git: 9b65fa694078 - main - linuxolator: implement Linux' PROT_GROWSDOWN

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=9b65fa69407808e710748875b0af98902110f128

commit 9b65fa69407808e710748875b0af98902110f128
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2023-07-29 21:00:51 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2023-08-12 06:28:14 +0000

    linuxolator: implement Linux' PROT_GROWSDOWN
    
    From the Linux man page for mprotect(2):
       PROT_GROWSDOWN
           Apply  the  protection  mode  down to the beginning of a mapping
           that grows downward (which should be a stack segment or a
           segment mapped with the MAP_GROWSDOWN flag set).
    
    Reported by:    dchagin
    Reviewed by:    alc, markj
    Tested by:      pho
    Sponsored by:   The FreeBSD Foundation
    MFC after:      1 week
    Differential revision:  https://reviews.freebsd.org/D41099
---
 sys/compat/freebsd32/freebsd32_misc.c |  2 +-
 sys/compat/linux/linux_mmap.c         | 14 ++++++++++----
 sys/sys/syscallsubr.h                 |  3 ++-
 sys/vm/vm_mmap.c                      |  9 +++++----
 4 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/sys/compat/freebsd32/freebsd32_misc.c b/sys/compat/freebsd32/freebsd32_misc.c
index b7ad379df6e0..07ad68d56037 100644
--- a/sys/compat/freebsd32/freebsd32_misc.c
+++ b/sys/compat/freebsd32/freebsd32_misc.c
@@ -512,7 +512,7 @@ freebsd32_mprotect(struct thread *td, struct freebsd32_mprotect_args *uap)
 		prot |= PROT_EXEC;
 #endif
 	return (kern_mprotect(td, (uintptr_t)PTRIN(uap->addr), uap->len,
-	    prot));
+	    prot, 0));
 }
 
 int
diff --git a/sys/compat/linux/linux_mmap.c b/sys/compat/linux/linux_mmap.c
index 07df6f5fd43d..580f15379e31 100644
--- a/sys/compat/linux/linux_mmap.c
+++ b/sys/compat/linux/linux_mmap.c
@@ -229,16 +229,22 @@ out:
 int
 linux_mprotect_common(struct thread *td, uintptr_t addr, size_t len, int prot)
 {
+	int flags = 0;
 
-	/* XXX Ignore PROT_GROWSDOWN and PROT_GROWSUP for now. */
-	prot &= ~(LINUX_PROT_GROWSDOWN | LINUX_PROT_GROWSUP);
-	if ((prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC)) != 0)
+	/* XXX Ignore PROT_GROWSUP for now. */
+	prot &= ~LINUX_PROT_GROWSUP;
+	if ((prot & ~(LINUX_PROT_GROWSDOWN | PROT_READ | PROT_WRITE |
+	    PROT_EXEC)) != 0)
 		return (EINVAL);
+	if ((prot & LINUX_PROT_GROWSDOWN) != 0) {
+		prot &= ~LINUX_PROT_GROWSDOWN;
+		flags |= VM_MAP_PROTECT_GROWSDOWN;
+	}
 
 #if defined(__amd64__)
 	linux_fixup_prot(td, &prot);
 #endif
-	return (kern_mprotect(td, addr, len, prot));
+	return (kern_mprotect(td, addr, len, prot, flags));
 }
 
 /*
diff --git a/sys/sys/syscallsubr.h b/sys/sys/syscallsubr.h
index 64f1b16f92b9..660b70136714 100644
--- a/sys/sys/syscallsubr.h
+++ b/sys/sys/syscallsubr.h
@@ -216,7 +216,8 @@ int	kern_mmap(struct thread *td, const struct mmap_req *mrp);
 int	kern_mmap_racct_check(struct thread *td, struct vm_map *map,
 	    vm_size_t size);
 int	kern_mmap_maxprot(struct proc *p, int prot);
-int	kern_mprotect(struct thread *td, uintptr_t addr, size_t size, int prot);
+int	kern_mprotect(struct thread *td, uintptr_t addr, size_t size,
+	    int prot, int flags);
 int	kern_msgctl(struct thread *, int, int, struct msqid_ds *);
 int	kern_msgrcv(struct thread *, int, void *, size_t, long, int, long *);
 int	kern_msgsnd(struct thread *, int, const void *, size_t, int, long);
diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c
index 328fef007b1e..7876a055ca91 100644
--- a/sys/vm/vm_mmap.c
+++ b/sys/vm/vm_mmap.c
@@ -658,16 +658,17 @@ int
 sys_mprotect(struct thread *td, struct mprotect_args *uap)
 {
 
-	return (kern_mprotect(td, (uintptr_t)uap->addr, uap->len, uap->prot));
+	return (kern_mprotect(td, (uintptr_t)uap->addr, uap->len,
+	    uap->prot, 0));
 }
 
 int
-kern_mprotect(struct thread *td, uintptr_t addr0, size_t size, int prot)
+kern_mprotect(struct thread *td, uintptr_t addr0, size_t size, int prot,
+    int flags)
 {
 	vm_offset_t addr;
 	vm_size_t pageoff;
 	int vm_error, max_prot;
-	int flags;
 
 	addr = addr0;
 	if ((prot & ~(_PROT_ALL | PROT_MAX(_PROT_ALL))) != 0)
@@ -687,7 +688,7 @@ kern_mprotect(struct thread *td, uintptr_t addr0, size_t size, int prot)
 	if (addr + size < addr)
 		return (EINVAL);
 
-	flags = VM_MAP_PROTECT_SET_PROT;
+	flags |= VM_MAP_PROTECT_SET_PROT;
 	if (max_prot != 0)
 		flags |= VM_MAP_PROTECT_SET_MAXPROT;
 	vm_error = vm_map_protect(&td->td_proc->p_vmspace->vm_map,