Hello.
As the man page for utime/utimes states [1], EPERM is returned if the
second argument of utime/utimes is not NULL and:
* the caller's effective user id does not match the owner of the file
* the caller does not have write access to the file
* the caller is not privileged
However, I don't see this behavior with NFS, I see EACCES is generated
instead.
Please, consider this test:
#include <stdio.h>
#include <sys/types.h>
#include <sys/time.h>
#include <utime.h>
int main(int argc, char *argv[])
{
struct utimbuf u = { .actime = 0, .modtime = 0 };
struct timeval tv = { .tv_sec = 0, .tv_usec = 0 };
if (utime(argv[1], &u))
perror("utime() failed");
if (utimes(argv[1], &tv))
perror("utimes() failed");
return 0;
}
In my environment the kernel is 4.1.0-rc6 x86_64, and there are 2 NFS
mounted directories:
127.0.0.1:/opt/export/disk0 on /mnt/lin type nfs (rw,vers=3,addr=127.0.0.1)
192.168.0.12:/export/bla on /mnt/sol type nfs (rw,vers=3,addr=192.168.0.12)
/mnt/sol is from Solaris 11.2 x86_64. /opt/export/disk0 is handled by
the in-kernel nfs server.
Execution of the above test program gives:
* the server is Linux -> EACCES is generated:
[stas@ol6-x64 tmp]$ ls -l /mnt/lin/test_file
-rw-r--r-- 1 root root 0 Jun 1 17:28 /mnt/lin/test_file
[stas@ol6-x64 tmp]$ strace -e utime,utimes ./utime_test /mnt/lin/test_file
utime("/mnt/lin/test_file", [0, 0]) = -1 EACCES (Permission denied)
utime() failed: Permission denied
utimes("/mnt/lin/test_file", {{0, 0}, {0, 0}}) = -1 EACCES (Permission
denied)
utimes() failed: Permission denied
* the server is Solaris 11.2 -> EPERM is generated
[stas@ol6-x64 tmp]$ ls -l /mnt/sol/test_file
-rw-r--r--+ 1 root root 0 Jun 1 2015 /mnt/sol/test_file
[stas@ol6-x64 tmp]$ strace -e utime,utimes ./utime_test /mnt/sol/test_file
utime("/mnt/sol/test_file", [0, 0]) = -1 EPERM (Operation not permitted)
utime() failed: Operation not permitted
utimes("/mnt/sol/test_file", {{0, 0}, {0, 0}}) = -1 EPERM (Operation not
permitted)
utimes() failed: Operation not permitted
* on a local ext4 file system EPERM is generated:
[stas@ol6-x64 tmp]$ ls -l /tmp/test_file
-rw-r--r-- 1 root root 0 Jun 1 17:51 /tmp/test_file
[stas@ol6-x64 tmp]$ strace -e utime,utimes ./utime_test /tmp/test_file
utime("/tmp/test_file", [0, 0]) = -1 EPERM (Operation not permitted)
utime() failed: Operation not permitted
utimes("/tmp/test_file", {{0, 0}, {0, 0}}) = -1 EPERM (Operation not
permitted)
utimes() failed: Operation not permitted
Plus EPERM is generated when the NFS server is FreeBSD 9.1.
Could anybody, clarify, if the described behavior a bug in the Linux NFS
server implementation or not?
Thank you.
[1] http://man7.org/linux/man-pages/man2/utime.2.html
PS: this all was found using utime06, utimes01 LTP test cases.
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