Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit e1d12606 authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: make check_gpte et. al return bool. 



This is a bit neater: we can immediately return if a PTE/PGD/PMD entry
is invalid (which also kills the guest).  It means we don't risk using
invalid entries as we reshuffle the code.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 93a2cdff

drivers/lguest/page_tables.c

+23 −10
Original line number Original line Diff line number Diff line
@@ -259,26 +259,35 @@ static void release_pte(pte_t pte) 
}

}

/*:*/

/*:*/





static void check_gpte(struct lg_cpu *cpu, pte_t gpte)

static bool check_gpte(struct lg_cpu *cpu, pte_t gpte)

{

{

	if ((pte_flags(gpte) & _PAGE_PSE) ||

	if ((pte_flags(gpte) & _PAGE_PSE) ||

	    pte_pfn(gpte) >= cpu->lg->pfn_limit)

	    pte_pfn(gpte) >= cpu->lg->pfn_limit) {

		kill_guest(cpu, "bad page table entry");

		kill_guest(cpu, "bad page table entry");

		return false;

	}

	return true;

}

}





static void check_gpgd(struct lg_cpu *cpu, pgd_t gpgd)

static bool check_gpgd(struct lg_cpu *cpu, pgd_t gpgd)

{

{

	if ((pgd_flags(gpgd) & ~CHECK_GPGD_MASK) ||

	if ((pgd_flags(gpgd) & ~CHECK_GPGD_MASK) ||

	   (pgd_pfn(gpgd) >= cpu->lg->pfn_limit))

	    (pgd_pfn(gpgd) >= cpu->lg->pfn_limit)) {

		kill_guest(cpu, "bad page directory entry");

		kill_guest(cpu, "bad page directory entry");

		return false;

	}

	return true;

}

}





#ifdef CONFIG_X86_PAE

#ifdef CONFIG_X86_PAE

static void check_gpmd(struct lg_cpu *cpu, pmd_t gpmd)

static bool check_gpmd(struct lg_cpu *cpu, pmd_t gpmd)

{

{

	if ((pmd_flags(gpmd) & ~_PAGE_TABLE) ||

	if ((pmd_flags(gpmd) & ~_PAGE_TABLE) ||

	   (pmd_pfn(gpmd) >= cpu->lg->pfn_limit))

	    (pmd_pfn(gpmd) >= cpu->lg->pfn_limit)) {

		kill_guest(cpu, "bad page middle directory entry");

		kill_guest(cpu, "bad page middle directory entry");

		return false;

	}

	return true;

}

}

#endif

#endif
@@ -336,7 +345,8 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode) 
			return false;

			return false;

		}

		}

		/* We check that the Guest pgd is OK. */

		/* We check that the Guest pgd is OK. */

		check_gpgd(cpu, gpgd);

		if (!check_gpgd(cpu, gpgd))

			return false;

		/*

		/*

		 * And we copy the flags to the shadow PGD entry.  The page

		 * And we copy the flags to the shadow PGD entry.  The page

		 * number in the shadow PGD is the page we just allocated.

		 * number in the shadow PGD is the page we just allocated.
@@ -372,7 +382,8 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode) 
		}

		}





		/* We check that the Guest pmd is OK. */

		/* We check that the Guest pmd is OK. */

		check_gpmd(cpu, gpmd);

		if (!check_gpmd(cpu, gpmd))

			return false;





		/*

		/*

		 * And we copy the flags to the shadow PMD entry.  The page

		 * And we copy the flags to the shadow PMD entry.  The page
@@ -421,7 +432,8 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode) 
	 * Check that the Guest PTE flags are OK, and the page number is below

	 * Check that the Guest PTE flags are OK, and the page number is below

	 * the pfn_limit (ie. not mapping the Launcher binary).

	 * the pfn_limit (ie. not mapping the Launcher binary).

	 */

	 */

	check_gpte(cpu, gpte);

	if (!check_gpte(cpu, gpte))

		return false;





	/* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */

	/* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */

	gpte = pte_mkyoung(gpte);

	gpte = pte_mkyoung(gpte);
@@ -857,7 +869,8 @@ static void do_set_pte(struct lg_cpu *cpu, int idx, 
			 * micro-benchmark.

			 * micro-benchmark.

			 */

			 */

			if (pte_flags(gpte) & (_PAGE_DIRTY | _PAGE_ACCESSED)) {

			if (pte_flags(gpte) & (_PAGE_DIRTY | _PAGE_ACCESSED)) {

				check_gpte(cpu, gpte);

				if (!check_gpte(cpu, gpte))

					return;

				set_pte(spte,

				set_pte(spte,

					gpte_to_spte(cpu, gpte,

					gpte_to_spte(cpu, gpte,

						pte_flags(gpte) & _PAGE_DIRTY));

						pte_flags(gpte) & _PAGE_DIRTY));