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Add support for SystemdOptions EFI var to augment /proc/cmdline

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In various circumstances, overriding the kernel commandline can be inconvenient.
People have different bootloaders, and e.g. the grub config can be pretty scary.
grubby helps, but it isn't always available.

This option adds an alternative mechanism that can quite convenient on EFI
systems. cmdline settings have higher priority, because they can be (usually)
changed on the bootloader prompt.

$SYSTEMD_EFI_OPTIONS can be used to override, same as $SYSTEMD_PROC_CMDLINE.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2019-09-16 18:08:54 +02:00
parent e825ea2f4c
commit 53aa0d02ad
5 changed files with 132 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/basic/efivars.c
+25
View File
@@ -222,4 +222,29 @@ int efi_set_variable_string(sd_id128_t vendor, const char *name, const char *v)
return efi_set_variable(vendor, name, u16, (char16_strlen(u16) + 1) * sizeof(char16_t));
}
int efi_systemd_options_variable(char **line) {
const char *e;
int r;
assert(line);
/* For testing purposes it is sometimes useful to be able to override this */
e = secure_getenv("SYSTEMD_EFI_OPTIONS");
if (e) {
char *m;
m = strdup(e);
if (!m)
return -ENOMEM;
*line = m;
return 0;
}
r = efi_get_variable_string(EFI_VENDOR_SYSTEMD, "SystemdOptions", line);
if (r == -ENOENT)
return -ENODATA;
return r;
}
#endif
src/basic/efivars.h
+9 -2
View File
@@ -13,8 +13,9 @@
#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_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_VENDOR_SYSTEMD SD_ID128_MAKE(8c,f2,64,4b,4b,0b,42,8f,93,87,6d,87,60,50,dc,67)
#define EFI_VARIABLE_NON_VOLATILE 0x0000000000000001
#define EFI_VARIABLE_BOOTSERVICE_ACCESS 0x0000000000000002
#define EFI_VARIABLE_RUNTIME_ACCESS 0x0000000000000004
@@ -27,6 +28,8 @@ 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);
int efi_systemd_options_variable(char **line);
#else
static inline char* efi_variable_path(sd_id128_t vendor, const char *name) {
@@ -49,4 +52,8 @@ static inline int efi_set_variable_string(sd_id128_t vendor, const char *name, c
return -EOPNOTSUPP;
}
static inline int efi_systemd_options_variable(char **line) {
return -ENODATA;
}
#endif
src/basic/proc-cmdline.c
+58 -24
View File
@@ -5,6 +5,7 @@
#include <string.h>
#include "alloc-util.h"
#include "efivars.h"
#include "extract-word.h"
#include "fileio.h"
#include "macro.h"
@@ -117,6 +118,17 @@ int proc_cmdline_parse(proc_cmdline_parse_t parse_item, void *data, ProcCmdlineF
assert(parse_item);
/* We parse the EFI variable first, because later settings have higher priority. */
r = efi_systemd_options_variable(&line);
if (r < 0 && r != -ENODATA)
log_debug_errno(r, "Failed to get SystemdOptions EFI variable, ignoring: %m");
r = proc_cmdline_parse_given(line, parse_item, data, flags);
if (r < 0)
return r;
line = mfree(line);
r = proc_cmdline(&line);
if (r < 0)
return r;
@@ -156,34 +168,14 @@ bool proc_cmdline_key_streq(const char *x, const char *y) {
return true;
}
int proc_cmdline_get_key(const char *key, ProcCmdlineFlags flags, char **ret_value) {
_cleanup_free_ char *line = NULL, *ret = NULL;
static int cmdline_get_key(const char *line, const char *key, ProcCmdlineFlags flags, char **ret_value) {
_cleanup_free_ char *ret = NULL;
bool found = false;
const char *p;
int r;
/* Looks for a specific key on the kernel command line. Supports three modes:
*
* a) The "ret_value" parameter is used. In this case a parameter beginning with the "key" string followed by
* "=" is searched for, and the value following it is returned in "ret_value".
*
* b) as above, but the PROC_CMDLINE_VALUE_OPTIONAL flag is set. In this case if the key is found as a separate
* word (i.e. not followed by "=" but instead by whitespace or the end of the command line), then this is
* also accepted, and "value" is returned as NULL.
*
* c) The "ret_value" parameter is NULL. In this case a search for the exact "key" parameter is performed.
*
* In all three cases, > 0 is returned if the key is found, 0 if not. */
if (isempty(key))
return -EINVAL;
if (FLAGS_SET(flags, PROC_CMDLINE_VALUE_OPTIONAL) && !ret_value)
return -EINVAL;
r = proc_cmdline(&line);
if (r < 0)
return r;
assert(line);
assert(key);
p = line;
for (;;) {
@@ -226,6 +218,48 @@ int proc_cmdline_get_key(const char *key, ProcCmdlineFlags flags, char **ret_val
return found;
}
int proc_cmdline_get_key(const char *key, ProcCmdlineFlags flags, char **ret_value) {
_cleanup_free_ char *line = NULL;
int r;
/* Looks for a specific key on the kernel command line and (with lower priority) the EFI variable.
* Supports three modes:
*
* a) The "ret_value" parameter is used. In this case a parameter beginning with the "key" string followed by
* "=" is searched for, and the value following it is returned in "ret_value".
*
* b) as above, but the PROC_CMDLINE_VALUE_OPTIONAL flag is set. In this case if the key is found as a separate
* word (i.e. not followed by "=" but instead by whitespace or the end of the command line), then this is
* also accepted, and "value" is returned as NULL.
*
* c) The "ret_value" parameter is NULL. In this case a search for the exact "key" parameter is performed.
*
* In all three cases, > 0 is returned if the key is found, 0 if not. */
if (isempty(key))
return -EINVAL;
if (FLAGS_SET(flags, PROC_CMDLINE_VALUE_OPTIONAL) && !ret_value)
return -EINVAL;
r = proc_cmdline(&line);
if (r < 0)
return r;
r = cmdline_get_key(line, key, flags, ret_value);
if (r != 0) /* Either error or true if found. */
return r;
line = mfree(line);
r = efi_systemd_options_variable(&line);
if (r == -ENODATA)
return false; /* Not found */
if (r < 0)
return r;
return cmdline_get_key(line, key, flags, ret_value);
}
int proc_cmdline_get_bool(const char *key, bool *ret) {
_cleanup_free_ char *v = NULL;
int r;