diff options
| -rw-r--r-- | applets/applets.c | 395 |
1 files changed, 220 insertions, 175 deletions
diff --git a/applets/applets.c b/applets/applets.c index 4af569d..f24679a 100644 --- a/applets/applets.c +++ b/applets/applets.c @@ -29,6 +29,7 @@ #include <stdio.h> #include <stdlib.h> #include <string.h> +#include <assert.h> #include "busybox.h" #undef APPLET @@ -53,9 +54,7 @@ static void check_suid (struct BB_applet *app); #include "pwd_.h" #include "grp_.h" -static int parse_config_file (void); - -static int config_ok; +static void parse_config_file (void); #define CONFIG_FILE "/etc/busybox.conf" @@ -127,7 +126,7 @@ run_applet_by_name (const char *name, int argc, char **argv) #ifdef CONFIG_FEATURE_SUID_CONFIG if (recurse_level == 0) - config_ok = parse_config_file (); + parse_config_file (); #endif recurse_level++; @@ -193,7 +192,7 @@ check_suid (struct BB_applet *applet) uid_t rgid = getgid (); #ifdef CONFIG_FEATURE_SUID_CONFIG - if (config_ok) { + if (suid_config) { struct BB_suid_config *sct; for (sct = suid_config; sct; sct = sct->m_next) { @@ -253,191 +252,237 @@ check_suid (struct BB_applet *applet) #ifdef CONFIG_FEATURE_SUID_CONFIG +/* This should probably be a libbb routine. In that case, + * I'd probably rename it to something like bb_trimmed_slice. + */ +static char *get_trimmed_slice(char *s, char *e) +{ + /* First, consider the value at e to be nul and back up until we + * reach a non-space char. Set the char after that (possibly at + * the original e) to nul. */ + while (e-- > s) { + if (!isspace(*e)) { + break; + } + } + e[1] = 0; + + /* Next, advance past all leading space and return a ptr to the + * first non-space char; possibly the terminating nul. */ + return (char *) bb_skip_whitespace(s); +} + #define parse_error(x) { err=x; goto pe_label; } +/* Don't depend on the tools to combine strings. */ +static const char config_file[] = CONFIG_FILE; + +/* There are 4 chars + 1 nul for each of user/group/other. */ +static const char mode_chars[] = "Ssx-\0Ssx-\0Ttx-"; + +/* We don't supply a value for the nul, so an index adjustment is + * necessary below. Also, we use unsigned short here to save some + * space even though these are really mode_t values. */ +static const unsigned short mode_mask[] = { + /* SST sst xxx --- */ + S_ISUID, S_ISUID|S_IXUSR, S_IXUSR, 0, /* user */ + S_ISGID, S_ISGID|S_IXGRP, S_IXGRP, 0, /* group */ + 0, S_IXOTH, S_IXOTH, 0 /* other */ +}; -int -parse_config_file (void) +static void parse_config_file(void) { - struct stat st; - char *err = 0; - FILE *f = 0; - int lc = 0; - - suid_config = 0; - - /* is there a config file ? */ - if (stat (CONFIG_FILE, &st) == 0) { - /* is it owned by root with no write perm. for group and others ? */ - if (S_ISREG (st.st_mode) && (st.st_uid == 0) - && (!(st.st_mode & (S_IWGRP | S_IWOTH)))) { - /* that's ok .. then try to open it */ - f = fopen (CONFIG_FILE, "r"); - - if (f) { - char buffer[256]; - int section = 0; - - while (fgets (buffer, sizeof (buffer) - 1, f)) { - char c = buffer[0]; - char *p; - - lc++; - - p = strchr (buffer, '#'); - if (p) - *p = 0; - p = buffer + bb_strlen (buffer); - while ((p > buffer) && isspace (*--p)) - *p = 0; - - if (p == buffer) - continue; + struct BB_suid_config *sct_head; + struct BB_suid_config *sct; + struct BB_applet *applet; + FILE *f; + char *err; + char *s; + char *e; + int i, lc, section; + char buffer[256]; + struct stat st; + + assert(!suid_config); /* Should be set to NULL by bss init. */ + + if ((stat(config_file, &st) != 0) /* No config file? */ + || !S_ISREG(st.st_mode) /* Not a regular file? */ + || (st.st_uid != 0) /* Not owned by root? */ + || (st.st_mode & (S_IWGRP | S_IWOTH)) /* Writable by non-root? */ + || !