9p: attach-per-user
The 9P2000 protocol requires the authentication and permission checks to be
done in the file server. For that reason every user that accesses the file
server tree has to authenticate and attach to the server separately.
Multiple users can share the same connection to the server.
Currently v9fs does a single attach and executes all I/O operations as a
single user. This makes using v9fs in multiuser environment unsafe as it
depends on the client doing the permission checking.
This patch improves the 9P2000 support by allowing every user to attach
separately. The patch defines three modes of access (new mount option
'access'):
- attach-per-user (access=user) (default mode for 9P2000.u)
If a user tries to access a file served by v9fs for the first time, v9fs
sends an attach command to the server (Tattach) specifying the user. If
the attach succeeds, the user can access the v9fs tree.
As there is no uname->uid (string->integer) mapping yet, this mode works
only with the 9P2000.u dialect.
- allow only one user to access the tree (access=<uid>)
Only the user with uid can access the v9fs tree. Other users that attempt
to access it will get EPERM error.
- do all operations as a single user (access=any) (default for 9P2000)
V9fs does a single attach and all operations are done as a single user.
If this mode is selected, the v9fs behavior is identical with the current
one.
Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index 15e05a1..b364da7 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -1,6 +1,7 @@
/*
* V9FS FID Management
*
+ * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
* Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
@@ -34,9 +35,9 @@
#include "fid.h"
/**
- * v9fs_fid_insert - add a fid to a dentry
+ * v9fs_fid_add - add a fid to a dentry
+ * @dentry: dentry that the fid is being added to
* @fid: fid to add
- * @dentry: dentry that it is being added to
*
*/
@@ -66,52 +67,144 @@
}
/**
- * v9fs_fid_lookup - return a locked fid from a dentry
+ * v9fs_fid_find - retrieve a fid that belongs to the specified uid
+ * @dentry: dentry to look for fid in
+ * @uid: return fid that belongs to the specified user
+ * @any: if non-zero, return any fid associated with the dentry
+ *
+ */
+
+static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any)
+{
+ struct v9fs_dentry *dent;
+ struct p9_fid *fid, *ret;
+
+ P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
+ dentry->d_iname, dentry, uid, any);
+ dent = (struct v9fs_dentry *) dentry->d_fsdata;
+ ret = NULL;
+ if (dent) {
+ spin_lock(&dent->lock);
+ list_for_each_entry(fid, &dent->fidlist, dlist) {
+ if (any || fid->uid == uid) {
+ ret = fid;
+ break;
+ }
+ }
+ spin_unlock(&dent->lock);
+ }
+
+ return ret;
+}
+
+/**
+ * v9fs_fid_lookup - lookup for a fid, try to walk if not found
* @dentry: dentry to look for fid in
*
- * find a fid in the dentry, obtain its semaphore and return a reference to it.
- * code calling lookup is responsible for releasing lock
- *
- * TODO: only match fids that have the same uid as current user
- *
+ * Look for a fid in the specified dentry for the current user.
+ * If no fid is found, try to create one walking from a fid from the parent
+ * dentry (if it has one), or the root dentry. If the user haven't accessed
+ * the fs yet, attach now and walk from the root.
*/
struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
{
- struct v9fs_dentry *dent;
+ int i, n, l, clone, any, access;
+ u32 uid;
struct p9_fid *fid;
+ struct dentry *d, *ds;
+ struct v9fs_session_info *v9ses;
+ char **wnames, *uname;
- P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
- dent = dentry->d_fsdata;
- if (dent)
- fid = list_entry(dent->fidlist.next, struct p9_fid, dlist);
- else
- fid = ERR_PTR(-EBADF);
+ v9ses = v9fs_inode2v9ses(dentry->d_inode);
+ access = v9ses->flags & V9FS_ACCESS_MASK;
+ switch (access) {
+ case V9FS_ACCESS_SINGLE:
+ case V9FS_ACCESS_USER:
+ uid = current->fsuid;
