[PATCH v15 05/17] arms64: untag user pointers passed to memory syscalls

Andrey Konovalov
2019-05-06T16:33:20Z

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

This patch allows tagged pointers to be passed to the following memory
syscalls: brk, get_mempolicy, madvise, mbind, mincore, mlock, mlock2,
mmap, mmap_pgoff, mprotect, mremap, msync, munlock, munmap,
remap_file_pages, shmat and shmdt.

This is done by untagging pointers passed to these syscalls in the
prologues of their handlers.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
arch/arm64/kernel/sys.c | 128 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 127 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
index b44065fb1616..933bb9f3d6ec 100644
--- a/arch/arm64/kernel/sys.c
+++ b/arch/arm64/kernel/sys.c
@@ -35,10 +35,33 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
{
if (offset_in_page(off) != 0)
return -EINVAL;
-
+ addr = untagged_addr(addr);
return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
}

+SYSCALL_DEFINE6(arm64_mmap_pgoff, unsigned long, addr, unsigned long, len,
+ unsigned long, prot, unsigned long, flags,
+ unsigned long, fd, unsigned long, pgoff)
+{
+ addr = untagged_addr(addr);
+ return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
+}
+
+SYSCALL_DEFINE5(arm64_mremap, unsigned long, addr, unsigned long, old_len,
+ unsigned long, new_len, unsigned long, flags,
+ unsigned long, new_addr)
+{
+ addr = untagged_addr(addr);
+ new_addr = untagged_addr(new_addr);
+ return ksys_mremap(addr, old_len, new_len, flags, new_addr);
+}
+
+SYSCALL_DEFINE2(arm64_munmap, unsigned long, addr, size_t, len)
+{
+ addr = untagged_addr(addr);
+ return ksys_munmap(addr, len);
+}
+
SYSCALL_DEFINE1(arm64_personality, unsigned int, personality)
{
if (personality(personality) == PER_LINUX32 &&
@@ -47,10 +70,113 @@ SYSCALL_DEFINE1(arm64_personality, unsigned int, personality)
return ksys_personality(personality);
}

+SYSCALL_DEFINE1(arm64_brk, unsigned long, brk)
+{
+ brk = untagged_addr(brk);
+ return ksys_brk(brk);
+}
+
+SYSCALL_DEFINE5(arm64_get_mempolicy, int __user *, policy,
+ unsigned long __user *, nmask, unsigned long, maxnode,
+ unsigned long, addr, unsigned long, flags)
+{
+ addr = untagged_addr(addr);
+ return ksys_get_mempolicy(policy, nmask, maxnode, addr, flags);
+}
+
+SYSCALL_DEFINE3(arm64_madvise, unsigned long, start,
+ size_t, len_in, int, behavior)
+{
+ start = untagged_addr(start);
+ return ksys_madvise(start, len_in, behavior);
+}
+
+SYSCALL_DEFINE6(arm64_mbind, unsigned long, start, unsigned long, len,
+ unsigned long, mode, const unsigned long __user *, nmask,
+ unsigned long, maxnode, unsigned int, flags)
+{
+ start = untagged_addr(start);
+ return ksys_mbind(start, len, mode, nmask, maxnode, flags);
+}
+
+SYSCALL_DEFINE2(arm64_mlock, unsigned long, start, size_t, len)
+{
+ start = untagged_addr(start);
+ return ksys_mlock(start, len, VM_LOCKED);
+}
+
+SYSCALL_DEFINE2(arm64_mlock2, unsigned long, start, size_t, len)
+{
+ start = untagged_addr(start);
+ return ksys_mlock(start, len, VM_LOCKED);
+}
+
+SYSCALL_DEFINE2(arm64_munlock, unsigned long, start, size_t, len)
+{
+ start = untagged_addr(start);
+ return ksys_munlock(start, len);
+}
+
+SYSCALL_DEFINE3(arm64_mprotect, unsigned long, start, size_t, len,
+ unsigned long, prot)
+{
+ start = untagged_addr(start);
+ return ksys_mprotect_pkey(start, len, prot, -1);
+}
+
+SYSCALL_DEFINE3(arm64_msync, unsigned long, start, size_t, len, int, flags)
+{
+ start = untagged_addr(start);
+ return ksys_msync(start, len, flags);
+}
+
+SYSCALL_DEFINE3(arm64_mincore, unsigned long, start, size_t, len,
+ unsigned char __user *, vec)
+{
+ start = untagged_addr(start);
+ return ksys_mincore(start, len, vec);
+}
+
+SYSCALL_DEFINE5(arm64_remap_file_pages, unsigned long, start,
+ unsigned long, size, unsigned long, prot,
+ unsigned long, pgoff, unsigned long, flags)
+{
+ start = untagged_addr(start);
+ return ksys_remap_file_pages(start, size, prot, pgoff, flags);
+}
+
+SYSCALL_DEFINE3(arm64_shmat, int, shmid, char __user *, shmaddr, int, shmflg)
+{
+ shmaddr = untagged_addr(shmaddr);
+ return ksys_shmat(shmid, shmaddr, shmflg);
+}
+
+SYSCALL_DEFINE1(arm64_shmdt, char __user *, shmaddr)
+{
+ shmaddr = untagged_addr(shmaddr);
+ return ksys_shmdt(shmaddr);
+}
+
/*
* Wrappers to pass the pt_regs argument.
*/
#define sys_personality sys_arm64_personality
+#define sys_mmap_pgoff sys_arm64_mmap_pgoff
+#define sys_mremap sys_arm64_mremap
+#define sys_munmap sys_arm64_munmap
+#define sys_brk sys_arm64_brk
+#define sys_get_mempolicy sys_arm64_get_mempolicy
+#define sys_madvise sys_arm64_madvise
+#define sys_mbind sys_arm64_mbind
+#define sys_mlock sys_arm64_mlock
+#define sys_mlock2 sys_arm64_mlock2
+#define sys_munlock sys_arm64_munlock
+#define sys_mprotect sys_arm64_mprotect
+#define sys_msync sys_arm64_msync
+#define sys_mincore sys_arm64_mincore
+#define sys_remap_file_pages sys_arm64_remap_file_pages
+#define sys_shmat sys_arm64_shmat
+#define sys_shmdt sys_arm64_shmdt

asmlinkage long sys_ni_syscall(const struct pt_regs *);
#define __arm64_sys_ni_syscall sys_ni_syscall
--
2.21.0.1020.gf2820cf01a-goog