debian/patches/extra/0003-9pfs-handle-walk-of-.-in-the-root-directory.patch

   1 From 348503ea115b336343166b87271208ffc0bdeb0a Mon Sep 17 00:00:00 2001
   2 From: Greg Kurz <groug@kaod.org>
   3 Date: Tue, 30 Aug 2016 17:02:27 +0200
   4 Subject: [PATCH 3/6] 9pfs: handle walk of ".." in the root directory
   5
   6 The 9P spec at http://man.cat-v.org/plan_9/5/intro says:
   7
   8 All directories must support walks to the directory .. (dot-dot) meaning
   9 parent directory, although by convention directories contain no explicit
  10 entry for .. or . (dot).  The parent of the root directory of a server's
  11 tree is itself.
  12
  13 This means that a client cannot walk further than the root directory
  14 exported by the server. In other words, if the client wants to walk
  15 "/.." or "/foo/../..", the server should answer like the request was
  16 to walk "/".
  17
  18 This patch just does that:
  19 - we cache the QID of the root directory at attach time
  20 - during the walk we compare the QID of each path component with the root
  21   QID to detect if we're in a "/.." situation
  22 - if so, we skip the current component and go to the next one
  23
  24 Signed-off-by: Greg Kurz <groug@kaod.org>
  25 Reviewed-by: Eric Blake <eblake@redhat.com>
  26 Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
  27 ---
  28  hw/9pfs/9p.c | 40 +++++++++++++++++++++++++++++++---------
  29  hw/9pfs/9p.h |  1 +
  30  2 files changed, 32 insertions(+), 9 deletions(-)
  31
  32 diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
  33 index 1e96427..1ac05b2 100644
  34 --- a/hw/9pfs/9p.c
  35 +++ b/hw/9pfs/9p.c
  36 @@ -1008,6 +1008,7 @@ static void v9fs_attach(void *opaque)
  37          goto out;
  38      }
  39      err += offset;
  40 +    memcpy(&s->root_qid, &qid, sizeof(qid));
  41      trace_v9fs_attach_return(pdu->tag, pdu->id,
  42                               qid.type, qid.version, qid.path);
  43      /*
  44 @@ -1259,6 +1260,14 @@ static bool name_is_illegal(const char *name)
  45      return !*name || strchr(name, '/') != NULL;
  46  }
  47
  48 +static bool not_same_qid(const V9fsQID *qid1, const V9fsQID *qid2)
  49 +{
  50 +    return
  51 +        qid1->type != qid2->type ||
  52 +        qid1->version != qid2->version ||
  53 +        qid1->path != qid2->path;
  54 +}
  55 +
  56  static void v9fs_walk(void *opaque)
  57  {
  58      int name_idx;
  59 @@ -1274,6 +1283,7 @@ static void v9fs_walk(void *opaque)
  60      V9fsFidState *newfidp = NULL;
  61      V9fsPDU *pdu = opaque;
  62      V9fsState *s = pdu->s;
  63 +    V9fsQID qid;
  64
  65      err = pdu_unmarshal(pdu, offset, "ddw", &fid, &newfid, &nwnames);
  66      if (err < 0) {
  67 @@ -1307,6 +1317,12 @@ static void v9fs_walk(void *opaque)
  68          err = -ENOENT;
  69          goto out_nofid;
  70      }
  71 +
  72 +    err = fid_to_qid(pdu, fidp, &qid);
  73 +    if (err < 0) {
  74 +        goto out;
  75 +    }
  76 +
  77      v9fs_path_init(&dpath);
  78      v9fs_path_init(&path);
  79      /*
  80 @@ -1316,16 +1332,22 @@ static void v9fs_walk(void *opaque)
  81      v9fs_path_copy(&dpath, &fidp->path);
  82      v9fs_path_copy(&path, &fidp->path);
  83      for (name_idx = 0; name_idx < nwnames; name_idx++) {
  84 -        err = v9fs_co_name_to_path(pdu, &dpath, wnames[name_idx].data, &path);
  85 -        if (err < 0) {
  86 -            goto out;
  87 -        }
  88 -        err = v9fs_co_lstat(pdu, &path, &stbuf);
  89 -        if (err < 0) {
  90 -            goto out;
  91 +        if (not_same_qid(&pdu->s->root_qid, &qid) ||
  92 +            strcmp("..", wnames[name_idx].data)) {
  93 +            err = v9fs_co_name_to_path(pdu, &dpath, wnames[name_idx].data,
  94 +                                       &path);
  95 +            if (err < 0) {
  96 +                goto out;
  97 +            }
  98 +
  99 +            err = v9fs_co_lstat(pdu, &path, &stbuf);
 100 +            if (err < 0) {
 101 +                goto out;
 102 +            }
 103 +            stat_to_qid(&stbuf, &qid);
 104 +            v9fs_path_copy(&dpath, &path);
 105          }
 106 -        stat_to_qid(&stbuf, &qids[name_idx]);
 107 -        v9fs_path_copy(&dpath, &path);
 108 +        memcpy(&qids[name_idx], &qid, sizeof(qid));
 109      }
 110      if (fid == newfid) {
 111          BUG_ON(fidp->fid_type != P9_FID_NONE);
 112 diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
 113 index 1a19418..589b3a5 100644
 114 --- a/hw/9pfs/9p.h
 115 +++ b/hw/9pfs/9p.h
 116 @@ -219,6 +219,7 @@ typedef struct V9fsState
 117      int32_t root_fid;
 118      Error *migration_blocker;
 119      V9fsConf fsconf;
 120 +    V9fsQID root_qid;
 121  } V9fsState;
 122
 123  /* 9p2000.L open flags */
 124 --
 125 2.1.4
 126