linux-kernel - [RFC PATCH 4/6] mm: mempolicy: Add and expose mpol

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <17bb8e925c08f27c627cd1f2bbb2714daf590c1d.1681430907.git.ackerleytng@google.com>
Date:   Fri, 14 Apr 2023 00:11:53 +0000
From:   Ackerley Tng <ackerleytng@...gle.com>
To:     kvm@...r.kernel.org, linux-api@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, qemu-devel@...gnu.org
Cc:     aarcange@...hat.com, ak@...ux.intel.com, akpm@...ux-foundation.org,
        arnd@...db.de, bfields@...ldses.org, bp@...en8.de,
        chao.p.peng@...ux.intel.com, corbet@....net, dave.hansen@...el.com,
        david@...hat.com, ddutile@...hat.com, dhildenb@...hat.com,
        hpa@...or.com, hughd@...gle.com, jlayton@...nel.org,
        jmattson@...gle.com, joro@...tes.org, jun.nakajima@...el.com,
        kirill.shutemov@...ux.intel.com, linmiaohe@...wei.com,
        luto@...nel.org, mail@...iej.szmigiero.name, mhocko@...e.com,
        michael.roth@....com, mingo@...hat.com, naoya.horiguchi@....com,
        pbonzini@...hat.com, qperret@...gle.com, rppt@...nel.org,
        seanjc@...gle.com, shuah@...nel.org, steven.price@....com,
        tabba@...gle.com, tglx@...utronix.de, vannapurve@...gle.com,
        vbabka@...e.cz, vkuznets@...hat.com, wanpengli@...cent.com,
        wei.w.wang@...el.com, x86@...nel.org, yu.c.zhang@...ux.intel.com,
        muchun.song@...ux.dev, feng.tang@...el.com, brgerst@...il.com,
        rdunlap@...radead.org, masahiroy@...nel.org,
        mailhol.vincent@...adoo.fr, Ackerley Tng <ackerleytng@...gle.com>
Subject: [RFC PATCH 4/6] mm: mempolicy: Add and expose mpol_create

mpol_create builds a mempolicy based on mode, nmask and maxnode.

mpol_create is exposed for use in memfd_restricted_bind() in a later
patch.

Signed-off-by: Ackerley Tng <ackerleytng@...gle.com>
---
 include/linux/mempolicy.h |  2 ++
 mm/mempolicy.c            | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 9a2a2dd95432..15facd9de087 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -125,6 +125,8 @@ struct shared_policy {
 };
 
 int vma_dup_policy(struct vm_area_struct *src, struct vm_area_struct *dst);
+struct mempolicy *mpol_create(
+	unsigned long mode, const unsigned long __user *nmask, unsigned long maxnode)
 void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol);
 int __mpol_set_shared_policy(struct shared_policy *info, struct mempolicy *mpol,
 			     unsigned long pgoff_start, unsigned long npages);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index f3fa5494e4a8..f4fe241c17ff 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -3181,3 +3181,42 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
 		p += scnprintf(p, buffer + maxlen - p, ":%*pbl",
 			       nodemask_pr_args(&nodes));
 }
+
+/**
+ * mpol_create - build mempolicy based on mode, nmask and maxnode
+ * @mode:  policy mode, as in MPOL_MODE_FLAGS
+ * @nmask:  node mask from userspace
+ * @maxnode:  number of valid bits in nmask
+ *
+ * Will allocate a new struct mempolicy that has to be released with
+ * mpol_put. Will also take and release the write lock mmap_lock in current->mm.
+ */
+struct mempolicy *mpol_create(
+	unsigned long mode, const unsigned long __user *nmask, unsigned long maxnode)
+{
+	int err;
+	unsigned short mode_flags;
+	nodemask_t nodes;
+	int lmode = mode;
+	struct mempolicy *mpol;
+
+	err = sanitize_mpol_flags(&lmode, &mode_flags);
+	if (err)
+		return ERR_PTR(err);
+
+	err = get_nodes(&nodes, nmask, maxnode);
+	if (err)
+		return ERR_PTR(err);
+
+	mpol = mpol_new(mode, mode_flags, &nodes);
+	if (IS_ERR(mpol))
+		return mpol;
+
+	err = mpol_init_from_nodemask(mpol, &nodes, true);
+	if (err) {
+		mpol_put(mpol);
+		return ERR_PTR(err);
+	}
+
+	return mpol;
+}
-- 
2.40.0.634.g4ca3ef3211-goog