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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 | /* * linux/fs/binfmt_script.c * * Copyright (C) 1996 Martin von Löwis * original #!-checking implemented by tytso. */ #include <linux/module.h> #include <linux/string.h> #include <linux/stat.h> #include <linux/binfmts.h> #include <linux/init.h> #include <linux/file.h> #include <linux/err.h> #include <linux/fs.h> static inline bool spacetab(char c) { return c == ' ' || c == '\t'; } static inline char *next_non_spacetab(char *first, const char *last) { for (; first <= last; first++) if (!spacetab(*first)) return first; return NULL; } static inline char *next_terminator(char *first, const char *last) { for (; first <= last; first++) if (spacetab(*first) || !*first) return first; return NULL; } static int load_script(struct linux_binprm *bprm) { const char *i_arg, *i_name; char *cp, *buf_end; struct file *file; char interp[BINPRM_BUF_SIZE]; int retval; /* Not ours to exec if we don't start with "#!". */ if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!')) return -ENOEXEC; /* * If the script filename will be inaccessible after exec, typically * because it is a "/dev/fd/<fd>/.." path against an O_CLOEXEC fd, give * up now (on the assumption that the interpreter will want to load * this file). */ if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) return -ENOENT; /* Release since we are not mapping a binary into memory. */ allow_write_access(bprm->file); fput(bprm->file); bprm->file = NULL; /* * This section handles parsing the #! line into separate * interpreter path and argument strings. We must be careful * because bprm->buf is not yet guaranteed to be NUL-terminated * (though the buffer will have trailing NUL padding when the * file size was smaller than the buffer size). * * We do not want to exec a truncated interpreter path, so either * we find a newline (which indicates nothing is truncated), or * we find a space/tab/NUL after the interpreter path (which * itself may be preceded by spaces/tabs). Truncating the * arguments is fine: the interpreter can re-read the script to * parse them on its own. */ buf_end = bprm->buf + sizeof(bprm->buf) - 1; cp = strnchr(bprm->buf, sizeof(bprm->buf), '\n'); if (!cp) { cp = next_non_spacetab(bprm->buf + 2, buf_end); if (!cp) return -ENOEXEC; /* Entire buf is spaces/tabs */ /* * If there is no later space/tab/NUL we must assume the * interpreter path is truncated. */ if (!next_terminator(cp, buf_end)) return -ENOEXEC; cp = buf_end; } /* NUL-terminate the buffer and any trailing spaces/tabs. */ *cp = '\0'; while (cp > bprm->buf) { cp--; if ((*cp == ' ') || (*cp == '\t')) *cp = '\0'; else break; } for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++); if (*cp == '\0') return -ENOEXEC; /* No interpreter name found */ i_name = cp; i_arg = NULL; for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++) /* nothing */ ; while ((*cp == ' ') || (*cp == '\t')) *cp++ = '\0'; if (*cp) i_arg = cp; strcpy (interp, i_name); /* * OK, we've parsed out the interpreter name and * (optional) argument. * Splice in (1) the interpreter's name for argv[0] * (2) (optional) argument to interpreter * (3) filename of shell script (replace argv[0]) * * This is done in reverse order, because of how the * user environment and arguments are stored. */ retval = remove_arg_zero(bprm); if (retval) return retval; retval = copy_strings_kernel(1, &bprm->interp, bprm); if (retval < 0) return retval; bprm->argc++; if (i_arg) { retval = copy_strings_kernel(1, &i_arg, bprm); if (retval < 0) return retval; bprm->argc++; } retval = copy_strings_kernel(1, &i_name, bprm); if (retval) return retval; bprm->argc++; retval = bprm_change_interp(interp, bprm); if (retval < 0) return retval; /* * OK, now restart the process with the interpreter's dentry. */ file = open_exec(interp); if (IS_ERR(file)) return PTR_ERR(file); bprm->file = file; retval = prepare_binprm(bprm); if (retval < 0) return retval; return search_binary_handler(bprm); } static struct linux_binfmt script_format = { .module = THIS_MODULE, .load_binary = load_script, }; static int __init init_script_binfmt(void) { register_binfmt(&script_format); return 0; } static void __exit exit_script_binfmt(void) { unregister_binfmt(&script_format); } core_initcall(init_script_binfmt); module_exit(exit_script_binfmt); MODULE_LICENSE("GPL"); |