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Wed, 22 Mar 2023 07:19:04 -0700 (PDT) Received: from lucifer.home ([2a00:23c5:dc8c:8701:1663:9a35:5a7b:1d76]) by smtp.googlemail.com with ESMTPSA id f20-20020a7bcd14000000b003e203681b26sm16872855wmj.29.2023.03.22.07.19.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Mar 2023 07:19:03 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton Cc: Baoquan He , Uladzislau Rezki , Matthew Wilcox , David Hildenbrand , Liu Shixin , Jiri Olsa , Jens Axboe , Alexander Viro , Lorenzo Stoakes Subject: [PATCH v5 2/4] fs/proc/kcore: convert read_kcore() to read_kcore_iter() Date: Wed, 22 Mar 2023 14:18:49 +0000 Message-Id: X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 26A69C001E X-Rspamd-Server: rspam01 X-Stat-Signature: 4uqezwabid7ag5w8tessfph4dekkhtuo X-HE-Tag: 1679494745-632385 X-HE-Meta: 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 KCvdQwnP vLCBAz7KB5WX1bbFVZQsarqR3dVXXI5b0zDuQiRCh0Lw3P6mPhnU4yEhmbDfxuUezO9xVTXSjPPLYzLkYyVEw/ssFYZZpX0ilNlu0kmno0dWOjbsVAV9rfCr39/hhkeBMt46738cKrqcS1k7JQtL+BREdLWXAA3E6JrCkwgHIMygn6y2opd6tYwUZX1NnOIlALrllT6NdanfGTRMZA/6DGveiNF1r8wEeGf7Xx1z46o6ohJSkH0kP7V3YOgehZIT+SoBaCdrc1APh3fjorWbGgAbItjw7vgXEF8tZTiiY18lxuxEY8ojMr/XOZtIoLT+QJePvI4s5fcFmGHZ9rmZRadHpt99e9YbrmET7xEFg61A50SXSoZDSdc2EZKbzfV3MzgRueLqu6x9GUF6NnI6eDGEo2P2mrLDglrFdL5iU9DbyBVc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: For the time being we still use a bounce buffer for vread(), however in the next patch we will convert this to interact directly with the iterator and eliminate the bounce buffer altogether. Signed-off-by: Lorenzo Stoakes Reviewed-by: David Hildenbrand --- fs/proc/kcore.c | 36 ++++++++++++++++++------------------ 1 file changed, 18 insertions(+), 18 deletions(-) diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 556f310d6aa4..08b795fd80b4 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -24,7 +24,7 @@ #include #include #include -#include +#include #include #include #include @@ -308,9 +308,12 @@ static void append_kcore_note(char *notes, size_t *i, const char *name, } static ssize_t -read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) +read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) { + struct file *file = iocb->ki_filp; char *buf = file->private_data; + loff_t *fpos = &iocb->ki_pos; + size_t phdrs_offset, notes_offset, data_offset; size_t page_offline_frozen = 1; size_t phdrs_len, notes_len; @@ -318,6 +321,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) size_t tsz; int nphdr; unsigned long start; + size_t buflen = iov_iter_count(iter); size_t orig_buflen = buflen; int ret = 0; @@ -356,12 +360,11 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) }; tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos); - if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) { + if (copy_to_iter((char *)&ehdr + *fpos, tsz, iter) != tsz) { ret = -EFAULT; goto out; } - buffer += tsz; buflen -= tsz; *fpos += tsz; } @@ -398,15 +401,14 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) } tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos); - if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset, - tsz)) { + if (copy_to_iter((char *)phdrs + *fpos - phdrs_offset, tsz, + iter) != tsz) { kfree(phdrs); ret = -EFAULT; goto out; } kfree(phdrs); - buffer += tsz; buflen -= tsz; *fpos += tsz; } @@ -448,14 +450,13 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) min(vmcoreinfo_size, notes_len - i)); tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos); - if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) { + if (copy_to_iter(notes + *fpos - notes_offset, tsz, iter) != tsz) { kfree(notes); ret = -EFAULT; goto out; } kfree(notes); - buffer += tsz; buflen -= tsz; *fpos += tsz; } @@ -497,7 +498,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) } if (!m) { - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -508,14 +509,14 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) case KCORE_VMALLOC: vread(buf, (char *)start, tsz); /* we have to zero-fill user buffer even if no read */ - if (copy_to_user(buffer, buf, tsz)) { + if (copy_to_iter(buf, tsz, iter) != tsz) { ret = -EFAULT; goto out; } break; case KCORE_USER: /* User page is handled prior to normal kernel page: */ - if (copy_to_user(buffer, (char *)start, tsz)) { + if (copy_to_iter((char *)start, tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -531,7 +532,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) */ if (!page || PageOffline(page) || is_page_hwpoison(page) || !pfn_is_ram(pfn)) { - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -541,17 +542,17 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) case KCORE_VMEMMAP: case KCORE_TEXT: /* - * We use _copy_to_user() to bypass usermode hardening + * We use _copy_to_iter() to bypass usermode hardening * which would otherwise prevent this operation. */ - if (_copy_to_user(buffer, (char *)start, tsz)) { + if (_copy_to_iter((char *)start, tsz, iter) != tsz) { ret = -EFAULT; goto out; } break; default: pr_warn_once("Unhandled KCORE type: %d\n", m->type); - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -559,7 +560,6 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) skip: buflen -= tsz; *fpos += tsz; - buffer += tsz; start += tsz; tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); } @@ -603,7 +603,7 @@ static int release_kcore(struct inode *inode, struct file *file) } static const struct proc_ops kcore_proc_ops = { - .proc_read = read_kcore, + .proc_read_iter = read_kcore_iter, .proc_open = open_kcore, .proc_release = release_kcore, .proc_lseek = default_llseek, -- 2.39.2