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Tue, 05 May 2020 14:39:11 -0700 (PDT) Subject: Re: [PATCH for-5.7] splice: move f_mode checks to do_{splice,tee}() To: Clay Harris Cc: Jens Axboe , Alexander Viro , Jann Horn , io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <51b4370ef70eebf941f6cef503943d7f7de3ea4d.1588621153.git.asml.silence@gmail.com> <20200505211029.azfj2c4scoh6x2kx@ps29521.dreamhostps.com> From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Message-ID: <2146b60d-d982-59c4-33d3-a5e6ad68fc8e@gmail.com> Date: Wed, 6 May 2020 00:38:05 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20200505211029.azfj2c4scoh6x2kx@ps29521.dreamhostps.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 06/05/2020 00:10, Clay Harris wrote: > On Mon, May 04 2020 at 22:39:35 +0300, Pavel Begunkov quoth thus: > >> do_splice() is used by io_uring, as will be do_tee(). Move f_mode >> checks from sys_{splice,tee}() to do_{splice,tee}(), so they're >> enforced for io_uring as well. > > I'm not seeing any check against splicing a pipe to itself in the > io_uring path, although maybe I just missed it. As the comment > below says: /* Splicing to self would be fun, but... */ . io_uring just forwards a request to do_splice(), which do the check at the exact place you mentioned. The similar story is with do_tee(). > >> Fixes: 7d67af2c0134 ("io_uring: add splice(2) support") >> Reported-by: Jann Horn >> Signed-off-by: Pavel Begunkov >> --- >> fs/splice.c | 45 ++++++++++++++++++--------------------------- >> 1 file changed, 18 insertions(+), 27 deletions(-) >> >> diff --git a/fs/splice.c b/fs/splice.c >> index 4735defc46ee..fd0a1e7e5959 100644 >> --- a/fs/splice.c >> +++ b/fs/splice.c >> @@ -1118,6 +1118,10 @@ long do_splice(struct file *in, loff_t __user *off_in, >> loff_t offset; >> long ret; >> >> + if (unlikely(!(in->f_mode & FMODE_READ) || >> + !(out->f_mode & FMODE_WRITE))) >> + return -EBADF; >> + >> ipipe = get_pipe_info(in); >> opipe = get_pipe_info(out); >> >> @@ -1125,12 +1129,6 @@ long do_splice(struct file *in, loff_t __user *off_in, >> if (off_in || off_out) >> return -ESPIPE; >> >> - if (!(in->f_mode & FMODE_READ)) >> - return -EBADF; >> - >> - if (!(out->f_mode & FMODE_WRITE)) >> - return -EBADF; >> - >> /* Splicing to self would be fun, but... */ >> if (ipipe == opipe) >> return -EINVAL; >> @@ -1153,9 +1151,6 @@ long do_splice(struct file *in, loff_t __user *off_in, >> offset = out->f_pos; >> } >> >> - if (unlikely(!(out->f_mode & FMODE_WRITE))) >> - return -EBADF; >> - >> if (unlikely(out->f_flags & O_APPEND)) >> return -EINVAL; >> >> @@ -1440,15 +1435,11 @@ SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, >> error = -EBADF; >> in = fdget(fd_in); >> if (in.file) { >> - if (in.file->f_mode & FMODE_READ) { >> - out = fdget(fd_out); >> - if (out.file) { >> - if (out.file->f_mode & FMODE_WRITE) >> - error = do_splice(in.file, off_in, >> - out.file, off_out, >> - len, flags); >> - fdput(out); >> - } >> + out = fdget(fd_out); >> + if (out.file) { >> + error = do_splice(in.file, off_in, out.file, off_out, >> + len, flags); >> + fdput(out); >> } >> fdput(in); >> } >> @@ -1770,6 +1761,10 @@ static long do_tee(struct file *in, struct file *out, size_t len, >> struct pipe_inode_info *opipe = get_pipe_info(out); >> int ret = -EINVAL; >> >> + if (unlikely(!(in->f_mode & FMODE_READ) || >> + !(out->f_mode & FMODE_WRITE))) >> + return -EBADF; >> + >> /* >> * Duplicate the contents of ipipe to opipe without actually >> * copying the data. >> @@ -1795,7 +1790,7 @@ static long do_tee(struct file *in, struct file *out, size_t len, >> >> SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) >> { >> - struct fd in; >> + struct fd in, out; >> int error; >> >> if (unlikely(flags & ~SPLICE_F_ALL)) >> @@ -1807,14 +1802,10 @@ SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) >> error = -EBADF; >> in = fdget(fdin); >> if (in.file) { >> - if (in.file->f_mode & FMODE_READ) { >> - struct fd out = fdget(fdout); >> - if (out.file) { >> - if (out.file->f_mode & FMODE_WRITE) >> - error = do_tee(in.file, out.file, >> - len, flags); >> - fdput(out); >> - } >> + out = fdget(fdout); >> + if (out.file) { >> + error = do_tee(in.file, out.file, len, flags); >> + fdput(out); >> } >> fdput(in); >> } >> -- >> 2.24.0 -- Pavel Begunkov