diff options
Diffstat (limited to 'lib/vsprintf.c')
| -rw-r--r-- | lib/vsprintf.c | 286 |
1 files changed, 220 insertions, 66 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 1746bae94d41..77ee6ced11b1 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -33,6 +33,8 @@ #include <linux/uuid.h> #include <linux/of.h> #include <net/addrconf.h> +#include <linux/siphash.h> +#include <linux/compiler.h> #ifdef CONFIG_BLOCK #include <linux/blkdev.h> #endif @@ -40,7 +42,6 @@ #include "../mm/internal.h" /* For the trace_print_flags arrays */ #include <asm/page.h> /* for PAGE_SIZE */ -#include <asm/sections.h> /* for dereference_function_descriptor() */ #include <asm/byteorder.h> /* cpu_to_le16 */ #include <linux/string_helpers.h> @@ -1343,6 +1344,59 @@ char *uuid_string(char *buf, char *end, const u8 *addr, return string(buf, end, uuid, spec); } +int kptr_restrict __read_mostly; + +static noinline_for_stack +char *restricted_pointer(char *buf, char *end, const void *ptr, + struct printf_spec spec) +{ + spec.base = 16; + spec.flags |= SMALL; + if (spec.field_width == -1) { + spec.field_width = 2 * sizeof(ptr); + spec.flags |= ZEROPAD; + } + + switch (kptr_restrict) { + case 0: + /* Always print %pK values */ + break; + case 1: { + const struct cred *cred; + + /* + * kptr_restrict==1 cannot be used in IRQ context + * because its test for CAP_SYSLOG would be meaningless. + */ + if (in_irq() || in_serving_softirq() || in_nmi()) + return string(buf, end, "pK-error", spec); + + /* + * Only print the real pointer value if the current + * process has CAP_SYSLOG and is running with the + * same credentials it started with. This is because + * access to files is checked at open() time, but %pK + * checks permission at read() time. We don't want to + * leak pointer values if a binary opens a file using + * %pK and then elevates privileges before reading it. + */ + cred = current_cred(); + if (!has_capability_noaudit(current, CAP_SYSLOG) || + !uid_eq(cred->euid, cred->uid) || + !gid_eq(cred->egid, cred->gid)) + ptr = NULL; + break; + } + case 2: + default: + /* Always print 0's for %pK */ + ptr = NULL; + break; + } + + return number(buf, end, (unsigned long)ptr, spec); +} + static noinline_for_stack char *netdev_bits(char *buf, char *end, const void *addr, const char *fmt) { @@ -1591,7 +1645,86 @@ char *device_node_string(char *buf, char *end, struct device_node *dn, return widen_string(buf, buf - buf_start, end, spec); } -int kptr_restrict __read_mostly; +static noinline_for_stack +char *pointer_string(char *buf, char *end, const void *ptr, + struct printf_spec spec) +{ + spec.base = 16; + spec.flags |= SMALL; + if (spec.field_width == -1) { + spec.field_width = 2 * sizeof(ptr); + spec.flags |= ZEROPAD; + } + + return number(buf, end, (unsigned long int)ptr, spec); +} + +static bool have_filled_random_ptr_key __read_mostly; +static siphash_key_t ptr_key __read_mostly; + +static void fill_random_ptr_key(struct random_ready_callback *unused) +{ + get_random_bytes(&ptr_key, sizeof(ptr_key)); + /* + * have_filled_random_ptr_key==true is dependent on get_random_bytes(). + * ptr_to_id() needs to see have_filled_random_ptr_key==true + * after get_random_bytes() returns. + */ + smp_mb(); + WRITE_ONCE(have_filled_random_ptr_key, true); +} + +static struct random_ready_callback random_ready = { + .func = fill_random_ptr_key +}; + +static int __init initialize_ptr_random(void) +{ + int ret = add_random_ready_callback(&random_ready); + + if (!ret) { + return 0; + } else if (ret == -EALREADY) { + fill_random_ptr_key(&random_ready); + return 0; + } + + return ret; +} +early_initcall(initialize_ptr_random); + +/* Maps a pointer to a 32 bit unique identifier. */ +static char *ptr_to_id(char *buf, char *end, void *ptr, struct printf_spec spec) +{ + unsigned long hashval; + const int default_width = 2 * sizeof(ptr); + + if (unlikely(!have_filled_random_ptr_key)) { + spec.field_width = default_width; + /* string length must be less than default_width */ + return string(buf, end, "(ptrval)", spec); + } + +#ifdef CONFIG_64BIT + hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key); + /* + * Mask off the first 32 bits, this makes explicit that we have + * modified the address (and 32 bits is plenty for a unique ID). + */ + hashval = hashval & 0xffffffff; +#else + hashval = (unsigned long)siphash_1u32((u32)ptr, &ptr_key); +#endif + + spec.flags |= SMALL; + if (spec.field_width == -1) { + spec.field_width = default_width; + spec.flags |= ZEROPAD; + } + spec.base = 16; + + return number(buf, end, hashval, spec); +} /* * Show a '%p' thing. A kernel extension is that the '%p' is followed @@ -1698,11 +1831,17 @@ int kptr_restrict __read_mostly; * c major compatible string * C full compatible string * - * ** Please update also Documentation/printk-formats.txt when making changes ** + * - 'x' For printing the address. Equivalent to "%lx". + * + * ** When making changes please also update: + * Documentation/core-api/printk-formats.rst * * Note: The difference between 'S' and 'F' is that on ia64 and ppc64 * function pointers are really function descriptors, which contain a * pointer to the real address. + * + * Note: The default behaviour (unadorned %p) is to hash the address, + * rendering it useful as a unique identifier. */ static noinline_for_stack char *pointer(const char *fmt, char *buf, char *end, void *ptr, @@ -1723,10 +1862,10 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, switch (*fmt) { case 'F': case 'f': - ptr = dereference_function_descriptor(ptr); - /* Fallthrough */ case 'S': case 's': + ptr = dereference_symbol_descriptor(ptr); + /* Fallthrough */ case 'B': return symbol_string(buf, end, ptr, spec, fmt); case 'R': @@ -1792,47 +1931,9 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, return buf; } case 'K': - switch (kptr_restrict) { - case 0: - /* Always print %pK values */ - break; - case 1: { - const struct cred *cred; - - /* - * kptr_restrict==1 cannot be used in IRQ context - * because its test for CAP_SYSLOG would be meaningless. - */ - if (in_irq() || in_serving_softirq() || in_nmi()) { - if (spec.field_width == -1) - spec.field_width = default_width; - return string(buf, end, "pK-error", spec); - } - - /* - * Only print the real pointer value if the current - * process has CAP_SYSLOG and is running with the - * same credentials it started with. This is because - * access to files is checked at open() time, but %pK - * checks permission at read() time. We don't want to - * leak pointer values if a binary opens a file using - * %pK and then elevates privileges before reading it. - */ - cred = current_cred(); - if (!has_capability_noaudit(current, CAP_SYSLOG) || - !uid_eq(cred->euid, cred->uid) || - !gid_eq(cred->egid, cred->gid)) - ptr = NULL; + if (!kptr_restrict) break; - } - case 2: - default: - /* Always print 0's for %pK */ - ptr = NULL; - break; - } - break; - + return restricted_pointer(buf, end, ptr, spec); case 'N': return netdev_bits(buf, end, ptr, fmt); case 'a': @@ -1857,15 +1958,12 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, case 