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Add permission changing kernel function

This commit is contained in:
Danila Fedorin 2019-04-19 17:36:23 -07:00
parent e484704ce8
commit e1d239139a
1 changed files with 61 additions and 11 deletions
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72
kern/monitor.c
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@ -30,7 +30,9 @@ static struct Command commands[] = {
{ "help", "Display this list of commands", mon_help },
{ "kerninfo", "Display information about the kernel", mon_kerninfo },
{ "backtrace", "Display current backtrace", mon_backtrace },
{ "showmappings", "Display the physical mappings for range", mon_showmappings }
{ "showmappings", "Display the physical mappings for range", mon_showmappings },
{ "mperms", "Change the permissions of a memory range", mon_mperms }
};
/***** Implementations of basic kernel monitor commands *****/
@ -104,21 +106,26 @@ decode_pte_perms(pte_t pte, char* buffer) {
return buffer;
}
void
get_pagebounds(char* one, char* two, uintptr_t* pone, uintptr_t* ptwo) {
long from = strtol(one, NULL, 0);
long to = strtol(two, NULL, 0);
*pone = ROUNDDOWN(from, PGSIZE);
*ptwo = ROUNDUP(to, PGSIZE);
if(*pone != from) cprintf(ACOL_WARN("Aligning start address %p down to %p\n"),
from, *pone);
if(*ptwo != to) cprintf(ACOL_WARN("Aligning end address %p up to %p\n"),
to, *ptwo);
}
int
mon_showmappings(int argc, char** argv, struct Trapframe* tf) {
EXPECT_ARGS(2, argc);
long from = strtol(argv[1], NULL, 0);
long to = strtol(argv[2], NULL, 0);
uintptr_t va_start = ROUNDDOWN(from, PGSIZE);
uintptr_t va_end = ROUNDUP(to, PGSIZE);
if(va_start != from) cprintf(ACOL_WARN("Aligning start address %p down to %p\n"),
from, va_start);
if(va_end != to) cprintf(ACOL_WARN("Aligning end address %p up to %p\n"),
to, va_end);
uintptr_t va_start, va_end;
char buffer[3] = {0};
get_pagebounds(argv[1], argv[2], &va_start, &va_end);
if(va_start == va_end) va_end += PGSIZE;
while(va_start < va_end) {
pte_t* pte = pgdir_walk(kern_pgdir, (const void*) va_start, 0);
@ -137,6 +144,49 @@ mon_showmappings(int argc, char** argv, struct Trapframe* tf) {
return 0;
}
int mon_mperms(int argc, char** argv, struct Trapframe* tf) {
EXPECT_ARGS(3, argc);
pte_t perms = 0;
enum {
PERM_ADD,
PERM_REMOVE,
PERM_SET
} pmode;
const char* str = argv[1];
if(str[0] == '+') { pmode = PERM_ADD; str++; }
else if(str[0] == '-') { pmode = PERM_REMOVE; str++; }
else pmode = PERM_SET;
while(*str) {
if(*str == 'w') perms |= PTE_W;
else if(*str == 'u') perms |= PTE_U;
else {
cprintf(ACOL_ERR("Unknown permission character %c\n"), *str);
return 1;
}
str++;
}
uintptr_t va_start, va_end;
get_pagebounds(argv[2], argv[3], &va_start, &va_end);
if(va_start == va_end) va_end += PGSIZE;
while(va_start < va_end) {
pte_t* pte = pgdir_walk(kern_pgdir, (void*) va_start, 0);
if(!pte || !(*pte & PTE_P)) { va_start += PGSIZE; continue; }
if(pmode == PERM_ADD) {
*pte |= perms;
} else if(pmode == PERM_REMOVE) {
*pte &= ~perms;
} else if(pmode == PERM_SET) {
*pte = PTE_ADDR(*pte) | perms | PTE_P;
}
va_start += PGSIZE;
}
return 0;
}
/***** Kernel monitor command interpreter *****/