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    Subject[PATCH 16/24] fs: add a kern_symlink helper
    Date
    Add a simple helper perform a symlink 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_symlinkat
    into the callers. Remove the now unused ksys_symlink.

    Signed-off-by: Christoph Hellwig <hch@lst.de>
    ---
    fs/internal.h | 2 --
    fs/namei.c | 27 ++++++++++++++++++---------
    include/linux/fs.h | 1 +
    include/linux/syscalls.h | 9 ---------
    init/initramfs.c | 2 +-
    5 files changed, 20 insertions(+), 21 deletions(-)

    diff --git a/fs/internal.h b/fs/internal.h
    index f0869d5dc4dbfa..46f727c0bd84e2 100644
    --- a/fs/internal.h
    +++ b/fs/internal.h
    @@ -64,8 +64,6 @@ extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
    const char *, unsigned int, struct path *);
    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);

    /*
    * namespace.c
    diff --git a/fs/namei.c b/fs/namei.c
    index 9d80a5bce1051a..01e43676008644 100644
    --- a/fs/namei.c
    +++ b/fs/namei.c
    @@ -3991,20 +3991,21 @@ int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
    }
    EXPORT_SYMBOL(vfs_symlink);

    -long do_symlinkat(const char __user *oldname, int newdfd,
    - const char __user *newname)
    +static int do_symlinkat(struct filename *from, int newdfd,
    + struct filename *newname)
    {
    int error;
    - struct filename *from;
    struct dentry *dentry;
    struct path path;
    unsigned int lookup_flags = 0;

    - from = getname(oldname);
    - if (IS_ERR(from))
    + if (IS_ERR(from)) {
    + if (!IS_ERR(newname))
    + putname(newname);
    return PTR_ERR(from);
    + }
    retry:
    - dentry = user_path_create(newdfd, newname, &path, lookup_flags);
    + dentry = filename_create(newdfd, newname, &path, lookup_flags);
    error = PTR_ERR(dentry);
    if (IS_ERR(dentry))
    goto out_putname;
    @@ -4017,20 +4018,28 @@ long do_symlinkat(const char __user *oldname, int newdfd,
    lookup_flags |= LOOKUP_REVAL;
    goto retry;
    }
    + putname(newname);
    out_putname:
    - putname(from);
    + if (!IS_ERR(from))
    + putname(from);
    return error;
    }

    +int __init kern_symlink(const char *oldname, const char *newname)
    +{
    + return do_symlinkat(getname_kernel(oldname), AT_FDCWD,
    + getname_kernel(newname));
    +}
    +
    SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
    int, newdfd, const char __user *, newname)
    {
    - return do_symlinkat(oldname, newdfd, newname);
    + return do_symlinkat(getname(oldname), newdfd, getname(newname));
    }

    SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
    {
    - return do_symlinkat(oldname, AT_FDCWD, newname);
    + return do_symlinkat(getname(oldname), AT_FDCWD, getname(newname));
    }

    /**
    diff --git a/include/linux/fs.h b/include/linux/fs.h
    index fc3b09d473945f..7a7b3bf1b8aa53 100644
    --- a/include/linux/fs.h
    +++ b/include/linux/fs.h
    @@ -3680,5 +3680,6 @@ 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);
    +int __init kern_symlink(const char *oldname, const char *newname);

    #endif /* _LINUX_FS_H */
    diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
    index 467cc4413874ed..474d5d165048c8 100644
    --- a/include/linux/syscalls.h
    +++ b/include/linux/syscalls.h
    @@ -1284,15 +1284,6 @@ static inline long ksys_rmdir(const char __user *pathname)
    return do_rmdir(AT_FDCWD, pathname);
    }

    -extern long do_symlinkat(const char __user *oldname, int newdfd,
    - const char __user *newname);
    -
    -static inline long ksys_symlink(const char __user *oldname,
    - const char __user *newname)
    -{
    - return do_symlinkat(oldname, AT_FDCWD, newname);
    -}
    -
    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 e484381c6c131b..4efd78427996da 100644
    --- a/init/initramfs.c
    +++ b/init/initramfs.c
    @@ -389,7 +389,7 @@ static int __init do_symlink(void)
    {
    collected[N_ALIGN(name_len) + body_len] = '\0';
    clean_path(collected, 0);
    - ksys_symlink(collected + N_ALIGN(name_len), collected);
    + kern_symlink(collected + N_ALIGN(name_len), collected);
    kern_chown(collected, uid, gid, AT_SYMLINK_NOFOLLOW);
    do_utime(collected, mtime);
    state = SkipIt;
    --
    2.27.0
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