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Message-Id: <20200720155902.181712-16-hch@lst.de>
Date: Mon, 20 Jul 2020 17:58:53 +0200
From: Christoph Hellwig <hch@....de>
To: Al Viro <viro@...iv.linux.org.uk>,
Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org
Subject: [PATCH 15/24] fs: add a kern_link helper
Add a simple helper perform a link with a kernel space file name and use
it in the early init code instead of relying on the implicit
set_fs(KERNEL_DS) there. To do so push the getname from do_linkat into the
callers. Remove the now unused ksys_link.
Signed-off-by: Christoph Hellwig <hch@....de>
---
fs/internal.h | 2 --
fs/namei.c | 39 +++++++++++++++++++++++++++++----------
include/linux/fs.h | 1 +
include/linux/syscalls.h | 9 ---------
init/initramfs.c | 2 +-
5 files changed, 31 insertions(+), 22 deletions(-)
diff --git a/fs/internal.h b/fs/internal.h
index 1e7a72bd183e63..f0869d5dc4dbfa 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -66,8 +66,6 @@ long do_rmdir(int dfd, const char __user *pathname);
long do_unlinkat(int dfd, struct filename *name);
long do_symlinkat(const char __user *oldname, int newdfd,
const char __user *newname);
-int do_linkat(int olddfd, const char __user *oldname, int newdfd,
- const char __user *newname, int flags);
/*
* namespace.c
diff --git a/fs/namei.c b/fs/namei.c
index de97edac21849d..9d80a5bce1051a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4122,8 +4122,8 @@ EXPORT_SYMBOL(vfs_link);
* with linux 2.0, and to avoid hard-linking to directories
* and other special files. --ADM
*/
-int do_linkat(int olddfd, const char __user *oldname, int newdfd,
- const char __user *newname, int flags)
+static int do_linkat(int olddfd, struct filename *oldname, int newdfd,
+ struct filename *newname, int flags)
{
struct dentry *new_dentry;
struct path old_path, new_path;
@@ -4131,27 +4131,29 @@ int do_linkat(int olddfd, const char __user *oldname, int newdfd,
int how = 0;
int error;
+ error = -EINVAL;
if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
- return -EINVAL;
+ goto out_put_both_names;
/*
* To use null names we require CAP_DAC_READ_SEARCH
* This ensures that not everyone will be able to create
* handlink using the passed filedescriptor.
*/
if (flags & AT_EMPTY_PATH) {
+ error = -ENOENT;
if (!capable(CAP_DAC_READ_SEARCH))
- return -ENOENT;
+ goto out_put_both_names;
how = LOOKUP_EMPTY;
}
if (flags & AT_SYMLINK_FOLLOW)
how |= LOOKUP_FOLLOW;
retry:
- error = user_path_at(olddfd, oldname, how, &old_path);
+ error = filename_lookup(olddfd, oldname, how, &old_path, NULL);
if (error)
- return error;
+ goto out_put_newname;
- new_dentry = user_path_create(newdfd, newname, &new_path,
+ new_dentry = filename_create(newdfd, newname, &new_path,
(how & LOOKUP_REVAL));
error = PTR_ERR(new_dentry);
if (IS_ERR(new_dentry))
@@ -4181,21 +4183,38 @@ int do_linkat(int olddfd, const char __user *oldname, int newdfd,
how |= LOOKUP_REVAL;
goto retry;
}
+ putname(newname);
out:
path_put(&old_path);
-
+ putname(oldname);
+ return error;
+out_put_both_names:
+ if (!IS_ERR(oldname))
+ putname(oldname);
+out_put_newname:
+ if (!IS_ERR(newname))
+ putname(newname);
return error;
}
+int __init kern_link(const char *oldname, const char *newname)
+{
+ return do_linkat(AT_FDCWD, getname_kernel(oldname), AT_FDCWD,
+ getname_kernel(newname), 0);
+}
+
SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
int, newdfd, const char __user *, newname, int, flags)
{
- return do_linkat(olddfd, oldname, newdfd, newname, flags);
+ int how = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
+
+ return do_linkat(olddfd, getname_flags(oldname, how, NULL), newdfd,
+ getname(newname), flags);
}
SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
{
- return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
+ return do_linkat(AT_FDCWD, getname(oldname), AT_FDCWD, getname(newname), 0);
}
/**
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 846a21a9b3e14c..fc3b09d473945f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3679,5 +3679,6 @@ int __init kern_chmod(const char *filename, umode_t mode);
int __init kern_utimes(const char *filename, struct timespec64 *tv, int flags);
int kern_mkdir(const char *pathname, umode_t mode);
int kern_mknod(const char *filename, umode_t mode, unsigned int dev);
+int __init kern_link(const char *oldname, const char *newname);
#endif /* _LINUX_FS_H */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 3dfcae351a077d..467cc4413874ed 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1293,15 +1293,6 @@ static inline long ksys_symlink(const char __user *oldname,
return do_symlinkat(oldname, AT_FDCWD, newname);
}
-extern int do_linkat(int olddfd, const char __user *oldname, int newdfd,
- const char __user *newname, int flags);
-
-static inline long ksys_link(const char __user *oldname,
- const char __user *newname)
-{
- return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
-}
-
extern long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
static inline long ksys_ftruncate(unsigned int fd, loff_t length)
diff --git a/init/initramfs.c b/init/initramfs.c
index f32226d0388100..e484381c6c131b 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -310,7 +310,7 @@ static int __init maybe_link(void)
char *old = find_link(major, minor, ino, mode, collected);
if (old) {
clean_path(collected, 0);
- return (ksys_link(old, collected) < 0) ? -1 : 1;
+ return (kern_link(old, collected) < 0) ? -1 : 1;
}
}
return 0;
--
2.27.0
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