From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5E55243E4B5; Thu, 30 Jul 2026 15:54:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785426897; cv=none; b=XscMHuoCcgxtsdrCYy1a6Nfk6Axsgjip89z+buuwzwogT1eqj911WkLehGPmI0Xtmzutb040RJmpA5Cuxg816l9TnHdT6kgJyRQ/O8VZWqzi1fsziiUbA+sf/cZspo8xcdyLno9GOWjWBwvAK/YuNEbOUFfcTCazvBvV8nsQvnQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785426897; c=relaxed/simple; bh=diuQmCYtFoF8YD5XxfJkaszCRUFnQOzanGghBJIgcQk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=D7i8NeVQn0DNA2kvtNX25UV9X6ZRkGIjey+5gg5bgndjJudZCryAiO0Q4AiPVNuNNlmZHNNS/JdVrpql4AfTka+unf6T4B/ODNIfMTv1nsBxxoBHa251G8iC1S2lU7fPN/8Sj+0D5xQMTyXYq2SiFk6fG7PQhrZbcgvjEHezsn4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=UKr41UlC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="UKr41UlC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA0261F00A3A; Thu, 30 Jul 2026 15:54:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785426896; bh=JsCzAKccDy+Zvw8KiH4eFin9JK703pwr/Qntf17+U3s=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UKr41UlCnCgWAdhx/uoMeF29n1o9g8qS4KDaOt7zSCxJprhOnshB+ToCY5DfyS3hM xx0Y2D25qDt7BxuFCdgbt8Q4VwtxZ3QtYNMrs0Bx4+YU7zxMRMOcJQLm/YcVQNr5BP dJUnmn/P6YnVC3hVupgy000hrcws4DSCdv8fb+ok= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Markus Suvanto , David Howells , Marc Dionne , linux-afs@lists.infradead.org, Christian Brauner , Sasha Levin Subject: [PATCH 6.12 581/602] afs: Fix dynamic lookup to fail on cell lookup failure Date: Thu, 30 Jul 2026 16:16:13 +0200 Message-ID: <20260730141448.262929051@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141435.976815864@linuxfoundation.org> References: <20260730141435.976815864@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Howells [ Upstream commit 330e2c514823008b22e6afd2055715bc46dd8d55 ] When a process tries to access an entry in /afs, normally what happens is that an automount dentry is created by ->lookup() and then triggered, which jumps through the ->d_automount() op. Currently, afs_dynroot_lookup() does not do cell DNS lookup, leaving that to afs_d_automount() to perform - however, it is possible to use access() or stat() on the automount point, which will always return successfully, have briefly created an afs_cell record if one did not already exist. This means that something like: test -d "/afs/.west" && echo Directory exists will print "Directory exists" even though no such cell is configured. This breaks the "west" python module available on PIP as it expects this access to fail. Now, it could be possible to make afs_dynroot_lookup() perform the DNS[*] lookup, but that would make "ls --color /afs" do this for each cell in /afs that is listed but not yet probed. kafs-client, probably wrongly, preloads the entire cell database and all the known cells are then listed in /afs - and doing ls /afs would be very, very slow, especially if any cell supplied addresses but was wholly inaccessible. [*] When I say "DNS", actually read getaddrinfo(), which could use any one of a host of mechanisms. Could also use static configuration. To fix this, make the following changes: (1) Create an enum to specify the origination point of a call to afs_lookup_cell() and pass this value into that function in place of the "excl" parameter (which can be derived from it). There are six points of origination: - Cell preload through /proc/net/afs/cells - Root cell config through /proc/net/afs/rootcell - Lookup in dynamic root - Automount trigger - Direct mount with mount() syscall - Alias check where YFS tells us the cell name is different (2) Add an extra state into the afs_cell state machine to indicate a cell that's been initialised, but not yet looked up. This is separate from one that can be considered active and has been looked up at least once. (3) Make afs_lookup_cell() vary its behaviour more, depending on where it was called from: If called from preload or root cell config, DNS lookup will not happen until we definitely want to use the cell (dynroot mount, automount, direct mount or alias check). The cell will appear in /afs but stat() won't trigger DNS lookup. If the cell already exists, dynroot will not wait for