From patchwork Sun Jan 26 16:38:55 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jordan Rome X-Patchwork-Id: 13950731 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mout.perfora.net (mout.perfora.net [74.208.4.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0780A1553AA for ; Sun, 26 Jan 2025 16:39:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.208.4.197 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737909558; cv=none; b=hwEMGJi4AF5EHuSN+cm7xxo8YSvhMGyE/Uyt3hVlGRkZnlpp0130WjIEl/ijxWGrfhhsQbszBx6A2gpLlLpLPBS5ppOm/QEUir6Ag87M1G+f/UoMOySbqNPW3pYG+V2vu2giDOF/mrXbUyELhFF4HL6eAz4prePbh6eZjE+gzpo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737909558; c=relaxed/simple; bh=9D85DV3lgPWy3EeDetLGNFfsU8kVPL/Pw5F7M7d2Urk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=JmzR08So1qCUfCpRQ/X7sMG4uoCzZjeVsvmm1biYxpex6qOlOj6IY3N0+d9SINHgbCZ+sME7/2GXpKR09vJi9AECfuXv7M05BcMaJfYKnOnOcBpkq5GuHuXdMJs3WBVLCHWZI9q2s7GRdbSWgUXat08e+WCVMn1YVebjnVRHqmk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=jordanrome.com; spf=pass smtp.mailfrom=jordanrome.com; dkim=pass (2048-bit key) header.d=jordanrome.com header.i=linux@jordanrome.com header.b=SotmuTQp; arc=none smtp.client-ip=74.208.4.197 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=jordanrome.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=jordanrome.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=jordanrome.com header.i=linux@jordanrome.com header.b="SotmuTQp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jordanrome.com; s=s1-ionos; t=1737909544; x=1738514344; i=linux@jordanrome.com; bh=WQqKKWz7ABhutvWGSnvN5g84wY9U59VZp9TK3/MXkQg=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:Message-ID: MIME-Version:Content-Transfer-Encoding:cc: content-transfer-encoding:content-type:date:from:message-id: mime-version:reply-to:subject:to; b=SotmuTQp6p9oe61i0QmsNyV44YyPzPm/r4fyWLx+1jgckxYbu2wW0wg/pz/YNLOI 9nUp8lXNsmJQoSYPmvlxPTWk593vl/G21YZg0Y7pi6VsH4Z9ku2vG85QZT0EhiR8m 4fpNJMtCo/0vvvIbe3us/lSo3sKnpRiVceZCRg5NpEQgC3uCVXxi7xoxfhcSbNlnn uzjhGbufZzqDeZtTrzcj0R0s6UTJ5WCm0HHKzqssaDv+NwbDt0Ir2as6ihEQ9p+4o v3KQKePRzdQH3bK3n+Gp15eUQQVjLw1SyvzK4PHo6yETWqSqyVTVQXl/d6oXqJg+F wRgwXxiNllNXFysSdQ== X-UI-Sender-Class: 55c96926-9e95-11ee-ae09-1f7a4046a0f6 Received: from localhost ([69.171.251.6]) by mrelay.perfora.net (mreueus002 [74.208.5.2]) with ESMTPSA (Nemesis) id 0LoWNw-1t0JCv3K1a-00iRAw; Sun, 26 Jan 2025 17:39:03 +0100 From: Jordan Rome To: bpf@vger.kernel.org Cc: linux-mm@kvack.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Kernel Team , Andrew Morton , Shakeel Butt , Alexander Potapenko Subject: [bpf-next v5 1/3] mm: add copy_remote_vm_str Date: Sun, 26 Jan 2025 08:38:55 -0800 Message-ID: <20250126163857.410463-1-linux@jordanrome.com> X-Mailer: git-send-email 2.43.5 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Provags-ID: V03:K1:mw4ISjNDeWsksWR4vWQ24w3F7PImn8YBiiD09AIq01XKohTzUzi ct03kS7aIUuRvvD1HoClOAH8/fUprAlc1i/vt18QjPFRPGhcr/eHxSF3a78iRNgm7ifrGSw uga4l9dFfErE/HgjZ1p33CTxwfVUfHyPfxixsBG5WaP8z2EZVvUu461KPrpQ8j70hnocm/Y DAME1ZYSbcNRzUtM/VYvw== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:1cTmql1GcGY=;9muYWIYUMt27NL+sb4Wf6AvVdYa fQzmY4srFsOgMGccHYmFmxbXE+UKd8LQ9kb4PUoLu6ubCRECrZeZmvpixjAM7FNW7Wxp7DiJT SUhpVkIKNekOO+8t6ze28S7HU5mLbh2bWCyK95uSLYfpSXCecRLpOcg5euk+nW1ZJrcMlNDS6 wYWzXkf8wR7l0+1W3YNERMMaDrVDlNCEIVJ+V5ruJgs2LCdVFRsoanRCol1IXRrTd5kggUBDe