From 7eb391299419a03cbe0fa5ab0e6b0932e42c7a36 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Thu, 11 Feb 2016 16:13:00 -0800 Subject: vsprintf: kptr_restrict is okay in IRQ when 2 The kptr_restrict flag, when set to 1, only prints the kernel address when the user has CAP_SYSLOG. When it is set to 2, the kernel address is always printed as zero. When set to 1, this needs to check whether or not we're in IRQ. However, when set to 2, this check is unneccessary, and produces confusing results in dmesg. Thus, only make sure we're not in IRQ when mode 1 is used, but not mode 2. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Jason A. Donenfeld Cc: Rasmus Villemoes Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/vsprintf.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) (limited to 'lib/vsprintf.c') diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 48ff9c36644d..f44e178e6ede 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1590,22 +1590,23 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, return buf; } case 'K': - /* - * %pK cannot be used in IRQ context because its test - * for CAP_SYSLOG would be meaningless. - */ - if (kptr_restrict && (in_irq() || in_serving_softirq() || - in_nmi())) { - if (spec.field_width == -1) - spec.field_width = default_width; - return string(buf, end, "pK-error", spec); - } - 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 @@ -1615,8 +1616,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, * leak pointer values if a binary opens a file using * %pK and then elevates privileges before reading it. */ - const struct cred *cred = current_cred(); - + cred = current_cred(); if (!has_capability_noaudit(current, CAP_SYSLOG) || !uid_eq(cred->euid, cred->uid) || !gid_eq(cred->egid, cred->gid)) -- cgit From edf14cdbf9a0e5ab52698ca66d07a76ade0d5c46 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Tue, 15 Mar 2016 14:55:56 -0700 Subject: mm, printk: introduce new format string for flags In mm we use several kinds of flags bitfields that are sometimes printed for debugging purposes, or exported to userspace via sysfs. To make them easier to interpret independently on kernel version and config, we want to dump also the symbolic flag names. So far this has been done with repeated calls to pr_cont(), which is unreliable on SMP, and not usable for e.g. sysfs export. To get a more reliable and universal solution, this patch extends printk() format string for pointers to handle the page flags (%pGp), gfp_flags (%pGg) and vma flags (%pGv). Existing users of dump_flag_names() are converted and simplified. It would be possible to pass flags by value instead of pointer, but the %p format string for pointers already has extensions for various kernel structures, so it's a good fit, and the extra indirection in a non-critical path is negligible. [linux@rasmusvillemoes.dk: lots of good implementation suggestions] Signed-off-by: Vlastimil Babka Acked-by: Michal Hocko Cc: Steven Rostedt Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Ingo Molnar Cc: Rasmus Villemoes Cc: Joonsoo Kim Cc: Minchan Kim Cc: Sasha Levin Cc: "Kirill A. Shutemov" Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/vsprintf.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) (limited to 'lib/vsprintf.c') diff --git a/lib/vsprintf.c b/lib/vsprintf.c index f44e178e6ede..525c8e19bda2 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -35,6 +35,8 @@ #include #endif +#include "../mm/internal.h" /* For the trace_print_flags arrays */ + #include /* for PAGE_SIZE */ #include /* for dereference_function_descriptor() */ #include /* cpu_to_le16 */ @@ -1407,6 +1409,72 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec, } } +static +char *format_flags(char *buf, char *end, unsigned long flags, + const struct trace_print_flags *names) +{ + unsigned long mask; + const struct printf_spec strspec = { + .field_width = -1, + .precision = -1, + }; + const struct printf_spec numspec = { + .flags = SPECIAL|SMALL, + .field_width = -1, + .precision = -1, + .base = 16, + }; + + for ( ; flags && names->name; names++) { + mask = names->mask; + if ((flags & mask) != mask) + continue; + + buf = string(buf, end, names->name, strspec); + + flags &= ~mask; + if (flags) { + if (buf < end) + *buf = '|'; + buf++; + } + } + + if (flags) + buf = number(buf, end, flags, numspec); + + return buf; +} + +static noinline_for_stack +char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt) +{ + unsigned long flags; + const struct trace_print_flags *names; + + switch (fmt[1]) { + case 'p': + flags = *(unsigned long *)flags_ptr; + /* Remove zone id */ + flags &= (1UL << NR_PAGEFLAGS) - 1; + names = pageflag_names; + break; + case 'v': + flags = *(unsigned long *)flags_ptr; + names = vmaflag_names; + break; + case 'g': + flags = *(gfp_t *)flags_ptr; + names = gfpflag_names; + break; + default: + WARN_ONCE(1, "Unsupported flags modifier: %c\n", fmt[1]); + return buf; + } + + return format_flags(buf, end, flags, names); +} + int kptr_restrict __read_mostly; /* @@ -1495,6 +1563,11 @@ int kptr_restrict __read_mostly; * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address * (legacy clock framework) of the clock * - 'Cr' For a clock, it prints the current rate of the clock + * - 'G' For flags to be printed as a collection of symbolic strings that would + * construct the specific value. Supported flags given by option: + * p page flags (see struct page) given as pointer to unsigned long + * g gfp flags (GFP_* and __GFP_*) given as pointer to gfp_t + * v vma flags (VM_*) given as pointer to unsigned long * * ** Please update also Documentation/printk-formats.txt when making changes ** * @@ -1648,6 +1721,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, return bdev_name(buf, end, ptr, spec, fmt); #endif + case 'G': + return flags_string(buf, end, ptr, fmt); } spec.flags |= SMALL; if (spec.field_width == -1) { -- cgit From f9310b2f9a19b7f16c7b1c1558f8b649b9b933c1 Mon Sep 17 00:00:00 2001 From: Jessica Yu Date: Thu, 17 Mar 2016 14:23:07 -0700 Subject: sscanf: implement basic character sets Implement basic character sets for the '%[' conversion specifier. The '%[' conversion specifier matches a nonempty sequence of characters from the specified set of accepted (or with '^', rejected) characters between the brackets. The substring matched is to be made up of characters in (or not in) the set. This is useful for matching substrings that are delimited by something other than spaces. This implementation differs from its glibc counterpart in the following ways: (1) No support for character ranges (e.g., 'a-z' or '0-9') (2) The hyphen '-' is not a special character (3) The closing bracket ']' cannot be matched (4) No support (yet) for discarding matching input ('%*[') The bitmap code is largely based upon sample code which was provided by Rasmus. The motivation for adding character set support to sscanf originally stemmed from the kernel livepatching project. An ongoing patchset utilizes new livepatch Elf symbol and section names to store important metadata livepatch needs to properly apply its patches. Such metadata is stored in these section and symbol names as substrings delimited by periods '.' and commas ','. For example, a livepatch symbol name might look like this: .klp.sym.vmlinux.printk,0 However, sscanf currently can only extract "substrings" delimited by whitespace using the "%s" specifier. Thus for the above symbol name, one cannot not use sscanf() to extract substrings "vmlinux" or "printk", for example. A number of discussions on the livepatch mailing list dealing with string parsing code for extracting these '.' and ',' delimited substrings eventually led to the conclusion that such code would be completely unnecessary if the kernel sscanf() supported character sets. Thus only a single sscanf() call would be necessary to extract these substrings. In addition, such an addition to sscanf() could benefit other areas of the kernel that might have a similar need in the future. [akpm@linux-foundation.org: 80-col tweaks] Signed-off-by: Jessica Yu Signed-off-by: Rasmus Villemoes Cc: Andy Shevchenko Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/vsprintf.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 58 insertions(+), 1 deletion(-) (limited to 'lib/vsprintf.c') diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 525c8e19bda2..ccb664b54280 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -2640,8 +2640,12 @@ int vsscanf(const char *buf, const char *fmt, va_list args) if (*fmt == '*') { if (!*str) break; - while (!isspace(*fmt) && *fmt != '%' && *fmt) + while (!isspace(*fmt) && *fmt != '%' && *fmt) { + /* '%*[' not yet supported, invalid format */ + if (*fmt == '[') + return num; fmt++; + } while (!isspace(*str) && *str) str++; continue; @@ -2714,6 +2718,59 @@ int vsscanf(const char *buf, const char *fmt, va_list args) num++; } continue; + /* + * Warning: This implementation of the '[' conversion specifier + * deviates from its glibc counterpart in the following ways: + * (1) It does NOT support ranges i.e. '-' is NOT a special + * character + * (2) It cannot match the closing bracket ']' itself + * (3) A field width is required + * (4) '%*[' (discard matching input) is currently not supported + * + * Example usage: + * ret = sscanf("00:0a:95","%2[^:]:%2[^:]:%2[^:]", + * buf1, buf2, buf3); + * if (ret < 3) + * // etc.. + */ + case '[': + { + char *s = (char *)va_arg(args, char *); + DECLARE_BITMAP(set, 256) = {0}; + unsigned int len = 0; + bool negate = (*fmt == '^'); + + /* field width is required */ + if (field_width == -1) + return num; + + if (negate) + ++fmt; + + for ( ; *fmt && *fmt != ']'; ++fmt, ++len) + set_bit((u8)*fmt, set); + + /* no ']' or no character set found */ + if (!*fmt || !len) + return num; + ++fmt; + + if (negate) { + bitmap_complement(set, set, 256); + /* exclude null '\0' byte */ + clear_bit(0, set); + } + + /* match must be non-empty */ + if (!test_bit((u8)*str, set)) + return num; + + while (test_bit((u8)*str, set) && field_width--) + *s++ = *str++; + *s = '\0'; + ++num; + } + continue; case 'o': base = 8; break; -- cgit