the DNS lookup to complete. If the cell did not already exist, dynroot will wait. If called from automount, direct mount or alias check, it will wait for the DNS lookup to complete. (4) Make afs_lookup_cell() return an error if lookup failed in one way or another. We try to return -ENOENT if the DNS says the cell does not exist and -EDESTADDRREQ if we couldn't access the DNS. Reported-by: Markus Suvanto Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220685 Signed-off-by: David Howells Link: https://patch.msgid.link/1784747.1761158912@warthog.procyon.org.uk Fixes: 1d0b929fc070 ("afs: Change dynroot to create contents on demand") Tested-by: Markus Suvanto cc: Marc Dionne cc: linux-afs@lists.infradead.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/afs/cell.c | 78 +++++++++++++++++++++++++++++++++++++++++++++--------- fs/afs/dynroot.c | 3 +- fs/afs/internal.h | 12 +++++++- fs/afs/mntpt.c | 3 +- fs/afs/proc.c | 3 +- fs/afs/super.c | 2 - fs/afs/vl_alias.c | 3 +- 7 files changed, 86 insertions(+), 18 deletions(-) --- a/fs/afs/cell.c +++ b/fs/afs/cell.c @@ -228,7 +228,7 @@ error: * @name: The name of the cell. * @namesz: The strlen of the cell name. * @vllist: A colon/comma separated list of numeric IP addresses or NULL. - * @excl: T if an error should be given if the cell name already exists. + * @reason: The reason we're doing the lookup * @trace: The reason to be logged if the lookup is successful. * * Look up a cell record by name and query the DNS for VL server addresses if @@ -238,7 +238,8 @@ error: */ struct afs_cell *afs_lookup_cell(struct afs_net *net, const char *name, unsigned int namesz, - const char *vllist, bool excl, + const char *vllist, + enum afs_lookup_cell_for reason, enum afs_cell_trace trace) { struct afs_cell *cell, *candidate, *cursor; @@ -246,12 +247,18 @@ struct afs_cell *afs_lookup_cell(struct enum afs_cell_state state; int ret, n; - _enter("%s,%s", name, vllist); + _enter("%s,%s,%u", name, vllist, reason); - if (!excl) { + if (reason != AFS_LOOKUP_CELL_PRELOAD) { cell = afs_find_cell(net, name, namesz, trace); - if (!IS_ERR(cell)) + if (!IS_ERR(cell)) { + if (reason == AFS_LOOKUP_CELL_DYNROOT) + goto no_wait; + if (cell->state == AFS_CELL_SETTING_UP || + cell->state == AFS_CELL_UNLOOKED) + goto lookup_cell; goto wait_for_cell; + } } /* Assume we're probably going to create a cell and preallocate and @@ -297,26 +304,69 @@ struct afs_cell *afs_lookup_cell(struct rb_insert_color(&cell->net_node, &net->cells); up_write(&net->cells_lock); - afs_queue_cell(cell, afs_cell_trace_queue_new); +lookup_cell: + if (reason != AFS_LOOKUP_CELL_PRELOAD && + reason != AFS_LOOKUP_CELL_ROOTCELL) { + set_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags); + afs_queue_cell(cell, afs_cell_trace_queue_new); + } wait_for_cell: - _debug("wait_for_cell"); state = smp_load_acquire(&cell->state); /* vs error */ - if (state != AFS_CELL_ACTIVE && - state != AFS_CELL_DEAD) { + switch (state) { + case AFS_CELL_ACTIVE: + case AFS_CELL_DEAD: + break; + case AFS_CELL_UNLOOKED: + default: + if (reason == AFS_LOOKUP_CELL_PRELOAD || + reason == AFS_LOOKUP_CELL_ROOTCELL) + break; + _debug("wait_for_cell"); afs_see_cell(cell, afs_cell_trace_wait); wait_var_event(&cell->state, ({ state = smp_load_acquire(&cell->state); /* vs error */ state == AFS_CELL_ACTIVE || state == AFS_CELL_DEAD; })); + _debug("waited_for_cell %d %d", cell->state, cell->error); } +no_wait: /* Check the state obtained from the wait check. */ + state = smp_load_acquire(&cell->state); /* vs error */ if (state == AFS_CELL_DEAD) { ret = cell->error; goto error; } + if (state == AFS_CELL_ACTIVE) { + switch (cell->dns_status) { + case DNS_LOOKUP_NOT_DONE: + if (cell->dns_source == DNS_RECORD_FROM_CONFIG) { + ret = 0; + break; + } + fallthrough; + default: + ret = -EIO; + goto error; + case DNS_LOOKUP_GOOD: + case DNS_LOOKUP_GOOD_WITH_BAD: + ret = 0; + break; + case DNS_LOOKUP_GOT_NOT_FOUND: + ret = -ENOENT; + goto error; + case DNS_LOOKUP_BAD: + ret = -EREMOTEIO; + goto error; + case DNS_LOOKUP_GOT_LOCAL_FAILURE: + case DNS_LOOKUP_GOT_TEMP_FAILURE: + case DNS_LOOKUP_GOT_NS_FAILURE: + ret = -EDESTADDRREQ; + goto error; + } + } _leave(" = %p [cell]", cell); return cell; @@ -324,7 +374,7 @@ wait_for_cell: cell_already_exists: _debug("cell exists"); cell = cursor; - if (excl) { + if (reason == AFS_LOOKUP_CELL_PRELOAD) { ret = -EEXIST; } else { afs_use_cell(cursor, trace); @@ -383,7 +433,8 @@ int afs_cell_init(struct afs_net *net, c return -EINVAL; /* allocate a cell record for the root/workstation cell */ - new_root = afs_lookup_cell(net, rootcell, len, vllist, false, + new_root = afs_lookup_cell(net, rootcell, len, vllist, + AFS_LOOKUP_CELL_ROOTCELL, afs_cell_trace_use_lookup_ws); if (IS_ERR(new_root)) { _leave(" = %ld", PTR_ERR(new_root)); @@ -778,6 +829,7 @@ static bool afs_manage_cell(struct afs_c switch (cell->state) { case AFS_CELL_SETTING_UP: goto set_up_cell; + case AFS_CELL_UNLOOKED: case AFS_CELL_ACTIVE: goto cell_is_active; case AFS_CELL_REMOVING: @@ -798,7 +850,7 @@ set_up_cell: goto remove_cell; } - afs_set_cell_state(cell, AFS_CELL_ACTIVE); + afs_set_cell_state(cell, AFS_CELL_UNLOOKED); cell_is_active: if (afs_has_cell_expired(cell, &next_manage)) @@ -808,6 +860,8 @@ cell_is_active: ret = afs_update_cell(cell); if (ret < 0) cell->error = ret; + if (cell->state == AFS_CELL_UNLOOKED) + afs_set_cell_state(cell, AFS_CELL_ACTIVE); } if (next_manage < TIME64_MAX && cell->net->live) { --- a/fs/afs/dynroot.c +++ b/fs/afs/dynroot.c @@ -108,7 +108,8 @@ static struct dentry *afs_dynroot_lookup dotted = true; } - cell = afs_lookup_cell(net, name, len, NULL, false, + cell = afs_lookup_cell(net, name, len, NULL, + AFS_LOOKUP_CELL_DYNROOT, afs_cell_trace_use_lookup_dynroot); if (IS_ERR(cell)) { ret = PTR_ERR(cell); --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -353,6 +353,7 @@ extern const char afs_init_sysname[]; enum afs_cell_state { AFS_CELL_SETTING_UP, + AFS_CELL_UNLOOKED, AFS_CELL_ACTIVE, AFS_CELL_REMOVING, AFS_CELL_DEAD, @@ -1034,9 +1035,18 @@ static inline bool afs_cb_is_broken(unsi extern int afs_cell_init(struct afs_net *, const char *); extern struct afs_cell *afs_find_cell(struct afs_net *, const char *, unsigned, enum afs_cell_trace); +enum afs_lookup_cell_for { + AFS_LOOKUP_CELL_DYNROOT, + AFS_LOOKUP_CELL_MOUNTPOINT, + AFS_LOOKUP_CELL_DIRECT_MOUNT, + AFS_LOOKUP_CELL_PRELOAD, + AFS_LOOKUP_CELL_ROOTCELL, + AFS_LOOKUP_CELL_ALIAS_CHECK, +}; struct afs_cell *afs_lookup_cell(struct afs_net *net, const char *name, unsigned int namesz, - const char *vllist, bool excl, + const char *vllist, + enum afs_lookup_cell_for reason, enum afs_cell_trace trace); extern struct afs_cell *afs_use_cell(struct afs_cell *, enum afs_cell_trace); void afs_unuse_cell(struct afs_cell *cell, enum afs_cell_trace reason); --- a/fs/afs/mntpt.c +++ b/fs/afs/mntpt.c @@ -107,7 +107,8 @@ static int afs_mntpt_set_params(struct f if (size > AFS_MAXCELLNAME) return -ENAMETOOLONG; - cell = afs_lookup_cell(ctx->net, p, size, NULL, false, + cell = afs_lookup_cell(ctx->net, p, size, NULL, + AFS_LOOKUP_CELL_MOUNTPOINT, afs_cell_trace_use_lookup_mntpt); if (IS_ERR(cell)) { pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt); --- a/fs/afs/proc.c +++ b/fs/afs/proc.c @@ -122,7 +122,8 @@ static int afs_proc_cells_write(struct f if (strcmp(buf, "add") == 0) { struct afs_cell *cell; - cell = afs_lookup_cell(net, name, strlen(name), args, true, + cell = afs_lookup_cell(net, name, strlen(name), args, + AFS_LOOKUP_CELL_PRELOAD, afs_cell_trace_use_lookup_add); if (IS_ERR(cell)) { ret = PTR_ERR(cell); --- a/fs/afs/super.c +++ b/fs/afs/super.c @@ -290,7 +290,7 @@ static int afs_parse_source(struct fs_co /* lookup the cell record */ if (cellname) { cell = afs_lookup_cell(ctx->net, cellname, cellnamesz, - NULL, false, + NULL, AFS_LOOKUP_CELL_DIRECT_MOUNT, afs_cell_trace_use_lookup_mount); if (IS_ERR(cell)) { pr_err("kAFS: unable to lookup cell '%*.*s'\n", --- a/fs/afs/vl_alias.c +++ b/fs/afs/vl_alias.c @@ -269,7 +269,8 @@ static int yfs_check_canonical_cell_name if (!name_len || name_len > AFS_MAXCELLNAME) master = ERR_PTR(-EOPNOTSUPP); else - master = afs_lookup_cell(cell->net, cell_name, name_len, NULL, false, + master = afs_lookup_cell(cell->net, cell_name, name_len, NULL, + AFS_LOOKUP_CELL_ALIAS_CHECK, afs_cell_trace_use_lookup_canonical); kfree(cell_name); if (IS_ERR(master))