From a664a834579ae8a6166ac9e5a3232976cab2c24d Mon Sep 17 00:00:00 2001 From: Peter Wu Date: Fri, 9 Aug 2019 01:39:11 +0100 Subject: [PATCH] tools: bpftool: fix reading from /proc/config.gz /proc/config has never existed as far as I can see, but /proc/config.gz is present on Arch Linux. Add support for decompressing config.gz using zlib which is a mandatory dependency of libelf anyway. Replace existing stdio functions with gzFile operations since the latter transparently handles uncompressed and gzip-compressed files. Cc: Quentin Monnet Signed-off-by: Peter Wu Reviewed-by: Quentin Monnet Signed-off-by: Daniel Borkmann --- tools/bpf/bpftool/Makefile | 2 +- tools/bpf/bpftool/feature.c | 109 ++++++++++++++++++------------------ 2 files changed, 56 insertions(+), 55 deletions(-) diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index a7afea4dec47..078bd0dcfba5 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -52,7 +52,7 @@ ifneq ($(EXTRA_LDFLAGS),) LDFLAGS += $(EXTRA_LDFLAGS) endif -LIBS = -lelf $(LIBBPF) +LIBS = -lelf -lz $(LIBBPF) INSTALL ?= install RM ?= rm -f diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c index d672d9086fff..03bdc5b3ac49 100644 --- a/tools/bpf/bpftool/feature.c +++ b/tools/bpf/bpftool/feature.c @@ -14,6 +14,7 @@ #include #include +#include #include "main.h" @@ -284,34 +285,32 @@ static void probe_jit_limit(void) } } -static char *get_kernel_config_option(FILE *fd, const char *option) +static bool read_next_kernel_config_option(gzFile file, char *buf, size_t n, + char **value) { - size_t line_n = 0, optlen = strlen(option); - char *res, *strval, *line = NULL; - ssize_t n; + char *sep; - rewind(fd); - while ((n = getline(&line, &line_n, fd)) > 0) { - if (strncmp(line, option, optlen)) + while (gzgets(file, buf, n)) { + if (strncmp(buf, "CONFIG_", 7)) continue; - /* Check we have at least '=', value, and '\n' */ - if (strlen(line) < optlen + 3) - continue; - if (*(line + optlen) != '=') + + sep = strchr(buf, '='); + if (!sep) continue; /* Trim ending '\n' */ - line[strlen(line) - 1] = '\0'; + buf[strlen(buf) - 1] = '\0'; - /* Copy and return config option value */ - strval = line + optlen + 1; - res = strdup(strval); - free(line); - return res; + /* Split on '=' and ensure that a value is present. */ + *sep = '\0'; + if (!sep[1]) + continue; + + *value = sep + 1; + return true; } - free(line); - return NULL; + return false; } static void probe_kernel_image_config(void) @@ -386,59 +385,61 @@ static void probe_kernel_image_config(void) /* test_bpf module for BPF tests */ "CONFIG_TEST_BPF", }; - char *value, *buf = NULL; + char *values[ARRAY_SIZE(options)] = { }; struct utsname utsn; char path[PATH_MAX]; - size_t i, n; - ssize_t ret; - FILE *fd; + gzFile file = NULL; + char buf[4096]; + char *value; + size_t i; - if (uname(&utsn)) - goto no_config; + if (!uname(&utsn)) { + snprintf(path, sizeof(path), "/boot/config-%s", utsn.release); - snprintf(path, sizeof(path), "/boot/config-%s", utsn.release); - - fd = fopen(path, "r"); - if (!fd && errno == ENOENT) { - /* Some distributions put the config file at /proc/config, give - * it a try. - * Sometimes it is also at /proc/config.gz but we do not try - * this one for now, it would require linking against libz. - */ - fd = fopen("/proc/config", "r"); + /* gzopen also accepts uncompressed files. */ + file = gzopen(path, "r"); } - if (!fd) { + + if (!file) { + /* Some distributions build with CONFIG_IKCONFIG=y and put the + * config file at /proc/config.gz. + */ + file = gzopen("/proc/config.gz", "r"); + } + if (!file) { p_info("skipping kernel config, can't open file: %s", strerror(errno)); - goto no_config; + goto end_parse; } /* Sanity checks */ - ret = getline(&buf, &n, fd); - ret = getline(&buf, &n, fd); - if (!buf || !ret) { + if (!gzgets(file, buf, sizeof(buf)) || + !gzgets(file, buf, sizeof(buf))) { p_info("skipping kernel config, can't read from file: %s", strerror(errno)); - free(buf); - goto no_config; + goto end_parse; } if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) { p_info("skipping kernel config, can't find correct file"); - free(buf); - goto no_config; + goto end_parse; } - free(buf); + + while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) { + for (i = 0; i < ARRAY_SIZE(options); i++) { + if (values[i] || strcmp(buf, options[i])) + continue; + + values[i] = strdup(value); + } + } + +end_parse: + if (file) + gzclose(file); for (i = 0; i < ARRAY_SIZE(options); i++) { - value = get_kernel_config_option(fd, options[i]); - print_kernel_option(options[i], value); - free(value); + print_kernel_option(options[i], values[i]); + free(values[i]); } - fclose(fd); - return; - -no_config: - for (i = 0; i < ARRAY_SIZE(options); i++) - print_kernel_option(options[i], NULL); } static bool probe_bpf_syscall(const char *define_prefix)