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bpf: factor out a bpf_trace_copy_string helper

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Split out a helper to do the fault free access to the string pointer
to get it out of a crazy indentation level.

Signed-off-by: Christoph Hellwig <hch@lst.de>
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/20200521152301.2587579-12-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Hellwig 2020-06-08 21:34:30 -07:00 • committed by Linus Torvalds
parent eab0c6089b
commit d7b2977b81
1 changed files with 24 additions and 18 deletions
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40
kernel/trace/bpf_trace.c
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@ -324,6 +324,28 @@ static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
return &bpf_probe_write_user_proto; return &bpf_probe_write_user_proto;
} }
static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype,
size_t bufsz)
{
void __user *user_ptr = (__force void __user *)unsafe_ptr;
buf[0] = 0;
switch (fmt_ptype) {
case 's':
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
strncpy_from_unsafe(buf, unsafe_ptr, bufsz);
break;
#endif
case 'k':
strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz);
break;
case 'u':
strncpy_from_user_nofault(buf, user_ptr, bufsz);
break;
}
}
/* /*
* Only limited trace_printk() conversion specifiers allowed: * Only limited trace_printk() conversion specifiers allowed:
* %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pks %pus %s * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pks %pus %s
@ -406,24 +428,8 @@ fmt_str:
break; break;
} }
buf[0] = 0; bpf_trace_copy_string(buf, unsafe_ptr, fmt_ptype,
switch (fmt_ptype) {
case 's':
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
strncpy_from_unsafe(buf, unsafe_ptr,
sizeof(buf)); sizeof(buf));
break;
#endif
case 'k':
strncpy_from_kernel_nofault(buf, unsafe_ptr,
sizeof(buf));
break;
case 'u':
strncpy_from_user_nofault(buf,
(__force void __user *)unsafe_ptr,
sizeof(buf));
break;
}
goto fmt_next; goto fmt_next;
} }