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

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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: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Lorenzo 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: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Vlastimil Babka
2025-06-24 15:03:46 +02:00
committed by Andrew Morton
parent 980d059558
commit 6b233784b1
3 changed files with 58 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
include/linux/mm.h
View File

@@ -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

50
kernel/sys.c
View File

@@ -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;

52
mm/madvise.c
View File

@@ -134,8 +134,8 @@ 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,
unsigned long len_in, struct anon_vma_name *anon_name)
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;
unsigned long len;
@@ -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