From: Jeff Xu <[email protected]> can_modify_mm: checks sealing flags for given memory range.
can_modify_vma: checks sealing flags for given vma. Signed-off-by: Jeff Xu <[email protected]> --- include/linux/mm.h | 26 ++++++++++++++++++++++++++ mm/mseal.c | 42 ++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 66 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index b511932df033..b09df8501987 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3299,6 +3299,32 @@ static inline void mm_populate(unsigned long addr, unsigned long len) static inline void mm_populate(unsigned long addr, unsigned long len) {} #endif +#ifdef CONFIG_MSEAL +extern bool can_modify_mm(struct mm_struct *mm, unsigned long start, + unsigned long end, unsigned long checkSeals); + +extern bool can_modify_vma(struct vm_area_struct *vma, + unsigned long checkSeals); + +static inline unsigned long vma_seals(struct vm_area_struct *vma) +{ + return (vma->vm_seals & MM_SEAL_ALL); +} + +#else +static inline bool can_modify_mm(struct mm_struct *mm, unsigned long start, + unsigned long end, unsigned long checkSeals) +{ + return true; +} + +static inline bool can_modify_vma(struct vm_area_struct *vma, + unsigned long checkSeals) +{ + return true; +} +#endif + /* These take the mm semaphore themselves */ extern int __must_check vm_brk(unsigned long, unsigned long); extern int __must_check vm_brk_flags(unsigned long, unsigned long, unsigned long); diff --git a/mm/mseal.c b/mm/mseal.c index ffe4c4c3f1bc..3e9d1c732c38 100644 --- a/mm/mseal.c +++ b/mm/mseal.c @@ -26,6 +26,44 @@ static bool can_do_mseal(unsigned long types, unsigned long flags) return true; } +/* + * check if a vma is sealed for modification. + * return true, if modification is allowed. + */ +bool can_modify_vma(struct vm_area_struct *vma, + unsigned long checkSeals) +{ + if (checkSeals & vma_seals(vma)) + return false; + + return true; +} + +/* + * Check if the vmas of a memory range are allowed to be modified. + * the memory ranger can have a gap (unallocated memory). + * return true, if it is allowed. + */ +bool can_modify_mm(struct mm_struct *mm, unsigned long start, unsigned long end, + unsigned long checkSeals) +{ + struct vm_area_struct *vma; + + VMA_ITERATOR(vmi, mm, start); + + if (!checkSeals) + return true; + + /* going through each vma to check */ + for_each_vma_range(vmi, vma, end) { + if (!can_modify_vma(vma, checkSeals)) + return false; + } + + /* Allow by default. */ + return true; +} + /* * Check if a seal type can be added to VMA. */ @@ -33,7 +71,7 @@ static bool can_add_vma_seals(struct vm_area_struct *vma, unsigned long newSeals { /* When SEAL_MSEAL is set, reject if a new type of seal is added */ if ((vma->vm_seals & MM_SEAL_MSEAL) && - (newSeals & ~(vma->vm_seals & MM_SEAL_ALL))) + (newSeals & ~(vma_seals(vma)))) return false; return true; @@ -45,7 +83,7 @@ static int mseal_fixup(struct vma_iterator *vmi, struct vm_area_struct *vma, { int ret = 0; - if (addtypes & ~(vma->vm_seals & MM_SEAL_ALL)) { + if (addtypes & ~(vma_seals(vma))) { /* * Handle split at start and end. * Note: sealed VMA doesn't merge with other VMAs. -- 2.42.0.655.g421f12c284-goog
