diff options
| -rw-r--r-- | lib/libc/gen/getentropy.c | 99 |
1 files changed, 9 insertions, 90 deletions
diff --git a/lib/libc/gen/getentropy.c b/lib/libc/gen/getentropy.c index 40debe4ab662..e87796ace58c 100644 --- a/lib/libc/gen/getentropy.c +++ b/lib/libc/gen/getentropy.c @@ -28,121 +28,40 @@ #include <sys/param.h> #include <sys/random.h> -#include <sys/sysctl.h> #include <errno.h> #include <signal.h> -#include <stdbool.h> -#include <stdlib.h> -#include <unistd.h> #include <ssp/ssp.h> #include "libc_private.h" -/* First __FreeBSD_version bump after introduction of getrandom(2) (r331279) */ -#define GETRANDOM_FIRST 1200061 - -extern int __sysctl(int *, u_int, void *, size_t *, void *, size_t); - static inline void _getentropy_fail(void) { raise(SIGKILL); } -static size_t -arnd_sysctl(u_char *buf, size_t size) -{ - int mib[2]; - size_t len, done; - - mib[0] = CTL_KERN; - mib[1] = KERN_ARND; - done = 0; - - do { - len = size; - if (__sysctl(mib, 2, buf, &len, NULL, 0) == -1) - return (done); - done += len; - buf += len; - size -= len; - } while (size > 0); - - return (done); -} - -/* - * If a newer libc is accidentally installed on an older kernel, provide high - * quality random data anyway. The sysctl interface is not as fast and does - * not block by itself, but is provided by even very old kernels. - */ -static int -getentropy_fallback(void *buf, size_t buflen) -{ - /* - * oldp (buf) == NULL has a special meaning for sysctl that results in - * no EFAULT. For compatibility with the kernel getrandom(2), detect - * this case and return the appropriate error. - */ - if (buf == NULL && buflen > 0) { - errno = EFAULT; - return (-1); - } - if (arnd_sysctl(buf, buflen) != buflen) { - if (errno == EFAULT) - return (-1); - /* - * This cannot happen. arnd_sysctl() spins until the random - * device is seeded and then repeatedly reads until the full - * request is satisfied. The only way for this to return a zero - * byte or short read is if sysctl(2) on the kern.arandom MIB - * fails. In this case, excepting the user-provided-a-bogus- - * buffer EFAULT, give up (like for arc4random(3)'s arc4_stir). - */ - _getentropy_fail(); - } - return (0); -} - int __ssp_real(getentropy)(void *buf, size_t buflen) { ssize_t rd; - bool have_getrandom; if (buflen > 256) { errno = EIO; return (-1); } - have_getrandom = (__getosreldate() >= GETRANDOM_FIRST); - while (buflen > 0) { - if (have_getrandom) { - rd = getrandom(buf, buflen, 0); - if (rd == -1) { - switch (errno) { - case ECAPMODE: - /* - * Kernel >= r331280 (4948f7bf1153) - * and < r337999 (ed1fa01ac45a) will - * return ECAPMODE when the caller is - * already in capability mode; fallback - * to traditional method in this case. - */ - have_getrandom = false; - continue; - case EINTR: - continue; - case EFAULT: - return (-1); - default: - _getentropy_fail(); - } + rd = getrandom(buf, buflen, 0); + if (rd == -1) { + switch (errno) { + case EINTR: + continue; + case EFAULT: + return (-1); + default: + _getentropy_fail(); } - } else { - return (getentropy_fallback(buf, buflen)); } /* This cannot happen. */ |