Commit 6b233784 authored by Vlastimil Babka's avatar Vlastimil Babka Committed by Andrew Morton
Browse files

mm, madvise: extract mm code from prctl_set_vma() to mm/madvise.c 

Setting anon_name is done via madvise_set_anon_name() and behaves a lot of
like other madvise operations.  However, apparently because madvise() has
lacked the 4th argument and prctl() not, the userspace entry point has
been implemented via prctl(PR_SET_VMA, ...) and handled first by
prctl_set_vma().

Currently prctl_set_vma() lives in kernel/sys.c but setting the
vma->anon_name is mm-specific code so extract it to a new
set_anon_vma_name() function under mm.  mm/madvise.c seems to be the most
straightforward place as that's where madvise_set_anon_name() lives.  Stop
declaring the latter in mm.h and instead declare set_anon_vma_name().

Link: https://lkml.kernel.org/r/20250624-anon_name_cleanup-v2-2-600075462a11@suse.cz


Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Tested-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: default avatarSuren Baghdasaryan <surenb@google.com>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Colin Cross <ccross@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 980d0595

include/linux/mm.h

+7 −7
Original line number Diff line number Diff line
@@ -4059,14 +4059,14 @@ unsigned long wp_shared_mapping_range(struct address_space *mapping, 
#endif



#ifdef CONFIG_ANON_VMA_NAME

int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,

			  unsigned long len_in,

			  struct anon_vma_name *anon_name);

int set_anon_vma_name(unsigned long addr, unsigned long size,

		      const char __user *uname);

#else

static inline int

madvise_set_anon_name(struct mm_struct *mm, unsigned long start,

		      unsigned long len_in, struct anon_vma_name *anon_name) {

	return 0;

static inline

int set_anon_vma_name(unsigned long addr, unsigned long size,

		      const char __user *uname)

{

	return -EINVAL;

}

#endif

kernel/sys.c

+1 −49
Original line number Diff line number Diff line
@@ -2343,54 +2343,14 @@ int __weak arch_lock_shadow_stack_status(struct task_struct *t, unsigned long st 


#define PR_IO_FLUSHER (PF_MEMALLOC_NOIO | PF_LOCAL_THROTTLE)



#ifdef CONFIG_ANON_VMA_NAME



#define ANON_VMA_NAME_MAX_LEN		80

#define ANON_VMA_NAME_INVALID_CHARS	"\\`$[]"



static inline bool is_valid_name_char(char ch)

{

	/* printable ascii characters, excluding ANON_VMA_NAME_INVALID_CHARS */

	return ch > 0x1f && ch < 0x7f &&

		!strchr(ANON_VMA_NAME_INVALID_CHARS, ch);

}



static int prctl_set_vma(unsigned long opt, unsigned long addr,

			 unsigned long size, unsigned long arg)

{

	struct mm_struct *mm = current->mm;

	const char __user *uname;

	struct anon_vma_name *anon_name = NULL;

	int error;



	switch (opt) {

	case PR_SET_VMA_ANON_NAME:

		uname = (const char __user *)arg;

		if (uname) {

			char *name, *pch;



			name = strndup_user(uname, ANON_VMA_NAME_MAX_LEN);

			if (IS_ERR(name))

				return PTR_ERR(name);



			for (pch = name; *pch != '\0'; pch++) {

				if (!is_valid_name_char(*pch)) {

					kfree(name);

					return -EINVAL;

				}

			}

			/* anon_vma has its own copy */

			anon_name = anon_vma_name_alloc(name);

			kfree(name);

			if (!anon_name)

				return -ENOMEM;



		}



		mmap_write_lock(mm);

		error = madvise_set_anon_name(mm, addr, size, anon_name);

		mmap_write_unlock(mm);

		anon_vma_name_put(anon_name);

		error = set_anon_vma_name(addr, size, (const char __user *)arg);

		break;

	default:

		error = -EINVAL;
@@ -2399,14 +2359,6 @@ static int prctl_set_vma(unsigned long opt, unsigned long addr, 
	return error;

}



#else /* CONFIG_ANON_VMA_NAME */

static int prctl_set_vma(unsigned long opt, unsigned long start,

			 unsigned long size, unsigned long arg)

{

	return -EINVAL;

}

#endif /* CONFIG_ANON_VMA_NAME */



static inline unsigned long get_current_mdwe(void)

{

	unsigned long ret = 0;

mm/madvise.c

+50 −2
Original line number Diff line number Diff line
@@ -134,7 +134,7 @@ static int replace_anon_vma_name(struct vm_area_struct *vma, 
	return 0;

}



int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,

static int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,

		unsigned long len_in, struct anon_vma_name *anon_name)

{

	unsigned long end;
@@ -2096,3 +2096,51 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, 
out:

	return ret;

}



#ifdef CONFIG_ANON_VMA_NAME



#define ANON_VMA_NAME_MAX_LEN		80

#define ANON_VMA_NAME_INVALID_CHARS	"\\`$[]"



static inline bool is_valid_name_char(char ch)

{

	/* printable ascii characters, excluding ANON_VMA_NAME_INVALID_CHARS */

	return ch > 0x1f && ch < 0x7f &&

		!strchr(ANON_VMA_NAME_INVALID_CHARS, ch);

}



int set_anon_vma_name(unsigned long addr, unsigned long size,

		      const char __user *uname)

{

	struct anon_vma_name *anon_name = NULL;

	struct mm_struct *mm = current->mm;

	int error;



	if (uname) {

		char *name, *pch;



		name = strndup_user(uname, ANON_VMA_NAME_MAX_LEN);

		if (IS_ERR(name))

			return PTR_ERR(name);



		for (pch = name; *pch != '\0'; pch++) {

			if (!is_valid_name_char(*pch)) {

				kfree(name);

				return -EINVAL;

			}

		}

		/* anon_vma has its own copy */

		anon_name = anon_vma_name_alloc(name);

		kfree(name);

		if (!anon_name)

			return -ENOMEM;

	}



	mmap_write_lock(mm);

	error = madvise_set_anon_name(mm, addr, size, anon_name);

	mmap_write_unlock(mm);

	anon_vma_name_put(anon_name);



	return error;

}

#endif