(f = fopen(config_file, "r")) /* Can not open? */ + ) { + return; + } + + sct_head = NULL; + section = lc = 0; + + do { + s = buffer; - if (c == '[') { - p = strchr (buffer, ']'); + if (!fgets(s, sizeof(buffer), f)) { /* Are we done? */ + if (ferror(f)) { /* Make sure it wasn't a read error. */ + parse_error("reading"); + } + fclose(f); + suid_config = sct_head; /* Success, so set the pointer. */ + return; + } - if (!p || (p == (buffer + 1))) /* no matching ] or empty [] */ - parse_error ("malformed section header"); + lc++; /* Got a (partial) line. */ + + /* If a line is too long for our buffer, we consider it an error. + * The following test does mistreat one corner case though. + * If the final line of the file does not end with a newline and + * yet exactly fills the buffer, it will be treated as too long + * even though there isn't really a problem. But it isn't really + * worth adding code to deal with such an unlikely situation, and + * we do err on the side of caution. Besides, the line would be + * too long if it did end with a newline. */ + if (!strchr(s, '\n') && !feof(f)) { + parse_error("line too long"); + } + + /* Trim leading and trailing whitespace, ignoring comments, and + * check if the resulting string is empty. */ + if (!*(s = get_trimmed_slice(s, strchrnul(s, '#')))) { + continue; + } - *p = 0; + /* Check for a section header. */ + + if (*s == '[') { + /* Unlike the old code, we ignore leading and trailing + * whitespace for the section name. We also require that + * there are no stray characters after the closing bracket. */ + if (!(e = strchr(s, ']')) /* Missing right bracket? */ + || e[1] /* Trailing characters? */ + || !*(s = get_trimmed_slice(s+1, e)) /* Missing name? */ + ) { + parse_error("section header"); + } + /* Right now we only have one section so just check it. + * If more sections are added in the future, please don't + * resort to cascading ifs with multiple strcasecmp calls. + * That kind of bloated code is all too common. A loop + * and a string table would be a better choice unless the + * number of sections is very small. */ + if (strcasecmp(s, "SUID") == 0) { + section = 1; + continue; + } + section = -1; /* Unknown section so set to skip. */ + continue; + } - if (strcasecmp (buffer + 1, "SUID") == 0) - section = 1; - else - section = -1; /* unknown section - just skip */ - } else if (section) { - switch (section) { - case 1:{ /* SUID */ - int l; - struct BB_applet *applet; + /* Process sections. */ - p = strchr (buffer, '='); /* <key>[::space::]*=[::space::]*<value> */ + if (section == 1) { /* SUID */ + /* Since we trimmed leading and trailing space above, we're + * now looking for strings of the form + * <key>[::space::]*=[::space::]*<value> + * where both key and value could contain inner whitespace. */ - if (!p || (p == (buffer + 1))) /* no = or key is empty */ - parse_error ("malformed keyword"); + /* First get the key (an applet name in our case). */ + if (!!(e = strchr(s, '='))) { + s = get_trimmed_slice(s, e); + } + if (!e || !*s) { /* Missing '=' or empty key. */ + parse_error("keyword"); + } - l = p - buffer; - while (isspace (buffer[--l])) { - /* skip whitespace */ + /* Ok, we have an applet name. Process the rhs if this + * applet is currently built in and ignore it otherwise. + * Note: This can hide config file bugs which only pop + * up when the busybox configuration is changed. */ + if ((applet = find_applet_by_name(s))) { + /* Note: We currently don't check for duplicates! + * The last config line for each applet will be the + * one used since we insert at the head of the list. + * I suppose this could be considered a feature. */ + sct = xmalloc(sizeof(struct BB_suid_config)); + sct->m_applet = applet; + sct->m_mode = 0; + sct->m_next = sct_head; + sct_head = sct; + + /* Get the specified mode. */ + + e = (char *) bb_skip_whitespace(e+1); + + for (i=0 ; i < 3 ; i++) { + const char *q; + if (!