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new helper: readlink_copy()

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2014-03-14 13:42:45 -04:00
parent 4efcc9ffcd
commit 5d826c847b
5 changed files with 12 additions and 47 deletions
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13
fs/namei.c
View File

@ -4297,11 +4297,9 @@ SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newna
return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
}
int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
int readlink_copy(char __user *buffer, int buflen, const char *link)
{
int len;
len = PTR_ERR(link);
int len = PTR_ERR(link);
if (IS_ERR(link))
goto out;
@ -4313,7 +4311,7 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const c
out:
return len;
}
EXPORT_SYMBOL(vfs_readlink);
EXPORT_SYMBOL(readlink_copy);
/*
* A helper for ->readlink(). This should be used *ONLY* for symlinks that
@ -4331,7 +4329,7 @@ int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
if (IS_ERR(cookie))
return PTR_ERR(cookie);
res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
res = readlink_copy(buffer, buflen, nd_get_link(&nd));
if (dentry->d_inode->i_op->put_link)
dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
return res;
@ -4356,8 +4354,7 @@ static char *page_getlink(struct dentry * dentry, struct page **ppage)
int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
struct page *page = NULL;
char *s = page_getlink(dentry, &page);
int res = vfs_readlink(dentry,buffer,buflen,s);
int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page));
if (page) {
kunmap(page);
page_cache_release(page);

14
fs/proc/namespaces.c
View File

@ -146,7 +146,7 @@ static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int bufl
struct task_struct *task;
void *ns;
char name[50];
int len = -EACCES;
int res = -EACCES;
task = get_proc_task(inode);
if (!task)
@ -155,24 +155,18 @@ static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int bufl
if (!ptrace_may_access(task, PTRACE_MODE_READ))
goto out_put_task;
len = -ENOENT;
res = -ENOENT;
ns = ns_ops->get(task);
if (!ns)
goto out_put_task;
snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns_ops->inum(ns));
len = strlen(name);
if (len > buflen)
len = buflen;
if (copy_to_user(buffer, name, len))
len = -EFAULT;
res = readlink_copy(buffer, buflen, name);
ns_ops->put(ns);
out_put_task:
put_task_struct(task);
out:
return len;
return res;
}
static const struct inode_operations proc_ns_link_inode_operations = {

2
fs/proc/self.c
View File

@ -16,7 +16,7 @@ static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
if (!tgid)
return -ENOENT;
sprintf(tmp, "%d", tgid);
return vfs_readlink(dentry,buffer,buflen,tmp);
return readlink_copy(buffer, buflen, tmp);
}
static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)

28
fs/xfs/xfs_ioctl.c
View File

@ -271,32 +271,6 @@ xfs_open_by_handle(
return error;
}
/*
* This is a copy from fs/namei.c:vfs_readlink(), except for removing it's
* unused first argument.
*/
STATIC int
do_readlink(
char __user *buffer,
int buflen,
const char *link)
{
int len;
len = PTR_ERR(link);
if (IS_ERR(link))
goto out;
len = strlen(link);
if (len > (unsigned) buflen)
len = buflen;
if (copy_to_user(buffer, link, len))
len = -EFAULT;
out:
return len;
}
int
xfs_readlink_by_handle(
struct file *parfilp,
@ -334,7 +308,7 @@ xfs_readlink_by_handle(
error = -xfs_readlink(XFS_I(dentry->d_inode), link);
if (error)
goto out_kfree;
error = do_readlink(hreq->ohandle, olen, link);
error = readlink_copy(hreq->ohandle, olen, link);
if (error)
goto out_kfree;

2
include/linux/fs.h
View File

@ -2517,7 +2517,7 @@ extern const struct file_operations generic_ro_fops;
#define special_file(m) (S_ISCHR(m)||S_ISBLK(m)||S_ISFIFO(m)||S_ISSOCK(m))
extern int vfs_readlink(struct dentry *, char __user *, int, const char *);
extern int readlink_copy(char __user *, int, const char *);
extern int page_readlink(struct dentry *, char __user *, int);
extern void *page_follow_link_light(struct dentry *, struct nameidata *);
extern void page_put_link(struct dentry *, struct nameidata *, void *);