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tracing/kprobes: handle mixed kernel/userspace probes better

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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.com

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Andrew 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.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Hellwig 2020-06-08 21:34:44 -07:00 committed by Linus Torvalds
parent 8d92db5c04
commit 9de1fec50b
1 changed files with 51 additions and 37 deletions
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88
kernel/trace/trace_kprobe.c
View File

@ -1200,21 +1200,6 @@ static const struct file_operations kprobe_profile_ops = {
/* Kprobe specific fetch functions */
/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
fetch_store_strlen(unsigned long addr)
{
int ret, len = 0;
u8 c;
do {
ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE);
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)
@ -1224,31 +1209,24 @@ fetch_store_strlen_user(unsigned long addr)
return strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
}
/*
* Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
* length and relative data location.
*/
/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
fetch_store_string(unsigned long addr, void *dest, void *base)
fetch_store_strlen(unsigned long addr)
{
int maxlen = get_loc_len(*(u32 *)dest);
void *__dest;
long ret;
int ret, len = 0;
u8 c;
if (unlikely(!maxlen))
return -ENOMEM;
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if (addr < TASK_SIZE)
return fetch_store_strlen_user(addr);
#endif
__dest = get_loc_data(dest, base);
do {
ret = probe_kernel_read_strict(&c, (u8 *)addr + len, 1);
len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE);
/*
* Try to get string again, since the string can be changed while
* probing.
*/
ret = strncpy_from_unsafe(__dest, (void *)addr, maxlen);
if (ret >= 0)
*(u32 *)dest = make_data_loc(ret, __dest - base);
return ret;
return (ret < 0) ? ret : len;
}
/*
@ -1275,10 +1253,36 @@ fetch_store_string_user(unsigned long addr, void *dest, void *base)
return ret;
}
/*
* Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
* length and relative data location.
*/
static nokprobe_inline int
probe_mem_read(void *dest, void *src, size_t size)
fetch_store_string(unsigned long addr, void *dest, void *base)
{
return probe_kernel_read(dest, src, size);
int maxlen = get_loc_len(*(u32 *)dest);
void *__dest;
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))
return -ENOMEM;
__dest = get_loc_data(dest, base);
/*
* 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)
*(u32 *)dest = make_data_loc(ret, __dest - base);
return ret;
}
static nokprobe_inline int
@ -1289,6 +1293,16 @@ probe_mem_read_user(void *dest, void *src, size_t 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 */
static int
process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,