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serenity/Kernel/Syscalls/pipe.cpp

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Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 23:38:15 +02:00
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <Kernel/FileSystem/FIFO.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Process.h>
namespace Kernel {
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
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KResultOr<int> Process::sys$pipe(int pipefd[2], int flags)
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 23:38:15 +02:00
{
REQUIRE_PROMISE(stdio);
if (number_of_open_file_descriptors() + 2 > max_open_file_descriptors())
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 13:49:16 +01:00
return EMFILE;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 23:38:15 +02:00
// Reject flags other than O_CLOEXEC.
if ((flags & O_CLOEXEC) != flags)
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 13:49:16 +01:00
return EINVAL;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 23:38:15 +02:00
u32 fd_flags = (flags & O_CLOEXEC) ? FD_CLOEXEC : 0;
Kernel: Move select Process members into protected memory Process member variable like m_euid are very valuable targets for kernel exploits and until now they have been writable at all times. This patch moves m_euid along with a whole bunch of other members into a new Process::ProtectedData struct. This struct is remapped as read-only memory whenever we don't need to write to it. This means that a kernel write primitive is no longer enough to overwrite a process's effective UID, you must first unprotect the protected data where the UID is stored. :^)
2021-03-10 19:59:46 +01:00
auto fifo = FIFO::create(uid());
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 23:38:15 +02:00
Kernel: Improve ProcFS behavior in low memory conditions When ProcFS could no longer allocate KBuffer objects to serve calls to read, it would just return 0, indicating EOF. This then triggered parsing errors because code assumed it read the file. Because read isn't supposed to return ENOMEM, change ProcFS to populate the file data upon file open or seek to the beginning. This also means that calls to open can now return ENOMEM if needed. This allows the caller to either be able to successfully open the file and read it, or fail to open it in the first place.
2020-09-17 13:51:09 -06:00
auto open_reader_result = fifo->open_direction(FIFO::Direction::Reader);
if (open_reader_result.is_error())
return open_reader_result.error();
auto open_writer_result = fifo->open_direction(FIFO::Direction::Writer);
if (open_writer_result.is_error())
return open_writer_result.error();
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 23:38:15 +02:00
int reader_fd = alloc_fd();
Kernel: Improve ProcFS behavior in low memory conditions When ProcFS could no longer allocate KBuffer objects to serve calls to read, it would just return 0, indicating EOF. This then triggered parsing errors because code assumed it read the file. Because read isn't supposed to return ENOMEM, change ProcFS to populate the file data upon file open or seek to the beginning. This also means that calls to open can now return ENOMEM if needed. This allows the caller to either be able to successfully open the file and read it, or fail to open it in the first place.
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m_fds[reader_fd].set(open_reader_result.release_value(), fd_flags);
Kernel: Turn Process::FileDescriptionAndFlags into a proper class
2020-07-30 23:50:31 +02:00
m_fds[reader_fd].description()->set_readable(true);
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
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if (!copy_to_user(&pipefd[0], &reader_fd))
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 13:49:16 +01:00
return EFAULT;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 23:38:15 +02:00
int writer_fd = alloc_fd();
Kernel: Improve ProcFS behavior in low memory conditions When ProcFS could no longer allocate KBuffer objects to serve calls to read, it would just return 0, indicating EOF. This then triggered parsing errors because code assumed it read the file. Because read isn't supposed to return ENOMEM, change ProcFS to populate the file data upon file open or seek to the beginning. This also means that calls to open can now return ENOMEM if needed. This allows the caller to either be able to successfully open the file and read it, or fail to open it in the first place.
2020-09-17 13:51:09 -06:00
m_fds[writer_fd].set(open_writer_result.release_value(), fd_flags);
Kernel: Turn Process::FileDescriptionAndFlags into a proper class
2020-07-30 23:50:31 +02:00
m_fds[writer_fd].description()->set_writable(true);
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-11 21:11:07 -06:00
if (!copy_to_user(&pipefd[1], &writer_fd))
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 13:49:16 +01:00
return EFAULT;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 23:38:15 +02:00
return 0;
}
}
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