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9p: attach-per-user

PATCH In review Latchesar Ionkov 2 participants 2 messages Sep 13, 2007

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Networking Documentation VFS 9P file system
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Latchesar Ionkov

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PATCH 1/1 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 <[email protected]>

---
commit c3daf49339c2ba13b1d8bc5087c196093f2f78f5
tree a401d3d055bbfa3be2a4c7259f3b25f81f8c1272
parent 13bf527796712619df072c0963e3f6c8c00189b8
author Latchesar Ionkov <lucho@eregion.(none)> Wed, 12 Sep 2007 22:38:59 -0600 committer Latchesar Ionkov <lucho@eregion.(none)> Wed, 12 Sep 2007 22:38:59 -0600

 Documentation/filesystems/9p.txt |   10 ++
 fs/9p/fid.c                      |  157 ++++++++++++++++++++++++++++++--------
 fs/9p/v9fs.c                     |   67 +++++++++++++---
 fs/9p/v9fs.h                     |   11 ++-
 fs/9p/vfs_inode.c                |   20 ++---
 include/net/9p/9p.h              |    7 +-
 include/net/9p/client.h          |    5 +
 net/9p/client.c                  |   10 +-
 net/9p/conv.c                    |   32 +++++++-
 9 files changed, 247 insertions(+), 72 deletions(-)
Documentation/filesystems/9p.txt +10 -0
index e694cd1..d6fd6c6 100644
@@ -88,6 +88,16 @@ OPTIONS
   		This can be used to share devices/named pipes/sockets between
 		hosts.  This functionality will be expanded in later versions.
 
+  access	there are three access modes.
+			user  = if a user tries to access a file on v9fs
+			        filesystem for the first time, v9fs sends an
+			        attach command (Tattach) for that user.
+				This is the default mode.
+			<uid> = allows only user with uid=<uid> to access
+				the files on the mounted filesystem
+			any   = v9fs does single attach and performs all
+				operations as one user
+
 RESOURCES
 =========
fs/9p/fid.c +125 -32

192 lines not on this page · raw message

fs/9p/v9fs.c +52 -15

133 lines not on this page · raw message

fs/9p/v9fs.h +8 -3
index 5d0280a..280dbd4 100644
@@ -36,10 +36,11 @@ struct v9fs_session_info {
 	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 @@ struct v9fs_session_info {
 
 /* 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 */
fs/9p/vfs_inode.c +10 -10
index f08a35d..175b4d9 100644
@@ -364,7 +364,7 @@ static int v9fs_remove(struct inode *dir, struct dentry *file, int rmdir)
 	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 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
 	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 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
 		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 @@ static struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
 	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 @@ v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	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_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	}
 
 	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 @@ static int v9fs_readlink(struct dentry *dentry, char *buffer, int buflen)
 	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 @@ v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
 		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();
include/net/9p/9p.h +5 -2
index 88884d3..cd693e3 100644
@@ -216,6 +216,7 @@ struct p9_tauth {
 	u32 afid;
 	struct p9_str uname;
 	struct p9_str aname;
+	u32 n_uname;		/* 9P2000.u extensions */
 };
 
 struct p9_rauth {

@@ -239,6 +240,7 @@ struct p9_tattach {
 	u32 afid;
 	struct p9_str uname;
 	struct p9_str aname;
+	u32 n_uname;		/* 9P2000.u extensions */
 };
 
 struct p9_rattach {

@@ -382,8 +384,9 @@ int p9_deserialize_fcall(void *buf, u32 buflen, struct p9_fcall *fc, int dotu);
 void p9_set_tag(struct p9_fcall *fc, u16 tag);
 struct p9_fcall *p9_create_tversion(u32 msize, char *version);
 struct p9_fcall *p9_create_tattach(u32 fid, u32 afid, char *uname,
-	char *aname);
-struct p9_fcall *p9_create_tauth(u32 afid, char *uname, char *aname);
+	char *aname, u32 n_uname, int dotu);
+struct p9_fcall *p9_create_tauth(u32 afid, char *uname, char *aname,
+	u32 n_uname, int dotu);
 struct p9_fcall *p9_create_tflush(u16 oldtag);
 struct p9_fcall *p9_create_twalk(u32 fid, u32 newfid, u16 nwname,
 	char **wnames);
include/net/9p/client.h +3 -2
index 0adafdb..9b9221a 100644
@@ -57,8 +57,9 @@ struct p9_client *p9_client_create(struct p9_trans *trans, int msize,
 void p9_client_destroy(struct p9_client *clnt);
 void p9_client_disconnect(struct p9_client *clnt);
 struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
-						     char *uname, char *aname);
-struct p9_fid *p9_client_auth(struct p9_client *clnt, char *uname, char *aname);
+					char *uname, u32 n_uname, char *aname);
+struct p9_fid *p9_client_auth(struct p9_client *clnt, char *uname,
+						u32 n_uname, char *aname);
 struct p9_fid *p9_client_walk(struct p9_fid *oldfid, int nwname, char **wnames,
 								int clone);
 int p9_client_open(struct p9_fid *fid, int mode);
net/9p/client.c +6 -4
index e161012..d83cc12 100644
@@ -146,7 +146,7 @@ void p9_client_disconnect(struct p9_client *clnt)
 EXPORT_SYMBOL(p9_client_disconnect);
 
 struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
-	char *uname, char *aname)
+	char *uname, u32 n_uname, char *aname)
 {
 	int err;
 	struct p9_fcall *tc, *rc;