+ any = 0;
+ break;
- P9_DPRINTK(P9_DEBUG_VFS, " fid: %p\n", fid);
+ case V9FS_ACCESS_ANY:
+ uid = v9ses->uid;
+ any = 1;
+ break;
+
+ default:
+ uid = ~0;
+ any = 0;
+ break;
+ }
+
+ fid = v9fs_fid_find(dentry, uid, any);
+ if (fid)
+ return fid;
+
+ 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_extended(v9ses))
+ uname = NULL;
+ else
+ uname = v9ses->uname;
+
+ fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
+ v9ses->aname);
+
+ if (IS_ERR(fid))
+ return fid;
+
+ v9fs_fid_add(ds, fid);
+ }
+ } else /* walk from the parent */
+ n = 1;
+
+ if (ds == dentry)
+ return fid;
+
+ wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
+ if (!wnames)
+ return ERR_PTR(-ENOMEM);
+
+ for (d = dentry, i = n; i >= 0; i--, d = d->d_parent)
+ wnames[i] = (char *) d->d_name.name;
+
+ clone = 1;
+ i = 0;
+ while (i < n) {
+ l = min(n - i, P9_MAXWELEM);
+ fid = p9_client_walk(fid, l, &wnames[i], clone);
+ if (!fid) {
+ kfree(wnames);
+ return fid;
+ }
+
+ i += l;
+ clone = 0;
+ }
+
+ kfree(wnames);
+ v9fs_fid_add(dentry, fid);
return fid;
}
-/**
- * v9fs_fid_clone - lookup the fid for a dentry, clone a private copy and
- * release it
- * @dentry: dentry to look for fid in
- *
- * find a fid in the dentry and then clone to a new private fid
- *
- * TODO: only match fids that have the same uid as current user
- *
- */
-
struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
{
- struct p9_fid *ofid, *fid;
+ struct p9_fid *fid, *ret;
- P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
- ofid = v9fs_fid_lookup(dentry);
- if (IS_ERR(ofid))
- return ofid;
+ fid = v9fs_fid_lookup(dentry);
+ if (IS_ERR(fid))
+ return fid;
- fid = p9_client_walk(ofid, 0, NULL, 1);
- return fid;
+ ret = p9_client_walk(fid, 0, NULL, 1);
+ return ret;
}
diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 68f82be..89ee0ba 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -91,6 +91,8 @@
Opt_legacy, Opt_nodevmap,
/* Cache options */
Opt_cache_loose,
+ /* Access options */
+ Opt_access,
/* Error token */
Opt_err
};
@@ -108,6 +110,7 @@
{Opt_nodevmap, "nodevmap"},
{Opt_cache_loose, "cache=loose"},
{Opt_cache_loose, "loose"},
+ {Opt_access, "access=%s"},
{Opt_err, NULL}
};
@@ -125,10 +128,10 @@
char *p;
int option;
int ret;
+ char *s, *e;
/* setup defaults */
v9ses->maxdata = 8192;
- v9ses->flags = V9FS_EXTENDED;
v9ses->afid = ~0;
v9ses->debug = 0;
v9ses->cache = 0;
@@ -172,10 +175,10 @@
v9ses->trans = v9fs_match_trans(&args[0]);
break;
case Opt_uname:
- match_strcpy(v9ses->name, &args[0]);
+ match_strcpy(v9ses->uname, &args[0]);
break;
case Opt_remotename:
- match_strcpy(v9ses->remotename, &args[0]);
+ match_strcpy(v9ses->aname, &args[0]);
break;
case Opt_legacy:
v9ses->flags &= ~V9FS_EXTENDED;
@@ -186,6 +189,22 @@
case Opt_cache_loose:
v9ses->cache = CACHE_LOOSE;
break;
+
+ case Opt_access:
+ s = match_strdup(&args[0]);
+ v9ses->flags &= ~V9FS_ACCESS_MASK;
+ if (strcmp(s, "user") == 0)
+ v9ses->flags |= V9FS_ACCESS_USER;
+ else if (strcmp(s, "any") == 0)
+ v9ses->flags |= V9FS_ACCESS_ANY;
+ else {
+ v9ses->flags |= V9FS_ACCESS_SINGLE;
+ v9ses->uid = simple_strtol(s, &e, 10);
+ if (*e != '\0')
+ v9ses->uid = ~0;
+ }
+ break;
+
default:
continue;
}
@@ -207,21 +226,22 @@
struct p9_trans *trans = NULL;
struct p9_fid *fid;
- v9ses->name = __getname();
- if (!v9ses->name)
+ v9ses->uname = __getname();
+ if (!v9ses->uname)
return ERR_PTR(-ENOMEM);
- v9ses->remotename = __getname();
- if (!v9ses->remotename) {
- __putname(v9ses->name);
+ v9ses->aname = __getname();
+ if (!v9ses->aname) {
+ __putname(v9ses->uname);
return ERR_PTR(-ENOMEM);
}
- strcpy(v9ses->name, V9FS_DEFUSER);
- strcpy(v9ses->remotename, V9FS_DEFANAME);
+ v9ses->flags = V9FS_EXTENDED | V9FS_ACCESS_USER;
+ strcpy(v9ses->uname, V9FS_DEFUSER);
+ strcpy(v9ses->aname, V9FS_DEFANAME);
+ v9ses->uid = ~0;
v9ses->dfltuid = V9FS_DEFUID;
v9ses->dfltgid = V9FS_DEFGID;
-
v9ses->options = kstrdup(data, GFP_KERNEL);
v9fs_parse_options(v9ses);
@@ -255,8 +275,20 @@
