diff options
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/generic/ldsodefs.h | 16 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/dl-execstack.c | 12 |
2 files changed, 25 insertions, 3 deletions
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 4ff8bbf217..53c3290e01 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -171,6 +171,17 @@ struct libname_list }; +/* Bit masks for the objects which valid callers can come from to + functions with restricted interface. */ +enum allowmask + { + allow_libc = 1, + allow_libdl = 2, + allow_libpthread = 4, + allow_ldso = 8 + }; + + /* Test whether given NAME matches any of the names of the given object. */ extern int _dl_name_match_p (const char *__name, struct link_map *__map) internal_function; @@ -492,6 +503,7 @@ struct rtld_global_ro const struct r_found_version *, int, int, struct link_map *); + int (*_dl_check_caller) (const void *, enum allowmask); }; # define __rtld_global_attribute__ @@ -878,6 +890,10 @@ extern size_t _dl_dst_count (const char *name, int is_path) attribute_hidden; extern char *_dl_dst_substitute (struct link_map *l, const char *name, char *result, int is_path) attribute_hidden; +/* Check validity of the caller. */ +extern int _dl_check_caller (const void *caller, enum allowmask mask) + attribute_hidden; + __END_DECLS #endif /* ldsodefs.h */ diff --git a/sysdeps/unix/sysv/linux/dl-execstack.c b/sysdeps/unix/sysv/linux/dl-execstack.c index d3b048192c..248196040a 100644 --- a/sysdeps/unix/sysv/linux/dl-execstack.c +++ b/sysdeps/unix/sysv/linux/dl-execstack.c @@ -20,8 +20,10 @@ #include <ldsodefs.h> #include <sys/mman.h> #include <errno.h> +#include <libintl.h> #include <stdbool.h> #include <stackinfo.h> +#include <caller.h> #include "kernel-features.h" @@ -31,13 +33,14 @@ internal_function _dl_make_stack_executable (void **stack_endp) { /* This gives us the highest/lowest page that needs to be changed. */ - uintptr_t page = ((uintptr_t) __libc_stack_end + uintptr_t page = ((uintptr_t) *stack_endp & -(intptr_t) GLRO(dl_pagesize)); /* Challenge the caller. */ - if (__builtin_expect (*stack_endp != __libc_stack_end, 0)) + if (__builtin_expect (__check_caller (__builtin_return_address (0), + allow_ldso|allow_libpthread) != 0, 0) + || __builtin_expect (*stack_endp != __libc_stack_end, 0)) return EPERM; - *stack_endp = NULL; #if _STACK_GROWS_DOWN /* Newer Linux kernels support a flag to make our job easy. */ @@ -151,6 +154,9 @@ _dl_make_stack_executable (void **stack_endp) #endif return_success: + /* Clear the address. */ + *stack_endp = NULL; + /* Remember that we changed the permission. */ GL(dl_stack_flags) |= PF_X; |