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main: make busybox.conf mode handling less obscure

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function                                             old     new   delta
static.mode_mask                                       -      20     +20
main                                                 782     785      +3
static.mode_chars                                     15      13      -2
run_applet_no_and_exit                               450     441      -9
mode_mask                                             24       -     -24
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 1/2 up/down: 41/-53)            Total: -12 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2011-05-16 13:19:25 +02:00
parent 9be4702a30
commit 3770b6b061
2 changed files with 43 additions and 34 deletions
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67
libbb/appletlib.c
View File

@@ -281,21 +281,11 @@ static char *get_trimmed_slice(char *s, char *e)
return skip_whitespace(s);
}
/* Don't depend on the tools to combine strings. */
static const char config_file[] ALIGN1 = "/etc/busybox.conf";
/* 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[] ALIGN2 = {
/* 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 */
};
static void parse_config_file(void)
{
/* Don't depend on the tools to combine strings. */
static const char config_file[] ALIGN1 = "/etc/busybox.conf";
struct suid_config_t *sct_head;
int applet_no;
FILE *f;
@@ -411,7 +401,7 @@ static void parse_config_file(void)
* up when the busybox configuration is changed. */
applet_no = find_applet_by_name(s);
if (applet_no >= 0) {
int i;
unsigned i;
struct suid_config_t *sct;
/* Note: We currently don't check for duplicates!
@@ -429,17 +419,24 @@ static void parse_config_file(void)
e = skip_whitespace(e+1);
for (i = 0; i < 3; i++) {
/* There are 4 chars + 1 nul for each of user/group/other. */
static const char mode_chars[] ALIGN1 = "Ssx-\0" "Ssx-\0" "Ttx-";
const char *q;
q = strchrnul(mode_chars + 5*i, *e++);
if (!*q) {
/* There are 4 chars for each of user/group/other.
* "x-xx" instead of "x-" are to make
* "idx > 3" check catch invalid chars.
*/
static const char mode_chars[] ALIGN1 = "Ssx-" "Ssx-" "x-xx";
static const unsigned short mode_mask[] ALIGN2 = {
S_ISUID, S_ISUID|S_IXUSR, S_IXUSR, 0, /* Ssx- */
S_ISGID, S_ISGID|S_IXGRP, S_IXGRP, 0, /* Ssx- */
S_IXOTH, 0 /* x- */
};
const char *q = strchrnul(mode_chars + 4*i, *e);
unsigned idx = q - (mode_chars + 4*i);
if (idx > 3) {
errmsg = "mode";
goto pe_label;
}
/* Adjust by -i to account for nul. */
sct->m_mode |= mode_mask[(q - mode_chars) - i];
sct->m_mode |= mode_mask[q - mode_chars];
e++;
}
/* Now get the user/group info. */
@@ -512,6 +509,7 @@ static void check_suid(int applet_no)
}
goto check_need_suid;
found:
/* Is this user allowed to run this applet? */
m = sct->m_mode;
if (sct->m_ugid.uid == ruid)
/* same uid */
@@ -519,28 +517,31 @@ static void check_suid(int applet_no)
else if ((sct->m_ugid.gid == rgid) || ingroup(ruid, sct->m_ugid.gid))
/* same group / in group */
m >>= 3;
if (!(m & S_IXOTH)) /* is x bit not set ? */
if (!(m & S_IXOTH)) /* is x bit not set? */
bb_error_msg_and_die("you have no permission to run this applet!");
/* _both_ sgid and group_exec have to be set for setegid */
if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
rgid = sct->m_ugid.gid;
/* else (no setegid) we will set egid = rgid */
/* We set effective AND saved ids. If saved-id is not set
* like we do below, seteiud(0) can still later succeed! */
* like we do below, seteuid(0) can still later succeed! */
/* Are we directed to change gid
* (APPLET = *s* USER.GROUP or APPLET = *S* USER.GROUP)?
*/
if (sct->m_mode & S_ISGID)
rgid = sct->m_ugid.gid;
/* else: we will set egid = rgid, thus dropping sgid effect */
if (setresgid(-1, rgid, rgid))
bb_perror_msg_and_die("setresgid");
/* do we have to set effective uid? */
/* Are we directed to change uid
* (APPLET = s** USER.GROUP or APPLET = S** USER.GROUP)?
*/
uid = ruid;
if (sct->m_mode & S_ISUID)
uid = sct->m_ugid.uid;
/* else (no seteuid) we will set euid = ruid */
/* else: we will set euid = ruid, thus dropping suid effect */
if (setresuid(-1, uid, uid))
bb_perror_msg_and_die("setresuid");
goto ret;
}
# if !ENABLE_FEATURE_SUID_CONFIG_QUIET