[PATCH v2 03/11] mm/mempolicy: refactor sanitize_mpol_flags for reuse

Gregory Price
2023-12-09T06:59:45Z

split sanitize_mpol_flags into sanitize and validate.

Sanitize is used by set_mempolicy to split (int mode) into mode
and mode_flags, and then validates them.

Validate validates already split flags.

Validate will be reused for new syscalls that accept already
split mode and mode_flags.

Signed-off-by: Gregory Price <gregory.price@memverge.com>
---
mm/mempolicy.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index b4d94646e6a2..65d023720e83 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1463,24 +1463,39 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0;
}

-/* Basic parameter sanity check used by both mbind() and set_mempolicy() */
-static inline int sanitize_mpol_flags(int *mode, unsigned short *flags)
+/*
+ * Basic parameter sanity check used by mbind/set_mempolicy
+ * May modify flags to include internal flags (e.g. MPOL_F_MOF/F_MORON)
+ */
+static inline int validate_mpol_flags(unsigned short mode, unsigned short *flags)
{
- *flags = *mode & MPOL_MODE_FLAGS;
- *mode &= ~MPOL_MODE_FLAGS;
-
- if ((unsigned int)(*mode) >= MPOL_MAX)
+ if ((unsigned int)(mode) >= MPOL_MAX)
return -EINVAL;
if ((*flags & MPOL_F_STATIC_NODES) && (*flags & MPOL_F_RELATIVE_NODES))
return -EINVAL;
if (*flags & MPOL_F_NUMA_BALANCING) {
- if (*mode != MPOL_BIND)
+ if (mode != MPOL_BIND)
return -EINVAL;
*flags |= (MPOL_F_MOF | MPOL_F_MORON);
}
return 0;
}

+/*
+ * Used by mbind/set_memplicy to split and validate mode/flags
+ * set_mempolicy combines (mode | flags), split them out into separate
+ * fields and return just the mode in mode_arg and flags in flags.
+ */
+static inline int sanitize_mpol_flags(int *mode_arg, unsigned short *flags)
+{
+ unsigned short mode = (*mode_arg & ~MPOL_MODE_FLAGS);
+
+ *flags = *mode_arg & MPOL_MODE_FLAGS;
+ *mode_arg = mode;
+
+ return validate_mpol_flags(mode, flags);
+}
+
static long kernel_mbind(unsigned long start, unsigned long len,
unsigned long mode, const unsigned long __user *nmask,
unsigned long maxnode, unsigned int flags)
--
2.39.1