diff options
Diffstat (limited to 'third_party/heimdal/lib/roken/getauxval.c')
| -rw-r--r-- | third_party/heimdal/lib/roken/getauxval.c | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/third_party/heimdal/lib/roken/getauxval.c b/third_party/heimdal/lib/roken/getauxval.c new file mode 100644 index 00000000000..f12bc932bc3 --- /dev/null +++ b/third_party/heimdal/lib/roken/getauxval.c @@ -0,0 +1,255 @@ +/* + * Copyright (c) 2016 - 2017 Kungliga Tekniska Högskolan + * (Royal Institute of Technology, Stockholm, Sweden). + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * 3. Neither the name of the Institute nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <config.h> + +#ifdef HAVE_SYS_AUXV_H +#include <sys/auxv.h> +#endif + +#if defined(ENABLE_PTHREAD_SUPPORT) && defined(HAVE_PTHREAD_H) +#include <pthread.h> +#endif + +#include <errno.h> + +#include "roken.h" +#include "getauxval.h" + +int rk_injected_auxv = 0; /* shared with issuid() for testing */ +static int has_proc_auxv = 1; +static int proc_auxv_ret = 0; + +#if defined(ENABLE_PTHREAD_SUPPORT) && defined(HAVE_PTHREAD_H) +pthread_once_t readprocauxv_once = PTHREAD_ONCE_INIT; +#endif + +/* + * There's no standard maximum. + * + * At the time of this writing we observe some 20 or so auxv entries. + * If eventually that grows much larger then rk_getprocaux*() will see a + * truncated auxv. + */ +#define MAX_AUXV_COUNT 128 +static auxv_t auxv[MAX_AUXV_COUNT]; + +static void +do_readprocauxv(void) +{ + char *p = (void *)auxv; + ssize_t bytes = 0; + size_t sz = sizeof(auxv) - sizeof(auxv[0]); /* leave terminator */ + int save_errno = errno; + int fd; + + errno = 0; + memset(auxv, 0, sizeof(auxv)); /* terminates our copy */ + if ((fd = open("/proc/self/auxv", O_RDONLY)) == -1) { + if (errno == ENOENT) + has_proc_auxv = 0; + goto out; + } + + do { + if ((bytes = read(fd, p, sz)) > 0) { + sz -= bytes; + p += bytes; + } + } while (sz && ((bytes == -1 && errno == EINTR) || bytes > 0)); + +out: + proc_auxv_ret = errno; + if (fd != -1) + (void) close(fd); + if (sz == 0 && bytes > 0) + warnx("/proc/self/auxv has more entries than expected"); + errno = save_errno; + return; +} + +static int +readprocauxv(void) +{ +#if defined(ENABLE_PTHREAD_SUPPORT) && defined(HAVE_PTHREAD_H) + pthread_once(&readprocauxv_once, do_readprocauxv); +#else + do_readprocauxv(); +#endif + return proc_auxv_ret; +} + +/** + * Looks up an auxv entry in /proc/self/auxv. Preserves errno. + * + * @return a pointer to an auxv_t if found, else NULL. + */ +ROKEN_LIB_FUNCTION const auxv_t * ROKEN_LIB_CALL +rk_getauxv(unsigned long type) +{ + auxv_t *a; + + if (!has_proc_auxv || type > INT_MAX) + return NULL; + + if (readprocauxv() != 0) + return NULL; + + for (a = auxv; a - auxv < MAX_AUXV_COUNT; a++) { + if ((int)a->a_type == (int)type) + return a; + if (a->a_type == 0 && a->a_un.a_val == 0) + break; + } + return NULL; +} + +#ifdef HAVE_GETAUXVAL +static unsigned long +rk_getprocauxval(unsigned long type) +{ + const auxv_t *a = rk_getauxv(type); + + if (a == NULL) { + errno = ENOENT; + return 0; + } + return a->a_un.a_val; +} +#endif + +/** + * Like the nearly-standard getauxval(). If the auxval is not found + * returns zero and always sets errno to ENOENT. Otherwise if auxval is + * found it leaves errno as it was, even if the value is zero. + * + * @return The value of the ELF auxiliary value for the given type, or + * zero and sets errno to ENOENT. + */ +ROKEN_LIB_FUNCTION unsigned long ROKEN_LIB_CALL +rk_getauxval(unsigned long type) +{ + const auxv_t *a; +#ifdef HAVE_GETAUXVAL +#ifdef GETAUXVAL_SETS_ERRNO + if (rk_injected_auxv) + return rk_getprocauxval(type); + return getauxval(type); +#else + unsigned long ret; + unsigned long ret2; + static int getauxval_sets_errno = -1; + int save_errno = errno; + + if (rk_injected_auxv) + return rk_getprocauxval(type); + + errno = 0; + ret = getauxval(type); + if (ret != 0 || errno == ENOENT || getauxval_sets_errno == 1) { + if (ret != 0) + errno = save_errno; + else if (getauxval_sets_errno > 0 && errno == 0) + errno = save_errno; + return ret; + } + + if (getauxval_sets_errno == 0) { + errno = save_errno; + a = rk_getauxv(type); + if (a == NULL) { + errno = ENOENT; + return 0; + } + return a->a_un.a_val; + } + + /* + * We've called getauxval() and it returned 0, but we don't know if + * getauxval() sets errno = ENOENT when entries are not found. + * + * Attempt to detect whether getauxval() sets errno = ENOENT by + * calling it with what should be a bogus type. + */ + + errno = 0; + ret2 = getauxval(~type); + if (ret2 == 0 && errno == ENOENT) { + getauxval_sets_errno = 1; + errno = save_errno; + return ret; + } + + getauxval_sets_errno = 0; + errno = save_errno; +#endif +#endif + if ((a = rk_getauxv(type)) == NULL) { + errno = ENOENT; + return 0; + } + return a->a_un.a_val; +} + +/** + * *Internal* function for testing by injecting or overwriting an ELF + * auxiliary vector entry. + * + * @return zero on success or ENOSPC if there are too many ELF auxiliary + * entries. + */ +ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL +rk_injectauxv(auxv_t *e) +{ + size_t i; + int ret; + + /* + * This function is racy, but as an internal function never meant to + * be called in a threaded program, we don't care. + */ + + if ((ret = readprocauxv()) != 0) + return ret; + + rk_injected_auxv = 1; + for (i = 0; i < MAX_AUXV_COUNT - 1 && auxv[i].a_type != 0; i++) { + /* e->a_type == 0 -> truncate auxv, delete all entries */ + if (auxv[i].a_type == e->a_type || e->a_type == 0) + break; + } + if (i == MAX_AUXV_COUNT - 1) + return ENOSPC; + auxv[i] = e[0]; + return 0; +} |