mirror of
git://git.musl-libc.org/musl
synced 2024-12-25 08:02:28 +00:00
support alternate backends for the passwd and group dbs
when we fail to find the entry in the commonly accepted files, we query a server over a Unix domain socket on /var/run/nscd/socket. the protocol used here is compatible with glibc's nscd protocol on most systems (all that use 32-bit numbers for all the protocol fields, which appears to be everything but Alpha).
This commit is contained in:
Josiah Worcester
Rich Felker
parent
0afef1aa24
commit
34b423d207
@ -1,5 +1,21 @@
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#include <pthread.h>
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#include <byteswap.h>
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#include <string.h>
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#include <unistd.h>
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#include "pwf.h"
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#include "nscd.h"
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static char *itoa(char *p, uint32_t x)
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{
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// number of digits in a uint32_t + NUL
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p += 11;
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*--p = 0;
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do {
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*--p = '0' + x % 10;
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x /= 10;
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} while (x);
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return p;
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}
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int __getgr_a(const char *name, gid_t gid, struct group *gr, char **buf, size_t *size, char ***mem, size_t *nmem, struct group **res)
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{
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@ -10,7 +26,6 @@ int __getgr_a(const char *name, gid_t gid, struct group *gr, char **buf, size_t
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*res = 0;
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pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
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f = fopen("/etc/group", "rbe");
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if (!f) {
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rv = errno;
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@ -25,6 +40,129 @@ int __getgr_a(const char *name, gid_t gid, struct group *gr, char **buf, size_t
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}
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fclose(f);
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if (!*res && (rv == 0 || rv == ENOENT || rv == ENOTDIR)) {
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int32_t req = name ? GETGRBYNAME : GETGRBYGID;
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int32_t i;
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const char *key;
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int32_t groupbuf[GR_LEN] = {0};
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size_t len = 0;
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size_t grlist_len = 0;
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char gidbuf[11] = {0};
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int swap = 0;
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char *ptr;
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if (name) {
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key = name;
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} else {
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if (gid < 0 || gid > UINT32_MAX) {
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rv = 0;
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goto done;
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}
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key = itoa(gidbuf, gid);
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}
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f = __nscd_query(req, key, groupbuf, sizeof groupbuf, &swap);
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if (!f) { rv = errno; goto done; }
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if (f == (FILE*)-1) { rv = 0; goto done; }
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if (!groupbuf[GRFOUND]) { rv = 0; goto cleanup_f; }
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if (!groupbuf[GRNAMELEN] || !groupbuf[GRPASSWDLEN]) {
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rv = EIO;
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goto cleanup_f;
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}
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if (groupbuf[GRNAMELEN] > SIZE_MAX - groupbuf[GRPASSWDLEN]) {
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rv = ENOMEM;
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goto cleanup_f;
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}
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len = groupbuf[GRNAMELEN] + groupbuf[GRPASSWDLEN];
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for (i = 0; i < groupbuf[GRMEMCNT]; i++) {
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uint32_t name_len;
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if (fread(&name_len, sizeof name_len, 1, f) < 1) {
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rv = ferror(f) ? errno : EIO;
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goto cleanup_f;
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}
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if (swap) {
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name_len = bswap_32(name_len);
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}
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if (name_len > SIZE_MAX - grlist_len
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|| name_len > SIZE_MAX - len) {
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rv = ENOMEM;
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goto cleanup_f;
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}
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len += name_len;
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grlist_len += name_len;
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}
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if (len > *size || !*buf) {
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char *tmp = realloc(*buf, len);
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if (!tmp) {
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rv = errno;
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goto cleanup_f;
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}
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*buf = tmp;
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*size = len;
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}
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if (!fread(*buf, len, 1, f)) {
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rv = ferror(f) ? errno : EIO;
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goto cleanup_f;
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}
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if (groupbuf[GRMEMCNT] + 1 > *nmem) {
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if (groupbuf[GRMEMCNT] + 1 > SIZE_MAX/sizeof(char*)) {
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rv = ENOMEM;
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goto cleanup_f;
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}
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char **tmp = realloc(*mem, (groupbuf[GRMEMCNT]+1)*sizeof(char*));
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if (!tmp) {
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rv = errno;
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goto cleanup_f;
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}
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*mem = tmp;
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*nmem = groupbuf[GRMEMCNT] + 1;
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}
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if (groupbuf[GRMEMCNT]) {
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mem[0][0] = *buf + groupbuf[GRNAMELEN] + groupbuf[GRPASSWDLEN];
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for (ptr = mem[0][0], i = 0; ptr != mem[0][0]+grlist_len; ptr++)
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if (!*ptr) mem[0][++i] = ptr+1;
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mem[0][i] = 0;
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if (i != groupbuf[GRMEMCNT]) {
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rv = EIO;
