1 | /* vi: set sw=4 ts=4: */
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2 | /* Copyright (C) 2014 Tito Ragusa <farmatito@tiscali.it>
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3 | *
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4 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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5 | */
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6 | /* This program is distributed in the hope that it will be useful,
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7 | * but WITHOUT ANY WARRANTY!!
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8 | *
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9 | * Rewrite of some parts. Main differences are:
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10 | *
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11 | * 1) the buffer for getpwuid, getgrgid, getpwnam, getgrnam is dynamically
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12 | * allocated.
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13 | * If ENABLE_FEATURE_CLEAN_UP is set the buffers are freed at program
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14 | * exit using the atexit function to make valgrind happy.
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15 | * 2) the passwd/group files:
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16 | * a) must contain the expected number of fields (as per count of field
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17 | * delimeters ":") or we will complain with a error message.
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18 | * b) leading and trailing whitespace in fields is stripped.
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19 | * c) some fields are not allowed to be empty (e.g. username, uid/gid),
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20 | * and in this case NULL is returned and errno is set to EINVAL.
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21 | * This behaviour could be easily changed by modifying PW_DEF, GR_DEF,
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22 | * SP_DEF strings (uppercase makes a field mandatory).
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23 | * d) the string representing uid/gid must be convertible by strtoXX
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24 | * functions, or errno is set to EINVAL.
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25 | * e) leading and trailing whitespace in group member names is stripped.
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26 | * 3) the internal function for getgrouplist uses dynamically allocated buffer.
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27 | * 4) at the moment only the functions really used by busybox code are
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28 | * implemented, if you need a particular missing function it should be
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29 | * easy to write it by using the internal common code.
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30 | */
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31 |
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32 | #include "libbb.h"
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33 |
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34 | struct const_passdb {
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35 | const char *filename;
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36 | char def[7 + 2*ENABLE_USE_BB_SHADOW];
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37 | uint8_t off[7 + 2*ENABLE_USE_BB_SHADOW];
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38 | uint8_t numfields;
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39 | uint8_t size_of;
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40 | };
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41 | struct passdb {
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42 | const char *filename;
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43 | char def[7 + 2*ENABLE_USE_BB_SHADOW];
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44 | uint8_t off[7 + 2*ENABLE_USE_BB_SHADOW];
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45 | uint8_t numfields;
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46 | uint8_t size_of;
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47 | FILE *fp;
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48 | char *malloced;
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49 | };
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50 | /* Note: for shadow db, def[] will not contain terminating NUL,
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51 | * but convert_to_struct() logic detects def[] end by "less than SP?",
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52 | * not by "is it NUL?" condition; and off[0] happens to be zero
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53 | * for every db anyway, so there _is_ in fact a terminating NUL there.
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54 | */
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55 |
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56 | /* S = string not empty, s = string maybe empty,
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57 | * I = uid,gid, l = long maybe empty, m = members,
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58 | * r = reserved
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59 | */
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60 | #define PW_DEF "SsIIsss"
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61 | #define GR_DEF "SsIm"
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62 | #define SP_DEF "Ssllllllr"
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63 |
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64 | static const struct const_passdb const_pw_db = {
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65 | _PATH_PASSWD, PW_DEF,
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66 | {
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67 | offsetof(struct passwd, pw_name), /* 0 S */
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68 | offsetof(struct passwd, pw_passwd), /* 1 s */
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69 | offsetof(struct passwd, pw_uid), /* 2 I */
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70 | offsetof(struct passwd, pw_gid), /* 3 I */
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71 | offsetof(struct passwd, pw_gecos), /* 4 s */
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72 | offsetof(struct passwd, pw_dir), /* 5 s */
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73 | offsetof(struct passwd, pw_shell) /* 6 s */
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74 | },
