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vfs: replace calling i_op->readlink with vfs_readlink()

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Also check d_is_symlink() in callers instead of inode->i_op->readlink
because following patches will allow NULL ->readlink for symlinks.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2016-12-09 16:45:04 +01:00
parent 2a07a1f5ab
commit fd4a0edf2a
6 changed files with 35 additions and 13 deletions
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21
fs/namei.c
View File

@ -4668,6 +4668,27 @@ int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
}
EXPORT_SYMBOL(generic_readlink);
/**
* vfs_readlink - copy symlink body into userspace buffer
* @dentry: dentry on which to get symbolic link
* @buffer: user memory pointer
* @buflen: size of buffer
*
* Does not touch atime. That's up to the caller if necessary
*
* Does not call security hook.
*/
int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
struct inode *inode = d_inode(dentry);
if (!inode->i_op->readlink)
return -EINVAL;
return inode->i_op->readlink(dentry, buffer, buflen);
}
EXPORT_SYMBOL(vfs_readlink);
/**
* vfs_get_link - get symlink body
* @dentry: dentry on which to get symbolic link

8
fs/nfsd/nfs4xdr.c
View File

@ -3576,10 +3576,10 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
if (!p)
return nfserr_resource;
/*
* XXX: By default, the ->readlink() VFS op will truncate symlinks
* if they would overflow the buffer. Is this kosher in NFSv4? If
* not, one easy fix is: if ->readlink() precisely fills the buffer,
* assume that truncation occurred, and return NFS4ERR_RESOURCE.
* XXX: By default, vfs_readlink() will truncate symlinks if they
* would overflow the buffer. Is this kosher in NFSv4? If not, one
* easy fix is: if vfs_readlink() precisely fills the buffer, assume
* that truncation occurred, and return NFS4ERR_RESOURCE.
*/
nfserr = nfsd_readlink(readlink->rl_rqstp, readlink->rl_fhp,
(char *)p, &maxcount);

6
fs/nfsd/vfs.c
View File

@ -1451,7 +1451,6 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
__be32
nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
{
struct inode *inode;
mm_segment_t oldfs;
__be32 err;
int host_err;
@ -1463,10 +1462,9 @@ nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
path.mnt = fhp->fh_export->ex_path.mnt;
path.dentry = fhp->fh_dentry;
inode = d_inode(path.dentry);
err = nfserr_inval;
if (!inode->i_op->readlink)
if (!d_is_symlink(path.dentry))
goto out;
touch_atime(&path);
@ -1475,7 +1473,7 @@ nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
*/
oldfs = get_fs(); set_fs(KERNEL_DS);
host_err = inode->i_op->readlink(path.dentry, (char __user *)buf, *lenp);
host_err = vfs_readlink(path.dentry, (char __user *)buf, *lenp);
set_fs(oldfs);
if (host_err < 0)

8
fs/stat.c
View File

@ -329,12 +329,14 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
struct inode *inode = d_backing_inode(path.dentry);
error = empty ? -ENOENT : -EINVAL;
if (inode->i_op->readlink) {
/*
* AFS mountpoints allow readlink(2) but are not symlinks
*/
if (d_is_symlink(path.dentry) || inode->i_op->readlink) {
error = security_inode_readlink(path.dentry);
if (!error) {
touch_atime(&path);
error = inode->i_op->readlink(path.dentry,
buf, bufsiz);
error = vfs_readlink(path.dentry, buf, bufsiz);
}
}
path_put(&path);

4
fs/xfs/xfs_ioctl.c
View File

@ -287,7 +287,7 @@ xfs_readlink_by_handle(
return PTR_ERR(dentry);
/* Restrict this handle operation to symlinks only. */
if (!d_inode(dentry)->i_op->readlink) {
if (!d_is_symlink(dentry)) {
error = -EINVAL;
goto out_dput;
}
@ -297,7 +297,7 @@ xfs_readlink_by_handle(
goto out_dput;
}
error = d_inode(dentry)->i_op->readlink(dentry, hreq->ohandle, olen);
error = vfs_readlink(dentry, hreq->ohandle, olen);
out_dput:
dput(dentry);

1
include/linux/fs.h
View File

@ -2935,6 +2935,7 @@ extern int vfs_lstat(const char __user *, struct kstat *);
extern int vfs_fstat(unsigned int, struct kstat *);
extern int vfs_fstatat(int , const char __user *, struct kstat *, int);
extern const char *vfs_get_link(struct dentry *, struct delayed_call *);
extern int vfs_readlink(struct dentry *, char __user *, int);
extern int __generic_block_fiemap(struct inode *inode,
struct fiemap_extent_info *fieinfo,