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goto cleanup_f;
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}
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} else {
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mem[0][0] = 0;
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}
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gr->gr_name = *buf;
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gr->gr_passwd = gr->gr_name + groupbuf[GRNAMELEN];
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gr->gr_gid = groupbuf[GRGID];
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gr->gr_mem = *mem;
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if (gr->gr_passwd[-1]
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|| gr->gr_passwd[groupbuf[GRPASSWDLEN]-1]) {
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rv = EIO;
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goto cleanup_f;
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}
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if (name && strcmp(name, gr->gr_name)
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|| !name && gid != gr->gr_gid) {
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rv = EIO;
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goto cleanup_f;
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}
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*res = gr;
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cleanup_f:
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fclose(f);
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goto done;
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}
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done:
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pthread_setcancelstate(cs, 0);
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if (rv) errno = rv;
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@ -1,5 +1,21 @@
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#include "pwf.h"
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#include <pthread.h>
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#include <byteswap.h>
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#include <string.h>
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#include <unistd.h>
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#include "pwf.h"
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#include "nscd.h"
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static char *itoa(char *p, uint32_t x)
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{
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// number of digits in a uint32_t + NUL
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p += 11;
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*--p = 0;
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do {
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*--p = '0' + x % 10;
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x /= 10;
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} while (x);
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return p;
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}
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int __getpw_a(const char *name, uid_t uid, struct passwd *pw, char **buf, size_t *size, struct passwd **res)
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{
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@ -24,6 +40,102 @@ int __getpw_a(const char *name, uid_t uid, struct passwd *pw, char **buf, size_t
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}
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fclose(f);
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if (!*res && (rv == 0 || rv == ENOENT || rv == ENOTDIR)) {
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int32_t req = name ? GETPWBYNAME : GETPWBYUID;
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const char *key;
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int32_t passwdbuf[PW_LEN] = {0};
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size_t len = 0;
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char uidbuf[11] = {0};
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if (name) {
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key = name;
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} else {
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/* uid outside of this range can't be queried with the
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* nscd interface, but might happen if uid_t ever
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* happens to be a larger type (this is not true as of
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* now)
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*/
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if(uid < 0 || uid > UINT32_MAX) {
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rv = 0;
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goto done;
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}
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key = itoa(uidbuf, uid);
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}
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f = __nscd_query(req, key, passwdbuf, sizeof passwdbuf, (int[]){0});
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if (!f) { rv = errno; goto done; }
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if (f == (FILE*)-1) { rv = 0; goto done; }
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if(!passwdbuf[PWFOUND]) { rv = 0; goto cleanup_f; }
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/* A zero length response from nscd is invalid. We ignore
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* invalid responses and just report an error, rather than
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* trying to do something with them.
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*/
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if (!passwdbuf[PWNAMELEN] || !passwdbuf[PWPASSWDLEN]
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|| !passwdbuf[PWGECOSLEN] || !passwdbuf[PWDIRLEN]
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|| !passwdbuf[PWSHELLLEN]) {
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rv = EIO;
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goto cleanup_f;
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}
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if ((passwdbuf[PWNAMELEN]|passwdbuf[PWPASSWDLEN]
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|passwdbuf[PWGECOSLEN]|passwdbuf[PWDIRLEN]
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|passwdbuf[PWSHELLLEN]) >= SIZE_MAX/8) {
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rv = ENOMEM;
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goto cleanup_f;
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}
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len = passwdbuf[PWNAMELEN] + passwdbuf[PWPASSWDLEN]
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+ passwdbuf[PWGECOSLEN] + passwdbuf[PWDIRLEN]
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+ passwdbuf[PWSHELLLEN];
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if (len > *size || !*buf) {
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char *tmp = realloc(*buf, len);
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if (!tmp) {
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rv = errno;
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goto cleanup_f;
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}
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*buf = tmp;
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*size = len;
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}
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if (!fread(*buf, len, 1, f)) {
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rv = ferror(f) ? errno : EIO;
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goto cleanup_f;
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}
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pw->pw_name = *buf;
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pw->pw_passwd = pw->pw_name + passwdbuf[PWNAMELEN];
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pw->pw_gecos = pw->pw_passwd + passwdbuf[PWPASSWDLEN];
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pw->pw_dir = pw->pw_gecos + passwdbuf[PWGECOSLEN];
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pw->pw_shell = pw->pw_dir + passwdbuf[PWDIRLEN];
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pw->pw_uid = passwdbuf[PWUID];
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pw->pw_gid = passwdbuf[PWGID];
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/* Don't assume that nscd made sure to null terminate strings.
