From 9ffaf63e34821ea60b2e1c8593f968d73728f82b Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Tue, 1 Jun 2010 09:26:18 +0000 Subject: fs/9p: Pass the correct user credentials during attach We need to make sure we pass the right uid value during attach. dotl is similar to dotu in this regard. Without this mapped security model on dotl doesn't work Signed-off-by: Aneesh Kumar K.V Signed-off-by: Eric Van Hensbergen --- fs/9p/fid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs/9p/fid.c') diff --git a/fs/9p/fid.c b/fs/9p/fid.c index 7317b39b2815..5d6cfcbf73e7 100644 --- a/fs/9p/fid.c +++ b/fs/9p/fid.c @@ -152,7 +152,8 @@ struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) if (access == V9FS_ACCESS_SINGLE) return ERR_PTR(-EPERM); - if (v9fs_proto_dotu(v9ses)) + if (v9fs_proto_dotu(v9ses) || + v9fs_proto_dotl(v9ses)) uname = NULL; else uname = v9ses->uname; -- cgit v1.2.2 From a534c8d15b1f1d0f861fc2bb9e0529bd8486ec3f Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Wed, 30 Jun 2010 19:18:50 +0530 Subject: fs/9p: Prevent parallel rename when doing fid_lookup During fid lookup we need to make sure that the dentry->d_parent doesn't change so that we can safely walk the parent dentries. To ensure that we need to prevent cross directory rename during fid_lookup. Add a per superblock rename_sem rw_semaphore to prevent parallel fid lookup and rename. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Venkateswararao Jujjuri Signed-off-by: Eric Van Hensbergen --- fs/9p/fid.c | 114 +++++++++++++++++++++++++++++++++++++++++------------------- 1 file changed, 78 insertions(+), 36 deletions(-) (limited to 'fs/9p/fid.c') diff --git a/fs/9p/fid.c b/fs/9p/fid.c index 5d6cfcbf73e7..358563689064 100644 --- a/fs/9p/fid.c +++ b/fs/9p/fid.c @@ -97,6 +97,34 @@ static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any) return ret; } +/* + * We need to hold v9ses->rename_sem as long as we hold references + * to returned path array. Array element contain pointers to + * dentry names. + */ +static int build_path_from_dentry(struct v9fs_session_info *v9ses, + struct dentry *dentry, char ***names) +{ + int n = 0, i; + char **wnames; + struct dentry *ds; + + for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) + n++; + + wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL); + if (!wnames) + goto err_out; + + for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent) + wnames[i] = (char *)ds->d_name.name; + + *names = wnames; + return n; +err_out: + return -ENOMEM; +} + /** * v9fs_fid_lookup - lookup for a fid, try to walk if not found * @dentry: dentry to look for fid in @@ -112,7 +140,7 @@ struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) int i, n, l, clone, any, access; u32 uid; struct p9_fid *fid, *old_fid = NULL; - struct dentry *d, *ds; + struct dentry *ds; struct v9fs_session_info *v9ses; char **wnames, *uname; @@ -139,50 +167,62 @@ struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) fid = v9fs_fid_find(dentry, uid, any); if (fid) return fid; - + /* + * we don't have a matching fid. To do a TWALK we need + * parent fid. We need to prevent rename when we want to + * look at the parent. + */ + down_read(&v9ses->rename_sem); ds = dentry->d_parent; fid = v9fs_fid_find(ds, uid, any); - if (!fid) { /* walk from the root */ - n = 0; - for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) - n++; - - fid = v9fs_fid_find(ds, uid, any); - if (!fid) { /* the user is not attached to the fs yet */ - if (access == V9FS_ACCESS_SINGLE) - return ERR_PTR(-EPERM); - - if (v9fs_proto_dotu(v9ses) || - v9fs_proto_dotl(v9ses)) - uname = NULL; - else - uname = v9ses->uname; + if (fid) { + /* Found the parent fid do a lookup with that */ + fid = p9_client_walk(fid, 1, (char **)&dentry->d_name.name, 1); + goto fid_out; + } + up_read(&v9ses->rename_sem); - fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, - v9ses->aname); + /* start from the root and try to do a lookup */ + fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any); + if (!fid) { + /* the user is not attached to the fs yet */ + if (access == V9FS_ACCESS_SINGLE) + return ERR_PTR(-EPERM); - if (IS_ERR(fid)) - return fid; + if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) + uname = NULL; + else + uname = v9ses->uname; - v9fs_fid_add(ds, fid); - } - } else /* walk from the parent */ - n = 1; + fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, + v9ses->aname); + if (IS_ERR(fid)) + return fid; - if (ds == dentry) + v9fs_fid_add(dentry->d_sb->s_root, fid); + } + /* If we are root ourself just return that */ + if (dentry->d_sb->s_root == dentry) return fid; - - wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL); - if (!wnames) - return ERR_PTR(-ENOMEM); - - for (d = dentry, i = (n-1); i >= 0; i--, d = d->d_parent) - wnames[i] = (char *) d->d_name.name; - + /* + * Do a multipath walk with attached root. + * When walking parent we need to make sure we + * don't have a parallel rename happening + */ + down_read(&v9ses->rename_sem); + n = build_path_from_dentry(v9ses, dentry, &wnames); + if (n < 0) { + fid = ERR_PTR(n); + goto err_out; + } clone = 1; i = 0; while (i < n) { l = min(n - i, P9_MAXWELEM); + /* + * We need to hold rename lock when doing a multipath + * walk to ensure none of the patch component change + */ fid = p9_client_walk(fid, l, &wnames[i], clone); if (IS_ERR(fid)) { if (old_fid) { @@ -194,15 +234,17 @@ struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) p9_client_clunk(old_fid); } kfree(wnames); - return fid; + goto err_out; } old_fid = fid; i += l; clone = 0; } - kfree(wnames); +fid_out: v9fs_fid_add(dentry, fid); +err_out: + up_read(&v9ses->rename_sem); return fid; } -- cgit v1.2.2