From cd514e727b18ff4d189b8e268db13729a4175091 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Mon, 13 Oct 2014 15:54:25 -0700 Subject: lib/string.c: remove duplicated function lib/string.c contains two functions, strnicmp and strncasecmp, which do roughly the same thing, namely compare two strings case-insensitively up to a given bound. They have slightly different implementations, but the only important difference is that strncasecmp doesn't handle len==0 appropriately; it effectively becomes strcasecmp in that case. strnicmp correctly says that two strings are always equal in their first 0 characters. strncasecmp is the POSIX name for this functionality. So rename the non-broken function to the standard name. To minimize the impact on the rest of the kernel (and since both are exported to modules), make strnicmp a wrapper for strncasecmp. Signed-off-by: Rasmus Villemoes Cc: Grant Likely Cc: Andi Kleen Cc: Dan Carpenter Cc: "H. Peter Anvin" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/string.c | 27 ++++++++++----------------- 1 file changed, 10 insertions(+), 17 deletions(-) (limited to 'lib/string.c') diff --git a/lib/string.c b/lib/string.c index f3c6ff596414..3181e267a033 100644 --- a/lib/string.c +++ b/lib/string.c @@ -27,14 +27,14 @@ #include #include -#ifndef __HAVE_ARCH_STRNICMP +#ifndef __HAVE_ARCH_STRNCASECMP /** - * strnicmp - Case insensitive, length-limited string comparison + * strncasecmp - Case insensitive, length-limited string comparison * @s1: One string * @s2: The other string * @len: the maximum number of characters to compare */ -int strnicmp(const char *s1, const char *s2, size_t len) +int strncasecmp(const char *s1, const char *s2, size_t len) { /* Yes, Virginia, it had better be unsigned */ unsigned char c1, c2; @@ -56,6 +56,13 @@ int strnicmp(const char *s1, const char *s2, size_t len) } while (--len); return (int)c1 - (int)c2; } +EXPORT_SYMBOL(strncasecmp); +#endif +#ifndef __HAVE_ARCH_STRNICMP +int strnicmp(const char *s1, const char *s2, size_t len) +{ + return strncasecmp(s1, s2, len); +} EXPORT_SYMBOL(strnicmp); #endif @@ -73,20 +80,6 @@ int strcasecmp(const char *s1, const char *s2) EXPORT_SYMBOL(strcasecmp); #endif -#ifndef __HAVE_ARCH_STRNCASECMP -int strncasecmp(const char *s1, const char *s2, size_t n) -{ - int c1, c2; - - do { - c1 = tolower(*s1++); - c2 = tolower(*s2++); - } while ((--n > 0) && c1 == c2 && c1 != 0); - return c1 - c2; -} -EXPORT_SYMBOL(strncasecmp); -#endif - #ifndef __HAVE_ARCH_STRCPY /** * strcpy - Copy a %NUL terminated string -- cgit v1.2.3 From b0bfb63118612e3614cf77b115c00f895a42c96a Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Mon, 13 Oct 2014 15:54:27 -0700 Subject: lib: string: Make all calls to strnicmp into calls to strncasecmp The previous patch made strnicmp into a wrapper for strncasecmp. This patch makes all in-tree users of strnicmp call strncasecmp directly, while still making sure that the strnicmp symbol can be used by out-of-tree modules. It should be considered a temporary hack until all in-tree callers have been converted. Signed-off-by: Rasmus Villemoes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/string.h | 2 +- lib/string.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) (limited to 'lib/string.c') diff --git a/include/linux/string.h b/include/linux/string.h index d36977e029af..e6edfe51575a 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -41,7 +41,7 @@ extern int strcmp(const char *,const char *); extern int strncmp(const char *,const char *,__kernel_size_t); #endif #ifndef __HAVE_ARCH_STRNICMP -extern int strnicmp(const char *, const char *, __kernel_size_t); +#define strnicmp strncasecmp #endif #ifndef __HAVE_ARCH_STRCASECMP extern int strcasecmp(const char *s1, const char *s2); diff --git a/lib/string.c b/lib/string.c index 3181e267a033..2fc20aa06f84 100644 --- a/lib/string.c +++ b/lib/string.c @@ -59,6 +59,7 @@ int strncasecmp(const char *s1, const char *s2, size_t len) EXPORT_SYMBOL(strncasecmp); #endif #ifndef __HAVE_ARCH_STRNICMP +#undef strnicmp int strnicmp(const char *s1, const char *s2, size_t len) { return strncasecmp(s1, s2, len); -- cgit v1.2.3 From d4c5efdb97773f59a2b711754ca0953f24516739 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 26 Aug 2014 23:16:35 -0400 Subject: random: add and use memzero_explicit() for clearing data zatimend has reported that in his environment (3.16/gcc4.8.3/corei7) memset() calls which clear out sensitive data in extract_{buf,entropy, entropy_user}() in random driver are being optimized away by gcc. Add a helper memzero_explicit() (similarly as explicit_bzero() variants) that can be used in such cases where a variable with sensitive data is being cleared out in the end. Other use cases might also be in crypto code. [ I have put this into lib/string.c though, as it's always built-in and doesn't need any dependencies then. ] Fixes kernel bugzilla: 82041 Reported-by: zatimend@hotmail.co.uk Signed-off-by: Daniel Borkmann Acked-by: Hannes Frederic Sowa Cc: Alexey Dobriyan Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org --- drivers/char/random.c | 8 ++++---- include/linux/string.h | 5 +++-- lib/string.c | 16 ++++++++++++++++ 3 files changed, 23 insertions(+), 6 deletions(-) (limited to 'lib/string.c') diff --git a/drivers/char/random.c b/drivers/char/random.c index c18d41db83d8..8c86a95203a0 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1106,7 +1106,7 @@ static void extract_buf(struct entropy_store *r, __u8 *out) __mix_pool_bytes(r, hash.w, sizeof(hash.w)); spin_unlock_irqrestore(&r->lock, flags); - memset(workspace, 0, sizeof(workspace)); + memzero_explicit(workspace, sizeof(workspace)); /* * In case the hash function has some recognizable output @@ -1118,7 +1118,7 @@ static void extract_buf(struct entropy_store *r, __u8 *out) hash.w[2] ^= rol32(hash.w[2], 16); memcpy(out, &hash, EXTRACT_SIZE); - memset(&hash, 0, sizeof(hash)); + memzero_explicit(&hash, sizeof(hash)); } /* @@ -1175,7 +1175,7 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf, } /* Wipe data just returned from memory */ - memset(tmp, 0, sizeof(tmp)); + memzero_explicit(tmp, sizeof(tmp)); return ret; } @@ -1218,7 +1218,7 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, } /* Wipe data just returned from memory */ - memset(tmp, 0, sizeof(tmp)); + memzero_explicit(tmp, sizeof(tmp)); return ret; } diff --git a/include/linux/string.h b/include/linux/string.h index d36977e029af..3b42b3732da6 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -132,7 +132,7 @@ int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4); #endif extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, - const void *from, size_t available); + const void *from, size_t available); /** * strstarts - does @str start with @prefix? @@ -144,7 +144,8 @@ static inline bool strstarts(const char *str, const char *prefix) return strncmp(str, prefix, strlen(prefix)) == 0; } -extern size_t memweight(const void *ptr, size_t bytes); +size_t memweight(const void *ptr, size_t bytes); +void memzero_explicit(void *s, size_t count); /** * kbasename - return the last part of a pathname. diff --git a/lib/string.c b/lib/string.c index 992bf30af759..3a3120452a1d 100644 --- a/lib/string.c +++ b/lib/string.c @@ -604,6 +604,22 @@ void *memset(void *s, int c, size_t count) EXPORT_SYMBOL(memset); #endif +/** + * memzero_explicit - Fill a region of memory (e.g. sensitive + * keying data) with 0s. + * @s: Pointer to the start of the area. + * @count: The size of the area. + * + * memzero_explicit() doesn't need an arch-specific version as + * it just invokes the one of memset() implicitly. + */ +void memzero_explicit(void *s, size_t count) +{ + memset(s, 0, count); + OPTIMIZER_HIDE_VAR(s); +} +EXPORT_SYMBOL(memzero_explicit); + #ifndef __HAVE_ARCH_MEMCPY /** * memcpy - Copy one area of memory to another -- cgit v1.2.3