From: Jeff Xu jeffxu@google.com
This patch enables PKEY_ENFORCE_API for the mprotect and mprotect_pkey syscalls.
Signed-off-by: Jeff Xujeffxu@google.com --- mm/mprotect.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/mm/mprotect.c b/mm/mprotect.c index 8a68fdca8487..1378be50567d 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -727,9 +727,13 @@ mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
/* * pkey==-1 when doing a legacy mprotect() + * syscall==true if this is called by syscall from userspace. + * Note: this is always true for now, added as a reminder in case that + * do_mprotect_pkey is called directly by kernel in the future. + * Also it is consistent with __do_munmap(). */ static int do_mprotect_pkey(unsigned long start, size_t len, - unsigned long prot, int pkey) + unsigned long prot, int pkey, bool syscall) { unsigned long nstart, end, tmp, reqprot; struct vm_area_struct *vma, *prev; @@ -794,6 +798,21 @@ static int do_mprotect_pkey(unsigned long start, size_t len, } }
+ /* + * When called by syscall from userspace, check if the calling + * thread has the PKEY permission to modify the memory mapping. + */ + if (syscall && + arch_check_pkey_enforce_api(current->mm, start, end) < 0) { + char comm[TASK_COMM_LEN]; + + pr_warn_ratelimited( + "munmap was denied on PKEY_ENFORCE_API memory, pid=%d '%s'\n", + task_pid_nr(current), get_task_comm(comm, current)); + error = -EACCES; + goto out; + } + prev = vma_prev(&vmi); if (start > vma->vm_start) prev = vma; @@ -878,7 +897,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len, SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, unsigned long, prot) { - return do_mprotect_pkey(start, len, prot, -1); + return do_mprotect_pkey(start, len, prot, -1, true); }
#ifdef CONFIG_ARCH_HAS_PKEYS @@ -886,7 +905,7 @@ SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, unsigned long, prot, int, pkey) { - return do_mprotect_pkey(start, len, prot, pkey); + return do_mprotect_pkey(start, len, prot, pkey, true); }
SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)