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fs/proc/kcore: convert read_kcore() to read_kcore_iter()

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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.

Link: https://lkml.kernel.org/r/ebe12c8d70eebd71f487d80095605f3ad0d1489c.1679511146.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes 2023-03-22 18:57:02 +00:00 committed by Andrew Morton
parent 2e1c017077
commit 46c0d6d090
1 changed files with 18 additions and 18 deletions
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36
fs/proc/kcore.c
View File

@ -24,7 +24,7 @@
#include <linux/memblock.h> #include <linux/memblock.h>
#include <linux/init.h> #include <linux/init.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/uaccess.h> #include <linux/uio.h>
#include <asm/io.h> #include <asm/io.h>
#include <linux/list.h> #include <linux/list.h>
#include <linux/ioport.h> #include <linux/ioport.h>
@ -308,9 +308,12 @@ static void append_kcore_note(char *notes, size_t *i, const char *name,
} }
static ssize_t 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; char *buf = file->private_data;
loff_t *fpos = &iocb->ki_pos;
size_t phdrs_offset, notes_offset, data_offset; size_t phdrs_offset, notes_offset, data_offset;
size_t page_offline_frozen = 1; size_t page_offline_frozen = 1;
size_t phdrs_len, notes_len; 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; size_t tsz;
int nphdr; int nphdr;
unsigned long start; unsigned long start;
size_t buflen = iov_iter_count(iter);
size_t orig_buflen = buflen; size_t orig_buflen = buflen;
int ret = 0; 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); 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; ret = -EFAULT;
goto out; goto out;
} }
buffer += tsz;
buflen -= tsz; buflen -= tsz;
*fpos += 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); tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos);
if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset, if (copy_to_iter((char *)phdrs + *fpos - phdrs_offset, tsz,
tsz)) { iter) != tsz) {
kfree(phdrs); kfree(phdrs);
ret = -EFAULT; ret = -EFAULT;
goto out; goto out;
} }
kfree(phdrs); kfree(phdrs);
buffer += tsz;
buflen -= tsz; buflen -= tsz;
*fpos += 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)); min(vmcoreinfo_size, notes_len - i));
tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos); 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); kfree(notes);
ret = -EFAULT; ret = -EFAULT;
goto out; goto out;
} }
kfree(notes); kfree(notes);
buffer += tsz;
buflen -= tsz; buflen -= tsz;
*fpos += tsz; *fpos += tsz;
} }
@ -497,7 +498,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
} }
if (!m) { if (!m) {
if (clear_user(buffer, tsz)) { if (iov_iter_zero(tsz, iter) != tsz) {
ret = -EFAULT; ret = -EFAULT;
goto out; goto out;
} }
@ -508,14 +509,14 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
case KCORE_VMALLOC: case KCORE_VMALLOC:
vread(buf, (char *)start, tsz); vread(buf, (char *)start, tsz);
/* we have to zero-fill user buffer even if no read */ /* 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; ret = -EFAULT;
goto out; goto out;
} }
break; break;
case KCORE_USER: case KCORE_USER:
/* User page is handled prior to normal kernel page: */ /* 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; ret = -EFAULT;
goto out; goto out;
} }
@ -531,7 +532,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
*/ */
if (!page || PageOffline(page) || if (!page || PageOffline(page) ||
is_page_hwpoison(page) || !pfn_is_ram(pfn)) { is_page_hwpoison(page) || !pfn_is_ram(pfn)) {
if (clear_user(buffer, tsz)) { if (iov_iter_zero(tsz, iter) != tsz) {
ret = -EFAULT; ret = -EFAULT;
goto out; 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_VMEMMAP:
case KCORE_TEXT: 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. * 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; ret = -EFAULT;
goto out; goto out;
} }
break; break;
default: default:
pr_warn_once("Unhandled KCORE type: %d\n", m->type); pr_warn_once("Unhandled KCORE type: %d\n", m->type);
if (clear_user(buffer, tsz)) { if (iov_iter_zero(tsz, iter) != tsz) {
ret = -EFAULT; ret = -EFAULT;
goto out; goto out;
} }
@ -559,7 +560,6 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
skip: skip:
buflen -= tsz; buflen -= tsz;
*fpos += tsz; *fpos += tsz;
buffer += tsz;
start += tsz; start += tsz;
tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); 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 = { static const struct proc_ops kcore_proc_ops = {
.proc_read = read_kcore, .proc_read_iter = read_kcore_iter,
.proc_open = open_kcore, .proc_open = open_kcore,
.proc_release = release_kcore, .proc_release = release_kcore,
.proc_lseek = default_llseek, .proc_lseek = default_llseek,