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().
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
include/linux/mm.h | 14 +++++++-------
kernel/sys.c | 50 +-------------------------------------------------
mm/madvise.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 58 insertions(+), 58 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e0549f3d681f6c7a78e8dfa341a810e5a8f96c1..ef40f68c1183d4c95016575a4ee0171e12df9ba4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -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
diff --git a/kernel/sys.c b/kernel/sys.c
index adc0de0aa364aebb23999f621717a5d32599921c..b153fb345ada28ea1a33386a32bcce9cb1b23475 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -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;
diff --git a/mm/madvise.c b/mm/madvise.c
index fca0e9b3e844ad766e83ac04cc0d7f4099c74005..7e8819b5e9a0f183213ffe19d7e52bd5fda5f49d 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -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
--
2.50.0On Tue, Jun 24, 2025 at 03:03:46PM +0200, Vlastimil Babka wrote:
> 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().
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
LGTM, so:
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Thanks for doing this! :)
> ---
> include/linux/mm.h | 14 +++++++-------
> kernel/sys.c | 50 +-------------------------------------------------
> mm/madvise.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> 3 files changed, 58 insertions(+), 58 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e0549f3d681f6c7a78e8dfa341a810e5a8f96c1..ef40f68c1183d4c95016575a4ee0171e12df9ba4 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -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
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index adc0de0aa364aebb23999f621717a5d32599921c..b153fb345ada28ea1a33386a32bcce9cb1b23475 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -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;
> diff --git a/mm/madvise.c b/mm/madvise.c
> index fca0e9b3e844ad766e83ac04cc0d7f4099c74005..7e8819b5e9a0f183213ffe19d7e52bd5fda5f49d 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -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
>
> --
> 2.50.0
>
On 24.06.25 15:03, Vlastimil Babka wrote:
> 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().
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> include/linux/mm.h | 14 +++++++-------
> kernel/sys.c | 50 +-------------------------------------------------
> mm/madvise.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> 3 files changed, 58 insertions(+), 58 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e0549f3d681f6c7a78e8dfa341a810e5a8f96c1..ef40f68c1183d4c95016575a4ee0171e12df9ba4 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -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
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index adc0de0aa364aebb23999f621717a5d32599921c..b153fb345ada28ea1a33386a32bcce9cb1b23475 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -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);
At first I thought whether passing current->mm as an argument might make
it clearer on what we actually operate. But then, "anon_vma" might give
a good hint.
Acked-by: David Hildenbrand <david@redhat.com>
--
Cheers,
David / dhildenb
On Tue, Jun 24, 2025 at 7:04 AM David Hildenbrand <david@redhat.com> wrote:
>
> On 24.06.25 15:03, Vlastimil Babka wrote:
> > 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().
> >
> > Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> > ---
> > include/linux/mm.h | 14 +++++++-------
> > kernel/sys.c | 50 +-------------------------------------------------
> > mm/madvise.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> > 3 files changed, 58 insertions(+), 58 deletions(-)
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 0e0549f3d681f6c7a78e8dfa341a810e5a8f96c1..ef40f68c1183d4c95016575a4ee0171e12df9ba4 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -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
> >
> > diff --git a/kernel/sys.c b/kernel/sys.c
> > index adc0de0aa364aebb23999f621717a5d32599921c..b153fb345ada28ea1a33386a32bcce9cb1b23475 100644
> > --- a/kernel/sys.c
> > +++ b/kernel/sys.c
> > @@ -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);
>
> At first I thought whether passing current->mm as an argument might make
> it clearer on what we actually operate. But then, "anon_vma" might give
> a good hint.
>
> Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
>
> --
> Cheers,
>
> David / dhildenb
>
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