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75 | sizeof(PW_DEF)-1, sizeof(struct passwd)
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76 | };
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77 | static const struct const_passdb const_gr_db = {
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78 | _PATH_GROUP, GR_DEF,
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79 | {
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80 | offsetof(struct group, gr_name), /* 0 S */
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81 | offsetof(struct group, gr_passwd), /* 1 s */
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82 | offsetof(struct group, gr_gid), /* 2 I */
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83 | offsetof(struct group, gr_mem) /* 3 m (char **) */
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84 | },
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85 | sizeof(GR_DEF)-1, sizeof(struct group)
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86 | };
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87 | #if ENABLE_USE_BB_SHADOW
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88 | static const struct const_passdb const_sp_db = {
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89 | _PATH_SHADOW, SP_DEF,
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90 | {
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91 | offsetof(struct spwd, sp_namp), /* 0 S Login name */
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92 | offsetof(struct spwd, sp_pwdp), /* 1 s Encrypted password */
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93 | offsetof(struct spwd, sp_lstchg), /* 2 l */
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94 | offsetof(struct spwd, sp_min), /* 3 l */
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95 | offsetof(struct spwd, sp_max), /* 4 l */
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96 | offsetof(struct spwd, sp_warn), /* 5 l */
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97 | offsetof(struct spwd, sp_inact), /* 6 l */
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98 | offsetof(struct spwd, sp_expire), /* 7 l */
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99 | offsetof(struct spwd, sp_flag) /* 8 r Reserved */
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100 | },
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101 | sizeof(SP_DEF)-1, sizeof(struct spwd)
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102 | };
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103 | #endif
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104 |
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105 | /* We avoid having big global data. */
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106 | struct statics {
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107 | /* We use same buffer (db[0].malloced) for getpwuid and getpwnam.
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108 | * Manpage says:
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109 | * "The return value may point to a static area, and may be overwritten
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110 | * by subsequent calls to getpwent(), getpwnam(), or getpwuid()."
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111 | */
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112 | struct passdb db[2 + ENABLE_USE_BB_SHADOW];
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113 | char *tokenize_end;
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114 | unsigned string_size;
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115 | };
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116 |
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117 | static struct statics *ptr_to_statics;
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118 | #define S (*ptr_to_statics)
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119 | #define has_S (ptr_to_statics)
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120 |
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121 | #if ENABLE_FEATURE_CLEAN_UP
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122 | static void free_static(void)
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123 | {
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124 | free(S.db[0].malloced);
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125 | free(S.db[1].malloced);
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126 | # if ENABLE_USE_BB_SHADOW
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127 | free(S.db[2].malloced);
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128 | # endif
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129 | free(ptr_to_statics);
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130 | }
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131 | #endif
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132 |
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133 | static struct statics *get_S(void)
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134 | {
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135 | if (!ptr_to_statics) {
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136 | ptr_to_statics = xzalloc(sizeof(S));
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137 | memcpy(&S.db[0], &const_pw_db, sizeof(const_pw_db));
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138 | memcpy(&S.db[1], &const_gr_db, sizeof(const_gr_db));
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139 | #if ENABLE_USE_BB_SHADOW
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140 | memcpy(&S.db[2], &const_sp_db, sizeof(const_sp_db));
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141 | #endif
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142 | #if ENABLE_FEATURE_CLEAN_UP
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143 | atexit(free_static);
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144 | #endif
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145 | }
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146 | return ptr_to_statics;
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147 | }
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148 |
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149 | /* Internal functions */
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150 |
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151 | /* Divide the passwd/group/shadow record in fields
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152 | * by substituting the given delimeter
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153 | * e.g. ':' or ',' with '\0'.
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154 | * Returns the number of fields found.
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155 | * Strips leading and trailing whitespace in fields.
