diff options
| author | David Howells <dhowells@redhat.com> | 2023-12-11 15:15:02 +0000 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2023-12-20 11:57:47 +0000 |
| commit | 74cef6872ceaefb5b6c5c60641371ea28702d358 (patch) | |
| tree | 625e298050a1987372b13c900ec9eb42f00c9b75 /fs/afs | |
| parent | 71f8b55bc30e82d6355e07811213d847981a32e2 (diff) | |
afs: Fix dynamic root lookup DNS check
In the afs dynamic root directory, the ->lookup() function does a DNS check
on the cell being asked for and if the DNS upcall reports an error it will
report an error back to userspace (typically ENOENT).
However, if a failed DNS upcall returns a new-style result, it will return
a valid result, with the status field set appropriately to indicate the
type of failure - and in that case, dns_query() doesn't return an error and
we let stat() complete with no error - which can cause confusion in
userspace as subsequent calls that trigger d_automount then fail with
ENOENT.
Fix this by checking the status result from a valid dns_query() and
returning an error if it indicates a failure.
Fixes: bbb4c4323a4d ("dns: Allow the dns resolver to retrieve a server set")
Reported-by: Markus Suvanto <markus.suvanto@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=216637
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Markus Suvanto <markus.suvanto@gmail.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Diffstat (limited to 'fs/afs')
| -rw-r--r-- | fs/afs/dynroot.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c index 34474a061654..1f656005018e 100644 --- a/fs/afs/dynroot.c +++ b/fs/afs/dynroot.c @@ -114,6 +114,7 @@ static int afs_probe_cell_name(struct dentry *dentry) struct afs_net *net = afs_d2net(dentry); const char *name = dentry->d_name.name; size_t len = dentry->d_name.len; + char *result = NULL; int ret; /* Names prefixed with a dot are R/W mounts. */ @@ -131,9 +132,22 @@ static int afs_probe_cell_name(struct dentry *dentry) } ret = dns_query(net->net, "afsdb", name, len, "srv=1", - NULL, NULL, false); - if (ret == -ENODATA || ret == -ENOKEY) + &result, NULL, false); + if (ret == -ENODATA || ret == -ENOKEY || ret == 0) ret = -ENOENT; + if (ret > 0 && ret >= sizeof(struct dns_server_list_v1_header)) { + struct dns_server_list_v1_header *v1 = (void *)result; + + if (v1->hdr.zero == 0 && + v1->hdr.content == DNS_PAYLOAD_IS_SERVER_LIST && + v1->hdr.version == 1 && + (v1->status != DNS_LOOKUP_GOOD && + v1->status != DNS_LOOKUP_GOOD_WITH_BAD)) + return -ENOENT; + + } + + kfree(result); return ret; } |