*(q = strchrnul(mode_chars + 5*i, *e++))) { + parse_error("mode"); + } + /* Adjust by -i to account for nul. */ + sct->m_mode |= mode_mask[(q - mode_chars) - i]; } - buffer[l + 1] = 0; - - if ((applet = find_applet_by_name (buffer))) { - struct BB_suid_config *sct = - xmalloc (sizeof (struct BB_suid_config)); - - sct->m_applet = applet; - sct->m_next = suid_config; - suid_config = sct; - - while (isspace (*++p)) { - /* skip whitespace */ - } - - sct->m_mode = 0; - - switch (*p++) { - case 'S': - sct->m_mode |= S_ISUID; - break; - case 's': - sct->m_mode |= S_ISUID; - /* no break */ - case 'x': - sct->m_mode |= S_IXUSR; - break; - case '-': - break; - default: - parse_error ("invalid user mode"); - } - - switch (*p++) { - case 's': - sct->m_mode |= S_ISGID; - /* no break */ - case 'x': - sct->m_mode |= S_IXGRP; - break; - case 'S': - break; - case '-': - break; - default: - parse_error ("invalid group mode"); - } - - switch (*p) { - case 't': - case 'x': - sct->m_mode |= S_IXOTH; - break; - case 'T': - case '-': - break; - default: - parse_error ("invalid other mode"); - } - - while (isspace (*++p)) { - /* skip whitespace */ - } - - if (isdigit (*p)) { - sct->m_uid = strtol (p, &p, 10); - if (*p++ != '.') - parse_error ("parsing <uid>.<gid>"); - } else { - struct passwd *pwd; - char *p2 = strchr (p, '.'); - - if (!p2) - parse_error ("parsing <uid>.<gid>"); - - *p2 = 0; - pwd = getpwnam (p); - - if (!pwd) - parse_error ("invalid user name"); - - sct->m_uid = pwd->pw_uid; - p = p2 + 1; - } - if (isdigit (*p)) - sct->m_gid = strtol (p, &p, 10); - else { - struct group *grp = getgrnam (p); - - if (!grp) - parse_error ("invalid group name"); - - sct->m_gid = grp->gr_gid; - } + /* Now get the the user/group info. */ + + s = (char *) bb_skip_whitespace(e); + + /* Note: We require whitespace between the mode and the + * user/group info. */ + if ((s == e) || !(e = strchr(s, '.'))) { + parse_error("<uid>.<gid>"); + } + *e++ = 0; + + /* We can't use get_ug_id here since it would exit() + * if a uid or gid was not found. Oh well... */ + { + char *e2; + + sct->m_uid = strtoul(s, &e2, 10); + if (*e2 || (s == e2)) { + struct passwd *pwd; + if (!(pwd = getpwnam(s))) { + parse_error("user"); + } + sct->m_uid = pwd->pw_uid; + } + + sct->m_gid = strtoul(e, &e2, 10); + if (*e2 || (e == e2)) { + struct group *grp; + if (!(grp = getgrnam(e))) { + parse_error("group"); + } + sct->m_gid = grp->gr_gid; + } } - break; - } - default: /* unknown - skip */ - break; } - } else - parse_error ("keyword not within section"); + continue; } - fclose (f); - return 1; - } - } - } - return 0; /* no config file or not readable (not an error) */ -pe_label: - fprintf (stderr, "Parse error in %s, line %d: %s\n", CONFIG_FILE, lc, err); + /* Unknown sections are ignored. */ - if (f) - fclose (f); - return 0; + /* Encountering configuration lines prior to seeing a + * section header is treated as an error. This is how + * the old code worked, but it may not be desireable. + * We may want to simply ignore such lines in case they + * are used in some future version of busybox. */ + if (!section) { + parse_error("keyword outside section"); + } + + } while (1); + + pe_label: + fprintf(stderr, "Parse error in %s, line %d: %s\n", + config_file, lc, err); + + fclose(f); + /* Release any allocated memory before returning. */ + while (sct_head) { + sct = sct_head->m_next; + free(sct_head); + sct_head = sct; + } + return; } #endif @@ -446,9 +491,9 @@ pe_label: /* END CODE */ /* -Local Variables: -c-file-style: "linux" -c-basic-offset: 4 -tab-width: 4 + Local Variables: + c-file-style: "linux" + c-basic-offset: 4 + tab-width: 4 End: */ |