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Tue, 25 Aug 2026 11:39:29 -0700 (PDT) From: Jann Horn Date: Tue, 25 Aug 2026 20:39:17 +0200 Subject: [PATCH v2 1/3] proc: refactor /proc/$pid/mem to use struct as private_data Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260825-selinux-pokemem-v2-1-b46bc64916d8@google.com> References: <20260825-selinux-pokemem-v2-0-b46bc64916d8@google.com> In-Reply-To: <20260825-selinux-pokemem-v2-0-b46bc64916d8@google.com> To: Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Jeff Xu , =?utf-8?q?Thi=C3=A9baud_Weksteen?= Cc: Alexander Viro , Christian Brauner , Jan Kara , linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, Ondrej Mosnacek , selinux@vger.kernel.org, Andrew Morton , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Pedro Falcato , David Hildenbrand , linux-mm@kvack.org, Jann Horn X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1787683163; l=2508; i=jannh@google.com; s=20240730; h=from:subject:message-id; bh=cMZpfmy5y60iCBgOY8zKfRDT8aXfoJ3FsT1GEaT5qgg=; b=etcdXt6YJPtLzJ6NsslFUvgTrScKbEiz++YkD+u7YgmV0etE8NJizSEaw4u8B+QgHDC0OYnkX 3FNCYVeg1SkCai4r7vUI2wYlcZQZ8x+LEATW601w5uzuzrhWwsKDhRj X-Developer-Key: i=jannh@google.com; a=ed25519; pk=AljNtGOzXeF6khBXDJVVvwSEkVDGnnZZYqfWhP1V+C8= Refactor the handlers for proc_mem_operations to use the new struct mem_private as ->private_data, rather than directly storing an mm_struct* in ->private_data. This is in preparation for adding more state in mem_private in the next commit. Reviewed-by: Jan Kara Acked-by: David Hildenbrand (Arm) Reviewed-by: Lorenzo Stoakes (ARM) Signed-off-by: Jann Horn --- fs/proc/base.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 780f81259052..bec6197329dc 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -848,11 +848,24 @@ static int __mem_open(struct inode *inode, struct file *file, unsigned int mode) return 0; } +/* private_data for proc_mem_operations */ +struct mem_private { + struct mm_struct *mm; +}; + static int mem_open(struct inode *inode, struct file *file) { + struct mem_private *priv __free(kfree) = kmalloc_obj(struct mem_private); + + if (!priv) + return -ENOMEM; if (WARN_ON_ONCE(!(file->f_op->fop_flags & FOP_UNSIGNED_OFFSET))) return -EINVAL; - return __mem_open(inode, file, PTRACE_MODE_ATTACH); + priv->mm = proc_mem_open(inode, PTRACE_MODE_ATTACH); + if (IS_ERR_OR_NULL(priv->mm)) + return priv->mm ? PTR_ERR(priv->mm) : -ESRCH; + file->private_data = no_free_ptr(priv); + return 0; } static bool proc_mem_foll_force(struct file *file, struct mm_struct *mm) @@ -880,7 +893,8 @@ static bool proc_mem_foll_force(struct file *file, struct mm_struct *mm) static ssize_t mem_rw(struct file *file, char __user *buf, size_t count, loff_t *ppos, int write) { - struct mm_struct *mm = file->private_data; + struct mem_private *priv = file->private_data; + struct mm_struct *mm = priv->mm; unsigned long addr = *ppos; ssize_t copied; char *page; @@ -970,12 +984,21 @@ static int mem_release(struct inode *inode, struct file *file) return 0; } +static int mem_release_with_private(struct inode *inode, struct file *file) +{ + struct mem_private *priv = file->private_data; + + mmdrop(priv->mm); + kfree(priv); + return 0; +} + static const struct file_operations proc_mem_operations = { .llseek = mem_lseek, .read = mem_read, .write = mem_write, .open = mem_open, - .release = mem_release, + .release = mem_release_with_private, .fop_flags = FOP_UNSIGNED_OFFSET, }; -- 2.55.0.860.g4b6b3295ed-goog