diff options
| -rw-r--r-- | drivers/char/mem.c | 8 | ||||
| -rw-r--r-- | include/linux/mm.h | 3 | ||||
| -rw-r--r-- | mm/internal.h | 4 | ||||
| -rw-r--r-- | mm/vma.c | 43 | ||||
| -rw-r--r-- | mm/vma_internal.h | 1 | ||||
| -rw-r--r-- | tools/testing/vma/include/dup.h | 36 |
6 files changed, 81 insertions, 14 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 63253d1de5d7..dcfd896b733d 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -506,11 +506,7 @@ static int mmap_zero_prepare(struct vm_area_desc *desc) if (vma_desc_test(desc, VMA_SHARED_BIT)) return shmem_zero_setup_desc(desc); - /* - * This is a highly unique situation where we mark a MAP_PRIVATE mapping - * of /dev/zero anonymous, despite it not being. - */ - vma_desc_set_anonymous(desc); + /* MAP_PRIVATE semantics are taken care for us by core mm. */ return 0; } @@ -698,7 +694,7 @@ static const struct memdev { #ifdef CONFIG_DEVPORT [4] = { "port", &port_fops, 0, 0 }, #endif - [5] = { "zero", &zero_fops, FMODE_NOWAIT, 0666 }, + [DEVZERO_MINOR] = { "zero", &zero_fops, FMODE_NOWAIT, 0666 }, [7] = { "full", &full_fops, 0, 0666 }, [8] = { "random", &random_fops, FMODE_NOWAIT, 0666 }, [9] = { "urandom", &urandom_fops, FMODE_NOWAIT, 0666 }, diff --git a/include/linux/mm.h b/include/linux/mm.h index b6503b5f0010..7614afe99c96 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -740,6 +740,9 @@ static inline bool fault_flag_allow_retry_first(enum fault_flag flags) { FAULT_FLAG_INTERRUPTIBLE, "INTERRUPTIBLE" }, \ { FAULT_FLAG_VMA_LOCK, "VMA_LOCK" } +/* /dev/zero minor device number. Special due to MAP_PRIVATE semantics. */ +#define DEVZERO_MINOR 5 + /* * vm_fault is filled by the pagefault handler and passed to the vma's * ->fault function. The vma's ->fault is responsible for returning a bitmask diff --git a/mm/internal.h b/mm/internal.h index 22f63cb85bd3..41561fdeb56d 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -240,6 +240,10 @@ static inline int mmap_file(struct file *file, struct vm_area_struct *vma) { int err = vfs_mmap(file, vma); + /* Hooks cannot mark themselves anonymous. */ + if (WARN_ON_ONCE(vma_is_anonymous(vma))) + err = -EINVAL; + if (likely(!err)) return 0; @@ -2612,6 +2612,29 @@ static int __mmap_new_file_vma(struct mmap_state *map, return 0; } +static bool map_is_dev_zero(const struct mmap_state *map) +{ + const struct file *file = map->file; + const struct inode *inode = file_inode(file); + + if (!S_ISCHR(inode->i_mode)) + return false; + return imajor(inode) == MEM_MAJOR && iminor(inode) == DEVZERO_MINOR; +} + +static bool map_is_private(const struct mmap_state *map) +{ + return !vma_flags_test(&map->vma_flags, VMA_SHARED_BIT); +} + +static bool map_is_anon(const struct mmap_state *map) +{ + if (!map_is_private(map)) + return false; + + return !map->file || map_is_dev_zero(map); +} + /* * __mmap_new_vma() - Allocate a new VMA for the region, as merging was not * possible. @@ -2625,8 +2648,7 @@ static int __mmap_new_file_vma(struct mmap_state *map, static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap, struct mmap_action *action) { - const bool is_anon = !map->file && - !vma_flags_test(&map->vma_flags, VMA_SHARED_BIT); + const bool is_anon = map_is_anon(map); struct vma_iterator *vmi = map->vmi; int error = 0; struct vm_area_struct *vma; @@ -2642,7 +2664,7 @@ static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap, vma_iter_config(vmi, map->addr, map->end); - if (is_anon) + if (is_anon && !map->file) vma_set_anonymous(vma); vma_set_range(vma, map->addr, map->end, map->pgoff, map->virt_pgoff); @@ -2660,6 +2682,10 @@ static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap, else if (!is_anon) error = shmem_zero_setup(vma); + /* Temporary MAP_PRIVATE-/dev/zero workaround. */ + if (is_anon && map->file) + vma_set_anonymous(vma); + if (error) goto free_iter_vma; @@ -2768,6 +2794,10 @@ static int call_mmap_prepare(struct mmap_state *map, if (err) return err; + /* Hooks cannot mark themselves anonymous. */ + if (!desc->vm_ops) + return -EINVAL; + err = call_action_prepare(map, desc); if (err) return err; @@ -2790,10 +2820,7 @@ static int call_mmap_prepare(struct mmap_state *map, static void set_vma_user_defined_fields(struct vm_area_struct *vma, struct mmap_state *map) { - if (map->vm_ops) - vma->vm_ops = map->vm_ops; - else /* Only /dev/zero should do this. */ - vma_set_anonymous(vma); + vma->vm_ops = map->vm_ops; vma->vm_private_data = map->vm_private_data; } @@ -2873,7 +2900,7 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr, allocated_new = true; } - if (have_mmap_prepare) + if (have_mmap_prepare && !map_is_anon(&map)) set_vma_user_defined_fields(vma, &map); __mmap_complete(&map, vma); diff --git a/mm/vma_internal.h b/mm/vma_internal.h index 4d300e7bbaf4..385c0ab13777 100644 --- a/mm/vma_internal.h +++ b/mm/vma_internal.h @@ -23,6 +23,7 @@ #include <linux/ksm.h> #include <linux/khugepaged.h> #include <linux/list.h> +#include <linux/major.h> #include <linux/maple_tree.h> #include <linux/mempolicy.h> #include <linux/mm.h> diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h index a4a0e2b40504..a5b673b06ee6 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -15,6 +15,20 @@ struct task_struct *get_current(void); #define MMF_HAS_MDWE 28 #define current get_current() +#define MINORBITS 20 +#define MINORMASK ((1U << MINORBITS) - 1) + +#define MAJOR(dev) ((unsigned int) ((dev) >> MINORBITS)) +#define MINOR(dev) ((unsigned int) ((dev) & MINORMASK)) + +#define S_IFMT 00170000 +#define S_IFCHR 0020000 + +#define S_ISCHR(m) (((m) & S_IFMT) == S_IFCHR) + +#define MEM_MAJOR 1 +#define DEVZERO_MINOR 5 + /* * Define the task command name length as enum, then it can be visible to * BPF programs. @@ -23,6 +37,8 @@ enum { TASK_COMM_LEN = 16, }; +typedef unsigned short umode_t; + /* PARTIALLY implemented types. */ struct mm_struct { struct maple_tree mm_mt; @@ -45,6 +61,10 @@ struct address_space { unsigned long flags; atomic_t i_mmap_writable; }; +struct inode { + umode_t i_mode; + dev_t i_rdev; +}; struct file_operations { int (*mmap)(struct file *, struct vm_area_struct *); int (*mmap_prepare)(struct vm_area_desc *); @@ -52,6 +72,7 @@ struct file_operations { struct file { struct address_space *f_mapping; const struct file_operations *f_op; + struct inode *f_inode; }; struct anon_vma_chain { struct anon_vma *anon_vma; @@ -1633,3 +1654,18 @@ static inline pgoff_t linear_virt_page_index(const struct vm_area_struct *vma, return pgoff; } + +static inline struct inode *file_inode(const struct file *f) +{ + return f->f_inode; +} + +static inline unsigned iminor(const struct inode *inode) +{ + return MINOR(inode->i_rdev); +} + +static inline unsigned imajor(const struct inode *inode) +{ + return MAJOR(inode->i_rdev); +} |