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Implement __pthread_map_stacks_exec() callback for libc, to change the

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stack protection to allow execution for single-threaded processes.
This commit is contained in:
kib 2011-01-08 17:13:43 +00:00
parent 5cec74bed9
commit 6e23841922
3 changed files with 39 additions and 0 deletions
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2
lib/libc/gen/Symbol.map
View File

@ -453,6 +453,7 @@ FBSDprivate_1.0 {
_rtld_atfork_pre;
_rtld_atfork_post;
_rtld_error; /* for private use */
_rtld_get_stack_prot;
_rtld_thread_init; /* for private use */
__elf_phdr_match_addr;
_err;
@ -499,4 +500,5 @@ FBSDprivate_1.0 {
_libc_sem_getvalue_compat;
__elf_aux_vector;
__pthread_map_stacks_exec;
};

10
lib/libc/gen/dlfcn.c
View File

@ -30,6 +30,7 @@ __FBSDID("$FreeBSD$");
/*
* Linkage to services provided by the dynamic linker.
*/
#include <sys/mman.h>
#include <dlfcn.h>
#include <link.h>
#include <stddef.h>
@ -165,3 +166,12 @@ _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
return (0);
}
#pragma weak _rtld_get_stack_prot
int
_rtld_get_stack_prot(void)
{
return (PROT_EXEC | PROT_READ | PROT_WRITE);
}

27
lib/libc/gen/elf_utils.c
View File

@ -26,7 +26,12 @@
* $FreeBSD$
*/
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <sys/sysctl.h>
#include <link.h>
#include <stddef.h>
int
__elf_phdr_match_addr(struct dl_phdr_info *phdr_info, void *addr)
@ -45,3 +50,25 @@ __elf_phdr_match_addr(struct dl_phdr_info *phdr_info, void *addr)
}
return (i != phdr_info->dlpi_phnum);
}
#pragma weak __pthread_map_stacks_exec
void
__pthread_map_stacks_exec(void)
{
int mib[2];
struct rlimit rlim;
u_long usrstack;
size_t len;
mib[0] = CTL_KERN;
mib[1] = KERN_USRSTACK;
len = sizeof(usrstack);
if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), &usrstack, &len, NULL, 0)
== -1)
return;
if (getrlimit(RLIMIT_STACK, &rlim) == -1)
return;
mprotect((void *)(uintptr_t)(usrstack - rlim.rlim_cur),
rlim.rlim_cur, _rtld_get_stack_prot());
}