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138 lines
5.7 KiB
138 lines
5.7 KiB
From 1d11e79fefea34b4395043e8e951414c5b7817ba Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Mon, 1 Jun 2020 17:06:19 +0200
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Subject: [PATCH] parse-util: allow tweaking how to parse integers
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This allows disabling a few alternative ways to decode integers
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formatted as strings, for safety reasons.
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See: #15991
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(cherry picked from commit 707e93aff8f358f8a62117e54b857530d6594e4b)
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Related: #1848373
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---
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src/basic/parse-util.c | 65 +++++++++++++++++++++++++++++++++---------
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src/basic/parse-util.h | 6 ++++
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2 files changed, 58 insertions(+), 13 deletions(-)
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diff --git a/src/basic/parse-util.c b/src/basic/parse-util.c
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index 67056c0434..6cc4fc3e57 100644
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--- a/src/basic/parse-util.c
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+++ b/src/basic/parse-util.c
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@@ -383,20 +383,35 @@ int safe_atou_full(const char *s, unsigned base, unsigned *ret_u) {
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unsigned long l;
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assert(s);
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- assert(base <= 16);
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+ assert(SAFE_ATO_MASK_FLAGS(base) <= 16);
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- /* strtoul() is happy to parse negative values, and silently
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- * converts them to unsigned values without generating an
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- * error. We want a clean error, hence let's look for the "-"
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- * prefix on our own, and generate an error. But let's do so
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- * only after strtoul() validated that the string is clean
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- * otherwise, so that we return EINVAL preferably over
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- * ERANGE. */
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+ /* strtoul() is happy to parse negative values, and silently converts them to unsigned values without
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+ * generating an error. We want a clean error, hence let's look for the "-" prefix on our own, and
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+ * generate an error. But let's do so only after strtoul() validated that the string is clean
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+ * otherwise, so that we return EINVAL preferably over ERANGE. */
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+
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+ if (FLAGS_SET(base, SAFE_ATO_REFUSE_LEADING_WHITESPACE) &&
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+ strchr(WHITESPACE, s[0]))
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+ return -EINVAL;
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s += strspn(s, WHITESPACE);
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+ if (FLAGS_SET(base, SAFE_ATO_REFUSE_PLUS_MINUS) &&
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+ IN_SET(s[0], '+', '-'))
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+ return -EINVAL; /* Note that we check the "-" prefix again a second time below, but return a
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+ * different error. I.e. if the SAFE_ATO_REFUSE_PLUS_MINUS flag is set we
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+ * blanket refuse +/- prefixed integers, while if it is missing we'll just
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+ * return ERANGE, because the string actually parses correctly, but doesn't
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+ * fit in the return type. */
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+
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+ if (FLAGS_SET(base, SAFE_ATO_REFUSE_LEADING_ZERO) &&
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+ s[0] == '0' && !streq(s, "0"))
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+ return -EINVAL; /* This is particularly useful to avoid ambiguities between C's octal
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+ * notation and assumed-to-be-decimal integers with a leading zero. */
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+
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errno = 0;
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- l = strtoul(s, &x, base);
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+ l = strtoul(s, &x, SAFE_ATO_MASK_FLAGS(base) /* Let's mask off the flags bits so that only the actual
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+ * base is left */);
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if (errno > 0)
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return -errno;
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if (!x || x == s || *x != 0)
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@@ -438,11 +453,24 @@ int safe_atollu_full(const char *s, unsigned base, long long unsigned *ret_llu)
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unsigned long long l;
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assert(s);
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+ assert(SAFE_ATO_MASK_FLAGS(base) <= 16);
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+
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+ if (FLAGS_SET(base, SAFE_ATO_REFUSE_LEADING_WHITESPACE) &&
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+ strchr(WHITESPACE, s[0]))
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+ return -EINVAL;
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s += strspn(s, WHITESPACE);
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+ if (FLAGS_SET(base, SAFE_ATO_REFUSE_PLUS_MINUS) &&
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+ IN_SET(s[0], '+', '-'))
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+ return -EINVAL;
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+
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+ if (FLAGS_SET(base, SAFE_ATO_REFUSE_LEADING_ZERO) &&
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+ s[0] == '0' && s[1] != 0)
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+ return -EINVAL;
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+
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errno = 0;
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- l = strtoull(s, &x, base);
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+ l = strtoull(s, &x, SAFE_ATO_MASK_FLAGS(base));
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if (errno > 0)
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return -errno;
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if (!x || x == s || *x != 0)
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@@ -504,13 +532,24 @@ int safe_atou16_full(const char *s, unsigned base, uint16_t *ret) {
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unsigned long l;
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assert(s);
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- assert(ret);
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- assert(base <= 16);
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+ assert(SAFE_ATO_MASK_FLAGS(base) <= 16);
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+
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+ if (FLAGS_SET(base, SAFE_ATO_REFUSE_LEADING_WHITESPACE) &&
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+ strchr(WHITESPACE, s[0]))
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+ return -EINVAL;
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s += strspn(s, WHITESPACE);
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+ if (FLAGS_SET(base, SAFE_ATO_REFUSE_PLUS_MINUS) &&
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+ IN_SET(s[0], '+', '-'))
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+ return -EINVAL;
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+
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+ if (FLAGS_SET(base, SAFE_ATO_REFUSE_LEADING_ZERO) &&
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+ s[0] == '0' && s[1] != 0)
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+ return -EINVAL;
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+
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errno = 0;
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- l = strtoul(s, &x, base);
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+ l = strtoul(s, &x, SAFE_ATO_MASK_FLAGS(base));
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if (errno > 0)
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return -errno;
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if (!x || x == s || *x != 0)
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diff --git a/src/basic/parse-util.h b/src/basic/parse-util.h
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index 8a49257050..c6bbc98dff 100644
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--- a/src/basic/parse-util.h
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+++ b/src/basic/parse-util.h
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@@ -26,6 +26,12 @@ int parse_syscall_and_errno(const char *in, char **name, int *error);
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#define FORMAT_BYTES_MAX 8
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char *format_bytes(char *buf, size_t l, uint64_t t);
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+#define SAFE_ATO_REFUSE_PLUS_MINUS (1U << 30)
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+#define SAFE_ATO_REFUSE_LEADING_ZERO (1U << 29)
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+#define SAFE_ATO_REFUSE_LEADING_WHITESPACE (1U << 28)
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+#define SAFE_ATO_ALL_FLAGS (SAFE_ATO_REFUSE_PLUS_MINUS|SAFE_ATO_REFUSE_LEADING_ZERO|SAFE_ATO_REFUSE_LEADING_WHITESPACE)
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+#define SAFE_ATO_MASK_FLAGS(base) ((base) & ~SAFE_ATO_ALL_FLAGS)
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+
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int safe_atou_full(const char *s, unsigned base, unsigned *ret_u);
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static inline int safe_atou(const char *s, unsigned *ret_u) {
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