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156 | */
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157 | static int tokenize(char *buffer, int ch)
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158 | {
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159 | char *p = buffer;
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160 | char *s = p;
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161 | int num_fields = 0;
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162 |
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163 | for (;;) {
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164 | if (isblank(*s)) {
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165 | overlapping_strcpy(s, skip_whitespace(s));
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166 | }
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167 | if (*p == ch || *p == '\0') {
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168 | char *end = p;
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169 | while (p != s && isblank(p[-1]))
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170 | p--;
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171 | if (p != end)
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172 | overlapping_strcpy(p, end);
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173 | num_fields++;
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174 | if (*end == '\0') {
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175 | S.tokenize_end = p + 1;
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176 | return num_fields;
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177 | }
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178 | *p = '\0';
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179 | s = p + 1;
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180 | }
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181 | p++;
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182 | }
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183 | }
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184 |
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185 | /* Returns !NULL on success and matching line broken up in fields by '\0' in buf.
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186 | * We require the expected number of fields to be found.
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187 | */
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188 | static char *parse_common(FILE *fp, struct passdb *db,
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189 | const char *key, int field_pos)
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190 | {
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191 | char *buf;
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192 |
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193 | while ((buf = xmalloc_fgetline(fp)) != NULL) {
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194 | /* Skip empty lines, comment lines */
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195 | if (buf[0] == '\0' || buf[0] == '#')
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196 | goto free_and_next;
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197 | if (tokenize(buf, ':') != db->numfields) {
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198 | /* number of fields is wrong */
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199 | bb_error_msg("%s: bad record", db->filename);
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200 | goto free_and_next;
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201 | }
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202 |
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203 | if (field_pos == -1) {
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204 | /* no key specified: sequential read, return a record */
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205 | break;
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206 | }
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207 | if (strcmp(key, nth_string(buf, field_pos)) == 0) {
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208 | /* record found */
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209 | break;
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210 | }
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211 | free_and_next:
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212 | free(buf);
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213 | }
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214 |
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215 | S.string_size = S.tokenize_end - buf;
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216 | /*
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217 | * Ugly hack: group db requires additional buffer space
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218 | * for members[] array. If there is only one group, we need space
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219 | * for 3 pointers: alignment padding, group name, NULL.
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220 | * +1 for every additional group.
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221 | */
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222 | if (buf && db->numfields == sizeof(GR_DEF)-1) { /* if we read group file... */
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223 | int cnt = 3;
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224 | char *p = buf;
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225 | while (p < S.tokenize_end)
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226 | if (*p++ == ',')
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227 | cnt++;
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228 | S.string_size += cnt * sizeof(char*);
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229 | //bb_error_msg("+%d words = %u key:%s buf:'%s'", cnt, S.string_size, key, buf);
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230 | buf = xrealloc(buf, S.string_size);
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231 | }
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232 |
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233 | return buf;
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234 | }
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235 |
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236 | static char *parse_file(struct passdb *db,
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237 | const char *key, int field_pos)
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238 | {
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239 | char *buf = NULL;
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240 | FILE *fp = fopen_for_read(db->filename);
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241 |
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242 | if (fp) {
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243 | buf = parse_common(fp, db, key, field_pos);
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244 | fclose(fp);
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245 | }
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246 | return buf;
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247 | }
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248 |
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249 | /* Convert passwd/group/shadow file record in buffer to a struct */
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250 | static void *convert_to_struct(struct passdb *db,
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251 | char *buffer, void *result)
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252 | {
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253 | const char *def = db->def;
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254 | const uint8_t *off = db->off;
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255 |
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256 | /* For consistency, zero out all fields */
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257 | memset(result, 0, db->size_of);
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258 |
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259 | for (;;) {
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260 | void *member = (char*)result + (*off++);
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261 |
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262 | if ((*def | 0x20) == 's') { /* s or S */
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263 | *(char **)member = (char*)buffer;
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264 | if (!buffer[0] && (*def == 'S')) {
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265 | errno = EINVAL;
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266 | }
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267 | }
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268 | if (*def == 'I') {
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269 | *(int *)member = bb_strtou(buffer, NULL, 10);
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270 | }
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271 | #if ENABLE_USE_BB_SHADOW
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272 | if (*def == 'l') {
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273 | long n = -1;
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274 | if (buffer[0])
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275 | n = bb_strtol(buffer, NULL, 10);
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276 | *(long *)member = n;
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277 | }
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278 | #endif
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279 | if (*def == 'm') {
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280 | char **members;
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281 | int i = tokenize(buffer, ',');
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282 |
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283 | /* Store members[] after buffer's end.
