[Bug 833300] [NEW] NFSv4 mount point does not allow binary files to run when permissions are set only to execute

[Leonardo Borda]

Public bug reported:

Affected releases:
- Lucid, Natty when running NFSv4

One cannot run binary files when permissions are set to ---x--x--x on
systems running NFSv4.

Expected behaviour:
- Allow binaries to run by just having --x (execute) permissions. This works when the mount point is created using NFSv3. According to the literature if it is a binary it makes an exec() call to the kernel therefore you don't need to have (read) permissions on the file.

PS: Scripts run as expected when they have the following r-x
permissions. Since scripts have to pass by an interpreter ( perl, bash )
they do need to have (read and exec) permissions.

Steps to reproduce

1. Install nfs
2. configure /etc/export
/data/nfs	*(rw,fsid=0,sync,no_subtree_check)
3. Mount using nfsv4
sudo mount -t nfs4 -o proto=tcp,port=2049 localhost:/ /mnt

4. cd /mnt
ls -la a.out script.sh 
---x--x--x 1 ubuntu ubuntu 8461 2011-08-24 17:59 a.out
---x--x--x 1 ubuntu ubuntu   27 2011-08-24 17:58 script.sh
5. running binary and script
ubuntu at ip-10-194-34-180:/mnt$ ./a.out 
-bash: ./a.out: Permission denied
ubuntu at ip-10-194-34-180:/mnt$ ./script.sh 
-bash: ./script.sh: Permission denied

ubuntu at ip-10-194-34-180:/mnt$ mount -v
/dev/sda1 on / type ext3 (rw)
proc on /proc type proc (rw,noexec,nosuid,nodev)
none on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
none on /dev type devtmpfs (rw,mode=0755)
none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
none on /dev/shm type tmpfs (rw,nosuid,nodev)
none on /var/run type tmpfs (rw,nosuid,mode=0755)
none on /var/lock type tmpfs (rw,noexec,nosuid,nodev)
none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
nfsd on /proc/fs/nfsd type nfsd (rw)
rpc_pipefs on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
localhost:/ on /mnt type nfs4 (rw,proto=tcp,port=2049,clientaddr=127.0.0.1,addr=127.0.0.1)


==
When running nfsv3
1. sudo mount -t nfs -o vers=3 localhost:/data/nfs /mnt

2. testing again
ubuntu at ip-10-194-34-180:/mnt$ ./a.out 
Hello Ubuntu!
ubuntu at ip-10-194-34-180:/mnt$ ./script.sh 
/bin/bash: ./script.sh: Permission denied
ubuntu at ip-10-194-34-180:/mnt$ 

ubuntu at ip-10-194-34-180:~$ mount -v
/dev/sda1 on / type ext3 (rw)
proc on /proc type proc (rw,noexec,nosuid,nodev)
none on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
none on /dev type devtmpfs (rw,mode=0755)
none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
none on /dev/shm type tmpfs (rw,nosuid,nodev)
none on /var/run type tmpfs (rw,nosuid,mode=0755)
none on /var/lock type tmpfs (rw,noexec,nosuid,nodev)
none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
nfsd on /proc/fs/nfsd type nfsd (rw)
rpc_pipefs on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
localhost:/data/nfs on /mnt type nfs (rw,vers=3,addr=127.0.0.1)

** Affects: nfs-utils (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/833300

Title:
  NFSv4 mount point does not allow binary files to run when permissions
  are set only to execute

Status in “nfs-utils” package in Ubuntu:
  New

Bug description:
  Affected releases:
  - Lucid, Natty when running NFSv4

  One cannot run binary files when permissions are set to ---x--x--x on
  systems running NFSv4.

  Expected behaviour:
  - Allow binaries to run by just having --x (execute) permissions. This works when the mount point is created using NFSv3. According to the literature if it is a binary it makes an exec() call to the kernel therefore you don't need to have (read) permissions on the file.

  PS: Scripts run as expected when they have the following r-x
  permissions. Since scripts have to pass by an interpreter ( perl, bash
  ) they do need to have (read and exec) permissions.

  Steps to reproduce

  1. Install nfs
  2. configure /etc/export
  /data/nfs	*(rw,fsid=0,sync,no_subtree_check)
  3. Mount using nfsv4
  sudo mount -t nfs4 -o proto=tcp,port=2049 localhost:/ /mnt

  4. cd /mnt
  ls -la a.out script.sh 
  ---x--x--x 1 ubuntu ubuntu 8461 2011-08-24 17:59 a.out
  ---x--x--x 1 ubuntu ubuntu   27 2011-08-24 17:58 script.sh
  5. running binary and script
  ubuntu at ip-10-194-34-180:/mnt$ ./a.out 
  -bash: ./a.out: Permission denied
  ubuntu at ip-10-194-34-180:/mnt$ ./script.sh 
  -bash: ./script.sh: Permission denied

  ubuntu at ip-10-194-34-180:/mnt$ mount -v
  /dev/sda1 on / type ext3 (rw)
  proc on /proc type proc (rw,noexec,nosuid,nodev)
  none on /sys type sysfs (rw,noexec,nosuid,nodev)
  none on /sys/kernel/debug type debugfs (rw)
  none on /sys/kernel/security type securityfs (rw)
  none on /dev type devtmpfs (rw,mode=0755)
  none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
  none on /dev/shm type tmpfs (rw,nosuid,nodev)
  none on /var/run type tmpfs (rw,nosuid,mode=0755)
  none on /var/lock type tmpfs (rw,noexec,nosuid,nodev)
  none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
  nfsd on /proc/fs/nfsd type nfsd (rw)
  rpc_pipefs on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
  localhost:/ on /mnt type nfs4 (rw,proto=tcp,port=2049,clientaddr=127.0.0.1,addr=127.0.0.1)


  ==
  When running nfsv3
  1. sudo mount -t nfs -o vers=3 localhost:/data/nfs /mnt

  2. testing again
  ubuntu at ip-10-194-34-180:/mnt$ ./a.out 
  Hello Ubuntu!
  ubuntu at ip-10-194-34-180:/mnt$ ./script.sh 
  /bin/bash: ./script.sh: Permission denied
  ubuntu at ip-10-194-34-180:/mnt$ 

  ubuntu at ip-10-194-34-180:~$ mount -v
  /dev/sda1 on / type ext3 (rw)
  proc on /proc type proc (rw,noexec,nosuid,nodev)
  none on /sys type sysfs (rw,noexec,nosuid,nodev)
  none on /sys/kernel/debug type debugfs (rw)
  none on /sys/kernel/security type securityfs (rw)
  none on /dev type devtmpfs (rw,mode=0755)
  none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
  none on /dev/shm type tmpfs (rw,nosuid,nodev)
  none on /var/run type tmpfs (rw,nosuid,mode=0755)
  none on /var/lock type tmpfs (rw,noexec,nosuid,nodev)
  none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
  nfsd on /proc/fs/nfsd type nfsd (rw)
  rpc_pipefs on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
  localhost:/data/nfs on /mnt type nfs (rw,vers=3,addr=127.0.0.1)

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