Use the recently introduced PCuABI reservation interfaces and add the relevant capability/reservation constraint checks on the mprotect syscall parameters.
Signed-off-by: Amit Daniel Kachhap amitdaniel.kachhap@arm.com --- mm/mprotect.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/mm/mprotect.c b/mm/mprotect.c index c9188e2cb2a6..6b034fb7b5b1 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -32,6 +32,7 @@ #include <linux/sched/sysctl.h> #include <linux/userfaultfd_k.h> #include <linux/memory-tiers.h> +#include <linux/cap_addr_mgmt.h> #include <asm/cacheflush.h> #include <asm/mmu_context.h> #include <asm/tlbflush.h> @@ -728,7 +729,7 @@ mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, /* * pkey==-1 when doing a legacy mprotect() */ -static int do_mprotect_pkey(user_uintptr_t start, size_t len, +static int do_mprotect_pkey(user_uintptr_t usrptr, size_t len, unsigned long prot, int pkey) { unsigned long nstart, end, tmp, reqprot; @@ -739,9 +740,7 @@ static int do_mprotect_pkey(user_uintptr_t start, size_t len, (prot & PROT_READ); struct mmu_gather tlb; struct vma_iterator vmi; - - /* TODO [PCuABI] - capability checks for uaccess */ - start = untagged_addr(start); + unsigned long start = untagged_addr((ptraddr_t)usrptr);
prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ @@ -755,6 +754,12 @@ static int do_mprotect_pkey(user_uintptr_t start, size_t len, end = start + len; if (end <= start) return -ENOMEM; + +#ifdef CONFIG_CHERI_PURECAP_UABI + usrptr = cheri_address_set(usrptr, start); +#endif + if (!capability_owns_range(usrptr, start, len)) + return -EINVAL; if (!arch_validate_prot(prot, start)) return -EINVAL;
@@ -812,6 +817,12 @@ static int do_mprotect_pkey(user_uintptr_t start, size_t len, break; }
+ /* Check if the capability range is valid with mmap lock. */ + if (!reserv_vma_valid_capability(vma, usrptr)) { + error = -ERESERVATION; + break; + } + /* Does the application expect PROT_READ to imply PROT_EXEC */ if (rier && (vma->vm_flags & VM_MAYEXEC)) prot |= PROT_EXEC; @@ -876,18 +887,18 @@ static int do_mprotect_pkey(user_uintptr_t start, size_t len, return error; }
-SYSCALL_DEFINE3(mprotect, user_uintptr_t, start, size_t, len, +SYSCALL_DEFINE3(mprotect, user_uintptr_t, usrptr, size_t, len, unsigned long, prot) { - return do_mprotect_pkey(start, len, prot, -1); + return do_mprotect_pkey(usrptr, len, prot, -1); }
#ifdef CONFIG_ARCH_HAS_PKEYS
-SYSCALL_DEFINE4(pkey_mprotect, user_uintptr_t, start, size_t, len, +SYSCALL_DEFINE4(pkey_mprotect, user_uintptr_t, usrptr, size_t, len, unsigned long, prot, int, pkey) { - return do_mprotect_pkey(start, len, prot, pkey); + return do_mprotect_pkey(usrptr, len, prot, pkey); }
SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)