diff options
| -rw-r--r-- | include/linux/string_helpers.h | 31 | ||||
| -rw-r--r-- | lib/string_helpers.c | 274 | ||||
| -rw-r--r-- | lib/test-string_helpers.c | 240 |
3 files changed, 541 insertions, 4 deletions
diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h index 5a30f2a..6eb567a 100644 --- a/include/linux/string_helpers.h +++ b/include/linux/string_helpers.h @@ -37,4 +37,35 @@ static inline int string_unescape_any_inplace(char *buf) return string_unescape_any(buf, buf, 0); } +#define ESCAPE_SPACE 0x01 +#define ESCAPE_SPECIAL 0x02 +#define ESCAPE_NULL 0x04 +#define ESCAPE_OCTAL 0x08 +#define ESCAPE_ANY \ + (ESCAPE_SPACE | ESCAPE_OCTAL | ESCAPE_SPECIAL | ESCAPE_NULL) +#define ESCAPE_NP 0x10 +#define ESCAPE_ANY_NP (ESCAPE_ANY | ESCAPE_NP) +#define ESCAPE_HEX 0x20 + +int string_escape_mem(const char *src, size_t isz, char **dst, size_t osz, + unsigned int flags, const char *esc); + +static inline int string_escape_mem_any_np(const char *src, size_t isz, + char **dst, size_t osz, const char *esc) +{ + return string_escape_mem(src, isz, dst, osz, ESCAPE_ANY_NP, esc); +} + +static inline int string_escape_str(const char *src, char **dst, size_t sz, + unsigned int flags, const char *esc) +{ + return string_escape_mem(src, strlen(src), dst, sz, flags, esc); +} + +static inline int string_escape_str_any_np(const char *src, char **dst, + size_t sz, const char *esc) +{ + return string_escape_str(src, dst, sz, ESCAPE_ANY_NP, esc); +} + #endif diff --git a/lib/string_helpers.c b/lib/string_helpers.c index 74ec604..58b78ba 100644 --- a/lib/string_helpers.c +++ b/lib/string_helpers.c @@ -8,6 +8,8 @@ #include <linux/math64.h> #include <linux/export.h> #include <linux/ctype.h> +#include <linux/errno.h> +#include <linux/string.h> #include <linux/string_helpers.h> /** @@ -240,3 +242,275 @@ int string_unescape(char *src, char *dst, size_t size, unsigned int flags) return out - dst; } EXPORT_SYMBOL(string_unescape); + +static int escape_passthrough(unsigned char c, char **dst, size_t *osz) +{ + char *out = *dst; + + if (*osz < 1) + return -ENOMEM; + + *out++ = c; + + *dst = out; + *osz -= 1; + + return 1; +} + +static int escape_space(unsigned char c, char **dst, size_t *osz) +{ + char *out = *dst; + unsigned char to; + + if (*osz < 2) + return -ENOMEM; + + switch (c) { + case '\n': + to = 'n'; + break; + case '\r': + to = 'r'; + break; + case '\t': + to = 't'; + break; + case '\v': + to = 'v'; + break; + case '\f': + to = 'f'; + break; + default: + return 0; + } + + *out++ = '\\'; + *out++ = to; + + *dst = out; + *osz -= 2; + + return 1; +} + +static int escape_special(unsigned char c, char **dst, size_t *osz) +{ + char *out = *dst; + unsigned char to; + + if (*osz < 2) + return -ENOMEM; + + switch (c) { + case '\\': + to = '\\'; + break; + case '\a': + to = 'a'; + break; + case '\e': + to = 'e'; + break; + default: + return 0; + } + + *out++ = '\\'; + *out++ = to; + + *dst = out; + *osz -= 2; + + return 1; +} + +static int escape_null(unsigned char c, char **dst, size_t *osz) +{ + char *out = *dst; + + if (*osz < 2) + return -ENOMEM; + + if (c) + return 0; + + *out++ = '\\'; + *out++ = '0'; + + *dst = out; + *osz -= 2; + + return 1; +} + +static int escape_octal(unsigned char c, char **dst, size_t *osz) +{ + char *out = *dst; + + if (*osz < 4) + return -ENOMEM; + + *out++ = '\\'; + *out++ = ((c >> 6) & 0x07) + '0'; + *out++ = ((c >> 3) & 0x07) + '0'; + *out++ = ((c >> 0) & 0x07) + '0'; + + *dst = out; + *osz -= 4; + + return 