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* It's supposed to, but malicious nscd should be ignored
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* rather than causing a crash.
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*/
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if (pw->pw_passwd[-1] || pw->pw_gecos[-1] || pw->pw_dir[-1]
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|| pw->pw_shell[passwdbuf[PWSHELLLEN]-1]) {
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rv = EIO;
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goto cleanup_f;
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}
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if (name && strcmp(name, pw->pw_name)
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|| !name && uid != pw->pw_uid) {
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rv = EIO;
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goto cleanup_f;
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}
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*res = pw;
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cleanup_f:
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fclose(f);
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goto done;
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}
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done:
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pthread_setcancelstate(cs, 0);
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if (rv) errno = rv;
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38
src/passwd/nscd.h
Normal file
38
src/passwd/nscd.h
Normal file
@ -0,0 +1,38 @@
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#ifndef NSCD_H
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#define NSCD_H
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#include <stdint.h>
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#define NSCDVERSION 2
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#define GETPWBYNAME 0
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#define GETPWBYUID 1
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#define GETGRBYNAME 2
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#define GETGRBYGID 3
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#define REQVERSION 0
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#define REQTYPE 1
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#define REQKEYLEN 2
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#define REQ_LEN 3
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#define PWVERSION 0
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#define PWFOUND 1
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#define PWNAMELEN 2
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#define PWPASSWDLEN 3
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#define PWUID 4
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#define PWGID 5
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#define PWGECOSLEN 6
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#define PWDIRLEN 7
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#define PWSHELLLEN 8
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#define PW_LEN 9
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#define GRVERSION 0
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#define GRFOUND 1
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#define GRNAMELEN 2
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#define GRPASSWDLEN 3
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#define GRGID 4
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#define GRMEMCNT 5
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#define GR_LEN 6
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FILE *__nscd_query(int32_t req, const char *key, int32_t *buf, size_t len, int *swap);
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#endif
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100
src/passwd/nscd_query.c
Normal file
100
src/passwd/nscd_query.c
Normal file
@ -0,0 +1,100 @@
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#include <sys/socket.h>
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#include <byteswap.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include "nscd.h"
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static const struct {
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short sun_family;
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char sun_path[21];
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} addr = {
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AF_UNIX,
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"/var/run/nscd/socket"
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};
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FILE *__nscd_query(int32_t req, const char *key, int32_t *buf, size_t len, int *swap)
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{
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size_t i;
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int fd;
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FILE *f = 0;
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int32_t req_buf[REQ_LEN] = {
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NSCDVERSION,
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req,
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strlen(key)+1
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};
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struct msghdr msg = {
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.msg_iov = (struct iovec[]){
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{&req_buf, sizeof(req_buf)},
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{(char*)key, strlen(key)+1}
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},
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.msg_iovlen = 2
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};
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if (strlen(key) > INT32_MAX - 1) {
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return (FILE*)-1;
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}
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*swap = 0;
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retry:
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fd = socket(PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
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if (fd < 0) return NULL;
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if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
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/* If there isn't a running nscd we return -1 to indicate that
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* that is precisely what happened
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*/
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if (errno == EACCES || errno == ECONNREFUSED || errno == ENOENT) {
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close(fd);
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return (FILE *)-1;
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}
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goto error;
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}
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if (sendmsg(fd, &msg, MSG_NOSIGNAL) < 0)
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goto error;
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if(!(f = fdopen(fd, "r"))) goto error;
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if (!fread(buf, len, 1, f)) {
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/* If the VERSION entry mismatches nscd will disconnect. The
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* most likely cause is that the endianness mismatched. So, we
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* byteswap and try once more. (if we already swapped, just
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* fail out)
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*/
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if (ferror(f)) goto error;
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if (!*swap) {
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fclose(f);
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for (i = 0; i < sizeof(req_buf)/sizeof(req_buf[0]); i++) {
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req_buf[i] = bswap_32(req_buf[i]);
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}
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*swap = 1;
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goto retry;
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} else {
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errno = EIO;
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goto error;
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}
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}
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if (*swap) {
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for (i = 0; i < len/sizeof(buf[0]); i++) {
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buf[i] = bswap_32(buf[i]);
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}
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}
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/* The first entry in every nscd response is the version number. This
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* really shouldn't happen, and is evidence of some form of malformed
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* response.
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*/
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if(buf[0] != NSCDVERSION) {
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errno = EIO;
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goto error;
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}
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return f;
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error:
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if (f) fclose(f); else close(fd);
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return 0;
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}
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Block a user