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diff --git a/debian/patches/efivar-check-that-efivarfs-is-writeable.patch b/debian/patches/efivar-check-that-efivarfs-is-writeable.patch
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new file mode 100644
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new file mode 100644
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index 0000000..93bcf16
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--- /dev/null
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+++ b/debian/patches/efivar-check-that-efivarfs-is-writeable.patch
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@@ -0,0 +1,117 @@
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1
From 5bf070ddb6cbcc5af3725908a2e092fd02352f4c Mon Sep 17 00:00:00 2001
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From: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
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Date: Fri, 18 Mar 2022 15:21:33 +0100
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Subject: [PATCH 1/1] efivar: check that efivarfs is writeable
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Some UEFI implementations (notably U-Boot) don't implement the
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SetVariable() runtime service. On these systems the GRUB installation
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must be completed manually. Write a warning in this case but avoid
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throwing an error.
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Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
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---
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 grub-core/osdep/unix/efivar.c | 81 +++++++++++++++++++++++++++++++++++
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 1 file changed, 81 insertions(+)
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diff --git a/grub-core/osdep/unix/efivar.c b/grub-core/osdep/unix/efivar.c
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index d34df0f70..8a7ee0c94 100644
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--- a/grub-core/osdep/unix/efivar.c
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+++ b/grub-core/osdep/unix/efivar.c
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@@ -511,6 +511,79 @@ devices_equal (const_efidp a, const_efidp b)
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   return false;
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 }
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+/**
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+ * efivar_is_rw - detect if the efivar file system exists and is writeable
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+ *
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+ * Return:	true if efivarfs is writeable
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+ */
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+static bool
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+efivar_is_rw (void)
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+{
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+  const char filename[] = "/proc/self/mounts";
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+  int fd;
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+  grub_uint64_t size;
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+  char *data = NULL, *start, *end, *pos;
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+  bool ret = false;
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+
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+  fd = grub_util_fd_open (filename, GRUB_UTIL_FD_O_RDONLY);
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+  if (fd == -1)
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+    {
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+      grub_util_warn (_("cannot open `%s': %s"), filename, strerror (errno));
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+      return 0;
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+    }
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+
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+  /*
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+   * /proc/self/mounts does not provide a filesize. So read it into an initial
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+   * buffer. If the last byte of the buffer is overwritten, retry with double
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+   * the buffer size.
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+   */
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+  size = 4096;
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+  for (;;) {
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+    ssize_t s;
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+
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+    fd = grub_util_fd_open (filename, GRUB_UTIL_FD_O_RDONLY);
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+    if (fd == -1)
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+      {
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+        grub_util_warn (_("cannot open `%s': %s"), filename, strerror (errno));
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+        return 0;
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+      }
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+
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+    grub_util_info ("size %ld", size);
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+    data = xmalloc (size);
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63
+    grub_memset (data, 0, size);
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64
+    if (!data)
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+      {
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+        grub_util_warn ("%s", _("out of memory"));
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+        goto out;
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+      }
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+    s = read(fd, data, size);
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+    if (s < 0)
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+      {
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+        grub_util_warn (_("cannot read `%s': %s"), filename, strerror (errno));
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+        goto out;
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+      }
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+    grub_util_fd_close (fd);
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+    if (!data[size - 1])
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+        break;
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+    free(data);
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+    size *= 2;
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+  }
87
81
+
88
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+  start = grub_strstr (data, "efivarfs ");
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+  if (!start)
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+    goto out;
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+  end = grub_strstr (start, "\n");
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86
+  if (!end)
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+    goto out;
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+  pos = grub_strstr (start, " rw,");
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+  if (pos && pos < end)
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+    ret = true;
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+
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+out:
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+  grub_free (data);
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+  return ret;
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95
+}
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+
103
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 int
104
98
 grub_install_efivar_register_efi (grub_device_t efidir_grub_dev,
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 				  const char *efidir, const char *efifile_path,
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@@ -528,6 +601,14 @@ grub_install_efivar_register_efi (grub_device_t efidir_grub_dev,
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   int rc;
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102
   bool is_boot_efi;
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110
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+  /* Check if EFI variable can be written */
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+  if (!efivar_is_rw ())
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+    {
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+      grub_util_warn ("EFI variables cannot be set on this system");
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+      grub_util_warn ("You will have to complete the GRUB setup manually");
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+      return 0;
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+    }
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+
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   is_boot_efi = strstr (efidir, "/boot/efi") != NULL;
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   efidir_disk = grub_util_biosdisk_get_osdev (efidir_grub_dev->disk);
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   efidir_part = efidir_grub_dev->disk->partition ? efidir_grub_dev->disk->partition->number + 1 : 1;
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-- 
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2.34.1
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diff --git a/debian/patches/series b/debian/patches/series
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index 7942ada..0a4b388 100644
126
--- a/debian/patches/series
127
+++ b/debian/patches/series
128
@@ -121,3 +121,4 @@ ubuntu-os-prober-auto.patch
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121
efi-correct-struct-grub_efi_boot_services.patch
121
efi-correct-struct-grub_efi_boot_services.patch
130
122
efi-implement-grub_efi_run_image.patch
122
efi-implement-grub_efi_run_image.patch
131
123
fat-fix-listing-the-root-directory.patch
123
fat-fix-listing-the-root-directory.patch
132
124
efivar-check-that-efivarfs-is-writeable.patch
Status:	Superseded
Proposed branch:	~xypron/grub:efivarfs
Merge into:	~ubuntu-core-dev/grub/+git/ubuntu:ubuntu
Diff against target:	132 lines (+118/-0) 2 files modified debian/patches/efivar-check-that-efivarfs-is-writeable.patch (+117/-0) debian/patches/series (+1/-0)
Related bugs:	Link a bug report
Reviewer	Review Type	Date Requested	Status
Ubuntu Core Development Team		2022-03-21	Pending
Review via email: mp+417181@code.launchpad.net