nI8kxYavJbYiahv5km5G9SMztq0hLqYpBSglH3ZOce/wVc6JPCwslSmfSXNcewE680YT+o1Mk /sWLGzNDIFoQwXdgApGxPIZJroYQQdkRrV/uf7S5xaGL8LDGDE6Sb71KGINin/o/Z4XWk2pTu o56LxH+9N3OfdvhqdZf3m1uP7L4Ttzb3/wsxgFvKfLZWv3RpM02NvIUaMUrJy5v7vwnk/yjb4 COkE28hPvbhurB8qNQT9w0Ensa9rc99WZPY5I8990GgEk4g0WAQD2x/rq7WJvyZsNFxThsMt3 1pO3HlnhCDEyQzMoukkdTaXa6epiBgBKsyMoSSRD1VRDYWc5jkAPy8oKro9L+l/AjmEIJ2OmR 3ngO4g1QoQgUXb8BrB1QVdVso9DIfj6Rozu0DD/PJHR5jSTGzESC8sq5S3ho4l4YGox/JU8os ftEJEz6A0RYH+9Jf/DCDNwu7QY29XvQ9YmMfBnCoWgorLRx/HpgaBGsFwLgdDio65xNNbhEmf 7FkdbffekrS6twmX4ZI/eFE9xqsb+2F4JTK2J2PpITLmdSeBcanhXruGYoEBdPjBaUFZ3vBUG JKkLP8NskSrtI6Q8emOY5Y3o6GeddFdfU8U/nJHbBeN6zGTQp+FAAs5V/es/yXBDtXXdjmH5I DIiminQGIwlj90i1lYrk4QPdwhzsoxi+5KutvZJn1IvYUosEn1R4aYBIisA6WTXTusA5V6QH+ 7GiAWAJBwsOM1E9ylJM4V3vaZ1ut7v1Xu2IUyrrOgkxG+vAMUyS1tLZGUM7192uCRCnYLo2L8 a352UZs9znlJRIbdDL4sr9pF1Dg52bj5l7sz2imRk0hU2e9hl1Sl/ljx6W5iT29+kg4bYHa3V XnQ0toJLc3nyRZmJgrSlm55vOKswUTn+WQcLJHSC+AbbEDxOZJyw== X-Patchwork-Delegate: bpf@iogearbox.net Similar to `access_process_vm` but specific to strings. Also chunks reads by page and utilizes `strscpy` for handling null termination. Signed-off-by: Jordan Rome --- include/linux/mm.h | 3 ++ mm/memory.c | 118 +++++++++++++++++++++++++++++++++++++++++++++ mm/nommu.c | 67 +++++++++++++++++++++++++ 3 files changed, 188 insertions(+) -- 2.43.5 diff --git a/include/linux/mm.h b/include/linux/mm.h index f02925447e59..f3a05b3eb2f2 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2485,6 +2485,9 @@ extern int access_process_vm(struct task_struct *tsk, unsigned long addr, extern int access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, int len, unsigned int gup_flags); +extern int copy_remote_vm_str(struct task_struct *tsk, unsigned long addr, + void *buf, int len, unsigned int gup_flags); + long get_user_pages_remote(struct mm_struct *mm, unsigned long start, unsigned long nr_pages, unsigned int gup_flags, struct page **pages, diff --git a/mm/memory.c b/mm/memory.c index 398c031be9ba..e1ed5095b258 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -6714,6 +6714,124 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, } EXPORT_SYMBOL_GPL(access_process_vm); +/* + * Copy a string from another process's address space as given in mm. + * If there is any error return -EFAULT. + */ +static int __copy_remote_vm_str(struct mm_struct *mm, unsigned long addr, + void *buf, int len, unsigned int gup_flags) +{ + void *old_buf = buf; + int err = 0; + + if (mmap_read_lock_killable(mm)) + return -EFAULT; + + /* Untag the address before looking up the VMA */ + addr = untagged_addr_remote(mm, addr); + + /* Avoid triggering the temporary warning in __get_user_pages */ + if (!vma_lookup(mm, addr)) { + err = -EFAULT; + goto out; + } + + while (len) { + int bytes, offset, retval; + void *maddr; + struct page *page; + struct vm_area_struct *vma = NULL; + + page = get_user_page_vma_remote(mm, addr, gup_flags, &vma); + + if (IS_ERR(page)) { + /* + * Treat as a total failure for now until we decide how + * to handle the CONFIG_HAVE_IOREMAP_PROT case and + * stack expansion. + */ + err = -EFAULT; + goto out; + } + + bytes = len; + offset = addr & (PAGE_SIZE - 1); + if (bytes > PAGE_SIZE - offset) + bytes = PAGE_SIZE - offset; + + maddr = kmap_local_page(page); + retval = strscpy(buf, maddr + offset, bytes); + unmap_and_put_page(page, maddr); + + if (retval > -1) { + /* Found the end of the string */ + buf += retval; + goto out; + } + + retval = bytes - 1; + buf += retval; + + if (bytes == len) + goto out; + + /* + * Because strscpy always NUL terminates we need to + * copy the last byte in the page if we are going to + * load more pages + */ + addr += retval; + len -= retval; + copy_from_user_page(vma, + page, + addr, + buf, + maddr + (PAGE_SIZE - 1), + 1); + len -= 1; + buf += 1; + addr += 1; + } + +out: + mmap_read_unlock(mm); + if (err) + return err; + + return buf - old_buf; +} + +/** + * copy_remote_vm_str - copy a string from another process's address space. + * @tsk: the task of the target address space + * @addr: start address to read from + * @buf: destination buffer + * @len: number of bytes to copy + * @gup_flags: flags modifying lookup behaviour + * + * The caller must hold a reference on @mm. + * + * Return: number of bytes copied from @addr (source) to @buf (destination); + * not including the trailing NUL. On any error, return -EFAULT. + */ +int copy_remote_vm_str(struct task_struct *tsk, unsigned long addr, + void *buf, int len, unsigned int gup_flags) +{ + struct mm_struct *mm; + int ret; + + mm = get_task_mm(tsk); + if (!mm) + return -EFAULT; + + ret = __copy_remote_vm_str(mm, addr, buf, len, gup_flags); + + mmput(mm); + + return ret; +} +EXPORT_SYMBOL_GPL(copy_remote_vm_str); + /* * Print the name of a VMA. */ diff --git a/mm/nommu.c b/mm/nommu.c index 9cb6e99215e2..ce24ea829c73 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1701,6 +1701,73 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in } EXPORT_SYMBOL_GPL(access_process_vm); +/* + * Copy a string from another process's address space as given in mm. + * If there is any error return -EFAULT. + */ +static int __copy_remote_vm_str(struct mm_struct *mm, unsigned long addr, + void *buf, int len) +{ + int ret; + struct vm_area_struct *vma; + + if (mmap_read_lock_killable(mm)) + return -EFAULT; + + /* the access must start within one of the target process's mappings */ + vma = find_vma(mm, addr); + if (vma) { + /* don't overrun this mapping */ + if (addr + len >= vma->vm_end) + len = vma->vm_end - addr; + + /* only read mappings where it is permitted */ + if (vma->vm_flags & VM_MAYREAD) { + ret = strscpy(buf, (char *)addr, len); + if (ret < 0) + ret = len - 1; + } else { + ret = -EFAULT; + } + } else { + ret = -EFAULT; + } + + mmap_read_unlock(mm); + return ret; +} + +/** + * copy_remote_vm_str - copy a string from another process's address space. + * @tsk: the task of the target address space + * @addr: start address to read from + * @buf: destination buffer + * @len: number of bytes to copy + * @gup_flags: flags modifying lookup behaviour (unused) + * + * The caller must hold a reference on @mm. + * + * Return: number of bytes copied from @addr (source) to @buf (destination); + * not including the trailing NUL. On any error, return -EFAULT. + */ +int copy_remote_vm_str(struct task_struct *tsk, unsigned long addr, + void *buf, int len, unsigned int gup_flags) +{ + struct mm_struct *mm; + int ret; + + mm = get_task_mm(tsk); + if (!mm) + return -EFAULT; + + ret = __copy_remote_vm_str(mm, addr, buf, len); + + mmput(mm); + + return ret; +} +EXPORT_SYMBOL_GPL(copy_remote_vm_str); + /** * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode * @inode: The inode to check