On Tue, Sep 17, 2019 at 10:38:47PM +0200, Heinrich Schuchardt wrote:
> On 9/6/19 8:09 AM, AKASHI Takahiro wrote:
> >If EFI_VARIABLE_APPEND_WRITE is specified in attributes at
> >efi_set_variable(), specified data will be appended to the variable's
> >original value. Attributes other than APPEND_WRITE should not be
> >modified.
> >
> >With this patch, APPEND_WRITE test in 'variables' selftest will pass.
> >
> >Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org>
> >---
> > lib/efi_loader/efi_variable.c | 70 ++++++++++++++++++++++-------------
> > 1 file changed, 44 insertions(+), 26 deletions(-)
> >
> >diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
> >index 6687b69a400d..48ee255f879b 100644
> >--- a/lib/efi_loader/efi_variable.c
> >+++ b/lib/efi_loader/efi_variable.c
> >@@ -424,17 +424,17 @@ efi_status_t EFIAPI efi_set_variable(u16
> >*variable_name,
> > efi_uintn_t data_size, const void *data)
> > {
> > char *native_name = NULL, *val = NULL, *s;
> >+ const char *old_val;
> >+ size_t old_size;
> > efi_status_t ret = EFI_SUCCESS;
> > u32 attr;
> >
> > EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
> > data_size, data);
> >
> >- /* TODO: implement APPEND_WRITE */
> > if (!variable_name || !*variable_name || !vendor ||
> > ((attributes & EFI_VARIABLE_RUNTIME_ACCESS) &&
> >- !(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)) ||
> >- (attributes & EFI_VARIABLE_APPEND_WRITE)) {
> >+ !(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS))) {
> > ret = EFI_INVALID_PARAMETER;
> > goto out;
> > }
> >@@ -445,35 +445,51 @@ efi_status_t EFIAPI efi_set_variable(u16
> >*variable_name,
> >
> > #define ACCESS_ATTR (EFI_VARIABLE_RUNTIME_ACCESS |
> > EFI_VARIABLE_BOOTSERVICE_ACCESS)
> >
> >- if ((data_size == 0) || !(attributes & ACCESS_ATTR)) {
> >- /* delete the variable: */
> >- env_set(native_name, NULL);
> >- ret = EFI_SUCCESS;
> >- goto out;
> >- }
> >+ old_val = env_get(native_name);
> >+ if (old_val) {
> >+ old_val = parse_attr(old_val, &attr);
> >
> >- val = env_get(native_name);
> >- if (val) {
> >- parse_attr(val, &attr);
> >-
> >- /* We should not free val */
> >- val = NULL;
> >+ /* check read-only first */
> > if (attr & READ_ONLY) {
> > ret = EFI_WRITE_PROTECTED;
> > goto out;
> > }
> >
> >- /*
> >- * attributes won't be changed
> >- * TODO: take care of APPEND_WRITE once supported
> >- */
> >- if (attr != attributes) {
> >+ if ((data_size == 0) || !(attributes & ACCESS_ATTR)) {
>
> The understanding of EDK2 is that no access attributes means 'attributes
> == 0' (Function VariableServiceSetVariable() in
> MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c).
No, it's not correct. The right place you should refer to is:
UpdateVariable (
[snip up to l.2279 or so]
//
// Setting a data variable with no access, or zero DataSize attributes
// causes it to be deleted.
// When the EFI_VARIABLE_APPEND_WRITE attribute is set, DataSize of zero
will
// not delete the variable.
//
if ((((Attributes & EFI_VARIABLE_APPEND_WRITE) == 0) && (DataSize == 0))||
((Attributes & (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS))
== 0)) {
> EFI_VARIABLE_APPEND_WRITE and data_size = 0 should not delete a variable
> according to the UEFI spec:
This is correct.
Thanks,
-Takahiro Akashi
> "Unless the EFI_VARIABLE_APPEND_WRITE,
> EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS, or
> EFI_VARIABLE_ENHANCED_AUTHENTICATED_ACCESS attribute is set (see below),
> using SetVariable() with a DataSize of zero will cause the entire
> variable to be deleted."
>
> Best regards
>
> Heinrich
>
> >+ /* delete the variable: */
> >+ env_set(native_name, NULL);
> >+ ret = EFI_SUCCESS;
> >+ goto out;
> >+ }
> >+
> >+ /* attributes won't be changed */
> >+ if (attr != (attributes & ~EFI_VARIABLE_APPEND_WRITE)) {
> > ret = EFI_INVALID_PARAMETER;
> > goto out;
> > }
> >+
> >+ if (attributes & EFI_VARIABLE_APPEND_WRITE) {
> >+ if (!prefix(old_val, "(blob)")) {
> >+ return EFI_DEVICE_ERROR;
> >+ goto out;
> >+ }
> >+ old_size = strlen(old_val);
> >+ } else {
> >+ old_size = 0;
> >+ }
> >+ } else {
> >+ if ((data_size == 0) || !(attributes & ACCESS_ATTR) ||
> >+ (attributes & EFI_VARIABLE_APPEND_WRITE)) {
> >+ /* delete, but nothing to do */
> >+ ret = EFI_NOT_FOUND;
> >+ goto out;
> >+ }
> >+
> >+ old_size = 0;
> > }
> >
> >- val = malloc(2 * data_size + strlen("{ro,run,boot,nv}(blob)") + 1);
> >+ val = malloc(old_size + 2 * data_size
> >+ + strlen("{ro,run,boot,nv}(blob)") + 1);
> > if (!val) {
> > ret = EFI_OUT_OF_RESOURCES;
> > goto out;
> >@@ -481,10 +497,7 @@ efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
> >
> > s = val;
> >
> >- /*
> >- * store attributes
> >- * TODO: several attributes are not supported
> >- */
> >+ /* store attributes */
> > attributes &= (EFI_VARIABLE_NON_VOLATILE |
> > EFI_VARIABLE_BOOTSERVICE_ACCESS |
> > EFI_VARIABLE_RUNTIME_ACCESS);
> >@@ -505,8 +518,13 @@ efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
> > }
> > s += sprintf(s, "}");
> >
> >+ if (old_size)
> >+ /* APPEND_WRITE */
> >+ s += sprintf(s, old_val);
> >+ else
> >+ s += sprintf(s, "(blob)");
> >+
> > /* store payload: */
> >- s += sprintf(s, "(blob)");
> > s = bin2hex(s, data, data_size);
> > *s = '\0';
> >
> >
>
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