rpc.mountd: Turn off root_squash on pseudo roots, its not needed.

PATCH In review Steve Dickson 2 participants 2 messages Jun 2, 2010 – Jun 9, 2010 1 message not in the archive

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Steve Dickson

author

2010-06-02 21:14 UTC #0 lore raw

PATCH 1/1 rpc.mountd: Turn off root_squash on pseudo roots, its not needed.

Hello,

It turns out the setting of NFSEXP_ROOTSQUASH option on pseudo roots breaks v4 exports when the no_root_squash is set on the 'real' export. For example,

The export:

/home/user/dir *(rw,no_root_squash)

the /home/user directory has the 0700 permission modes

Now from an v4 enabled client do the following mount will fail with permission denied.
mount server:/home/user/dir /mnt

The reason being, the 'no_root_squash' option is only being applied to the 'dir' part of the path. So then root tries to lookup the 'user' part, its denied.

Now turns out the NFSEXP_ROOTSQUASH option is not need to be set on pseudo roots because one, they are marked as read only and two only the export part of the path are exposed if by chance the actual pseudo root is mounted. For example:

    # mount server:/ /mnt
    # ls /mnt
     ./  ../  home/
    # ls /mnt/home
    ./  ../  user/

only the above directories would be shown and they would be read-only

steved.

Currently the default setting of a pseudo root is to have NFSEXP_ROOTSQUASH enabled. This setting will cause the looking up of real export to fail when have the no_root_squash set.

It turns the setting of NFSEXP_ROOTSQUASH is not needed on pseudo roots for two reasons. 1) pseudo roots are marked as read-only so they can not be written on. 2) pseudo roots only show exported entries when they are mounted.

Signed-off-by Steve Dickson <[email protected]>

---
 utils/mountd/v4root.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

utils/mountd/v4root.c +2 -3

index 7fd6af3..41b77eb 100644
@@ -35,9 +35,8 @@ static nfs_export pseudo_root = {
 	.m_export = {
 		.e_hostname = "*",
 		.e_path = "/",
-		.e_flags = NFSEXP_READONLY | NFSEXP_ROOTSQUASH
-				| NFSEXP_NOSUBTREECHECK | NFSEXP_FSID
-				| NFSEXP_V4ROOT,
+		.e_flags = NFSEXP_READONLY | NFSEXP_NOSUBTREECHECK | 
+				NFSEXP_FSID | NFSEXP_V4ROOT,
 		.e_anonuid = 65534,
 		.e_anongid = 65534,
 		.e_squids = NULL,

J. Bruce Fields

Acked-by

2010-06-09 00:31 UTC #2 lore raw

In reply to a message not in the archive

Quoted 5 lines · Steve Dickson

Hello,
It turns out the setting of NFSEXP_ROOTSQUASH option on pseudo roots breaks v4 exports when the no_root_squash is set on the 'real' export. For example,

I remember thinking about this sort of case as we were working on this, but can't remember why I left ROOTSQUASH set. I think it may just have been paranoia, combined with skepticism that anyone would want to nfs-export a filesystem that could only be looked up by root.

Apparently someone is? I'd still be curious why. But I think your patch is right; for what it's worth:

Acked-by J. Bruce Fields <[email protected]>

--b.

Quoted 68 lines

The export:
/home/user/dir *(rw,no_root_squash)
the /home/user directory has the 0700 permission modes
Now from an v4 enabled client do the following mount will fail with permission denied.
mount server:/home/user/dir /mnt
The reason being, the 'no_root_squash' option is only being applied to the 'dir' part of the path. So then root tries to lookup the 'user' part, its denied.
Now turns out the NFSEXP_ROOTSQUASH option is not need to be set on pseudo roots because one, they are marked as read only and two only the export part of the path are exposed if by chance the actual pseudo root is mounted. For example:
    # mount server:/ /mnt
    # ls /mnt
     ./  ../  home/
    # ls /mnt/home
    ./  ../  user/
only the above directories would be shown and they would be read-only
steved.
Currently the default setting of a pseudo root is to have NFSEXP_ROOTSQUASH enabled. This setting will cause the looking up of real export to fail when have the no_root_squash set.
It turns the setting of NFSEXP_ROOTSQUASH is not needed on pseudo roots for two reasons. 1) pseudo roots are marked as read-only so they can not be written on. 2) pseudo roots only show exported entries when they are mounted.
Signed-off-by Steve Dickson <[email protected]>
---
 utils/mountd/v4root.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)
utils/mountd/v4root.c +2 -4
index 7fd6af3..41b77eb 100644
@@ -35,9 +35,8 @@ static nfs_export pseudo_root = {
 	.m_export = {
 		.e_hostname = "*",
 		.e_path = "/",
-		.e_flags = NFSEXP_READONLY | NFSEXP_ROOTSQUASH
-				| NFSEXP_NOSUBTREECHECK | NFSEXP_FSID
-				| NFSEXP_V4ROOT,
+		.e_flags = NFSEXP_READONLY | NFSEXP_NOSUBTREECHECK | 
+				NFSEXP_FSID | NFSEXP_V4ROOT,
 		.e_anonuid = 65534,
 		.e_anongid = 65534,
 		.e_squids = NULL,
 
 
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