The exported interface read_from_oldmem() passes user pointer
without __user annotation and does unnecessary user/kernel pointer
conversions during the pointer propagation.
Hence it is modified to have a new parameter for user pointer.
Also a helper macro read_from_oldmem_to_kernel is added for clear
readability from callsite when calling read_from_oldmem() for copying
to kernel buffer.
There are several internal functions used here such as read_vmcore(),
__read_vmcore(), copy_to() and vmcoredd_copy_dumps() which are
re-structured to avoid the unnecessary user/kernel pointer conversions.
x86_64 crash dump is also modified to use this new interface.
No functionality change intended.
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: x86 <x86@xxxxxxxxxx>
Cc: kexec <kexec@xxxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel <linux-fsdevel@xxxxxxxxxxxxxxx>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@xxxxxxx>
---
arch/x86/kernel/crash_dump_64.c | 4 +-
fs/proc/vmcore.c | 88 +++++++++++++++++++--------------
include/linux/crash_dump.h | 12 +++--
3 files changed, 60 insertions(+), 44 deletions(-)
diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
index a7f617a3981d..6433513ef43a 100644
--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c
@@ -74,6 +74,6 @@ ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
{
- return read_from_oldmem(buf, count, ppos, 0,
- cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
+ return read_from_oldmem_to_kernel(buf, count, ppos,
+ cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
}
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 509f85148fee..39b4353bd37c 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -70,6 +70,14 @@ static bool vmcore_cb_unstable;
/* Whether the vmcore has been opened once. */
static bool vmcore_opened;
+#define ptr_add(utarget, ktarget, size) \
+({ \
+ if (utarget) \
+ utarget += size; \
+ else \
+ ktarget += size; \
+})
+
void register_vmcore_cb(struct vmcore_cb *cb)
{
down_write(&vmcore_cb_rwsem);
@@ -132,9 +140,8 @@ static int open_vmcore(struct inode *inode, struct file *file)
}
/* Reads a page from the oldmem device from given offset. */
-ssize_t read_from_oldmem(char *buf, size_t count,
- u64 *ppos, int userbuf,
- bool encrypted)
+ssize_t read_from_oldmem(char __user *ubuf, char *kbuf, size_t count,
+ u64 *ppos, bool encrypted)
{
unsigned long pfn, offset;
size_t nr_bytes;
@@ -156,19 +163,27 @@ ssize_t read_from_oldmem(char *buf, size_t count,
/* If pfn is not ram, return zeros for sparse dump files */
if (!pfn_is_ram(pfn)) {
tmp = 0;
- if (!userbuf)
- memset(buf, 0, nr_bytes);
- else if (clear_user(buf, nr_bytes))
+ if (kbuf)
+ memset(kbuf, 0, nr_bytes);
+ else if (clear_user(ubuf, nr_bytes))
tmp = -EFAULT;
} else {
- if (encrypted)
- tmp = copy_oldmem_page_encrypted(pfn, buf,
+ if (encrypted && ubuf)
+ tmp = copy_oldmem_page_encrypted(pfn,
+ (__force char *)ubuf,
+ nr_bytes,
+ offset, 1);
+ else if (encrypted && kbuf)
+ tmp = copy_oldmem_page_encrypted(pfn,
+ kbuf,
nr_bytes,
- offset,
- userbuf);
+ offset, 0);
+ else if (ubuf)
+ tmp = copy_oldmem_page(pfn, (__force char *)ubuf,
+ nr_bytes, offset, 1);
else
- tmp = copy_oldmem_page(pfn, buf, nr_bytes,
- offset, userbuf);
+ tmp = copy_oldmem_page(pfn, kbuf, nr_bytes,
+ offset, 0);
}
if (tmp < 0) {
up_read(&vmcore_cb_rwsem);
@@ -177,7 +192,7 @@ ssize_t read_from_oldmem(char *buf, size_t count,
*ppos += nr_bytes;
count -= nr_bytes;
- buf += nr_bytes;
+ ptr_add(ubuf, kbuf, nr_bytes);
read += nr_bytes;
++pfn;
offset = 0;
@@ -206,7 +221,7 @@ void __weak elfcorehdr_free(unsigned long long addr)
*/
ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
{
- return read_from_oldmem(buf, count, ppos, 0, false);
+ return read_from_oldmem_to_kernel(buf, count, ppos, false);
}
/*
@@ -214,7 +229,7 @@ ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
*/
ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
{
- return read_from_oldmem(buf, count, ppos, 0, cc_platform_has(CC_ATTR_MEM_ENCRYPT));
+ return read_from_oldmem_to_kernel(buf, count, ppos, cc_platform_has(CC_ATTR_MEM_ENCRYPT));
}
/*
@@ -239,21 +254,21 @@ copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
}
/*
- * Copy to either kernel or user space
+ * Copy to either kernel or user space buffer
*/
-static int copy_to(void *target, void *src, size_t size, int userbuf)
+static int copy_to(void __user *utarget, void *ktarget, void *src, size_t size)
{
- if (userbuf) {
- if (copy_to_user((char __user *) target, src, size))
+ if (utarget) {
+ if (copy_to_user(utarget, src, size))
return -EFAULT;
} else {
- memcpy(target, src, size);
+ memcpy(ktarget, src, size);
}
return 0;
}
#ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
-static int vmcoredd_copy_dumps(void *dst, u64 start, size_t size, int userbuf)
+static int vmcoredd_copy_dumps(void __user *udst, void *kdst, u64 start, size_t size)
{
struct vmcoredd_node *dump;
u64 offset = 0;
@@ -266,15 +281,14 @@ static int vmcoredd_copy_dumps(void *dst, u64 start, size_t size, int userbuf)
if (start < offset + dump->size) {
tsz = min(offset + (u64)dump->size - start, (u64)size);
buf = dump->buf + start - offset;
- if (copy_to(dst, buf, tsz, userbuf)) {
+ if (copy_to(udst, kdst, buf, tsz)) {
ret = -EFAULT;
goto out_unlock;
}
size -= tsz;
start += tsz;
- dst += tsz;
-
+ ptr_add(udst, kdst, tsz);
/* Leave now if buffer filled already */
if (!size)
goto out_unlock;
@@ -329,8 +343,8 @@ static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst,
/* Read from the ELF header and then the crash dump. On error, negative value is
* returned otherwise number of bytes read are returned.
