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SubjectRe: [PATCH 9/9] Remove string_escape_mem_ascii
On Thu, Sep 05, 2019 at 03:44:33PM -0400, J. Bruce Fields wrote:
> From: "J. Bruce Fields" <bfields@redhat.com>
>
> It's easier to do this in string_escape_mem now.
>
> Might also consider non-ascii and quote-mark sprintf modifiers and then
> we might make do with seq_printk.

With '\' always handled, it can be dropped from the "esc" args below. I
wonder if ESCAPE_QUOTES is needed or if "esc" can just continue to be
used for that.

(Also, do we want to add the "hex escape" modifier back to snprintf's
%pE stuff?)

-Kees

> ---
> fs/seq_file.c | 3 ++-
> include/linux/string_helpers.h | 3 +--
> lib/string_helpers.c | 24 ++++--------------------
> 3 files changed, 7 insertions(+), 23 deletions(-)
>
> diff --git a/fs/seq_file.c b/fs/seq_file.c
> index 63e5a7c4dbf7..0e45a25523ad 100644
> --- a/fs/seq_file.c
> +++ b/fs/seq_file.c
> @@ -390,7 +390,8 @@ void seq_escape_mem_ascii(struct seq_file *m, const char *src, size_t isz)
> size_t size = seq_get_buf(m, &buf);
> int ret;
>
> - ret = string_escape_mem_ascii(src, isz, buf, size);
> + ret = string_escape_mem(src, isz, buf, size, ESCAPE_NP|ESCAPE_NONASCII|
> + ESCAPE_STYLE_SLASH|ESCAPE_STYLE_HEX, "\"\\");
> seq_commit(m, ret < size ? ret : -1);
> }
> EXPORT_SYMBOL(seq_escape_mem_ascii);
> diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
> index 5d350f7f6874..f3388591d83f 100644
> --- a/include/linux/string_helpers.h
> +++ b/include/linux/string_helpers.h
> @@ -43,6 +43,7 @@ static inline int string_unescape_any_inplace(char *buf)
>
> #define ESCAPE_SPECIAL 0x01
> #define ESCAPE_NP 0x02
> +#define ESCAPE_NONASCII 0x04
> #define ESCAPE_ANY_NP (ESCAPE_SPECIAL | ESCAPE_NP)
> #define ESCAPE_STYLE_SLASH 0x20
> #define ESCAPE_STYLE_OCTAL 0x40
> @@ -52,8 +53,6 @@ static inline int string_unescape_any_inplace(char *buf)
> int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
> unsigned int flags, const char *only);
>
> -int string_escape_mem_ascii(const char *src, size_t isz, char *dst,
> - size_t osz);
> static inline int string_escape_str(const char *src, char *dst, size_t sz,
> unsigned int flags, const char *only)
> {
> diff --git a/lib/string_helpers.c b/lib/string_helpers.c
> index 6f553f893fda..1dacf76eada0 100644
> --- a/lib/string_helpers.c
> +++ b/lib/string_helpers.c
> @@ -439,6 +439,8 @@ static bool is_special(char c)
> * '\a' - alert (BEL)
> * '\e' - escape
> * '\0' - null
> + * %ESCAPE_NONASCII:
> + * escape characters with the high bit set
> * %ESCAPE_NP:
> * escape only non-printable characters (checked by isprint)
> * %ESCAPE_ANY_NP:
> @@ -468,7 +470,8 @@ int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
>
> if ((is_dict && strchr(esc, c)) ||
> (flags & ESCAPE_NP && !isprint(c)) ||
> - (flags & ESCAPE_SPECIAL && is_special(c))) {
> + (flags & ESCAPE_SPECIAL && is_special(c)) ||
> + (flags & ESCAPE_NONASCII && !isascii(c))) {
>
> if (flags & ESCAPE_STYLE_SLASH &&
> escape_special(c, &p, end))
> @@ -491,25 +494,6 @@ int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
> }
> EXPORT_SYMBOL(string_escape_mem);
>
> -int string_escape_mem_ascii(const char *src, size_t isz, char *dst,
> - size_t osz)
> -{
> - char *p = dst;
> - char *end = p + osz;
> -
> - while (isz--) {
> - unsigned char c = *src++;
> -
> - if (!isprint(c) || !isascii(c) || c == '"' || c == '\\')
> - escape_hex(c, &p, end);
> - else
> - escape_passthrough(c, &p, end);
> - }
> -
> - return p - dst;
> -}
> -EXPORT_SYMBOL(string_escape_mem_ascii);
> -
> /*
> * Return an allocated string that has been escaped of special characters
> * and double quotes, making it safe to log in quotes.
> --
> 2.21.0
>

--
Kees Cook

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