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284 | * This is safe ONLY because there is a hack
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285 | * in parse_common() which allocates additional space
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286 | * at the end of malloced buffer!
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287 | */
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288 | members = (char **)
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289 | ( ((intptr_t)S.tokenize_end + sizeof(members[0]))
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290 | & -(intptr_t)sizeof(members[0])
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291 | );
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292 | ((struct group *)result)->gr_mem = members;
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293 | while (--i >= 0) {
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294 | if (buffer[0]) {
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295 | *members++ = buffer;
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296 | // bb_error_msg("member[]='%s'", buffer);
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297 | }
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298 | buffer += strlen(buffer) + 1;
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299 | }
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300 | *members = NULL;
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301 | }
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302 | /* def "r" does nothing */
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303 |
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304 | def++;
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305 | if ((unsigned char)*def <= (unsigned char)' ')
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306 | break;
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307 | buffer += strlen(buffer) + 1;
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308 | }
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309 |
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310 | if (errno)
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311 | result = NULL;
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312 | return result;
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313 | }
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314 |
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315 | static int massage_data_for_r_func(struct passdb *db,
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316 | char *buffer, size_t buflen,
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317 | void **result,
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318 | char *buf)
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319 | {
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320 | void *result_buf = *result;
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321 | *result = NULL;
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322 | if (buf) {
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323 | if (S.string_size > buflen) {
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324 | errno = ERANGE;
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325 | } else {
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326 | memcpy(buffer, buf, S.string_size);
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327 | *result = convert_to_struct(db, buffer, result_buf);
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328 | }
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329 | free(buf);
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330 | }
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331 | /* "The reentrant functions return zero on success.
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332 | * In case of error, an error number is returned."
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333 | * NB: not finding the record is also a "success" here:
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334 | */
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335 | return errno;
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336 | }
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337 |
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338 | static void* massage_data_for_non_r_func(struct passdb *db, char *buf)
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339 | {
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340 | if (!buf)
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341 | return NULL;
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342 |
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343 | free(db->malloced);
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344 | /* We enlarge buf and move string data up, freeing space
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345 | * for struct passwd/group/spwd at the beginning. This way,
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346 | * entire result of getXXnam is in a single malloced block.
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347 | * This enables easy creation of xmalloc_getpwnam() API.
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348 | */
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349 | db->malloced = buf = xrealloc(buf, db->size_of + S.string_size);
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350 | memmove(buf + db->size_of, buf, S.string_size);
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351 | return convert_to_struct(db, buf + db->size_of, buf);
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352 | }
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353 |
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354 | /****** getXXnam/id_r */
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355 |
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356 | static int FAST_FUNC getXXnam_r(const char *name, uintptr_t db_and_field_pos,
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357 | char *buffer, size_t buflen,
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358 | void *result)
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359 | {
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360 | char *buf;
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361 | struct passdb *db = &get_S()->db[db_and_field_pos >> 2];
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362 |
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363 | buf = parse_file(db, name, 0 /*db_and_field_pos & 3*/);
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364 | /* "db_and_field_pos & 3" is commented out since so far we don't implement
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365 | * getXXXid_r() functions which would use that to pass 2 here */
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366 |
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367 | return massage_data_for_r_func(db, buffer, buflen, result, buf);
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368 | }
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369 |
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370 | int FAST_FUNC getpwnam_r(const char *name, struct passwd *struct_buf,
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371 | char *buffer, size_t buflen,
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372 | struct passwd **result)
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373 | {
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374 | /* Why the "store buffer address in result" trick?
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375 | * This way, getXXnam_r has the same ABI signature as getpwnam_r,
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376 | * hopefully compiler can optimize tail call better in this case.
