util-lib: split shared/efivars into basic/efivars and shared/efi-loader

I want to use efivars.[ch] in proc-cmdline.c, but most of the efivars stuff is not needed in basic/. Move the file from shared/ to basic/, but then move back most of the higher-level functions to the new shared/efi-loader.c file.
2019-09-16 18:08:53 +02:00
parent 2bfa8466c0
commit 0bb2f0f10e
18 changed files with 297 additions and 263 deletions
@@ -0,0 +1,225 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <linux/fs.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "sd-id128.h"
+
+#include "alloc-util.h"
+#include "chattr-util.h"
+#include "efivars.h"
+#include "fd-util.h"
+#include "io-util.h"
+#include "macro.h"
+#include "stdio-util.h"
+#include "strv.h"
+#include "time-util.h"
+#include "utf8.h"
+
+#if ENABLE_EFI
+
+char* efi_variable_path(sd_id128_t vendor, const char *name) {
+        char *p;
+
+        if (asprintf(&p,
+                     "/sys/firmware/efi/efivars/%s-" SD_ID128_UUID_FORMAT_STR,
+                     name, SD_ID128_FORMAT_VAL(vendor)) < 0)
+                return NULL;
+
+        return p;
+}
+
+int efi_get_variable(
+                sd_id128_t vendor,
+                const char *name,
+                uint32_t *ret_attribute,
+                void **ret_value,
+                size_t *ret_size) {
+
+        _cleanup_close_ int fd = -1;
+        _cleanup_free_ char *p = NULL;
+        _cleanup_free_ void *buf = NULL;
+        struct stat st;
+        uint32_t a;
+        ssize_t n;
+
+        assert(name);
+
+        p = efi_variable_path(vendor, name);
+        if (!p)
+                return -ENOMEM;
+
+        if (!ret_value && !ret_size && !ret_attribute) {
+                /* If caller is not interested in anything, just check if the variable exists and is readable
+                 * to us. */
+                if (access(p, R_OK) < 0)
+                        return -errno;
+
+                return 0;
+        }
+
+        fd = open(p, O_RDONLY|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+        if (st.st_size < 4)
+                return -ENODATA;
+        if (st.st_size > 4*1024*1024 + 4)
+                return -E2BIG;
+
+        if (ret_value || ret_attribute) {
+                n = read(fd, &a, sizeof(a));
+                if (n < 0)
+                        return -errno;
+                if (n != sizeof(a))
+                        return -EIO;
+        }
+
+        if (ret_value) {
+                buf = malloc(st.st_size - 4 + 2);
+                if (!buf)
+                        return -ENOMEM;
+
+                n = read(fd, buf, (size_t) st.st_size - 4);
+                if (n < 0)
+                        return -errno;
+                if (n != st.st_size - 4)
+                        return -EIO;
+
+                /* Always NUL terminate (2 bytes, to protect UTF-16) */
+                ((char*) buf)[st.st_size - 4] = 0;
+                ((char*) buf)[st.st_size - 4 + 1] = 0;
+        }
+
+        /* Note that efivarfs interestingly doesn't require ftruncate() to update an existing EFI variable
+         * with a smaller value. */
+
+        if (ret_attribute)
+                *ret_attribute = a;
+
+        if (ret_value)
+                *ret_value = TAKE_PTR(buf);
+
+        if (ret_size)
+                *ret_size = (size_t) st.st_size - 4;
+
+        return 0;
+}
+
+int efi_get_variable_string(sd_id128_t vendor, const char *name, char **p) {
+        _cleanup_free_ void *s = NULL;
+        size_t ss = 0;
+        int r;
+        char *x;
+
+        r = efi_get_variable(vendor, name, NULL, &s, &ss);
+        if (r < 0)
+                return r;
+
+        x = utf16_to_utf8(s, ss);
+        if (!x)
+                return -ENOMEM;
+
+        *p = x;
+        return 0;
+}
+
+int efi_set_variable(
+                sd_id128_t vendor,
+                const char *name,
+                const void *value,
+                size_t size) {
+
+        struct var {
+                uint32_t attr;
+                char buf[];
+        } _packed_ * _cleanup_free_ buf = NULL;
+        _cleanup_free_ char *p = NULL;
+        _cleanup_close_ int fd = -1;
+        bool saved_flags_valid = false;
+        unsigned saved_flags;
+        int r;
