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[PATCH] r/o bind mounts: elevate write count for xattr_permission() callers

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

[AV: add missing parts - removexattr() and nfsd posix acls, plug for a leak
spotted by Miklos]

Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Dave Hansen 2008-02-15 14:37:38 -08:00 committed by Al Viro
parent 9079b1eb17
commit 18f335aff8
3 changed files with 42 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
fs/nfsd/nfs4proc.c
View file

@ -658,14 +658,19 @@ nfsd4_setattr(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
return status;
}
}
status = mnt_want_write(cstate->current_fh.fh_export->ex_path.mnt);
if (status)
return status;
status = nfs_ok;
if (setattr->sa_acl != NULL)
status = nfsd4_set_nfs4_acl(rqstp, &cstate->current_fh,
setattr->sa_acl);
if (status)
return status;
goto out;
status = nfsd_setattr(rqstp, &cstate->current_fh, &setattr->sa_iattr,
0, (time_t)0);
out:
mnt_drop_write(cstate->current_fh.fh_export->ex_path.mnt);
return status;
}

4
fs/nfsd/vfs.c
View file

@ -2086,6 +2086,9 @@ nfsd_set_posix_acl(struct svc_fh *fhp, int type, struct posix_acl *acl)
} else
size = 0;
error = mnt_want_write(fhp->fh_export->ex_path.mnt);
if (error)
goto getout;
if (size)
error = vfs_setxattr(fhp->fh_dentry, name, value, size, 0);
else {
@ -2097,6 +2100,7 @@ nfsd_set_posix_acl(struct svc_fh *fhp, int type, struct posix_acl *acl)
error = 0;
}
}
mnt_drop_write(fhp->fh_export->ex_path.mnt);
getout:
kfree(value);

40
fs/xattr.c
View file

@ -11,6 +11,7 @@
#include <linux/slab.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>
@ -32,8 +33,6 @@ xattr_permission(struct inode *inode, const char *name, int mask)
* filesystem or on an immutable / append-only inode.
*/
if (mask & MAY_WRITE) {
if (IS_RDONLY(inode))
return -EROFS;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
return -EPERM;
}
@ -262,7 +261,11 @@ sys_setxattr(char __user *path, char __user *name, void __user *value,
error = user_path_walk(path, &nd);
if (error)
return error;
error = setxattr(nd.path.dentry, name, value, size, flags);
error = mnt_want_write(nd.path.mnt);
if (!error) {
error = setxattr(nd.path.dentry, name, value, size, flags);
mnt_drop_write(nd.path.mnt);
}
path_put(&nd.path);
return error;
}
@ -277,7 +280,11 @@ sys_lsetxattr(char __user *path, char __user *name, void __user *value,
error = user_path_walk_link(path, &nd);
if (error)
return error;
error = setxattr(nd.path.dentry, name, value, size, flags);
error = mnt_want_write(nd.path.mnt);
if (!error) {
error = setxattr(nd.path.dentry, name, value, size, flags);
mnt_drop_write(nd.path.mnt);
}
path_put(&nd.path);
return error;
}
@ -295,7 +302,12 @@ sys_fsetxattr(int fd, char __user *name, void __user *value,
return error;
dentry = f->f_path.dentry;
audit_inode(NULL, dentry);
error = setxattr(dentry, name, value, size, flags);
error = mnt_want_write(f->f_path.mnt);
if (!error) {
error = setxattr(dentry, name, value, size, flags);
mnt_drop_write(f->f_path.mnt);
}
out_fput:
fput(f);
return error;
}
@ -482,7 +494,11 @@ sys_removexattr(char __user *path, char __user *name)
error = user_path_walk(path, &nd);
if (error)
return error;
error = removexattr(nd.path.dentry, name);
error = mnt_want_write(nd.path.mnt);
if (!error) {
error = removexattr(nd.path.dentry, name);
mnt_drop_write(nd.path.mnt);
}
path_put(&nd.path);
return error;
}
@ -496,7 +512,11 @@ sys_lremovexattr(char __user *path, char __user *name)
error = user_path_walk_link(path, &nd);
if (error)
return error;
error = removexattr(nd.path.dentry, name);
error = mnt_want_write(nd.path.mnt);
if (!error) {
error = removexattr(nd.path.dentry, name);
mnt_drop_write(nd.path.mnt);
}
path_put(&nd.path);
return error;
}
@ -513,7 +533,11 @@ sys_fremovexattr(int fd, char __user *name)
return error;
dentry = f->f_path.dentry;
audit_inode(NULL, dentry);
error = removexattr(dentry, name);
error = mnt_want_write(f->f_path.mnt);
if (!error) {
error = removexattr(dentry, name);
mnt_drop_write(f->f_path.mnt);
}
fput(f);
return error;
}