On Mon, Jul 11, 2016 at 07:40:11PM +0200, Thomas Gambier wrote:
> Hello,
>
> I just discovered a problem with NFSv4 file system. I was using TCL
> scripts that were doing some file manipulation (mkdir, copy, ...) on
> my NFSv4 file system and sometimes the scripts failed with "permission
> denied" error.
>
> I ran strace and I found that the system call returning the error was:
> open("d1/in.txt", O_WRONLY|O_CREAT|O_TRUNC, 0100444) = -1 EACCES
> (Permission denied)
Is that even allowed? The open(2) man page says posix leaves behavior
in that case unspecified, and doesn't say anything I can find about
Linux behavior in this case.
I guess it would be nicer for client or server to do something
predictable, though. First steps might be to confirm what happens other
filesystems, then do a network trace (watch the traffic in wireshark) to
see if it's the client rejecting this open, or the client passing
through that bit in the mode and the server returning the error.
--b.
>
> And indeed the error was happening only when TCL wanted to copy files
> where permission were 444 (user don't have write permission).
>
> You can reproduce the error with the small C code attached. I tested
> with a fresh install of xubuntu 16.04 for both NFS client and NFS
> server and it fails. You can find all the logs and the version info
> attached.
>
> It seems that the error is not happening when we are using mode = 444
> instead of mode = 0100444 (no S_IFREG flag).
>
> It seems a bug in NFS to me since it doesn't happen in NFSv3, and the
> error is random with NFSv4. Also I found that the error doesn't happen
> at all with NFSv4 if both server and client are on Ubuntu 14.04.
>
> Let me know if you need more information. Also let me know if I should
> open a bug on kernel bugzilla.
>
> Thank you.
>
> Regards.
>
> Thomas.
> sigma@VM-tomo:~$ uname -a
> Linux VM-tomo 4.4.0-21-generic #37-Ubuntu SMP Mon Apr 18 18:33:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
>
>
> sigma@VM-tomo:~$ sudo mount testNFS:/export /mnt
>
>
> sigma@VM-tomo:~$ mount
> sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
> proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
> udev on /dev type devtmpfs (rw,nosuid,relatime,size=230708k,nr_inodes=57677,mode=755)
> devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
> tmpfs on /run type tmpfs (rw,nosuid,noexec,relatime,size=50028k,mode=755)
> /dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
> securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
> tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
> tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
> tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
> cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd,nsroot=/)
> pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
> cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct,nsroot=/)
> cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event,nsroot=/)
> cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset,nsroot=/)
> cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer,nsroot=/)
> cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio,nsroot=/)
> cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids,nsroot=/)
> cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices,nsroot=/)
> cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory,nsroot=/)
> cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb,nsroot=/)
> cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio,nsroot=/)
> systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=24,pgrp=1,timeout=0,minproto=5,maxproto=5,direct)
> debugfs on /sys/kernel/debug type debugfs (rw,relatime)