+
+        assert(name);
+        assert(value || size == 0);
+
+        p = efi_variable_path(vendor, name);
+        if (!p)
+                return -ENOMEM;
+
+        /* Newer efivarfs protects variables that are not in a whitelist with FS_IMMUTABLE_FL by default, to protect
+         * them for accidental removal and modification. We are not changing these variables accidentally however,
+         * hence let's unset the bit first. */
+
+        r = chattr_path(p, 0, FS_IMMUTABLE_FL, &saved_flags);
+        if (r < 0 && r != -ENOENT)
+                log_debug_errno(r, "Failed to drop FS_IMMUTABLE_FL flag from '%s', ignoring: %m", p);
+
+        saved_flags_valid = r >= 0;
+
+        if (size == 0) {
+                if (unlink(p) < 0) {
+                        r = -errno;
+                        goto finish;
+                }
+
+                return 0;
+        }
+
+        fd = open(p, O_WRONLY|O_CREAT|O_NOCTTY|O_CLOEXEC, 0644);
+        if (fd < 0) {
+                r = -errno;
+                goto finish;
+        }
+
+        buf = malloc(sizeof(uint32_t) + size);
+        if (!buf) {
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        buf->attr = EFI_VARIABLE_NON_VOLATILE|EFI_VARIABLE_BOOTSERVICE_ACCESS|EFI_VARIABLE_RUNTIME_ACCESS;
+        memcpy(buf->buf, value, size);
+
+        r = loop_write(fd, buf, sizeof(uint32_t) + size, false);
+        if (r < 0)
+                goto finish;
+
+        r = 0;
+
+finish:
+        if (saved_flags_valid) {
+                int q;
+
+                /* Restore the original flags field, just in case */
+                if (fd < 0)
+                        q = chattr_path(p, saved_flags, FS_IMMUTABLE_FL, NULL);
+                else
+                        q = chattr_fd(fd, saved_flags, FS_IMMUTABLE_FL, NULL);
+                if (q < 0)
+                        log_debug_errno(q, "Failed to restore FS_IMMUTABLE_FL on '%s', ignoring: %m", p);
+        }
+
+        return r;
+}
+
+int efi_set_variable_string(sd_id128_t vendor, const char *name, const char *v) {
+        _cleanup_free_ char16_t *u16 = NULL;
+
+        u16 = utf8_to_utf16(v, strlen(v));
+        if (!u16)
+                return -ENOMEM;
+
+        return efi_set_variable(vendor, name, u16, (char16_strlen(u16) + 1) * sizeof(char16_t));
+}
+
+#endif
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#if !ENABLE_EFI
+#  include <errno.h>
+#endif
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "sd-id128.h"
+
+#include "efi/loader-features.h"
+#include "time-util.h"
+
+#define EFI_VENDOR_LOADER SD_ID128_MAKE(4a,67,b0,82,0a,4c,41,cf,b6,c7,44,0b,29,bb,8c,4f)
+#define EFI_VENDOR_GLOBAL SD_ID128_MAKE(8b,e4,df,61,93,ca,11,d2,aa,0d,00,e0,98,03,2b,8c)
+#define EFI_VARIABLE_NON_VOLATILE       0x0000000000000001
+#define EFI_VARIABLE_BOOTSERVICE_ACCESS 0x0000000000000002
+#define EFI_VARIABLE_RUNTIME_ACCESS     0x0000000000000004
+
+#if ENABLE_EFI
+
+char* efi_variable_path(sd_id128_t vendor, const char *name);
+int efi_get_variable(sd_id128_t vendor, const char *name, uint32_t *attribute, void **value, size_t *size);
+int efi_get_variable_string(sd_id128_t vendor, const char *name, char **p);
+int efi_set_variable(sd_id128_t vendor, const char *name, const void *value, size_t size);
+int efi_set_variable_string(sd_id128_t vendor, const char *name, const char *p);
+
+#else
+
+static inline char* efi_variable_path(sd_id128_t vendor, const char *name) {
+        return NULL;
+}
+
+static inline int efi_get_variable(sd_id128_t vendor, const char *name, uint32_t *attribute, void **value, size_t *size) {
+        return -EOPNOTSUPP;
+}
+
+static inline int efi_get_variable_string(sd_id128_t vendor, const char *name, char **p) {
+        return -EOPNOTSUPP;
+}
+
+static inline int efi_set_variable(sd_id128_t vendor, const char *name, const void *value, size_t size) {
+        return -EOPNOTSUPP;
+}
+
+static inline int efi_set_variable_string(sd_id128_t vendor, const char *name, const char *p) {
+        return -EOPNOTSUPP;
+}
+
+#endif
@@ -39,6 +39,8 @@ basic_sources = files('''
        device-nodes.h
        dirent-util.c
        dirent-util.h
+        efivars.c
+        efivars.h
        env-file.c
        env-file.h
        env-util.c