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[kernel] Add new zero_ok flag to syscall params

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The new zero_ok flag is similar to optional for reference parameters,
but only in cases where there is a length parameter. If that parameter
is a reference parameter itself and is null, or it is non-null and
contains a non-zero length, or there is no length parameter, then the
main parameter may not be null.
This commit is contained in:
Justin C. Miller
2022-01-30 14:21:08 -08:00
parent b6218a1121
commit da5c1e9833
3 changed files with 37 additions and 13 deletions
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42
src/kernel/syscall_verify.cpp.cog
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@@ -22,11 +22,34 @@ for obj in syscalls.exposes:
//[[[end]]]
namespace {
enum class req { required, optional, zero_ok };
template <typename T>
__attribute__((always_inline))
inline bool check_refparam(const T* param, bool optional) {
return reinterpret_cast<uintptr_t>(param) < arch::kernel_offset &&
(optional || param);
inline bool range_check(const T* param) {
return reinterpret_cast<uintptr_t>(param) < arch::kernel_offset;
}
template <typename T>
__attribute__((always_inline))
inline bool check_refparam(const T* param, req required) {
return range_check(param) && ((required == req::optional) || param);
}
template <typename T>
__attribute__((always_inline))
inline bool check_refparam(const T* param, size_t len, req required) {
bool nullok = (required == req::optional) || (required == req::zero_ok && !len);
return range_check(param) && (param || nullok);
}
template <typename T>
__attribute__((always_inline))
inline bool check_refparam(const T* param, size_t *len, req required) {
if (!range_check(len)) return false;
if (len) return check_refparam(param, *len, required);
// if len is null but param is not, call that invalid.
else return !param && required == req::optional;
}
// When called with more than 6 arguments, the 7th argument to the
@@ -67,7 +90,7 @@ for id, scope, method in syscalls.methods:
argdefs.append(("j6_handle_t *", "self"))
cxxargdefs.append("j6_handle_t *self")
args.append("self")
refparams.append(("self", False))
refparams.append(("self", "required"))
elif not method.static:
argdefs.append(("j6_handle_t", "self"))
@@ -104,10 +127,9 @@ for id, scope, method in syscalls.methods:
if param.refparam:
subs = param.type.c_names(param.options)
refparams.append((param.name + subs[0][1], param.optional))
if param.outparam:
for sub in subs[1:]:
refparams.append((param.name + sub[1], param.optional))
checkargs = map(lambda x: f"{param.name}{x[1]}", subs)
refparams.append((", ".join(checkargs), param.optional))
first_args = ", ".join(map(lambda x: f"{x[0]} {x[1]}", argdefs[:6]))
extra_argdefs = argdefs[6:]
@@ -124,8 +146,8 @@ for id, scope, method in syscalls.methods:
if extra_argdefs:
cog.outl()
for pname, optional in refparams:
cog.outl(f" if (!check_refparam({pname}, {cbool[optional]}))")
for checkargs, optional in refparams:
cog.outl(f" if (!check_refparam({checkargs}, req::{optional}))")
cog.outl( " return j6_err_invalid_arg;")
cog.outl()