diff options
Diffstat (limited to 'src/utils/lib/env.c')
| -rw-r--r-- | src/utils/lib/env.c | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/src/utils/lib/env.c b/src/utils/lib/env.c new file mode 100644 index 0000000..c26a5be --- /dev/null +++ b/src/utils/lib/env.c @@ -0,0 +1,238 @@ +/* + * Security checks of environment + * Added from shadow-utils package + * by Arkadiusz Miśkiewicz <misiek@pld.ORG.PL> + * + */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#ifdef HAVE_SYS_PRCTL_H +#include <sys/prctl.h> +#else +#define PR_GET_DUMPABLE 3 +#endif +#if (!defined(HAVE_PRCTL) && defined(linux)) +#include <sys/syscall.h> +#endif +#include <unistd.h> +#include <sys/types.h> + +#include "env.h" + +#ifndef HAVE_ENVIRON_DECL +extern char **environ; +#endif + +static char * const forbid[] = { + "BASH_ENV=", /* GNU creeping featurism strikes again... */ + "ENV=", + "HOME=", + "IFS=", + "KRB_CONF=", + "LD_", /* anything with the LD_ prefix */ + "LIBPATH=", + "MAIL=", + "NLSPATH=", + "PATH=", + "SHELL=", + "SHLIB_PATH=", + (char *) 0 +}; + +/* these are allowed, but with no slashes inside + (to work around security problems in GNU gettext) */ +static char * const noslash[] = { + "LANG=", + "LANGUAGE=", + "LC_", /* anything with the LC_ prefix */ + (char *) 0 +}; + + +struct ul_env_list { + char *env; + struct ul_env_list *next; +}; + +/* + * Saves @name env.varable to @ls, returns pointer to the new head of the list. + */ +static struct ul_env_list *env_list_add(struct ul_env_list *ls0, const char *str) +{ + struct ul_env_list *ls; + char *p; + size_t sz = 0; + + if (!str || !*str) + return ls0; + + sz = strlen(str) + 1; + p = malloc(sizeof(struct ul_env_list) + sz); + + ls = (struct ul_env_list *) p; + p += sizeof(struct ul_env_list); + memcpy(p, str, sz); + ls->env = p; + + ls->next = ls0; + return ls; +} + +/* + * Use setenv() for all stuff in @ls. + * + * It would be possible to use putenv(), but we want to keep @ls free()-able. + */ +int env_list_setenv(struct ul_env_list *ls) +{ + int rc = 0; + + while (ls && rc == 0) { + if (ls->env) { + char *val = strchr(ls->env, '='); + if (!val) + continue; + *val = '\0'; + rc = setenv(ls->env, val + 1, 0); + *val = '='; + } + ls = ls->next; + } + return rc; +} + +void env_list_free(struct ul_env_list *ls) +{ + while (ls) { + struct ul_env_list *x = ls; + ls = ls->next; + free(x); + } +} + +/* + * Removes unwanted variables from environ[]. If @ls is not NULL than stores + * unwnated variables to the list. + */ +void __sanitize_env(struct ul_env_list **org) +{ + char **envp = environ; + char * const *bad; + char **cur; + int last = 0; + + for (cur = envp; *cur; cur++) + last++; + + for (cur = envp; *cur; cur++) { + for (bad = forbid; *bad; bad++) { + if (strncmp(*cur, *bad, strlen(*bad)) == 0) { + if (org) + *org = env_list_add(*org, *cur); + last = remote_entry(envp, cur - envp, last); + cur--; + break; + } + } + } + + for (cur = envp; *cur; cur++) { + for (bad = noslash; *bad; bad++) { + if (strncmp(*cur, *bad, strlen(*bad)) != 0) + continue; + if (!strchr(*cur, '/')) + continue; /* OK */ + if (org) + *org = env_list_add(*org, *cur); + last = remote_entry(envp, cur - envp, last); + cur--; + break; + } + } +} + +void sanitize_env(void) +{ + __sanitize_env(NULL); +} + +char *safe_getenv(const char *arg) +{ + uid_t ruid = getuid(); + + if (ruid != 0 || (ruid != geteuid()) || (getgid() != getegid())) + return NULL; +#ifdef HAVE_PRCTL + if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0) + return NULL; +#else +#if (defined(linux) && defined(SYS_prctl)) + if (syscall(SYS_prctl, PR_GET_DUMPABLE, 0, 0, 0, 0) == 0) + return NULL; +#endif +#endif +#ifdef HAVE_SECURE_GETENV +return secure_getenv(arg); +#elif HAVE___SECURE_GETENV + return __secure_getenv(arg); +#else + return getenv(arg); +#endif +} + +#ifdef TEST_PROGRAM +int main(void) +{ + char *const *bad; + char copy[32]; + char *p; + int retval = EXIT_SUCCESS; + struct ul_env_list *removed = NULL; + + for (bad = forbid; *bad; bad++) { + strcpy(copy, *bad); + p = strchr(copy, '='); + if (p) + *p = '\0'; + setenv(copy, copy, 1); + } + + /* removed */ + __sanitize_env(&removed); + + /* check removal */ + for (bad = forbid; *bad; bad++) { + strcpy(copy, *bad); + p = strchr(copy, '='); + if (p) + *p = '\0'; + p = getenv(copy); + if (p) { + warnx("%s was not removed", copy); + retval = EXIT_FAILURE; + } + } + + /* restore removed */ + env_list_setenv(removed); + + /* check restore */ + for (bad = forbid; *bad; bad++) { + strcpy(copy, *bad); + p = strchr(copy, '='); + if (p) + *p = '\0'; + p = getenv(copy); + if (!p) { + warnx("%s was not restored", copy); + retval = EXIT_FAILURE; + } + } + + env_list_free(removed); + + return retval; +} +#endif |