diff options
| -rw-r--r-- | coreutils/test.c | 33 | ||||
| -rw-r--r-- | include/libbb.h | 9 | ||||
| -rw-r--r-- | libbb/bb_getgroups.c | 47 |
3 files changed, 63 insertions, 26 deletions
diff --git a/coreutils/test.c b/coreutils/test.c index edc625f57..edcf2a2d8 100644 --- a/coreutils/test.c +++ b/coreutils/test.c @@ -563,26 +563,11 @@ static int binop(void) /*return 1; - NOTREACHED */ } - static void initialize_group_array(void) { - int n; - - /* getgroups may be expensive, try to use it only once */ - ngroups = 32; - do { - /* FIXME: ash tries so hard to not die on OOM, - * and we spoil it with just one xrealloc here */ - /* We realloc, because test_main can be entered repeatedly by shell. - * Testcase (ash): 'while true; do test -x some_file; done' - * and watch top. (some_file must have owner != you) */ - n = ngroups; - group_array = xrealloc(group_array, n * sizeof(gid_t)); - ngroups = getgroups(n, group_array); - } while (ngroups > n); + group_array = bb_getgroups(&ngroups, NULL); } - /* Return non-zero if GID is one that we have in our groups list. */ //XXX: FIXME: duplicate of existing libbb function? // see toplevel TODO file: @@ -610,14 +595,10 @@ static int is_a_group_member(gid_t gid) /* Do the same thing access(2) does, but use the effective uid and gid, and don't make the mistake of telling root that any file is executable. */ -static int test_eaccess(char *path, int mode) +static int test_eaccess(struct stat *st, int mode) { - struct stat st; unsigned int euid = geteuid(); - if (stat(path, &st) < 0) - return -1; - if (euid == 0) { /* Root can read or write any file. */ if (mode != X_OK) @@ -625,16 +606,16 @@ static int test_eaccess(char *path, int mode) /* Root can execute any file that has any one of the execute * bits set. */ - if (st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) + if (st->st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) return 0; } - if (st.st_uid == euid) /* owner */ + if (st->st_uid == euid) /* owner */ mode <<= 6; - else if (is_a_group_member(st.st_gid)) + else if (is_a_group_member(st->st_gid)) mode <<= 3; - if (st.st_mode & mode) + if (st->st_mode & mode) return 0; return -1; @@ -667,7 +648,7 @@ static int filstat(char *nm, enum token mode) i = W_OK; if (mode == FILEX) i = X_OK; - return test_eaccess(nm, i) == 0; + return test_eaccess(&s, i) == 0; } if (is_file_type(mode)) { if (mode == FILREG) diff --git a/include/libbb.h b/include/libbb.h index 557978e66..1c9de3af0 100644 --- a/include/libbb.h +++ b/include/libbb.h @@ -1033,6 +1033,15 @@ void die_if_bad_username(const char* name) FAST_FUNC; #else #define die_if_bad_username(name) ((void)(name)) #endif +/* + * Returns (-1) terminated malloced result of getgroups(). + * Reallocs group_array (useful for repeated calls). + * ngroups is an initial size of array. It is rounded up to 32 for realloc. + * ngroups is updated on return. + * ngroups can be NULL: bb_getgroups(NULL, NULL) is valid usage. + * Dies on errors (on Linux, only xrealloc can cause this, not internal getgroups call). + */ +gid_t *bb_getgroups(int *ngroups, gid_t *group_array) FAST_FUNC; #if ENABLE_FEATURE_UTMP void FAST_FUNC write_new_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname); diff --git a/libbb/bb_getgroups.c b/libbb/bb_getgroups.c new file mode 100644 index 000000000..59ae53738 --- /dev/null +++ b/libbb/bb_getgroups.c @@ -0,0 +1,47 @@ +/* + * Utility routines. + * + * Copyright (C) 2017 Denys Vlasenko + * + * Licensed under GPLv2, see file LICENSE in this source tree. + */ + +//kbuild:lib-y += bb_getgroups.o + +#include "libbb.h" + +gid_t* FAST_FUNC bb_getgroups(int *ngroups, gid_t *group_array) +{ + int n = ngroups ? *ngroups : 0; + + /* getgroups may be a bit expensive, try to use it only once */ + if (n < 32) + n = 32; + + for (;;) { +// FIXME: ash tries so hard to not die on OOM (when we are called from test), +// and we spoil it with just one xrealloc here + group_array = xrealloc(group_array, (n+1) * sizeof(group_array[0])); + n = getgroups(n, group_array); + /* + * If buffer is too small, kernel does not return new_n > n. + * It returns -1 and EINVAL: + */ + if (n >= 0) { + /* Terminator for bb_getgroups(NULL, NULL) usage */ + group_array[n] = (gid_t) -1; + break; + } + if (errno == EINVAL) { /* too small? */ + /* This is the way to ask kernel how big the array is */ + n = getgroups(0, group_array); + continue; + } + /* Some other error (should never happen on Linux) */ + bb_perror_msg_and_die("getgroups"); + } + + if (ngroups) + *ngroups = n; + return group_array; +} |