Commit 9de1fec5 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Linus Torvalds

tracing/kprobes: handle mixed kernel/userspace probes better

Instead of using the dangerous probe_kernel_read and strncpy_from_unsafe
helpers, rework probes to try a user probe based on the address if the
architecture has a common address space for kernel and userspace.

[svens@linux.ibm.com:use strncpy_from_kernel_nofault() in fetch_store_string()]
  Link: http://lkml.kernel.org/r/20200606181903.49384-1-svens@linux.ibm.comSigned-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarSven Schnelle <svens@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200521152301.2587579-15-hch@lst.deSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8d92db5c
...@@ -1200,6 +1200,15 @@ static const struct file_operations kprobe_profile_ops = { ...@@ -1200,6 +1200,15 @@ static const struct file_operations kprobe_profile_ops = {
/* Kprobe specific fetch functions */ /* Kprobe specific fetch functions */
/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
fetch_store_strlen_user(unsigned long addr)
{
const void __user *uaddr = (__force const void __user *)addr;
return strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
}
/* Return the length of string -- including null terminal byte */ /* Return the length of string -- including null terminal byte */
static nokprobe_inline int static nokprobe_inline int
fetch_store_strlen(unsigned long addr) fetch_store_strlen(unsigned long addr)
...@@ -1207,30 +1216,27 @@ fetch_store_strlen(unsigned long addr) ...@@ -1207,30 +1216,27 @@ fetch_store_strlen(unsigned long addr)
int ret, len = 0; int ret, len = 0;
u8 c; u8 c;
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if (addr < TASK_SIZE)
return fetch_store_strlen_user(addr);
#endif
do { do {
ret = probe_kernel_read(&c, (u8 *)addr + len, 1); ret = probe_kernel_read_strict(&c, (u8 *)addr + len, 1);
len++; len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE); } while (c && ret == 0 && len < MAX_STRING_SIZE);
return (ret < 0) ? ret : len; return (ret < 0) ? ret : len;
} }
/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
fetch_store_strlen_user(unsigned long addr)
{
const void __user *uaddr = (__force const void __user *)addr;
return strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
}
/* /*
* Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
* length and relative data location. * with max length and relative data location.
*/ */
static nokprobe_inline int static nokprobe_inline int
fetch_store_string(unsigned long addr, void *dest, void *base) fetch_store_string_user(unsigned long addr, void *dest, void *base)
{ {
const void __user *uaddr = (__force const void __user *)addr;
int maxlen = get_loc_len(*(u32 *)dest); int maxlen = get_loc_len(*(u32 *)dest);
void *__dest; void *__dest;
long ret; long ret;
...@@ -1240,11 +1246,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base) ...@@ -1240,11 +1246,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
__dest = get_loc_data(dest, base); __dest = get_loc_data(dest, base);
/* ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
* Try to get string again, since the string can be changed while
* probing.
*/
ret = strncpy_from_unsafe(__dest, (void *)addr, maxlen);
if (ret >= 0) if (ret >= 0)
*(u32 *)dest = make_data_loc(ret, __dest - base); *(u32 *)dest = make_data_loc(ret, __dest - base);
...@@ -1252,35 +1254,37 @@ fetch_store_string(unsigned long addr, void *dest, void *base) ...@@ -1252,35 +1254,37 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
} }
/* /*
* Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
* with max length and relative data location. * length and relative data location.
*/ */
static nokprobe_inline int static nokprobe_inline int
fetch_store_string_user(unsigned long addr, void *dest, void *base) fetch_store_string(unsigned long addr, void *dest, void *base)
{ {
const void __user *uaddr = (__force const void __user *)addr;
int maxlen = get_loc_len(*(u32 *)dest); int maxlen = get_loc_len(*(u32 *)dest);
void *__dest; void *__dest;
long ret; long ret;
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if ((unsigned long)addr < TASK_SIZE)
return fetch_store_string_user(addr, dest, base);
#endif
if (unlikely(!maxlen)) if (unlikely(!maxlen))
return -ENOMEM; return -ENOMEM;
__dest = get_loc_data(dest, base); __dest = get_loc_data(dest, base);
ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); /*
* Try to get string again, since the string can be changed while
* probing.
*/
ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
if (ret >= 0) if (ret >= 0)
*(u32 *)dest = make_data_loc(ret, __dest - base); *(u32 *)dest = make_data_loc(ret, __dest - base);
return ret; return ret;
} }
static nokprobe_inline int
probe_mem_read(void *dest, void *src, size_t size)
{
return probe_kernel_read(dest, src, size);
}
static nokprobe_inline int static nokprobe_inline int
probe_mem_read_user(void *dest, void *src, size_t size) probe_mem_read_user(void *dest, void *src, size_t size)
{ {
...@@ -1289,6 +1293,16 @@ probe_mem_read_user(void *dest, void *src, size_t size) ...@@ -1289,6 +1293,16 @@ probe_mem_read_user(void *dest, void *src, size_t size)
return probe_user_read(dest, uaddr, size); return probe_user_read(dest, uaddr, size);
} }
static nokprobe_inline int
probe_mem_read(void *dest, void *src, size_t size)
{
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if ((unsigned long)src < TASK_SIZE)
return probe_mem_read_user(dest, src, size);
#endif
return probe_kernel_read_strict(dest, src, size);
}
/* Note that we don't verify it, since the code does not come from user space */ /* Note that we don't verify it, since the code does not come from user space */
static int static int
process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest, process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
......
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