diff options
Diffstat (limited to 'nptl/init.c')
| -rw-r--r-- | nptl/init.c | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/nptl/init.c b/nptl/init.c index e58dae0ba6..aad2c9001f 100644 --- a/nptl/init.c +++ b/nptl/init.c @@ -32,6 +32,7 @@ #include <version.h> #include <shlib-compat.h> #include <smp.h> +#include <lowlevellock.h> #ifndef __NR_set_tid_address @@ -131,7 +132,8 @@ static const struct pthread_functions pthread_functions = .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore, .ptr_nthreads = &__nptl_nthreads, .ptr___pthread_unwind = &__pthread_unwind, - .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd + .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd, + .ptr__nptl_setxid = __nptl_setxid }; # define ptr_pthread_functions &pthread_functions #else @@ -144,7 +146,7 @@ static void sigcancel_handler (int sig, siginfo_t *si, void *ctx) { /* Safety check. It would be possible to call this function for - other signals and send a signal from another thread. This is not + other signals and send a signal from another process. This is not correct and might even be a security problem. Try to catch as many incorrect invocations as possible. */ if (sig != SIGCANCEL @@ -190,6 +192,34 @@ sigcancel_handler (int sig, siginfo_t *si, void *ctx) } +struct xid_command *__xidcmd attribute_hidden; + +/* For asynchronous cancellation we use a signal. This is the handler. */ +static void +sighandler_setxid (int sig, siginfo_t *si, void *ctx) +{ + /* Safety check. It would be possible to call this function for + other signals and send a signal from another process. This is not + correct and might even be a security problem. Try to catch as + many incorrect invocations as possible. */ + if (sig != SIGSETXID +#ifdef __ASSUME_CORRECT_SI_PID + /* Kernels before 2.5.75 stored the thread ID and not the process + ID in si_pid so we skip this test. */ + || si->si_pid != THREAD_GETMEM (THREAD_SELF, pid) +#endif + || si->si_code != SI_TKILL) + return; + + INTERNAL_SYSCALL_DECL (err); + INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0], + __xidcmd->id[1], __xidcmd->id[2]); + + if (atomic_decrement_val (&__xidcmd->cntr) == 0) + lll_futex_wake (&__xidcmd->cntr, 1); +} + + /* When using __thread for this, we do it in libc so as not to give libpthread its own TLS segment just for this. */ extern void **__libc_dl_error_tsd (void) __attribute__ ((const)); @@ -242,6 +272,12 @@ __pthread_initialize_minimal_internal (void) (void) __libc_sigaction (SIGCANCEL, &sa, NULL); + /* Install the handle to change the threads' uid/gid. */ + sa.sa_sigaction = sighandler_setxid; + sa.sa_flags = SA_SIGINFO | SA_RESTART; + + (void) __libc_sigaction (SIGSETXID, &sa, NULL); + /* The parent process might have left the signal blocked. Just in case, unblock it. We reuse the signal mask in the sigaction structure. It is already cleared. */ |