@@ -165,7 +165,8 @@ struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
 		goto error;
 	}
 
-	tc = p9_create_tattach(fid->fid, afid?afid->fid:P9_NOFID, uname, aname);
+	tc = p9_create_tattach(fid->fid, afid?afid->fid:P9_NOFID, uname, aname,
+		n_uname, clnt->dotu);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;

@@ -190,7 +191,8 @@ error:
 }
 EXPORT_SYMBOL(p9_client_attach);
 
-struct p9_fid *p9_client_auth(struct p9_client *clnt, char *uname, char *aname)
+struct p9_fid *p9_client_auth(struct p9_client *clnt, char *uname,
+	u32 n_uname, char *aname)
 {
 	int err;
 	struct p9_fcall *tc, *rc;

@@ -209,7 +211,7 @@ struct p9_fid *p9_client_auth(struct p9_client *clnt, char *uname, char *aname)
 		goto error;
 	}
 
-	tc = p9_create_tauth(fid->fid, uname, aname);
+	tc = p9_create_tauth(fid->fid, uname, aname, n_uname, clnt->dotu);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
net/9p/conv.c +28 -4
index d979d95..aa2aa98 100644
@@ -547,7 +547,8 @@ error:
 }
 EXPORT_SYMBOL(p9_create_tversion);
 
-struct p9_fcall *p9_create_tauth(u32 afid, char *uname, char *aname)
+struct p9_fcall *p9_create_tauth(u32 afid, char *uname, char *aname,
+	u32 n_uname, int dotu)
 {
 	int size;
 	struct p9_fcall *fc;

@@ -555,7 +556,16 @@ struct p9_fcall *p9_create_tauth(u32 afid, char *uname, char *aname)
 	struct cbuf *bufp = &buffer;
 
 	/* afid[4] uname[s] aname[s] */
-	size = 4 + 2 + strlen(uname) + 2 + strlen(aname);
+	size = 4 + 2 + 2;
+	if (uname)
+		size += strlen(uname);
+
+	if (aname)
+		size += strlen(aname);
+
+	if (dotu)
+		size += 4;	/* n_uname */
+
 	fc = p9_create_common(bufp, size, P9_TAUTH);
 	if (IS_ERR(fc))
 		goto error;

@@ -563,6 +573,8 @@ struct p9_fcall *p9_create_tauth(u32 afid, char *uname, char *aname)
 	p9_put_int32(bufp, afid, &fc->params.tauth.afid);
 	p9_put_str(bufp, uname, &fc->params.tauth.uname);
 	p9_put_str(bufp, aname, &fc->params.tauth.aname);
+	if (dotu)
+		p9_put_int32(bufp, n_uname, &fc->params.tauth.n_uname);
 
 	if (buf_check_overflow(bufp)) {
 		kfree(fc);

@@ -574,7 +586,8 @@ error:
 EXPORT_SYMBOL(p9_create_tauth);
 
 struct p9_fcall *
-p9_create_tattach(u32 fid, u32 afid, char *uname, char *aname)
+p9_create_tattach(u32 fid, u32 afid, char *uname, char *aname,
+	u32 n_uname, int dotu)
 {
 	int size;
 	struct p9_fcall *fc;

@@ -582,7 +595,16 @@ p9_create_tattach(u32 fid, u32 afid, char *uname, char *aname)
 	struct cbuf *bufp = &buffer;
 
 	/* fid[4] afid[4] uname[s] aname[s] */
-	size = 4 + 4 + 2 + strlen(uname) + 2 + strlen(aname);
+	size = 4 + 4 + 2 + 2;
+	if (uname)
+		size += strlen(uname);
+
+	if (aname)
+		size += strlen(aname);
+
+	if (dotu)
+		size += 4;	/* n_uname */
+
 	fc = p9_create_common(bufp, size, P9_TATTACH);
 	if (IS_ERR(fc))
 		goto error;

@@ -591,6 +613,8 @@ p9_create_tattach(u32 fid, u32 afid, char *uname, char *aname)
 	p9_put_int32(bufp, afid, &fc->params.tattach.afid);
 	p9_put_str(bufp, uname, &fc->params.tattach.uname);
 	p9_put_str(bufp, aname, &fc->params.tattach.aname);
+	if (dotu)
+		p9_put_int32(bufp, n_uname, &fc->params.tattach.n_uname);
 
 error:
 	return fc;
#1 lore raw
Quoted 5 lines · Latchesar Ionkov

- 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.

While access=<uid> and dfltuid=<some-other-uid> creates an interesting flexibility in the way things can be used, I'm wondering if access=<uid> dfltuid=DEFAULT_UID is intuitive, it might be nice for the default behavior to be setting defltuid to the uid specified in access when that access option is used. This can be overridden with the dfltuid option, but I think it makes more sense to attach as the uid you are restricting access to.

If that's the way we want to go, I think that can be handled in a separate patch.

I've merged this stuff into my test tree, as soon as regressions pass and I confirm they compile clean on another architecture I'll push them into my devel to be picked up by -mm.

-eric