| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <2af52908-7e1f-40cd-9297-6eb972dce0ab@lucifer.local>
Date: Tue, 24 Jun 2025 16:28:55 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
David Hildenbrand <david@...hat.com>, Jann Horn <jannh@...gle.com>,
Mike Rapoport <rppt@...nel.org>,
Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
Colin Cross <ccross@...gle.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/4] mm, madvise: extract mm code from prctl_set_vma()
to mm/madvise.c
On 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@...e.cz>
LGTM, so:
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.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
>
Powered by blists - more mailing lists