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Message-Id: <20250623-anon_name_cleanup-v1-2-04c94384046f@suse.cz>
Date: Mon, 23 Jun 2025 16:59:51 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Andrew Morton <akpm@...ux-foundation.org>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Lorenzo Stoakes <lorenzo.stoakes@...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>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH RFC 2/2] mm, madvise: move 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 it's mm code so move
it under mm. mm/madvise.c seems to be the most straightforward place as
that's where madvise_set_anon_name() lives, so we can stop declaring the
latter in the header and instead declare prctl_set_vma(). It's not ideal
as prctl is not madvise, but that's the reality we live in, as described
above.
Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
include/linux/mm.h | 13 +++++------
kernel/sys.c | 64 ------------------------------------------------------
mm/madvise.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 63 insertions(+), 73 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e0549f3d681f6c7a78e8dfa341a810e5a8f96c1..1f8c2561c8cf77e9bb695094325401c09c15f3e6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4059,14 +4059,13 @@ 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 prctl_set_vma(unsigned long opt, unsigned long start,
+ unsigned long size, unsigned long arg);
#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 prctl_set_vma(unsigned long opt, unsigned long start,
+ unsigned long size, unsigned long arg)
+{
+ return -EINVAL;
}
#endif
diff --git a/kernel/sys.c b/kernel/sys.c
index adc0de0aa364aebb23999f621717a5d32599921c..247d8925daa6fc86134504042832c2164b5d8277 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2343,70 +2343,6 @@ 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);
- break;
- default:
- error = -EINVAL;
- }
-
- 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 ae29395b4fc7f65a449c5772b1901a90f4195885..4a8e61e2c5025726bc2ce1f323768c5b25cef2c9 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -31,6 +31,7 @@
#include <linux/swapops.h>
#include <linux/shmem_fs.h>
#include <linux/mmu_notifier.h>
+#include <linux/prctl.h>
#include <asm/tlb.h>
@@ -134,8 +135,8 @@ 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;
@@ -165,6 +166,60 @@ int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
madv_behavior.range.end = end;
return madvise_walk_vmas(&madv_behavior);
}
+
+#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 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);
+ break;
+ default:
+ error = -EINVAL;
+ }
+
+ return error;
+}
#else /* CONFIG_ANON_VMA_NAME */
static int replace_anon_vma_name(struct vm_area_struct *vma,
struct anon_vma_name *anon_name)
--
2.50.0
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