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https://github.com/RGBCube/serenity
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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.
This commit is contained in:
Tom
Andreas Kling
parent
7d1b8417bd
commit
c8d9f1b9c9
149 changed files with 1585 additions and 1244 deletions
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@ -65,8 +65,6 @@ int Process::sys$socket(int domain, int type, int protocol)
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int Process::sys$bind(int sockfd, Userspace<const sockaddr*> address, socklen_t address_length)
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{
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if (!validate_read(address, address_length))
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return -EFAULT;
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auto description = file_description(sockfd);
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if (!description)
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return -EBADF;
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@ -98,14 +96,8 @@ int Process::sys$accept(int accepting_socket_fd, Userspace<sockaddr*> user_addre
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REQUIRE_PROMISE(accept);
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socklen_t address_size = 0;
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if (user_address) {
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if (!validate_write_typed(user_address_size))
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return -EFAULT;
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if (!validate_read_and_copy_typed(&address_size, user_address_size))
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return -EFAULT;
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if (!validate_write(user_address, address_size))
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return -EFAULT;
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}
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if (user_address && !copy_from_user(&address_size, static_ptr_cast<const socklen_t*>(user_address_size)))
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return -EFAULT;
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int accepted_socket_fd = alloc_fd();
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if (accepted_socket_fd < 0)
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@ -132,8 +124,10 @@ int Process::sys$accept(int accepting_socket_fd, Userspace<sockaddr*> user_addre
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u8 address_buffer[sizeof(sockaddr_un)];
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address_size = min(sizeof(sockaddr_un), static_cast<size_t>(address_size));
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accepted_socket->get_peer_address((sockaddr*)address_buffer, &address_size);
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copy_to_user(user_address, address_buffer, address_size);
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copy_to_user(user_address_size, &address_size);
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if (!copy_to_user(user_address, address_buffer, address_size))
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return -EFAULT;
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if (!copy_to_user(user_address_size, &address_size))
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return -EFAULT;
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}
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auto accepted_socket_description = FileDescription::create(*accepted_socket);
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@ -151,8 +145,6 @@ int Process::sys$accept(int accepting_socket_fd, Userspace<sockaddr*> user_addre
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int Process::sys$connect(int sockfd, Userspace<const sockaddr*> user_address, socklen_t user_address_size)
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{
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if (!validate_read(user_address, user_address_size))
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return -EFAULT;
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int fd = alloc_fd();
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if (fd < 0)
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return fd;
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@ -165,11 +157,7 @@ int Process::sys$connect(int sockfd, Userspace<const sockaddr*> user_address, so
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auto& socket = *description->socket();
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REQUIRE_PROMISE_FOR_SOCKET_DOMAIN(socket.domain());
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u8 address[sizeof(sockaddr_un)];
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size_t address_size = min(sizeof(address), static_cast<size_t>(user_address_size));
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copy_from_user(address, user_address, address_size);
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return socket.connect(*description, (const sockaddr*)address, address_size, description->is_blocking() ? ShouldBlock::Yes : ShouldBlock::No);
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return socket.connect(*description, user_address, user_address_size, description->is_blocking() ? ShouldBlock::Yes : ShouldBlock::No);
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}
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int Process::sys$shutdown(int sockfd, int how)
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@ -192,17 +180,13 @@ ssize_t Process::sys$sendto(Userspace<const Syscall::SC_sendto_params*> user_par
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{
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REQUIRE_PROMISE(stdio);
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Syscall::SC_sendto_params params;
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if (!validate_read_and_copy_typed(¶ms, user_params))
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if (!copy_from_user(¶ms, user_params))
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return -EFAULT;
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int flags = params.flags;
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Userspace<const sockaddr*> addr = params.addr;
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Userspace<const sockaddr*> addr((FlatPtr)params.addr);
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socklen_t addr_length = params.addr_length;
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if (!validate(params.data))
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return -EFAULT;
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if (addr && !validate_read(addr, addr_length))
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return -EFAULT;
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auto description = file_description(params.sockfd);
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if (!description)
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return -EBADF;
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@ -212,7 +196,10 @@ ssize_t Process::sys$sendto(Userspace<const Syscall::SC_sendto_params*> user_par
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if (socket.is_shut_down_for_writing())
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return -EPIPE;
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SmapDisabler disabler;
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auto result = socket.sendto(*description, params.data.data, params.data.size, flags, addr, addr_length);
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auto data_buffer = UserOrKernelBuffer::for_user_buffer(const_cast<u8*>((const u8*)params.data.data), params.data.size);
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if (!data_buffer.has_value())
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return -EFAULT;
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auto result = socket.sendto(*description, data_buffer.value(), params.data.size, flags, addr, addr_length);
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if (result.is_error())
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return result.error();
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return result.value();
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@ -223,27 +210,17 @@ ssize_t Process::sys$recvfrom(Userspace<const Syscall::SC_recvfrom_params*> user
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REQUIRE_PROMISE(stdio);
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Syscall::SC_recvfrom_params params;
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if (!validate_read_and_copy_typed(¶ms, user_params))
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if (!copy_from_user(¶ms, user_params))
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return -EFAULT;
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int flags = params.flags;
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Userspace<sockaddr*> user_addr = params.addr;
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Userspace<socklen_t*> user_addr_length = params.addr_length;
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Userspace<sockaddr*> user_addr((FlatPtr)params.addr);
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Userspace<socklen_t*> user_addr_length((FlatPtr)params.addr_length);
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SmapDisabler disabler;
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if (!validate(params.buffer))
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return -EFAULT;
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if (user_addr_length) {
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socklen_t addr_length;
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if (!validate_read_and_copy_typed(&addr_length, user_addr_length))
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return -EFAULT;
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if (!validate_write_typed(user_addr_length))
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return -EFAULT;
