 0) + goto cant_alloc_ino; + candidate->dynroot_ino = ret; + set_bit(AFS_CELL_FL_HAVE_INO, &candidate->flags); + cell = candidate; candidate = NULL; afs_use_cell(cell, trace); @@ -380,6 +380,11 @@ no_wait: _leave(" = %p [cell]", cell); return cell; +cant_alloc_ino: + up_write(&net->cells_lock); + afs_put_cell(candidate, afs_cell_trace_put_candidate); + goto error_noput; + cell_already_exists: _debug("cell exists"); cell = cursor; @@ -596,9 +601,11 @@ static void afs_destroy_cell_work(struct work_struct *work) timer_delete_sync(&cell->management_timer); cancel_work_sync(&cell->manager); - down_write(&cell->net->cells_lock); - idr_remove(&cell->net->cells_dyn_ino, cell->dynroot_ino); - up_write(&cell->net->cells_lock); + if (test_bit(AFS_CELL_FL_HAVE_INO, &cell->flags)) { + down_write(&cell->net->cells_lock); + idr_remove(&cell->net->cells_dyn_ino, cell->dynroot_ino); + up_write(&cell->net->cells_lock); + } call_rcu(&cell->rcu, afs_cell_destroy); } diff --git a/fs/afs/internal.h b/fs/afs/internal.h index 785c646856d7..601f01e5c15f 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -388,6 +388,7 @@ struct afs_cell { #define AFS_CELL_FL_NO_GC 0 /* The cell was added manually, don't auto-gc */ #define AFS_CELL_FL_DO_LOOKUP 1 /* DNS lookup requested */ #define AFS_CELL_FL_CHECK_ALIAS 2 /* Need to check for aliases */ +#define AFS_CELL_FL_HAVE_INO 3 /* Have dynroot_ino */ enum afs_cell_state state; short error; enum dns_record_source dns_source:8; /* Latest source of data from lookup */ |