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377 | */
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378 | *result = struct_buf;
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379 | return getXXnam_r(name, (0 << 2) + 0, buffer, buflen, result);
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380 | }
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381 | #if ENABLE_USE_BB_SHADOW
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382 | int FAST_FUNC getspnam_r(const char *name, struct spwd *struct_buf, char *buffer, size_t buflen,
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383 | struct spwd **result)
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384 | {
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385 | *result = struct_buf;
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386 | return getXXnam_r(name, (2 << 2) + 0, buffer, buflen, result);
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387 | }
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388 | #endif
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389 |
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390 | #ifdef UNUSED
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391 | /****** getXXent_r */
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392 |
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393 | static int FAST_FUNC getXXent_r(uintptr_t db_idx, char *buffer, size_t buflen,
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394 | void *result)
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395 | {
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396 | char *buf;
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397 | struct passdb *db = &get_S()->db[db_idx];
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398 |
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399 | if (!db->fp) {
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400 | db->fp = fopen_for_read(db->filename);
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401 | if (!db->fp) {
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402 | return errno;
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403 | }
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404 | close_on_exec_on(fileno(db->fp));
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405 | }
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406 |
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407 | buf = parse_common(db->fp, db, /*no search key:*/ NULL, -1);
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408 | if (!buf && !errno)
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409 | errno = ENOENT;
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410 | return massage_data_for_r_func(db, buffer, buflen, result, buf);
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411 | }
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412 |
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413 | int FAST_FUNC getpwent_r(struct passwd *struct_buf, char *buffer, size_t buflen,
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414 | struct passwd **result)
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415 | {
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416 | *result = struct_buf;
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417 | return getXXent_r(0, buffer, buflen, result);
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418 | }
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419 | #endif
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420 |
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421 | /****** getXXent */
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422 |
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423 | static void* FAST_FUNC getXXent(uintptr_t db_idx)
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424 | {
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425 | char *buf;
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426 | struct passdb *db = &get_S()->db[db_idx];
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427 |
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428 | if (!db->fp) {
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429 | db->fp = fopen_for_read(db->filename);
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430 | if (!db->fp) {
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431 | return NULL;
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432 | }
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433 | close_on_exec_on(fileno(db->fp));