*/
-static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
- int userbuf)
+static ssize_t __read_vmcore(char __user *ubuffer, char *kbuffer, size_t buflen,
+ loff_t *fpos)
{
ssize_t acc = 0, tmp;
size_t tsz;
@@ -347,11 +361,11 @@ static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
/* Read ELF core header */
if (*fpos < elfcorebuf_sz) {
tsz = min(elfcorebuf_sz - (size_t)*fpos, buflen);
- if (copy_to(buffer, elfcorebuf + *fpos, tsz, userbuf))
+ if (copy_to(ubuffer, kbuffer, elfcorebuf + *fpos, tsz))
return -EFAULT;
buflen -= tsz;
*fpos += tsz;
- buffer += tsz;
+ ptr_add(ubuffer, kbuffer, tsz);
acc += tsz;
/* leave now if filled buffer already */
@@ -378,12 +392,12 @@ static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
tsz = min(elfcorebuf_sz + vmcoredd_orig_sz -
(size_t)*fpos, buflen);
start = *fpos - elfcorebuf_sz;
- if (vmcoredd_copy_dumps(buffer, start, tsz, userbuf))
+ if (vmcoredd_copy_dumps(ubuffer, kbuffer, start, tsz))
return -EFAULT;
buflen -= tsz;
*fpos += tsz;
- buffer += tsz;
+ ptr_add(ubuffer, kbuffer, tsz);
acc += tsz;
/* leave now if filled buffer already */
@@ -395,12 +409,12 @@ static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
/* Read remaining elf notes */
tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)*fpos, buflen);
kaddr = elfnotes_buf + *fpos - elfcorebuf_sz - vmcoredd_orig_sz;
- if (copy_to(buffer, kaddr, tsz, userbuf))
+ if (copy_to(ubuffer, kbuffer, kaddr, tsz))
return -EFAULT;
buflen -= tsz;
*fpos += tsz;
- buffer += tsz;
+ ptr_add(ubuffer, kbuffer, tsz);
acc += tsz;
/* leave now if filled buffer already */
@@ -414,13 +428,13 @@ static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
m->offset + m->size - *fpos,
buflen);
start = m->paddr + *fpos - m->offset;
- tmp = read_from_oldmem(buffer, tsz, &start,
- userbuf, cc_platform_has(CC_ATTR_MEM_ENCRYPT));
+ tmp = read_from_oldmem(ubuffer, kbuffer, tsz, &start,
+ cc_platform_has(CC_ATTR_MEM_ENCRYPT));
if (tmp < 0)
return tmp;
buflen -= tsz;
*fpos += tsz;
- buffer += tsz;
+ ptr_add(ubuffer, kbuffer, tsz);
acc += tsz;
/* leave now if filled buffer already */
@@ -435,7 +449,7 @@ static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
static ssize_t read_vmcore(struct file *file, char __user *buffer,
size_t buflen, loff_t *fpos)
{
- return __read_vmcore((__force char *) buffer, buflen, fpos, 1);
+ return __read_vmcore(buffer, NULL, buflen, fpos);
}
/*
@@ -461,7 +475,7 @@ static vm_fault_t mmap_vmcore_fault(struct vm_fault *vmf)
if (!PageUptodate(page)) {
offset = (loff_t) index << PAGE_SHIFT;
buf = __va((page_to_pfn(page) << PAGE_SHIFT));
- rc = __read_vmcore(buf, PAGE_SIZE, &offset, 0);
+ rc = __read_vmcore(NULL, buf, PAGE_SIZE, &offset);
if (rc < 0) {
unlock_page(page);
put_page(page);
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 620821549b23..eb0ed423ccc8 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -135,16 +135,18 @@ static inline int vmcore_add_device_dump(struct vmcoredd_data *data)
#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
#ifdef CONFIG_PROC_VMCORE
-ssize_t read_from_oldmem(char *buf, size_t count,
- u64 *ppos, int userbuf,
- bool encrypted);
+ssize_t read_from_oldmem(char __user *ubuf, char *kbuf, size_t count,
+ u64 *ppos, bool encrypted);
#else
-static inline ssize_t read_from_oldmem(char *buf, size_t count,
- u64 *ppos, int userbuf,
+static inline ssize_t read_from_oldmem(char __user *ubuf, char *kbuf,
+ size_t count, u64 *ppos,
bool encrypted)
{
return -EOPNOTSUPP;
}
#endif /* CONFIG_PROC_VMCORE */
+#define read_from_oldmem_to_kernel(buf, count, ppos, encrypted) \
+ read_from_oldmem(NULL, buf, count, ppos, encrypted)
+
#endif /* LINUX_CRASHDUMP_H */
--
2.17.1
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