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change env

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us now changes the environment variables listed in TODO before executing the
command, also added but commented out a version where the env gets copied and
the execution happens trough the musl implementation of execvpe(3)
This commit is contained in:
Alessandro Mauri 2021-04-04 12:42:03 +02:00
parent 72c217d74a
commit 5412a3785e
1 changed files with 68 additions and 2 deletions
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70
us.c
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@ -36,6 +36,7 @@ static int perm_set (struct passwd *, struct group *);
static int authenticate (const char *); static int authenticate (const char *);
static struct passwd* user_to_passwd (const char *); static struct passwd* user_to_passwd (const char *);
static struct group* group_to_grp (const char *); static struct group* group_to_grp (const char *);
//static int execvpe(const char *, char *const *, char *const *);
// FIXME: misc_conv is a separate library, should stick to plain PAM or make // FIXME: misc_conv is a separate library, should stick to plain PAM or make
// our own pam module // our own pam module
@ -48,7 +49,7 @@ int main (int argc, char *argv[])
char *t_usr = "root", *t_grp = NULL; char *t_usr = "root", *t_grp = NULL;
struct passwd *t_pw; struct passwd *t_pw;
struct group *t_gr; struct group *t_gr;
int opt; int opt, err;
int shellflag = 0; int shellflag = 0;
while ((opt = getopt(argc, argv, "A:u:g:C:s")) != -1) { while ((opt = getopt(argc, argv, "A:u:g:C:s")) != -1) {
switch (opt) { switch (opt) {
@ -134,10 +135,37 @@ int main (int argc, char *argv[])
c_argv[c_argc] = NULL; c_argv[c_argc] = NULL;
/* Authenticate */ /* Authenticate */
// FIXME: move this up
if (authenticate(uname) != PAM_SUCCESS) if (authenticate(uname) != PAM_SUCCESS)
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
// TODO: clean up env // TODO: clean up env
/* copy and filter env */
/*
char **c_env;
extern char **environ;
int size = 0;
for (int i = 0; environ[i]; i++, size++);
c_env = malloc(sizeof(char *) * (size + 1));
if (!c_env) {
fprintf(stderr, "malloc: %s\n", strerror(errno));
exit(errno);
}
for (int i = 0; environ[i]; i++) {
c_env[i] = strdup(environ[i]);
if (!c_env[i]) {
fprintf(stderr, "strdup: %s\n", strerror(errno));
exit(errno);
}
}
c_env[size] = NULL;
*/
// TODO: check err value
// TODO: add all this to list and loop over it
err = setenv("USER", t_pw->pw_name, 1);
err = setenv("LOGNAME", t_pw->pw_name, 1);
err = setenv("SHELL", t_pw->pw_shell, 1);
err = setenv("HOME", t_pw->pw_dir, 1);
errno = 0; errno = 0;
/* Set permissions */ /* Set permissions */
@ -147,7 +175,6 @@ int main (int argc, char *argv[])
} }
/* Execute the command */ /* Execute the command */
int err;
err = execvp(c_argv[0], c_argv); err = execvp(c_argv[0], c_argv);
if (err == -1) if (err == -1)
fprintf(stderr, "execl: %s\n", strerror(errno)); fprintf(stderr, "execl: %s\n", strerror(errno));
@ -305,3 +332,42 @@ static struct group* group_to_grp (const char *group)
} }
return gr; return gr;
} }
/*
static int execvpe(const char *file, char *const argv[], char *const envp[])
{
const char *p, *z, *path = getenv("PATH");
size_t l, k;
errno = ENOENT;
if (!*file) return -1;
if (strchr(file, '/'))
return execve(file, argv, envp);
if (!path) path = "/usr/local/bin:/bin:/usr/bin";
k = strnlen(file, NAME_MAX+1);
if (k > NAME_MAX) {
errno = ENAMETOOLONG;
return -1;
}
l = strnlen(path, PATH_MAX-1)+1;
for(p=path; ; p=z) {
char b[l+k+1];
z = strchr(p, ':');
if (!z) z = p+strlen(p);
if ((size_t)(z-p) >= l) {
if (!*z++) break;
continue;
}
memcpy(b, p, z-p);
b[z-p] = '/';
memcpy(b+(z-p)+(z>p), file, k+1);
execve(b, argv, envp);
if (errno != ENOENT) return -1;
if (!*z++) break;
}
return -1;
}
*/