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434 | }
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435 |
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436 | buf = parse_common(db->fp, db, /*no search key:*/ NULL, -1);
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437 | return massage_data_for_non_r_func(db, buf);
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438 | }
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439 |
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440 | struct passwd* FAST_FUNC getpwent(void)
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441 | {
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442 | return getXXent(0);
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443 | }
|
---|
444 |
|
---|
445 | /****** getXXnam/id */
|
---|
446 |
|
---|
447 | static void* FAST_FUNC getXXnam(const char *name, unsigned db_and_field_pos)
|
---|
448 | {
|
---|
449 | char *buf;
|
---|
450 | struct passdb *db = &get_S()->db[db_and_field_pos >> 2];
|
---|
451 |
|
---|
452 | buf = parse_file(db, name, db_and_field_pos & 3);
|
---|
453 | return massage_data_for_non_r_func(db, buf);
|
---|
454 | }
|
---|
455 |
|
---|
456 | struct passwd* FAST_FUNC getpwnam(const char *name)
|
---|
457 | {
|
---|
458 | return getXXnam(name, (0 << 2) + 0);
|
---|
459 | }
|
---|
460 | struct group* FAST_FUNC getgrnam(const char *name)
|
---|
461 | {
|
---|
462 | return getXXnam(name, (1 << 2) + 0);
|
---|
463 | }
|
---|
464 | struct passwd* FAST_FUNC getpwuid(uid_t id)
|
---|
465 | {
|
---|
466 | return getXXnam(utoa(id), (0 << 2) + 2);
|
---|
467 | }
|
---|
468 | struct group* FAST_FUNC getgrgid(gid_t id)
|
---|
469 | {
|
---|
470 | return getXXnam(utoa(id), (1 << 2) + 2);
|
---|
471 | }
|
---|
472 |
|
---|
473 | /****** end/setXXend */
|
---|
474 |
|
---|
475 | void FAST_FUNC endpwent(void)
|
---|
476 | {
|
---|
477 | if (has_S && S.db[0].fp) {
|
---|
478 | fclose(S.db[0].fp);
|
---|
479 | S.db[0].fp = NULL;
|
---|
480 | }
|
---|
481 | }
|
---|
482 | void FAST_FUNC setpwent(void)
|
---|
483 | {
|
---|
484 | if (has_S && S.db[0].fp) {
|
---|
485 | rewind(S.db[0].fp);
|
---|
486 | }
|
---|
487 | }
|
---|
488 | void FAST_FUNC endgrent(void)
|
---|
489 | {
|
---|
490 | if (has_S && S.db[1].fp) {
|
---|
491 | fclose(S.db[1].fp);
|
---|
492 | S.db[1].fp = NULL;
|
---|
493 | }
|
---|
494 | }
|
---|
495 |
|
---|
496 | /****** initgroups and getgrouplist */
|
---|
497 |
|
---|
498 | static gid_t* FAST_FUNC getgrouplist_internal(int *ngroups_ptr,
|
---|
499 | const char *user, gid_t gid)
|
---|
500 | {
|
---|
501 | FILE *fp;
|
---|
502 | gid_t *group_list;
|
---|
503 | int ngroups;
|
---|
504 |
|
---|
505 | /* We alloc space for 8 gids at a time. */
|
---|
506 | group_list = xzalloc(8 * sizeof(group_list[0]));
|
---|
507 | group_list[0] = gid;
|
---|
508 | ngroups = 1;
|
---|
509 |
|
---|
510 | fp = fopen_for_read(_PATH_GROUP);
|
---|
511 | if (fp) {
|
---|
512 | struct passdb *db = &get_S()->db[1];
|
---|
513 | char *buf;
|
---|
514 | while ((buf = parse_common(fp, db, NULL, -1)) != NULL) {
|
---|
515 | char **m;
|
---|
516 | struct group group;
|
---|
517 | if (!convert_to_struct(db, buf, &group))
|
---|
518 | goto next;
|
---|
519 | if (group.gr_gid == gid)
|
---|
520 | goto next;
|
---|
521 | for (m = group.gr_mem; *m; m++) {
|
---|
522 | if (strcmp(*m, user) != 0)
|
---|
523 | continue;
|
---|
524 | group_list = xrealloc_vector(group_list, /*8=2^3:*/ 3, ngroups);
|
---|
525 | group_list[ngroups++] = group.gr_gid;
|
---|
526 | goto next;
|
---|
527 | }
|
---|
528 | next:
|
---|
529 | free(buf);
|
---|
530 | }
|
---|
531 | fclose(fp);
|
---|
532 | }
|
---|
533 | *ngroups_ptr = ngroups;
|
---|
534 | return group_list;
|
---|
535 | }
|
---|
536 |
|
---|
537 | int FAST_FUNC initgroups(const char *user, gid_t gid)
|
---|
538 | {
|
---|
539 | int ngroups;
|
---|
540 | gid_t *group_list = getgrouplist_internal(&ngroups, user, gid);
|
---|
541 |
|
---|
542 | ngroups = setgroups(ngroups, group_list);
|
---|
543 | free(group_list);
|
---|
544 | return ngroups;
|
---|
545 | }
|
---|
546 |
|
---|
547 | int FAST_FUNC getgrouplist(const char *user, gid_t gid, gid_t *groups, int *ngroups)
|
---|
548 | {
|
---|
549 | int ngroups_old = *ngroups;
|
---|
550 | gid_t *group_list = getgrouplist_internal(ngroups, user, gid);
|
---|
551 |
|
---|
552 | if (*ngroups <= ngroups_old) {
|
---|
553 | ngroups_old = *ngroups;
|
---|
554 | memcpy(groups, group_list, ngroups_old * sizeof(groups[0]));
|
---|
555 | } else {
|
---|
556 | ngroups_old = -1;
|
---|
557 | }
|
---|
558 | free(group_list);
|
---|
559 | return ngroups_old;
|
---|
560 | }
|
---|