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    Subject[RFC PATCH 31/35] syscalls: do not call sys_{f,}chmod{at,}() within the kernel
    Date
    CC: Al Viro <viro@zeniv.linux.org.uk>
    CC: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
    ---
    fs/internal.h | 2 ++
    fs/open.c | 17 ++++++++++++++---
    include/linux/syscalls.h | 7 +++++++
    init/initramfs.c | 6 +++---
    4 files changed, 26 insertions(+), 6 deletions(-)

    diff --git a/fs/internal.h b/fs/internal.h
    index 91e6fc93fcb5..2474bf460f96 100644
    --- a/fs/internal.h
    +++ b/fs/internal.h
    @@ -119,6 +119,8 @@ extern struct file *do_filp_open(int dfd, struct filename *pathname,
    extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
    const char *, const struct open_flags *);

    +int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
    +
    extern int open_check_o_direct(struct file *f);
    extern int vfs_open(const struct path *, struct file *, const struct cred *);
    extern struct file *filp_clone_open(struct file *);
    diff --git a/fs/open.c b/fs/open.c
    index a19b8277c439..6037f2bf418c 100644
    --- a/fs/open.c
    +++ b/fs/open.c
    @@ -551,7 +551,7 @@ static int chmod_common(const struct path *path, umode_t mode)
    return error;
    }

    -SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
    +int ksys_fchmod(unsigned int fd, umode_t mode)
    {
    struct fd f = fdget(fd);
    int err = -EBADF;
    @@ -564,7 +564,12 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
    return err;
    }

    -SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode)
    +SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
    +{
    + return ksys_fchmod(fd, mode);
    +}
    +
    +int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
    {
    struct path path;
    int error;
    @@ -582,9 +587,15 @@ SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode
    return error;
    }

    +SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
    + umode_t, mode)
    +{
    + return do_fchmodat(dfd, filename, mode);
    +}
    +
    SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
    {
    - return sys_fchmodat(AT_FDCWD, filename, mode);
    + return do_fchmodat(AT_FDCWD, filename, mode);
    }

    static int chown_common(const struct path *path, uid_t user, gid_t group)
    diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
    index 27620caed7e4..87feef73c077 100644
    --- a/include/linux/syscalls.h
    +++ b/include/linux/syscalls.h
    @@ -962,6 +962,7 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
    int ksys_chdir(const char __user *filename);
    int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
    unsigned int flags);
    +int ksys_fchmod(unsigned int fd, umode_t mode);

    /*
    * The following kernel syscall equivalents are just wrappers to fs-internal
    @@ -1009,4 +1010,10 @@ static inline long ksys_link(const char __user *oldname,
    return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
    }

    +extern int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
    +static inline int ksys_chmod(const char __user *filename, umode_t mode)
    +{
    + return do_fchmodat(AT_FDCWD, filename, mode);
    +}
    +
    #endif
    diff --git a/init/initramfs.c b/init/initramfs.c
    index 5855ab632b4e..16c3c23076e2 100644
    --- a/init/initramfs.c
    +++ b/init/initramfs.c
    @@ -344,7 +344,7 @@ static int __init do_name(void)

    if (wfd >= 0) {
    sys_fchown(wfd, uid, gid);
    - sys_fchmod(wfd, mode);
    + ksys_fchmod(wfd, mode);
    if (body_len)
    sys_ftruncate(wfd, body_len);
    vcollected = kstrdup(collected, GFP_KERNEL);
    @@ -354,14 +354,14 @@ static int __init do_name(void)
    } else if (S_ISDIR(mode)) {
    ksys_mkdir(collected, mode);
    sys_chown(collected, uid, gid);
    - sys_chmod(collected, mode);
    + ksys_chmod(collected, mode);
    dir_add(collected, mtime);
    } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
    S_ISFIFO(mode) || S_ISSOCK(mode)) {
    if (maybe_link() == 0) {
    ksys_mknod(collected, mode, rdev);
    sys_chown(collected, uid, gid);
    - sys_chmod(collected, mode);
    + ksys_chmod(collected, mode);
    do_utime(collected, mtime);
    }
    }
    --
    2.16.2
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