Hi,
I am new to Linux kernel programming. i am trying to print current working
directory of process which are running under containers.
i have written code in kernel as below to get pwd
*********************************************************************
struct path pwd;
char *buf,*cwd;
uid_t process_uid = (current->cred)->uid.val;
pwd = current->fs->pwd;
path_get(&pwd);//it gets the reference to path. which is argument to
d_path
if((buf = (char *)kmalloc(100*sizeof(char),GFP_KERNEL))!=NULL)
{ //GFP_KERNEL is a flag specifies the behavior of the memory
allocator
cwd = d_path(&pwd,buf,100*sizeof(char)); // returns pointer to
buffer
printk("process name %s (pid = %d)pwd= %s and (uid=%u)\n",current->comm,
current->pid,cwd,process_uid);
}
//printk("check pwd\n");
kfree(buf);
**************************************************************************
it is printing pwd correctly in host machine. but unable to start docker
containers
root@sangeetha:/var/lib/docker# docker start 58e9277a7e8c
Error response from daemon: Cannot start container 58e9277a7e8c: [8] System
error: failed to add interface vethebc8876 to sandbox: failed in prefunc:
failed to set namespace on link "vethebc8876": invalid argument
Error: failed to start containers: [58e9277a7e8c]
if i comment d_path line, then i am able to start containers.can you please
help to understand the problem and how to resolve it?
docker version:
Client:
Version: 1.9.1
API version: 1.21
Go version: go1.4.2
Git commit: a34a1d5
Built: Fri Nov 20 13:12:04 UTC 2015
OS/Arch: linux/amd64
Server:
Version: 1.9.1
API version: 1.21
Go version: go1.4.2
Git commit: a34a1d5
Built: Fri Nov 20 13:12:04 UTC 2015
OS/Arch: linux/amd64
*******************************************
uname -a
Linux sangeetha 3.14.57 #56 SMP Wed Jan 6 09:37:22 IST 2016 x86_64 x86_64
x86_64 GNU/Linux
**************************************************8
in logs
process name docker (pid = 3754)pwd= /var/lib/docker and (uid=0)
[ 1743.097731] docker0: port 1(vethcf36114) entered forwarding state
[ 1743.097744] docker0: port 1(vethcf36114) entered forwarding state
[ 1743.100084] docker0: port 1(vethcf36114) entered disabled state
[ 1743.271360] process name docker (pid = 1667)pwd= / and (uid=0)
[ 1743.276427] process name docker (pid = 1507)pwd= / and (uid=0)
[ 1743.496652] docker0: port 1(vethcf36114) entered disabled state
[ 1743.497330] docker0: port 1(vethcf36114) entered disabled state
[ 1799.635904] process name bash (pid = 2894)pwd= /var/lib/docker and
(uid=0)
[ 2543.229052] process name bash (pid = 2894)pwd= /var/lib/docker and
(uid=0)
**************************************************************************
devicemapper fs is used for containers. ubuntu 14.04 os
Thanks in advance.
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