sys-log: log filter #634
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sys-log: log filter #634
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marmarek
reviewed
Feb 5, 2026
qubes-rpc/vm-log.c
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| /** | ||
| * Implements strict ASCII filtering and replaces non-printable control characters. | ||
| * All bytes outside the standard ASCII range (0x00 - 0x7F) are replaced with '?'. | ||
| * Control characters (0x00-0x1F) and DEL (0x7F) are replaced with ' '. | ||
| * | ||
| * @param str Input string (read-only) | ||
| * @param result Buffer to store the sanitized output (must be large enough) | ||
| * @param max_len Maximum length of the input string to process | ||
| * @return The length of the sanitized string written to result | ||
| */ | ||
| size_t filter_to_ascii_and_sanitize(const char *str, char *result, size_t max_len) { | ||
| size_t i; | ||
| size_t j = 0; | ||
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| for (i = 0; i < max_len && str[i] != '\0'; i++) { | ||
| unsigned char byte = (unsigned char)str[i]; | ||
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| if (byte > 0x7F) { | ||
| result[j++] = '?'; | ||
| continue; | ||
| } | ||
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| // Replace harmful control characters (0x00-0x1F) and DEL (0x7F) | ||
| if ((byte < 0x20) || byte == 0x7F) { | ||
| result[j++] = ' '; | ||
| } | ||
| // Keep printable ASCII characters | ||
| else { | ||
| result[j++] = str[i]; | ||
| } | ||
| } | ||
| result[j] = '\0'; | ||
| return j; | ||
| } |
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Ok, maybe limiting chars to only ASCII here was a bit paranoid. I'll move this function to qubes-linux-utils and extend the restrictions for better handling of utf.
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A simple and efficient log sanitizer, ready to work with rsyslog
first step in: QubesOS/qubes-issues/issues/830
requires: QubesOS/qubes-linux-utils/pull/136