X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/checkpath/blobdiff_plain/60538794f1efdac9d84632579e36b61ca58c925c..de1bcaacf00696ba09688b51c6c0bbfd8b60d778:/checkpath.c diff --git a/checkpath.c b/checkpath.c index 2047800..d874246 100644 --- a/checkpath.c +++ b/checkpath.c @@ -43,6 +43,7 @@ #include #include +#include #include "checkpath.h" @@ -58,16 +59,14 @@ struct elt { struct elt *e_link; /* Pointer to the next one along */ size_t e_offset; /* Offset of name in path string */ unsigned e_flags; /* Various useful flags */ +#define EF_STICKY 1u /* Directory has sticky bit set */ char e_name[1]; /* Name of the directory */ }; -#define f_sticky 1u /* Directory has sticky bit set */ - -#define f_last 1u /* This is the final item to check */ /*----- Static variables --------------------------------------------------*/ -static struct elt rootnode = { 0, 0, 0 }; /* Root of the list */ +static const struct elt rootnode = { 0, 0, 0 }; /* Root of the list */ static struct elt *sp; /* Stack pointer for list */ static dstr d = DSTR_INIT; /* Current path string */ @@ -138,7 +137,7 @@ static void pop(void) struct elt *e = sp->e_link; d.len = sp->e_offset; DPUTZ(&d); - sp = e; + xfree(sp); sp = e; } } @@ -271,13 +270,17 @@ static void report(const struct checkpath *cp, unsigned what, int verbose, * Arguments: @const char *p@ = name of directory to check * @struct stat *st@ = pointer to @stat@(2) block for it * @const struct checkpath *cp@ = pointer to caller parameters - * @unsigned f@ = various flags + * @unsigned f@ = various flags (@SF_...@) * * Returns: Zero if everything's OK, else bitmask of problems. * * Use: Performs the main load of sanity-checking on a directory. + * If @SF_LAST@ is not set then sticky directories are always + * acceptable. */ +#define SF_LAST 1u /* This is the final item to check */ + static unsigned sanity(const char *p, struct stat *st, const struct checkpath *cp, unsigned f) { @@ -287,13 +290,13 @@ static unsigned sanity(const char *p, struct stat *st, unsigned b; if (S_ISDIR(st->st_mode) && - (!(f & f_last) || (cp->cp_what & CP_STICKYOK))) - stickyok = 01000; + (!(f & SF_LAST) || (cp->cp_what & CP_STICKYOK))) + stickyok = S_ISVTX; /* --- Check for world-writability --- */ if ((cp->cp_what & CP_WRWORLD) && - (st->st_mode & (0002 | stickyok)) == 0002) { + (st->st_mode & (S_IWOTH | stickyok)) == S_IWOTH) { bad |= CP_WRWORLD; report(cp, CP_WRWORLD, 1, p, "** world writable **"); } @@ -301,7 +304,7 @@ static unsigned sanity(const char *p, struct stat *st, /* --- Check for group-writability --- */ if ((cp->cp_what & (CP_WRGRP | CP_WROTHGRP)) && - (st->st_mode & (0020 | stickyok)) == 0020) { + (st->st_mode & (S_IWGRP | stickyok)) == S_IWGRP) { b = CP_WRGRP; if (cp->cp_what & CP_WROTHGRP) { @@ -349,10 +352,11 @@ unsigned checkpath(const char *p, const struct checkpath *cp) struct elt *e, *ee; struct stat st; unsigned bad = 0; + dstr buf = DSTR_INIT; /* --- Initialize stack pointer and path string --- */ - sp = &rootnode; + sp = (/*unconst*/ struct elt *)&rootnode; dstr_destroy(&d); /* --- Try to find the current directory --- */ @@ -386,7 +390,7 @@ unsigned checkpath(const char *p, const struct checkpath *cp) /* --- Strip off simple `.' elements --- */ if (strcmp(ee->e_name, ".") == 0) { - free(ee); + xfree(ee); ee = e; continue; } @@ -395,7 +399,7 @@ unsigned checkpath(const char *p, const struct checkpath *cp) else if (strcmp(ee->e_name, "..") == 0) { pop(); - free(ee); + xfree(ee); ee = e; continue; } @@ -416,11 +420,11 @@ unsigned checkpath(const char *p, const struct checkpath *cp) /* --- Handle symbolic links specially --- */ if (S_ISLNK(st.st_mode)) { - dstr buf = DSTR_INIT; int i; /* --- Resolve the link --- */ + dstr_reset(&buf); dstr_ensure(&buf, st.st_size + 1); if ((i = readlink(d.buf, buf.buf, buf.sz)) < 0) { report(cp, CP_ERROR, 0, d.buf, "can't readlink: %e"); @@ -438,7 +442,7 @@ unsigned checkpath(const char *p, const struct checkpath *cp) */ if ((cp->cp_what & CP_WROTHUSR) && - (sp->e_link->e_flags & f_sticky) && + (sp->e_link->e_flags & EF_STICKY) && st.st_uid != cp->cp_uid && st.st_uid != 0) { bad |= CP_WROTHUSR; report(cp, CP_WROTHUSR, 1, d.buf, @@ -452,17 +456,16 @@ unsigned checkpath(const char *p, const struct checkpath *cp) else pop(); ee = splitpath(buf.buf, ee); - dstr_destroy(&buf); continue; } /* --- Run the sanity check on this path element --- */ - bad |= sanity(d.buf, &st, cp, ee ? 0 : f_last); + bad |= sanity(d.buf, &st, cp, ee ? 0 : SF_LAST); if (S_ISDIR(st.st_mode)) { - if (st.st_mode & 01000) - sp->e_flags |= f_sticky; + if (st.st_mode & S_ISVTX) + sp->e_flags |= EF_STICKY; report(cp, CP_REPORT, 4, d.buf, "directory"); continue; } @@ -479,39 +482,105 @@ unsigned checkpath(const char *p, const struct checkpath *cp) report(cp, CP_ERROR, 0, 0, "junk left over after reaching leaf"); while (ee) { e = ee->e_link; - free(ee); + xfree(ee); ee = e; } } popall(); + dstr_destroy(&buf); return (bad); } -/* --- @checkpath_setids@ --- * +/* --- @checkpath_addgid@ --- * * * Arguments: @struct checkpath *cp@ = pointer to block to fill in + * @gid_t g@ = group id to add * - * Returns: --- + * Returns: Zero if successful, nonzero if the array is full. * - * Use: Fills in the user ids and things in the structure. + * Use: Adds the group @g@ to the structure. */ -void checkpath_setids(struct checkpath *cp) +int checkpath_addgid(struct checkpath *cp, gid_t g) { - int n, i; - gid_t g = getgid(); + int i; - cp->cp_uid = getuid(); - n = getgroups(sizeof(cp->cp_gid) / sizeof(cp->cp_gid[0]), cp->cp_gid); + for (i = 0; i < cp->cp_gids; i++) { + if (cp->cp_gid[i] == g) + return (0); + } + if (cp->cp_gids >= N(cp->cp_gid)) + return (-1); + cp->cp_gid[cp->cp_gids++] = g; + return (0); +} + +/* --- @checkpath_setuid@ --- * + * + * Arguments: @struct checkpath *cp@ = pointer to block to fill in + * + * Returns: --- + * + * Use: Fills in the @cp_uid@ slot of the structure with the real uid + * of the current process. + */ + +void checkpath_setuid(struct checkpath *cp) { cp->cp_uid = getuid(); } + +/* --- @checkpath_setgid@ --- * + * + * Arguments: @struct checkpath *cp@ = pointer to block to fill in + * + * Returns: Zero if successful, nonzero if the array is full. + * + * Use: Adds the real gid of the current process to the @cp_gid@ + * array. + */ +int checkpath_setgid(struct checkpath *cp) + { return (checkpath_addgid(cp, getgid())); } + +/* --- @checkpath_setgroups@ --- * + * + * Arguments: @struct checkpath *cp@ = pointer to block to fill in + * + * Returns: Zero if successful, nonzero if the array is full. + * + * Use: Adds the current process's supplementary groups to the + * @cp_gid@ table. + */ + +int checkpath_setgroups(struct checkpath *cp) +{ + int i, n; + gid_t gg[NGROUPS_MAX]; + + n = getgroups(N(gg), gg); for (i = 0; i < n; i++) { - if (cp->cp_gid[i] == g) - goto gid_ok; + if (checkpath_addgid(cp, gg[i])) + return (-1); } - cp->cp_gid[n++] = g; -gid_ok: - cp->cp_gids = n; + return (0); +} + +/* --- @checkpath_setids@ --- * + * + * Arguments: @struct checkpath *cp@ = pointer to block to fill in + * + * Returns: --- + * + * Use: Fills in the user ids and things in the structure. This is + * equivalent to setting @cp_gids = 0@ and then calling + * @_setuid@, @_setgid@ and @_setgroups@. It can't fail. + */ + +void checkpath_setids(struct checkpath *cp) +{ + cp->cp_gids = 0; + checkpath_setuid(cp); + checkpath_setgid(cp); + checkpath_setgroups(cp); } /*----- That's all, folks -------------------------------------------------*/