> mqueue on /dev/mqueue type mqueue (rw,relatime)
> hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime)
> fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime)
> tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,size=50028k,mode=700,uid=1000,gid=1000)
> gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=1000)
> testNFS:/export on /mnt type nfs4 (rw,relatime,vers=4.0,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=172.27.64.79,local_lock=none,addr=172.27.64.74)
>
>
> sigma@VM-tomo:~$ gcc create.c -o create
> sigma@VM-tomo:~$ cd /mnt
> sigma@VM-tomo:/mnt$ strace -v ~/create
> execve("/home/sigma/create", ["/home/sigma/create"], ["XDG_VTNR=7", "LC_PAPER=fr_FR.UTF-8", "LC_ADDRESS=fr_FR.UTF-8", "XDG_SESSION_ID=c1", "XDG_GREETER_DATA_DIR=/var/lib/li"..., "LC_MONETARY=fr_FR.UTF-8", "CLUTTER_IM_MODULE=", "QT_STYLE_OVERRIDE=gtk", "SESSION=xubuntu", "GLADE_PIXMAP_PATH=:", "XDG_MENU_PREFIX=xfce-", "SHELL=/bin/bash", "TERM=xterm", "QT_LINUX_ACCESSIBILITY_ALWAYS_ON"..., "WINDOWID=52428804", "LC_NUMERIC=fr_FR.UTF-8", "OLDPWD=/home/sigma", "UPSTART_SESSION=unix:abstract=/c"..., "GNOME_KEYRING_CONTROL=", "USER=sigma", "LS_COLORS=rs=0:di=01;34:ln=01;36"..., "LC_TELEPHONE=fr_FR.UTF-8", "CLUTTER_BACKEND=x11", "QT_ACCESSIBILITY=1", "XDG_SESSION_PATH=/org/freedeskto"..., "GLADE_MODULE_PATH=:", "XDG_SEAT_PATH=/org/freedesktop/D"..., "SSH_AUTH_SOCK=/run/user/1000/key"..., "DEFAULTS_PATH=/usr/share/gconf/x"..., "SESSION_MANAGER=local/VM-tomo:@/"..., "XDG_CONFIG_DIRS=/etc/xdg/xdg-xub"..., "DESKTOP_SESSION=xubuntu", "PATH=/usr/local/sbin:/usr/local/"..., "QT_IM_MODULE=", "LC_IDENTIFICATION=fr_FR.UTF-8", "XDG_SESSION_TYPE=x11", "PWD=/mnt", "JOB=dbus", "XMODIFIERS=", "GNOME_KEYRING_PID=", "LANG=en_US.UTF-8", "GDM_LANG=en_US", "MANDATORY_PATH=/usr/share/gconf/"..., "LC_MEASUREMENT=fr_FR.UTF-8", "IM_CONFIG_PHASE=1", "GDMSESSION=xubuntu", "SESSIONTYPE=", "SHLVL=1", "HOME=/home/sigma", "XDG_SEAT=seat0", "LANGUAGE=en_US", "UPSTART_INSTANCE=", "GTK_OVERLAY_SCROLLING=0", "UPSTART_EVENTS=started xsession", "XDG_SESSION_DESKTOP=xubuntu", "LOGNAME=sigma", "DBUS_SESSION_BUS_ADDRESS=unix:ab"..., "XDG_DATA_DIRS=/usr/share/xubuntu"..., "QT4_IM_MODULE=", "LESSOPEN=| /usr/bin/lesspipe %s", "INSTANCE=", "UPSTART_JOB=startxfce4", "XDG_RUNTIME_DIR=/run/user/1000", "DISPLAY=:0.0", "GLADE_CATALOG_PATH=:", "XDG_CURRENT_DESKTOP=XFCE", "GTK_IM_MODULE=", "LESSCLOSE=/usr/bin/lesspipe %s %"..., "LC_TIME=fr_FR.UTF-8", "LC_NAME=fr_FR.UTF-8", "XAUTHORITY=/home/sigma/.Xauthori"..., "COLORTERM=xfce4-terminal", "_=/usr/bin/strace"]) = 0
> brk(NULL) = 0x8c7000
> access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
> mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff533ae6000
> access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
> open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
> fstat(3, {st_dev=makedev(8, 1), st_ino=273511, st_mode=S_IFREG|0644, st_nlink=1, st_uid=0, st_gid=0, st_blksize=4096, st_blocks=152, st_size=75920, st_atime=2016/07/11-19:24:38.838829302, st_mtime=2016/07/11-19:24:38.734829064, st_ctime=2016/07/11-19:24:38.734829064}) = 0
> mmap(NULL, 75920, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7ff533ad3000
> close(3) = 0
> access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
> open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
> read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\t\2\0\0\0\0\0"..., 832) = 832
> fstat(3, {st_dev=makedev(8, 1), st_ino=3412686, st_mode=S_IFREG|0755, st_nlink=1, st_uid=0, st_gid=0, st_blksize=4096, st_blocks=3648, st_size=1864888, st_atime=2016/07/11-18:13:54.616900188, st_mtime=2016/04/15-00:16:46, st_ctime=2016/07/11-18:07:12.442702138}) = 0