1; +} + +static int escape_hex(unsigned char c, char **dst, size_t *osz) +{ + char *out = *dst; + + if (*osz < 4) + return -ENOMEM; + + *out++ = '\\'; + *out++ = 'x'; + *out++ = hex_asc_hi(c); + *out++ = hex_asc_lo(c); + + *dst = out; + *osz -= 4; + + return 1; +} + +/** + * string_escape_mem - quote characters in the given memory buffer + * @src: source buffer (unescaped) + * @isz: source buffer size + * @dst: destination buffer (escaped) + * @osz: destination buffer size + * @flags: combination of the flags (bitwise OR): + * %ESCAPE_SPACE: + * '\f' - form feed + * '\n' - new line + * '\r' - carriage return + * '\t' - horizontal tab + * '\v' - vertical tab + * %ESCAPE_SPECIAL: + * '\\' - backslash + * '\a' - alert (BEL) + * '\e' - escape + * %ESCAPE_NULL: + * '\0' - null + * %ESCAPE_OCTAL: + * '\NNN' - byte with octal value NNN (3 digits) + * %ESCAPE_ANY: + * all previous together + * %ESCAPE_NP: + * escape only non-printable characters (checked by isprint) + * %ESCAPE_ANY_NP: + * all previous together + * %ESCAPE_HEX: + * '\xHH' - byte with hexadecimal value HH (2 digits) + * @esc: NULL-terminated string of characters any of which, if found in + * the source, has to be escaped + * + * Description: + * The process of escaping byte buffer includes several parts. They are applied + * in the following sequence. + * 1. The character is matched to the printable class, if asked, and in + * case of match it passes through to the output. + * 2. The character is not matched to the one from @esc string and thus + * must go as is to the output. + * 3. The character is checked if it falls into the class given by @flags. + * %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any + * character. Note that they actually can't go together, otherwise + * %ESCAPE_HEX will be ignored. + * + * Caller must provide valid source and destination pointers. Be aware that + * destination buffer will not be NULL-terminated, thus caller have to append + * it if needs. + * + * Return: + * The amount of the characters processed to the destination buffer, or + * %-ENOMEM if the size of buffer is not enough to put an escaped character is + * returned. + * + * Even in the case of error @dst pointer will be updated to point to the byte + * after the last processed character. + */ +int string_escape_mem(const char *src, size_t isz, char **dst, size_t osz, + unsigned int flags, const char *esc) +{ + char *out = *dst, *p = out; + bool is_dict = esc && *esc; + int ret = 0; + + while (isz--) { + unsigned char c = *src++; + + /* + * Apply rules in the following sequence: + * - the character is printable, when @flags has + * %ESCAPE_NP bit set + * - the @esc string is supplied and does not contain a + * character under question + * - the character doesn't fall into a class of symbols + * defined by given @flags + * In these cases we just pass through a character to the + * output buffer. + */ + if ((flags & ESCAPE_NP && isprint(c)) || + (is_dict && !strchr(esc, c))) { + /* do nothing */ + } else { + if (flags & ESCAPE_SPACE) { + ret = escape_space(c, &p, &osz); + if (ret < 0) + break; + if (ret > 0) + continue; + } + + if (flags & ESCAPE_SPECIAL) { + ret = escape_special(c, &p, &osz); + if (ret < 0) + break; + if (ret > 0) + continue; + } + + if (flags & ESCAPE_NULL) { + ret = escape_null(c, &p, &osz); + if (ret < 0) + break; + if (ret > 0) + continue; + } + + /* ESCAPE_OCTAL and ESCAPE_HEX always go last */ + if (flags & ESCAPE_OCTAL) { + ret = escape_octal(c, &p, &osz); + if (ret < 0) + break; + continue; + } + if (flags & ESCAPE_HEX) { + ret = escape_hex(c, &p, &osz); + if (ret < 0) + break; + continue; + } + } + + ret = escape_passthrough(c, &p, &osz); + if (ret < 0) + break; + } + + *dst = p; + + if (ret < 0) + return ret; + + return p - out; +} +EXPORT_SYMBOL(string_escape_mem); diff --git a/lib/test-string_helpers.c b/lib/test-string_helpers.c index ac44c92..ab0d30e 100644 --- a/lib/test-string_helpers.c +++ b/lib/test-string_helpers.c @@ -5,6 +5,7 @@ #include <linux/init.h> #include <linux/kernel.h> +#include <linux/slab.h> #include <linux/module.h> #include <linux/random.h> #include <linux/string.h> @@ -62,10 +63,14 @@ static const struct test_string strings[] __initconst = { static void __init test_string_unescape(const char *name, unsigned int flags, bool inplace) { - char in[256]; - char out_test[256]; - char out_real[256]; - int i, p = 0, q_test = 0, q_real = sizeof(out_real); + int q_real = 256; + char *in = kmalloc(q_real, GFP_KERNEL); + char *out_test = kmalloc(q_real, GFP_KERNEL); + char *out_real = kmalloc(q_real, GFP_KERNEL); + int i, p = 0, q_test = 0; + + if (!in || !out_test || !out_real) + goto out; for (i = 0; i < ARRAY_SIZE(strings); i++) { const char *s = strings[i].in; @@ -100,6 +105,223 @@ static void __init test_string_unescape(const char *name, unsigned int flags, test_string_check_buf(name, flags, in, p - 1, out_real, q_real, out_test, q_test); +out: + kfree(out_real); + kfree(out_test); + kfree(in); +} + +struct test_string_1 { + const char *out; + unsigned int flags; +}; + +#define TEST_STRING_2_MAX_S1 32 +struct test_string_2 { + const char *in; + struct test_string_1 s1[TEST_STRING_2_MAX_S1]; +}; + +#define TEST_STRING_2_DICT_0 NULL +static const struct test_string_2 escape0[] __initconst = {{ + .in = "\f\\ \n\r\t\v", + .s1 = {{ + .out = "\\f\\ \\n\\r\\t\\v", + .flags = ESCAPE_SPACE, + },{ + .out = "\\f\\134\\040\\n\\r\\t\\v", + .flags = ESCAPE_SPACE | ESCAPE_OCTAL, + },{ + .out = "\\f\\x5c\\x20\\n\\r\\t\\v", + .flags = ESCAPE_SPACE | ESCAPE_HEX, + },{ + /* terminator */ + }}, +},{ + .in = "\\h\\\"\a\e\\", + .s1 = {{ + .out = "\\\\h\\\\\"\\a\\e\\\\", + .flags = ESCAPE_SPECIAL, + },{ + .out = "\\\\\\150\\\\\\042\\a\\e\\\\", + .flags = ESCAPE_SPECIAL | ESCAPE_OCTAL, + },{ + .out = "\\\\\\x68\\\\\\x22\\a\\e\\\\", + .flags = ESCAPE_SPECIAL | ESCAPE_HEX, + },{ + /* terminator */ + }}, +},{ + .in = "\eb \\C\007\"\x90\r]", + .s1 = {{ + .out = "\eb \\C\007\"\x90\\r]", + .flags = ESCAPE_SPACE, + },{ + .out = "\\eb \\\\C\\a\"\x90\r]", + .flags = ESCAPE_SPECIAL, + },{ + .out = "\\eb \\\\C\\a\"\x90\\r]", + .flags = ESCAPE_SPACE | ESCAPE_SPECIAL, + },{ + .out = "\\033\\142\\040\\134\\103\\007\\042\\220\\015\\135", + .flags = ESCAPE_OCTAL, + },{ + .out = "\\033\\142\\040\\134\\103\\007\\042\\220\\r\\135", + .flags = ESCAPE_SPACE | ESCAPE_OCTAL, + },{ + .out = "\\e\\142\\040\\\\\\103\\a\\042\\220\\015\\135", + .flags = ESCAPE_SPECIAL | ESCAPE_OCTAL, + },{ + .out = "\\e\\142\\040\\\\\\103\\a\\042\\220\\r\\135", + .flags = ESCAPE_SPACE | ESCAPE_SPECIAL | ESCAPE_OCTAL, + },{ + .out = "\eb \\C\007\"\x90\r]", + .flags = ESCAPE_NP, + },{ + .out = "\eb \\C\007\"\x90\\r]", + .flags = ESCAPE_SPACE | ESCAPE_NP, + },{ + .out = "\\eb \\C\\a\"\x90\r]", + .flags = ESCAPE_SPECIAL | ESCAPE_NP, + },{ + .out = "\\eb \\C\\a\"\x90\\r]", + .flags = ESCAPE_SPACE | ESCAPE_SPECIAL | ESCAPE_NP, + },{ + .out = "\\033b \\C\\007\"\\220\\015]", + .flags = ESCAPE_OCTAL | ESCAPE_NP, + },{ + .out = "\\033b \\C\\007\"\\220\\r]", + .flags = ESCAPE_SPACE | ESCAPE_OCTAL | ESCAPE_NP, + },{ + .out = "\\eb \\C\\a\"\\220\\r]", + .flags = ESCAPE_SPECIAL | ESCAPE_SPACE | ESCAPE_OCTAL | + ESCAPE_NP, + },{ + .out = "\\x1bb \\C\\x07\"\\x90\\x0d]", + .flags = ESCAPE_NP | ESCAPE_HEX, + },{ + /* terminator */ + }}, +},{ + /* terminator */ +}}; + +#define TEST_STRING_2_DICT_1 "b\\ \t\r" +static const struct test_string_2 escape1[] __initconst = {{ + .in = "\f\\ \n\r\t\v", + .s1 = {{ + .out = "\f\\134\\040\n\\015\\011\v", + .flags = ESCAPE_OCTAL, + },{ + .out = "\f\\x5c\\x20\n\\x0d\\x09\v", + .flags = ESCAPE_HEX, + },{ + /* terminator */ + }}, +},{ + .in = "\\h\\\"\a\e\\", + .s1 = {{ + .out = "\\134h\\134\"\a\e\\134", + .flags = ESCAPE_OCTAL, + },{ + /* terminator */ + }}, +},{ + .in = "\eb \\C\007\"\x90\r]", + .s1 = {{ + .out = "\e\\142\\040\\134C\007\"\x90\\015]", + .flags = ESCAPE_OCTAL, + },{ + /* terminator */ + }}, +},{ + /* terminator */ +}}; + +static __init const char *test_string_find_match(const struct test_string_2 *s2, + unsigned int flags) +{ + const struct test_string_1 *s1 = s2->s1; + unsigned int i; + + if (!flags) + return s2->in; + + /* Test cases are NULL-aware */ + flags &= ~ESCAPE_NULL; + + /* ESCAPE_OCTAL has a higher priority */ + if (flags & ESCAPE_OCTAL) + flags &= ~ESCAPE_HEX; + + for (i = 0; i < TEST_STRING_2_MAX_S1 && s1->out; i++, s1++) + if (s1->flags == flags) + return s1->out; + return NULL; +} + +static __init void test_string_escape(const char *name, + const struct test_string_2 *s2, + unsigned int flags, const char *esc) +{ + int q_real = 512; + char *out_test = kmalloc(q_real, GFP_KERNEL); + char *out_real = kmalloc(q_real, GFP_KERNEL); + char *in = kmalloc(256, GFP_KERNEL); + char *buf = out_real; + int p = 0, q_test = 0; + + if (!out_test || !out_real || !in) + goto out; + + for (; s2->in; s2++) { + const char *out; + int len; + + /* NULL injection */ + if (flags & ESCAPE_NULL) { + in[p++] = '\0'; + out_test[q_test++] = '\\'; + out_test[q_test++] = '0'; + } + + /* Don't try strings that have no output */ + out = test_string_find_match(s2, flags); + if (!out) + continue; + + /* Copy string to in buffer */ + len = strlen(s2->in); + memcpy(&in[p], s2->in, len); + p += len; + + /* Copy expected result for given flags */ + len = strlen(out); + memcpy(&out_test[q_test], out, len); + q_test += len; + } + + q_real = string_escape_mem(in, p, &buf, q_real, flags, esc); + + test_string_check_buf(name, flags, in, p, out_real, q_real, out_test, + q_test); +out: + kfree(in); + kfree(out_real); + kfree(out_test); +} + +static __init void test_string_escape_nomem(void) +{ + char *in = "\eb \\C\007\"\x90\r]"; + char out[64], *buf = out; + int rc = -ENOMEM, ret; + + ret = string_escape_str_any_np(in, &buf, strlen(in), NULL); + if (ret == rc) + return; + + pr_err("Test 'escape nomem' failed: got %d instead of %d\n", ret, rc); } static int __init test_string_helpers_init(void) @@ -112,6 +334,16 @@ static int __init test_string_helpers_init(void) test_string_unescape("unescape inplace", get_random_int() % (UNESCAPE_ANY + 1), true); + /* Without dictionary */ + for (i = 0; i < (ESCAPE_ANY_NP | ESCAPE_HEX) + 1; i++) + test_string_escape("escape 0", escape0, i, TEST_STRING_2_DICT_0); + + /* With dictionary */ + for (i = 0; i < (ESCAPE_ANY_NP | ESCAPE_HEX) + 1; i++) + test_string_escape("escape 1", escape1, i, TEST_STRING_2_DICT_1); + + test_string_escape_nomem(); + return -EINVAL; } module_init(test_string_helpers_init); |