'F': return device_node_string(buf, end, ptr, spec, fmt + 1); } + case 'x': + return pointer_string(buf, end, ptr, spec); } - spec.flags |= SMALL; - if (spec.field_width == -1) { - spec.field_width = default_width; - spec.flags |= ZEROPAD; - } - spec.base = 16; - return number(buf, end, (unsigned long) ptr, spec); + /* default is to _not_ leak addresses, hash before printing */ + return ptr_to_id(buf, end, ptr, spec); } /* @@ -2096,7 +2194,7 @@ set_precision(struct printf_spec *spec, int prec) * - ``%n`` is unsupported * - ``%p*`` is handled by pointer() * - * See pointer() or Documentation/printk-formats.txt for more + * See pointer() or Documentation/core-api/printk-formats.rst for more * extensive description. * * **Please update the documentation in both places when making changes** @@ -2418,29 +2516,34 @@ int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args) { struct printf_spec spec = {0}; char *str, *end; + int width; str = (char *)bin_buf; end = (char *)(bin_buf + size); #define save_arg(type) \ -do { \ +({ \ + unsigned long long value; \ if (sizeof(type) == 8) { \ - unsigned long long value; \ + unsigned long long val8; \ str = PTR_ALIGN(str, sizeof(u32)); \ - value = va_arg(args, unsigned long long); \ + val8 = va_arg(args, unsigned long long); \ if (str + sizeof(type) <= end) { \ - *(u32 *)str = *(u32 *)&value; \ - *(u32 *)(str + 4) = *((u32 *)&value + 1); \ + *(u32 *)str = *(u32 *)&val8; \ + *(u32 *)(str + 4) = *((u32 *)&val8 + 1); \ } \ + value = val8; \ } else { \ - unsigned long value; \ + unsigned int val4; \ str = PTR_ALIGN(str, sizeof(type)); \ - value = va_arg(args, int); \ + val4 = va_arg(args, int); \ if (str + sizeof(type) <= end) \ - *(typeof(type) *)str = (type)value; \ + *(typeof(type) *)str = (type)(long)val4; \ + value = (unsigned long long)val4; \ } \ str += sizeof(type); \ -} while (0) + value; \ +}) while (*fmt) { int read = format_decode(fmt, &spec); @@ -2456,7 +2559,10 @@ do { \ case FORMAT_TYPE_WIDTH: case FORMAT_TYPE_PRECISION: - save_arg(int); + width = (int)save_arg(int); + /* Pointers may require the width */ + if (*fmt == 'p') + set_field_width(&spec, width); break; case FORMAT_TYPE_CHAR: @@ -2478,7 +2584,27 @@ do { \ } case FORMAT_TYPE_PTR: - save_arg(void *); + /* Dereferenced pointers must be done now */ + switch (*fmt) { + /* Dereference of functions is still OK */ + case 'S': + case 's': + case 'F': + case 'f': + save_arg(void *); + break; + default: + if (!isalnum(*fmt)) { + save_arg(void *); + break; + } + str = pointer(fmt, str, end, va_arg(args, void *), + spec); + if (str + 1 < end) + *str++ = '\0'; + else + end[-1] = '\0'; /* Must be nul terminated */ + } /* skip all alphanumeric pointer suffixes */ while (isalnum(*fmt)) fmt++; @@ -2630,11 +2756,39 @@ int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf) break; } - case FORMAT_TYPE_PTR: - str = pointer(fmt, str, end, get_arg(void *), spec); + case FORMAT_TYPE_PTR: { + bool process = false; + int copy, len; + /* Non function dereferences were already done */ + switch (*fmt) { + case 'S': + case 's': + case 'F': + case 'f': + process = true; + break; + default: + if (!isalnum(*fmt)) { + process = true; + break; + } + /* Pointer dereference was already processed */ + if (str < end) { + len = copy = strlen(args); + if (copy > end - str) + copy = end - str; + memcpy(str, args, copy); + str += len; + args += len; + } + } + if (process) + str = pointer(fmt, str, end, get_arg(void *), spec); + while (isalnum(*fmt)) fmt++; break; + } case FORMAT_TYPE_PERCENT_CHAR: if (str < end) |