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if (!validate_write(user_addr, addr_length))
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return -EFAULT;
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} else if (user_addr) {
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if (!user_addr_length && user_addr)
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return -EINVAL;
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}
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auto description = file_description(params.sockfd);
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if (!description)
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return -EBADF;
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@ -258,7 +235,10 @@ ssize_t Process::sys$recvfrom(Userspace<const Syscall::SC_recvfrom_params*> user
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if (flags & MSG_DONTWAIT)
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description->set_blocking(false);
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auto result = socket.recvfrom(*description, params.buffer.data, params.buffer.size, flags, user_addr, user_addr_length);
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auto data_buffer = UserOrKernelBuffer::for_user_buffer(const_cast<u8*>((const u8*)params.buffer.data), params.buffer.size);
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if (!data_buffer.has_value())
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return -EFAULT;
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auto result = socket.recvfrom(*description, data_buffer.value(), params.buffer.size, flags, user_addr, user_addr_length);
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if (flags & MSG_DONTWAIT)
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description->set_blocking(original_blocking);
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@ -271,18 +251,12 @@ template<bool sockname, typename Params>
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int Process::get_sock_or_peer_name(const Params& params)
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{
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socklen_t addrlen_value;
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if (!validate_read_and_copy_typed(&addrlen_value, params.addrlen))
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if (!copy_from_user(&addrlen_value, params.addrlen, sizeof(socklen_t)))
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return -EFAULT;
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if (addrlen_value <= 0)
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return -EINVAL;
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if (!validate_write(params.addr, addrlen_value))
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return -EFAULT;
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if (!validate_write_typed(params.addrlen))
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return -EFAULT;
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auto description = file_description(params.sockfd);
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if (!description)
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return -EBADF;
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@ -299,15 +273,17 @@ int Process::get_sock_or_peer_name(const Params& params)
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socket.get_local_address((sockaddr*)address_buffer, &addrlen_value);
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else
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socket.get_peer_address((sockaddr*)address_buffer, &addrlen_value);
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copy_to_user(params.addr, address_buffer, addrlen_value);
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copy_to_user(params.addrlen, &addrlen_value);
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if (!copy_to_user(params.addr, address_buffer, addrlen_value))
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return -EFAULT;
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if (!copy_to_user(params.addrlen, &addrlen_value))
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return -EFAULT;
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return 0;
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}
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int Process::sys$getsockname(Userspace<const Syscall::SC_getsockname_params*> user_params)
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{
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Syscall::SC_getsockname_params params;
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if (!validate_read_and_copy_typed(¶ms, user_params))
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if (!copy_from_user(¶ms, user_params))
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return -EFAULT;
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return get_sock_or_peer_name<true>(params);
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}
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@ -315,7 +291,7 @@ int Process::sys$getsockname(Userspace<const Syscall::SC_getsockname_params*> us
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int Process::sys$getpeername(Userspace<const Syscall::SC_getpeername_params*> user_params)
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{
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Syscall::SC_getpeername_params params;
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if (!validate_read_and_copy_typed(¶ms, user_params))
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if (!copy_from_user(¶ms, user_params))
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return -EFAULT;
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return get_sock_or_peer_name<false>(params);
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}
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@ -323,22 +299,19 @@ int Process::sys$getpeername(Userspace<const Syscall::SC_getpeername_params*> us
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int Process::sys$getsockopt(Userspace<const Syscall::SC_getsockopt_params*> user_params)
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{
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Syscall::SC_getsockopt_params params;
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if (!validate_read_and_copy_typed(¶ms, user_params))
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if (!copy_from_user(¶ms, user_params))
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return -EFAULT;
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int sockfd = params.sockfd;
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int level = params.level;
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int option = params.option;
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Userspace<void*> user_value = params.value;
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Userspace<socklen_t*> user_value_size = params.value_size;
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Userspace<void*> user_value((FlatPtr)params.value);
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Userspace<socklen_t*> user_value_size((FlatPtr)params.value_size);
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if (!validate_write_typed(user_value_size))
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return -EFAULT;
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socklen_t value_size;
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if (!validate_read_and_copy_typed(&value_size, user_value_size))
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return -EFAULT;
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if (!validate_write(user_value, value_size))
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if (!copy_from_user(&value_size, params.value_size, sizeof(socklen_t)))
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return -EFAULT;
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auto description = file_description(sockfd);
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if (!description)
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return -EBADF;
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@ -357,10 +330,9 @@ int Process::sys$getsockopt(Userspace<const Syscall::SC_getsockopt_params*> user
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int Process::sys$setsockopt(Userspace<const Syscall::SC_setsockopt_params*> user_params)
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{
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Syscall::SC_setsockopt_params params;
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if (!validate_read_and_copy_typed(¶ms, user_params))
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return -EFAULT;
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if (!validate_read(params.value, params.value_size))
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if (!copy_from_user(¶ms, user_params))
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return -EFAULT;
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Userspace<const void*> user_value((FlatPtr)params.value);
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auto description = file_description(params.sockfd);
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if (!description)
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return -EBADF;
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@ -368,7 +340,7 @@ int Process::sys$setsockopt(Userspace<const Syscall::SC_setsockopt_params*> user
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return -ENOTSOCK;
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auto& socket = *description->socket();
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REQUIRE_PROMISE_FOR_SOCKET_DOMAIN(socket.domain());
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return socket.setsockopt(params.level, params.option, params.value, params.value_size);
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return socket.setsockopt(params.level, params.option, user_value, params.value_size);
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}
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}
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