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Kernel: Add try_copy_kstring_from_user()

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This is a convenience function that works the same as our old
copy_string_from_user(), but this returns a KString (and can fail!)
This commit is contained in:
Andreas Kling 2021-05-28 09:29:16 +02:00
parent 279383a8f3
commit 856f20f91f
3 changed files with 43 additions and 0 deletions
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5
Kernel/Process.h
View file

@ -814,6 +814,11 @@ inline static String copy_string_from_user(const Kernel::Syscall::StringArgument
return copy_string_from_user(string.characters, string.length);
}
inline static KResultOr<NonnullOwnPtr<KString>> try_copy_kstring_from_user(const Kernel::Syscall::StringArgument& string)
{
return try_copy_kstring_from_user(string.characters, string.length);
}
template<>
struct AK::Formatter<Kernel::Process> : AK::Formatter<String> {
void format(FormatBuilder& builder, const Kernel::Process& value)

34
Kernel/StdLib.cpp
View file

@ -43,6 +43,40 @@ String copy_string_from_user(Userspace<const char*> user_str, size_t user_str_si
return copy_string_from_user(user_str.unsafe_userspace_ptr(), user_str_size);
}
Kernel::KResultOr<NonnullOwnPtr<Kernel::KString>> try_copy_kstring_from_user(const char* user_str, size_t user_str_size)
{
bool is_user = Kernel::is_user_range(VirtualAddress(user_str), user_str_size);
if (!is_user)
return EFAULT;
Kernel::SmapDisabler disabler;
void* fault_at;
ssize_t length = Kernel::safe_strnlen(user_str, user_str_size, fault_at);
if (length < 0) {
dbgln("copy_kstring_from_user({:p}, {}) failed at {} (strnlen)", static_cast<const void*>(user_str), user_str_size, VirtualAddress { fault_at });
return EFAULT;
}
char* buffer;
auto new_string = Kernel::KString::try_create_uninitialized(length, buffer);
if (!new_string)
return ENOMEM;
buffer[length] = '\0';
if (length == 0)
return new_string.release_nonnull();
if (!Kernel::safe_memcpy(buffer, user_str, (size_t)length, fault_at)) {
dbgln("copy_kstring_from_user({:p}, {}) failed at {} (memcpy)", static_cast<const void*>(user_str), user_str_size, VirtualAddress { fault_at });
return EFAULT;
}
return new_string.release_nonnull();
}
Kernel::KResultOr<NonnullOwnPtr<Kernel::KString>> try_copy_kstring_from_user(Userspace<const char*> user_str, size_t user_str_size)
{
return try_copy_kstring_from_user(user_str.unsafe_userspace_ptr(), user_str_size);
}
[[nodiscard]] Optional<Time> copy_time_from_user(const timespec* ts_user)
{
timespec ts;

4
Kernel/StdLib.h
View file

@ -10,6 +10,8 @@
#include <AK/Forward.h>
#include <AK/Time.h>
#include <AK/Userspace.h>
#include <Kernel/KResult.h>
#include <Kernel/KString.h>
#include <Kernel/UnixTypes.h>
namespace Syscall {
@ -18,6 +20,8 @@ struct StringArgument;
[[nodiscard]] String copy_string_from_user(const char*, size_t);
[[nodiscard]] String copy_string_from_user(Userspace<const char*>, size_t);
[[nodiscard]] Kernel::KResultOr<NonnullOwnPtr<Kernel::KString>> try_copy_kstring_from_user(const char*, size_t);
[[nodiscard]] Kernel::KResultOr<NonnullOwnPtr<Kernel::KString>> try_copy_kstring_from_user(Userspace<const char*>, size_t);
[[nodiscard]] Optional<Time> copy_time_from_user(const timespec*);
[[nodiscard]] Optional<Time> copy_time_from_user(const timeval*);
template<typename T>