goto error;
}
- fid = p9_client_attach(v9ses->clnt, NULL, v9ses->name,
- v9ses->remotename);
+ if (!v9ses->clnt->dotu)
+ v9ses->flags &= ~V9FS_EXTENDED;
+
+ /* for legacy mode, fall back to V9FS_ACCESS_ANY */
+ if (!v9fs_extended(v9ses) &&
+ ((v9ses->flags&V9FS_ACCESS_MASK) == V9FS_ACCESS_USER)) {
+
+ v9ses->flags &= ~V9FS_ACCESS_MASK;
+ v9ses->flags |= V9FS_ACCESS_ANY;
+ v9ses->uid = ~0;
+ }
+
+ fid = p9_client_attach(v9ses->clnt, NULL, v9ses->uname, ~0,
+ v9ses->aname);
if (IS_ERR(fid)) {
retval = PTR_ERR(fid);
fid = NULL;
@@ -264,6 +296,11 @@
goto error;
}
+ if ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_SINGLE)
+ fid->uid = v9ses->uid;
+ else
+ fid->uid = ~0;
+
return fid;
error:
@@ -284,8 +321,8 @@
v9ses->clnt = NULL;
}
- __putname(v9ses->name);
- __putname(v9ses->remotename);
+ __putname(v9ses->uname);
+ __putname(v9ses->aname);
kfree(v9ses->options);
}
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 8e0999b..db4b419 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -36,10 +36,11 @@
unsigned int cache; /* cache mode */
char *options; /* copy of mount options */
- char *name; /* user name to mount as */
- char *remotename; /* name of remote hierarchy being mounted */
+ char *uname; /* user name to mount as */
+ char *aname; /* name of remote hierarchy being mounted */
unsigned int dfltuid; /* default uid/muid for legacy support */
unsigned int dfltgid; /* default gid for legacy support */
+ u32 uid; /* if ACCESS_SINGLE, the uid that has access */
struct p9_trans_module *trans; /* 9p transport */
struct p9_client *clnt; /* 9p client */
struct dentry *debugfs_dir;
@@ -47,7 +48,11 @@
/* session flags */
enum {
- V9FS_EXTENDED,
+ V9FS_EXTENDED = 0x01, /* 9P2000.u */
+ V9FS_ACCESS_MASK = 0x06, /* access mask */
+ V9FS_ACCESS_SINGLE = 0x02, /* only one user can access the files */
+ V9FS_ACCESS_USER = 0x04, /* attache per user */
+ V9FS_ACCESS_ANY = 0x06, /* use the same attach for all users */
};
/* possible values of ->cache */
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index f08a35d..175b4d9 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -364,7 +364,7 @@
file_inode = file->d_inode;
v9ses = v9fs_inode2v9ses(file_inode);
v9fid = v9fs_fid_clone(file);
- if(IS_ERR(v9fid))
+ if (IS_ERR(v9fid))
return PTR_ERR(v9fid);
return p9_client_remove(v9fid);
@@ -398,7 +398,7 @@
fid = NULL;
name = (char *) dentry->d_name.name;
dfid = v9fs_fid_clone(dentry->d_parent);
- if(IS_ERR(dfid)) {
+ if (IS_ERR(dfid)) {
err = PTR_ERR(dfid);
dfid = NULL;
goto error;
@@ -432,7 +432,7 @@
goto error;
}
- if(v9ses->cache)
+ if (v9ses->cache)
dentry->d_op = &v9fs_cached_dentry_operations;
else
dentry->d_op = &v9fs_dentry_operations;
@@ -593,7 +593,7 @@
if (result < 0)
goto error;
- if((fid->qid.version)&&(v9ses->cache))
+ if ((fid->qid.version) && (v9ses->cache))
dentry->d_op = &v9fs_cached_dentry_operations;
else
dentry->d_op = &v9fs_dentry_operations;
@@ -658,17 +658,17 @@
old_inode = old_dentry->d_inode;
v9ses = v9fs_inode2v9ses(old_inode);
oldfid = v9fs_fid_lookup(old_dentry);
- if(IS_ERR(oldfid))
+ if (IS_ERR(oldfid))
return PTR_ERR(oldfid);
olddirfid = v9fs_fid_clone(old_dentry->d_parent);
- if(IS_ERR(olddirfid)) {
+ if (IS_ERR(olddirfid)) {
retval = PTR_ERR(olddirfid);
goto done;
}
newdirfid = v9fs_fid_clone(new_dentry->d_parent);
- if(IS_ERR(newdirfid)) {
+ if (IS_ERR(newdirfid)) {
retval = PTR_ERR(newdirfid);
goto clunk_olddir;
}
@@ -682,7 +682,7 @@
}
v9fs_blank_wstat(&wstat);
- wstat.muid = v9ses->name;
+ wstat.muid = v9ses->uname;
wstat.name = (char *) new_dentry->d_name.name;
retval = p9_client_wstat(oldfid, &wstat);
@@ -887,7 +887,7 @@
retval = -EPERM;
v9ses = v9fs_inode2v9ses(dentry->d_inode);
fid = v9fs_fid_lookup(dentry);
- if(IS_ERR(fid))
+ if (IS_ERR(fid))
return PTR_ERR(fid);
if (!v9fs_extended(v9ses))
@@ -1070,7 +1070,7 @@
old_dentry->d_name.name);
oldfid = v9fs_fid_clone(old_dentry);
- if(IS_ERR(oldfid))
+ if (IS_ERR(oldfid))
return PTR_ERR(oldfid);
name = __getname();