lkml.org 
[lkml]   [2020]   [Jul]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v7 4/9] fs: Move __scm_install_fd() to __receive_fd()
    Date
    In preparation for users of the "install a received file" logic outside
    of net/ (pidfd and seccomp), relocate and rename __scm_install_fd() from
    net/core/scm.c to __receive_fd() in fs/file.c, and provide a wrapper
    named receive_fd_user(), as future patches will change the interface
    to __receive_fd().

    Reviewed-by: Sargun Dhillon <sargun@sargun.me>
    Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
    Signed-off-by: Kees Cook <keescook@chromium.org>
    ---
    fs/file.c | 41 +++++++++++++++++++++++++++++++++++++++++
    include/linux/file.h | 8 ++++++++
    include/net/scm.h | 1 -
    net/compat.c | 2 +-
    net/core/scm.c | 27 +--------------------------
    5 files changed, 51 insertions(+), 28 deletions(-)

    diff --git a/fs/file.c b/fs/file.c
    index abb8b7081d7a..6220bf440809 100644
    --- a/fs/file.c
    +++ b/fs/file.c
    @@ -18,6 +18,7 @@
    #include <linux/bitops.h>
    #include <linux/spinlock.h>
    #include <linux/rcupdate.h>
    +#include <net/sock.h>

    unsigned int sysctl_nr_open __read_mostly = 1024*1024;
    unsigned int sysctl_nr_open_min = BITS_PER_LONG;
    @@ -931,6 +932,46 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)
    return err;
    }

    +/**
    + * __receive_fd() - Install received file into file descriptor table
    + *
    + * @file: struct file that was received from another process
    + * @ufd: __user pointer to write new fd number to
    + * @o_flags: the O_* flags to apply to the new fd entry
    + *
    + * Installs a received file into the file descriptor table, with appropriate
    + * checks and count updates. Writes the fd number to userspace.
    + *
    + * This helper handles its own reference counting of the incoming
    + * struct file.
    + *
    + * Returns -ve on error.
    + */
    +int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)
    +{
    + int new_fd;
    + int error;
    +
    + error = security_file_receive(file);
    + if (error)
    + return error;
    +
    + new_fd = get_unused_fd_flags(o_flags);
    + if (new_fd < 0)
    + return new_fd;
    +
    + error = put_user(new_fd, ufd);
    + if (error) {
    + put_unused_fd(new_fd);
    + return error;
    + }
    +
    + /* Bump the sock usage counts, if any. */
    + __receive_sock(file);
    + fd_install(new_fd, get_file(file));
    + return 0;
    +}
    +
    static int ksys_dup3(unsigned int oldfd, unsigned int newfd, int flags)
    {
    int err = -EBADF;
    diff --git a/include/linux/file.h b/include/linux/file.h
    index 122f80084a3e..b14ff2ffd0bd 100644
    --- a/include/linux/file.h
    +++ b/include/linux/file.h
    @@ -91,6 +91,14 @@ extern void put_unused_fd(unsigned int fd);

    extern void fd_install(unsigned int fd, struct file *file);

    +extern int __receive_fd(struct file *file, int __user *ufd,
    + unsigned int o_flags);
    +static inline int receive_fd_user(struct file *file, int __user *ufd,
    + unsigned int o_flags)
    +{
    + return __receive_fd(file, ufd, o_flags);
    +}
    +
    extern void flush_delayed_fput(void);
    extern void __fput_sync(struct file *);

    diff --git a/include/net/scm.h b/include/net/scm.h
    index 581a94d6c613..1ce365f4c256 100644
    --- a/include/net/scm.h
    +++ b/include/net/scm.h
    @@ -37,7 +37,6 @@ struct scm_cookie {
    #endif
    };

    -int __scm_install_fd(struct file *file, int __user *ufd, unsigned int o_flags);
    void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm);
    void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm);
    int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);
    diff --git a/net/compat.c b/net/compat.c
    index 27d477fdcaa0..e74cd3dae8b0 100644
    --- a/net/compat.c
    +++ b/net/compat.c
    @@ -298,7 +298,7 @@ void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm)
    int err = 0, i;

    for (i = 0; i < fdmax; i++) {
    - err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
    + err = receive_fd_user(scm->fp->fp[i], cmsg_data + i, o_flags);
    if (err)
    break;
    }
    diff --git a/net/core/scm.c b/net/core/scm.c
    index 44f03213dcab..67c166a7820d 100644
    --- a/net/core/scm.c
    +++ b/net/core/scm.c
    @@ -280,31 +280,6 @@ void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_inter
    }
    EXPORT_SYMBOL(put_cmsg_scm_timestamping);

    -int __scm_install_fd(struct file *file, int __user *ufd, unsigned int o_flags)
    -{
    - int new_fd;
    - int error;
    -
    - error = security_file_receive(file);
    - if (error)
    - return error;
    -
    - new_fd = get_unused_fd_flags(o_flags);
    - if (new_fd < 0)
    - return new_fd;
    -
    - error = put_user(new_fd, ufd);
    - if (error) {
    - put_unused_fd(new_fd);
    - return error;
    - }
    -
    - /* Bump the sock usage counts, if any. */
    - __receive_sock(file);
    - fd_install(new_fd, get_file(file));
    - return 0;
    -}
    -
    static int scm_max_fds(struct msghdr *msg)
    {
    if (msg->msg_controllen <= sizeof(struct cmsghdr))
    @@ -331,7 +306,7 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
    }

    for (i = 0; i < fdmax; i++) {
    - err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
    + err = receive_fd_user(scm->fp->fp[i], cmsg_data + i, o_flags);
    if (err)
    break;
    }
    --
    2.25.1
    \
     
     \ /
      Last update: 2020-07-09 20:28    [W:4.171 / U:0.056 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site