> mmap(NULL, 3967488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7ff5334fa000
> mprotect(0x7ff5336ba000, 2093056, PROT_NONE) = 0
> mmap(0x7ff5338b9000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1bf000) = 0x7ff5338b9000
> mmap(0x7ff5338bf000, 14848, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7ff5338bf000
> close(3) = 0
> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff533ad2000
> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff533ad1000
> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff533ad0000
> arch_prctl(ARCH_SET_FS, 0x7ff533ad1700) = 0
> mprotect(0x7ff5338b9000, 16384, PROT_READ) = 0
> mprotect(0x600000, 4096, PROT_READ) = 0
> mprotect(0x7ff533ae8000, 4096, PROT_READ) = 0
> munmap(0x7ff533ad3000, 75920) = 0
> open("testfile0.txt", O_WRONLY|O_CREAT|O_TRUNC, 0100444) = 3
> open("testfile1.txt", O_WRONLY|O_CREAT|O_TRUNC, 0100444) = 4
> open("testfile2.txt", O_WRONLY|O_CREAT|O_TRUNC, 0100444) = -1 EACCES (Permission denied)
> dup(2) = 5
> fcntl(5, F_GETFL) = 0x8002 (flags O_RDWR|O_LARGEFILE)
> brk(NULL) = 0x8c7000
> brk(0x8e8000) = 0x8e8000
> fstat(5, {st_dev=makedev(0, 14), st_ino=7, st_mode=S_IFCHR|0620, st_nlink=1, st_uid=1000, st_gid=5, st_blksize=1024, st_blocks=0, st_rdev=makedev(136, 4), st_atime=2016/07/11-19:31:12.028895038, st_mtime=2016/07/11-19:31:12.028895038, st_ctime=2016/07/11-18:35:39.028895038}) = 0
> write(5, "Open failed\n", 12Open failed
> ) = 12
> write(5, ": Permission denied\n", 20: Permission denied
> ) = 20
> close(5) = 0
> write(2, "Error creating testfile2.txt\n", 29Error creating testfile2.txt
> ) = 29
> exit_group(1) = ?
> +++ exited with 1 +++
>
> #include <unistd.h>
> #include <fcntl.h>
> #include <stdio.h>
>
>
> int main()
> {
> int filedesc, i;
> char filename[100];
>
> for (i=0; i<1000; i++)
> {
> sprintf(filename, "testfile%d.txt", i);
>
> filedesc = open(filename, O_WRONLY|O_CREAT|O_TRUNC, 0100444);
> if(filedesc < 0)
> {
> perror("Open failed\n");
> fprintf(stderr, "Error creating %s\n", filename);
> return 1;
> }
> }
>
> return 0;
> }
>
> sigma@testNFS:~$ uname -a
> Linux testNFS 4.4.0-21-generic #37-Ubuntu SMP Mon Apr 18 18:33:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
>
>
> sigma@testNFS:~$ apt-cache policy nfs-common
> nfs-common:
> Installed: 1:1.2.8-9ubuntu12
> Candidate: 1:1.2.8-9ubuntu12
> Version table:
> *** 1:1.2.8-9ubuntu12 500
> 500 http://fr.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
> 100 /var/lib/dpkg/status
>
>
> sigma@testNFS:~$ apt-cache policy nfs-kernel-server
> nfs-kernel-server:
> Installed: 1:1.2.8-9ubuntu12
> Candidate: 1:1.2.8-9ubuntu12
> Version table:
> *** 1:1.2.8-9ubuntu12 500
> 500 http://fr.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
> 100 /var/lib/dpkg/status
>
>
> sigma@testNFS:~$ cat /etc/exports
> # /etc/exports: the access control list for filesystems which may be exported
> # to NFS clients. See exports(5).
> #
> # Example for NFSv2 and NFSv3:
> # /srv/homes hostname1(rw,sync,no_subtree_check) hostname2(ro,sync,no_subtree_check)
> #
> # Example for NFSv4:
> # /srv/nfs4 gss/krb5i(rw,sync,fsid=0,crossmnt,no_subtree_check)
> # /srv/nfs4/homes gss/krb5i(rw,sync,no_subtree_check)
> #
>
> /export 172.27.0.0/255.255.0.0(rw,fsid=1,async,insecure,no_subtree_check)
>
>
> sigma@testNFS:~$ ls -al /export
> total 12
> drwxrwxrwx 3 root root 4096 juil. 11 18:58 .
> drwxr-xr-x 25 root root 4096 juil. 11 18:55 ..
>
>
> sigma@testNFS:~$ sudo exportfs -v
> [sudo] password for sigma:
> /export 172.27.0.0/255.255.0.0(rw,async,wdelay,insecure,root_squash,no_subtree_check,fsid=1,sec=sys,rw,root_squash,no_all_squash)
>
>
>
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