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Kernel/LibC: Implement mprotect

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There may be some race conditions with this but i think this is good
enough to start with
This commit is contained in:
Bananymous
2025-08-05 02:39:19 +03:00
parent eb7922ab88
commit f1369c8fd6
18 changed files with 167 additions and 61 deletions
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76
kernel/kernel/Process.cpp
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@@ -318,7 +318,8 @@ namespace Kernel
tls_size,
{ .start = master_addr, .end = USERSPACE_END },
MemoryRegion::Type::PRIVATE,
PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present
PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present,
O_EXEC | O_RDWR
));
BAN::Vector<uint8_t> temp_buffer;
@@ -2146,7 +2147,8 @@ namespace Kernel
page_table(),
args.len,
address_range,
region_type, page_flags
region_type, page_flags,
O_EXEC | O_RDWR
));
LockGuard _(m_process_lock);
@@ -2173,7 +2175,8 @@ namespace Kernel
page_table(),
args.off, args.len,
address_range,
region_type, page_flags
region_type, page_flags,
status_flags
));
}
else if (inode->is_device())
@@ -2182,7 +2185,8 @@ namespace Kernel
page_table(),
args.off, args.len,
address_range,
region_type, page_flags
region_type, page_flags,
status_flags
));
}
@@ -2228,6 +2232,70 @@ namespace Kernel
return 0;
}
BAN::ErrorOr<long> Process::sys_mprotect(void* addr, size_t len, int prot)
{
if (len == 0)
return BAN::Error::from_errno(EINVAL);
const vaddr_t vaddr = reinterpret_cast<vaddr_t>(addr);
if (vaddr % PAGE_SIZE != 0)
return BAN::Error::from_errno(EINVAL);
if (auto rem = len % PAGE_SIZE)
len += PAGE_SIZE - rem;
PageTable::flags_t flags = 0;
if (prot & PROT_READ)
flags |= PageTable::Flags::Present;
if (prot & PROT_WRITE)
flags |= PageTable::Flags::ReadWrite | PageTable::Flags::Present;
if (prot & PROT_EXEC)
flags |= PageTable::Flags::Execute | PageTable::Flags::Execute;
if (flags == 0)
flags = PageTable::Flags::Reserved;
else
flags |= PageTable::Flags::UserSupervisor;
LockGuard _(m_process_lock);
// FIXME: We should protect partial regions.
// This is a hack to only protect if the whole mmap region
// is contained within [addr, addr + len]
for (size_t i = 0; i < m_mapped_regions.size(); i++)
{
auto& region = m_mapped_regions[i];
const vaddr_t region_s = region->vaddr();
const vaddr_t region_e = region->vaddr() + region->size();
if (vaddr <= region_s && region_e <= vaddr + len)
{
const bool is_shared = (region->type() == MemoryRegion::Type::SHARED);
const bool is_writable = (region->status_flags() & O_WRONLY);
const bool want_write = (prot & PROT_WRITE);
if (is_shared && want_write && !is_writable)
return BAN::Error::from_errno(EACCES);
// FIXME: if the region is pinned writable, this may
// cause some problems :D
TRY(region->mprotect(flags));
}
else if (region->overlaps(vaddr, len))
{
const bool is_shared = (region->type() == MemoryRegion::Type::SHARED);
const bool is_writable = (region->status_flags() & O_WRONLY);
const bool want_write = (prot & PROT_WRITE);
if (is_shared && want_write && !is_writable)
return BAN::Error::from_errno(EACCES);
dwarnln("TODO: partial region mprotect");
TRY(region->mprotect(flags | region->flags()));
}
}
return 0;
}
BAN::ErrorOr<long> Process::sys_msync(void* addr, size_t len, int flags)
{
if (flags != MS_SYNC && flags != MS_ASYNC && flags != MS_INVALIDATE)