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Subject[RFC][PATCH 07/20] elevate mount count for extended attributes
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Date

This basically audits the callers of xattr_permission(), which
calls permission() and can perform writes to the filesystem.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---
lxc-dave/fs/nfsd/nfs4proc.c | 7 ++++++-
lxc-dave/fs/xattr.c | 14 ++++++++++++++
2 files changed, 20 insertions(+), 1 deletion(-)
diff -puN fs/nfsd/nfs4proc.c~C-xattr fs/nfsd/nfs4proc.c
--- lxc/fs/nfsd/nfs4proc.c~C-xattr 2006-06-16 15:58:03.000000000 -0700
+++ lxc-dave/fs/nfsd/nfs4proc.c 2006-06-16 15:58:03.000000000 -0700
@@ -604,13 +604,18 @@ nfsd4_setattr(struct svc_rqst *rqstp, st
return status;
}
}
+ status = mnt_want_write(current_fh->fh_export->ex_mnt);
+ if (status)
+ return status;
status = nfs_ok;
if (setattr->sa_acl != NULL)
status = nfsd4_set_nfs4_acl(rqstp, current_fh, setattr->sa_acl);
if (status)
- return status;
+ goto out;
status = nfsd_setattr(rqstp, current_fh, &setattr->sa_iattr,
0, (time_t)0);
+out:
+ mnt_drop_write(current_fh->fh_export->ex_mnt);
return status;
}

diff -puN fs/xattr.c~C-xattr fs/xattr.c
--- lxc/fs/xattr.c~C-xattr 2006-06-16 15:58:03.000000000 -0700
+++ lxc-dave/fs/xattr.c 2006-06-16 15:58:03.000000000 -0700
@@ -12,6 +12,7 @@
#include <linux/smp_lock.h>
#include <linux/file.h>
#include <linux/xattr.h>
+#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <linux/syscalls.h>
@@ -210,7 +211,11 @@ sys_setxattr(char __user *path, char __u
error = user_path_walk(path, &nd);
if (error)
return error;
+ error = mnt_want_write(nd.mnt);
+ if (error)
+ return error;
error = setxattr(nd.dentry, name, value, size, flags);
+ mnt_drop_write(nd.mnt);
path_release(&nd);
return error;
}
@@ -225,7 +230,11 @@ sys_lsetxattr(char __user *path, char __
error = user_path_walk_link(path, &nd);
if (error)
return error;
+ error = mnt_want_write(nd.mnt);
+ if (error)
+ return error;
error = setxattr(nd.dentry, name, value, size, flags);
+ mnt_drop_write(nd.mnt);
path_release(&nd);
return error;
}
@@ -241,9 +250,14 @@ sys_fsetxattr(int fd, char __user *name,
f = fget(fd);
if (!f)
return error;
+ error = mnt_want_write(f->f_vfsmnt);
+ if (error)
+ goto out_fput;
dentry = f->f_dentry;
audit_inode(NULL, dentry->d_inode, 0);
error = setxattr(dentry, name, value, size, flags);
+ mnt_drop_write(f->f_vfsmnt);
+out_fput:
fput(f);
return error;
}
_
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