[PATCH 20/24] init: add an init_link helper
From: Christoph Hellwig <hch@lst.de>
Date: 2020-07-21 16:29:13
Also in:
linux-fsdevel, linux-raid, lkml
Subsystem:
abi/api, filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
Add a simple helper to link with a kernel space file name and switch the early init code over to it. Remove the now unused ksys_link. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/internal.h | 3 +-- fs/namei.c | 4 ++-- include/linux/syscalls.h | 9 --------- init/do_mounts.h | 1 + init/fs.c | 33 +++++++++++++++++++++++++++++++++ init/initramfs.c | 2 +- 6 files changed, 38 insertions(+), 14 deletions(-)
diff --git a/fs/internal.h b/fs/internal.h
index 585968c0286cf7..9a1e937e484647 100644
--- a/fs/internal.h
+++ b/fs/internal.h@@ -69,8 +69,7 @@ long do_rmdir(int dfd, struct filename *name); 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); +int may_linkat(struct path *link); /* * namespace.c
diff --git a/fs/namei.c b/fs/namei.c
index d75a6039ae3966..13de64c6be7640 100644
--- a/fs/namei.c
+++ b/fs/namei.c@@ -1024,7 +1024,7 @@ static bool safe_hardlink_source(struct inode *inode) * * Returns 0 if successful, -ve on error. */ -static int may_linkat(struct path *link) +int may_linkat(struct path *link) { struct inode *inode = link->dentry->d_inode;
@@ -4086,7 +4086,7 @@ 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, +static int do_linkat(int olddfd, const char __user *oldname, int newdfd, const char __user *newname, int flags) { struct dentry *new_dentry;
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index a2779638e41445..4b18b91ce46573 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h@@ -1295,15 +1295,6 @@ static inline long ksys_mknod(const char __user *filename, umode_t mode, return do_mknodat(AT_FDCWD, filename, mode, dev); } -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 int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group, int flag);
diff --git a/init/do_mounts.h b/init/do_mounts.h
index b886aaa0d09716..c80105e47a8e66 100644
--- a/init/do_mounts.h
+++ b/init/do_mounts.h@@ -16,6 +16,7 @@ int __init init_chroot(const char *filename); int __init init_chown(const char *filename, uid_t user, gid_t group, int flags); int __init init_chmod(const char *filename, umode_t mode); int __init init_eaccess(const char *filename); +int __init init_link(const char *oldname, const char *newname); int __init init_unlink(const char *pathname); int __init init_rmdir(const char *pathname);
diff --git a/init/fs.c b/init/fs.c
index 9929cdd19affbe..fb5fb7aa498485 100644
--- a/init/fs.c
+++ b/init/fs.c@@ -103,6 +103,39 @@ int __init init_eaccess(const char *filename) return error; } +int __init init_link(const char *oldname, const char *newname) +{ + struct dentry *new_dentry; + struct path old_path, new_path; + int error; + + error = kern_path(oldname, 0, &old_path); + if (error) + return error; + + new_dentry = kern_path_create(AT_FDCWD, newname, &new_path, 0); + error = PTR_ERR(new_dentry); + if (IS_ERR(new_dentry)) + goto out; + + error = -EXDEV; + if (old_path.mnt != new_path.mnt) + goto out_dput; + error = may_linkat(&old_path); + if (unlikely(error)) + goto out_dput; + error = security_path_link(old_path.dentry, &new_path, new_dentry); + if (error) + goto out_dput; + error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, + NULL); +out_dput: + done_path_create(&new_path, new_dentry); +out: + path_put(&old_path); + return error; +} + int __init init_unlink(const char *pathname) { return do_unlinkat(AT_FDCWD, getname_kernel(pathname));
diff --git a/init/initramfs.c b/init/initramfs.c
index 771da27e87afa1..bdc3c0ec5a6c31 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c@@ -318,7 +318,7 @@ 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 (init_link(old, collected) < 0) ? -1 : 1; } } return 0;
--
2.27.0