Hi all,

On Thu, Jan 04, 2018 at 11:39:15AM +0100, Quentin Schulz wrote:

While the `env export` can take as parameters variables to be exported, `env import` does not have such a mechanism of variable selection.

Let's add a `-w` option that asks `env import` to look for the `whitelisted_vars` env variable for a space-separated list of variables that are whitelisted.

Every env variable present in env at `addr` and in `whitelisted_vars` env variable will override the value of the variable in the current env. All the remaining variables are left untouched.

One of its use case could be to load a secure environment from the signed U-Boot binary and load only a handful of variables from an other, unsecure, environment without completely losing control of U-Boot.

Signed-off-by: Quentin Schulz quentin.schulz@free-electrons.com

It's been two months since I posted this patch and there hasn't been any review.

Is there something to improve? Is there an other approach to take?

I'm all ears.

Thanks, Quentin

---

cmd/nvedit.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 64 insertions(+), 7 deletions(-)

diff --git a/cmd/nvedit.c b/cmd/nvedit.c index 4e79d03856..9f983b41a1 100644 --- a/cmd/nvedit.c +++ b/cmd/nvedit.c @@ -971,7 +971,7 @@ sep_err:

#ifdef CONFIG_CMD_IMPORTENV /*

• • env import [-d] [-t [-r] | -b | -c] addr [size]

• • env import [-d] [-t [-r] | -b | -c] [-w] addr [size]
  • -d: delete existing environment before importing;

  • otherwise overwrite / append to existing definitions
    

  • -t: assume text format; either "size" must be given or the

@@ -982,6 +982,10 @@ sep_err:

• for line endings. Only effective in addition to -t.
  

• -b: assume binary format ('\0' separated, "\0\0" terminated)
• -c: assume checksum protected environment format

• • -w: specify that whitelisting of variables should be used when

• • importing environment. The space-separated list of variables
    

• • that should override the ones in current environment is stored
    

• • in `whitelisted_vars`.
    

  • addr: memory address to read from
  • size: length of input data; if missing, proper '\0'

  • termination is mandatory
    

@@ -991,11 +995,16 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag, { ulong addr; char *cmd, *ptr;

• char **array = NULL; char sep = '\n'; int chk = 0; int fmt = 0; int del = 0; int crlf_is_lf = 0;

• int wl = 0;

• int wl_count = 0;

• int ret;

• unsigned int i; size_t size;

  cmd = *argv;

@@ -1026,6 +1035,9 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag, case 'd': del = 1; break;

• 	case 'w':
  

• 		wl = 1;
  

• 		break;
  default:
  	return CMD_RET_USAGE;
  }
  

@@ -1082,14 +1094,59 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag, ptr = (char *)ep->data; }

• if (himport_r(&env_htab, ptr, size, sep, del ? 0 : H_NOCLEAR,

• 	crlf_is_lf, 0, NULL) == 0) {
  

• if(wl) {

• char *str, *token, *tmp;
  

• wl_count = 1;
  

• str = env_get("whitelisted_vars");
  

• if (!str) {
  

• 	puts("## Error: whitelisted_vars is not set.\n");
  

• 	return CMD_RET_USAGE;
  

• }
  

• tmp = malloc(sizeof(char) * (strlen(str) + 1));
  

• strcpy(tmp, str);
  

• token = strchr(tmp, ' ');
  

• while (!token) {
  

• 	wl_count++;
  

• 	token = strchr(token + 1, ' ');
  

• }
  

• strcpy(tmp, str);
  

• array = malloc(sizeof(char *) * wl_count);
  

• wl_count = 0;
  

• token = strtok(tmp, " ");
  

• while (token) {
  

• 	array[wl_count] = malloc(sizeof(char) *
  

• 				 (strlen(token) + 1));
  

• 	strcpy(array[wl_count], token);
  

• 	wl_count++;
  

• 	token = strtok(NULL, " ");
  

• }
  

• free(tmp);
  

• }
• ret = himport_r(&env_htab, ptr, size, sep, del ? 0 : H_NOCLEAR,

• 	crlf_is_lf, wl ? wl_count : 0, wl ? array : NULL);
  

• if (!ret) { pr_err("Environment import failed: errno = %d\n", errno);

• return 1;
  

• ret = 1;
  

• } else {

• gd->flags |= GD_FLG_ENV_READY;
  

• ret = 0;
  

  }

• gd->flags |= GD_FLG_ENV_READY;

• return 0;

• if (wl) {

• for (i = 0; i < wl_count; i++)
  

• 	free(array[i]);
  

• free(array);
  

• }
• return ret;

sep_err: printf("## %s: only one of "-b", "-c" or "-t" allowed\n", @@ -1212,7 +1269,7 @@ static char env_help_text[] = #endif #endif #if defined(CONFIG_CMD_IMPORTENV)

• "env import [-d] [-t [-r] | -b | -c] addr [size] - import environment\n"

• "env import [-d] [-t [-r] | -b | -c] [-w] addr [size] - import environment\n"

#endif "env print [-a | name ...] - print environment\n"

#if defined(CONFIG_CMD_RUN)

2.14.1