diff options
Diffstat (limited to 'src/lib/eacces-error.c')
| -rw-r--r-- | src/lib/eacces-error.c | 310 |
1 files changed, 310 insertions, 0 deletions
diff --git a/src/lib/eacces-error.c b/src/lib/eacces-error.c new file mode 100644 index 0000000..954ea78 --- /dev/null +++ b/src/lib/eacces-error.c @@ -0,0 +1,310 @@ +/* Copyright (c) 2007-2018 Dovecot authors, see the included COPYING file */ + +#include "lib.h" +#include "str.h" +#include "path-util.h" +#include "ipwd.h" +#include "restrict-access.h" +#include "eacces-error.h" + +#include <sys/stat.h> +#include <unistd.h> + +static bool is_in_group(gid_t gid) +{ + const gid_t *gids; + unsigned int i, count; + + if (getegid() == gid) + return TRUE; + + gids = restrict_get_groups_list(&count); + for (i = 0; i < count; i++) { + if (gids[i] == gid) + return TRUE; + } + return FALSE; +} + +static void write_eacces_error(string_t *errmsg, const char *path, int mode) +{ + char c; + + switch (mode) { + case R_OK: + c = 'r'; + break; + case W_OK: + c = 'w'; + break; + case X_OK: + c = 'x'; + break; + default: + i_unreached(); + } + str_printfa(errmsg, " missing +%c perm: %s", c, path); +} + +static int +test_manual_access(const char *path, int access_mode, bool write_eacces, + string_t *errmsg) +{ + const struct group *group; + bool user_not_in_group = FALSE; + struct stat st; + int mode; + + if (stat(path, &st) < 0) { + str_printfa(errmsg, " stat(%s) failed: %m", path); + return -1; + } + + switch (access_mode) { + case R_OK: + mode = 04; + break; + case W_OK: + mode = 02; + break; + case X_OK: + mode = 01; + break; + default: + i_unreached(); + } + + if (st.st_uid == geteuid()) + st.st_mode = (st.st_mode & 0700) >> 6; + else if (is_in_group(st.st_gid)) + st.st_mode = (st.st_mode & 0070) >> 3; + else { + if ((((st.st_mode & 0070) >> 3) & mode) != 0) + user_not_in_group = TRUE; + st.st_mode = (st.st_mode & 0007); + } + + if ((st.st_mode & mode) != 0) + return 0; + + if (write_eacces) + write_eacces_error(errmsg, path, access_mode); + if (user_not_in_group) { + /* group would have had enough permissions, + but we don't belong to the group */ + str_printfa(errmsg, ", we're not in group %s", + dec2str(st.st_gid)); + group = getgrgid(st.st_gid); + if (group != NULL) + str_printfa(errmsg, "(%s)", group->gr_name); + } + errno = EACCES; + return -1; +} + +static int test_access(const char *path, int access_mode, string_t *errmsg) +{ + struct stat st; + + if (getuid() == geteuid()) { + if (access(path, access_mode) == 0) + return 0; + if (errno == EACCES) { + write_eacces_error(errmsg, path, access_mode); + if (test_manual_access(path, access_mode, + FALSE, errmsg) == 0) { + str_append(errmsg, ", UNIX perms appear ok " + "(ACL/MAC wrong?)"); + } + errno = EACCES; + } else { + str_printfa(errmsg, ", access(%s, %d) failed: %m", + path, access_mode); + } + return -1; + } + + /* access() uses real uid, not effective uid. + we'll have to do these checks manually. */ + switch (access_mode) { + case X_OK: + if (stat(t_strconcat(path, "/test", NULL), &st) == 0) + return 0; + if (errno == ENOENT || errno == ENOTDIR) + return 0; + if (errno == EACCES) + write_eacces_error(errmsg, path, access_mode); + else + str_printfa(errmsg, ", stat(%s/test) failed: %m", path); + return -1; + case R_OK: + case W_OK: + break; + default: + i_unreached(); + } + + return test_manual_access(path, access_mode, TRUE, errmsg); +} + +static const char * +eacces_error_get_full(const char *func, const char *path, bool creating) +{ + const char *prev_path, *dir = NULL, *p; + const char *pw_name = NULL, *gr_name = NULL; + struct passwd pw; + struct group group; + string_t *errmsg; + struct stat st; + int orig_errno, ret, missing_mode = 0; + + orig_errno = errno; + errmsg = t_str_new(256); + str_printfa(errmsg, "%s(%s)", func, path); + if (*path != '/') { + const char *error; + if (t_get_working_dir(&dir, &error) < 0) { + i_error("eacces_error_get_full: %s", error); + str_printfa(errmsg, " in an unknown directory"); + } else { + str_printfa(errmsg, " in directory %s", dir); + path = t_strconcat(dir, "/", path, NULL); + } + } + str_printfa(errmsg, " failed: Permission denied (euid=%s", + dec2str(geteuid())); + + switch (i_getpwuid(geteuid(), &pw)) { + case -1: + str_append(errmsg, "(<getpwuid() error>)"); + break; + case 0: + str_append(errmsg, "(<unknown>)"); + break; + default: + pw_name = t_strdup(pw.pw_name); + str_printfa(errmsg, "(%s)", pw_name); + break; + } + + str_printfa(errmsg, " egid=%s", dec2str(getegid())); + switch (i_getgrgid(getegid(), &group)) { + case -1: + str_append(errmsg, "(<getgrgid() error>)"); + break; + case 0: + str_append(errmsg, "(<unknown>)"); + break; + default: + gr_name = t_strdup(group.gr_name); + str_printfa(errmsg, "(%s)", gr_name); + break; + } + + prev_path = path; ret = -1; + while (strcmp(prev_path, "/") != 0) { + if ((p = strrchr(prev_path, '/')) == NULL) + break; + + dir = t_strdup_until(prev_path, p); + ret = stat(dir, &st); + if (ret == 0) + break; + if (errno == EACCES && strcmp(dir, "/") != 0) { + /* see if we have access to parent directory */ + } else if (errno == ENOENT && creating && + strcmp(dir, "/") != 0) { + /* probably mkdir_parents() failed here, find the first + parent directory we couldn't create */ + } else { + /* some other error, can't handle it */ + str_printfa(errmsg, " stat(%s) failed: %m", dir); + break; + } + prev_path = dir; + } + + if (ret == 0) { + /* dir is the first parent directory we can stat() */ + if (test_access(dir, X_OK, errmsg) < 0) { + if (errno == EACCES) + missing_mode = 1; + } else if (creating && test_access(dir, W_OK, errmsg) < 0) { + if (errno == EACCES) + missing_mode = 2; + } else if (prev_path == path && + test_access(path, R_OK, errmsg) < 0) { + } else if (!creating && test_access(path, W_OK, errmsg) < 0) { + /* this produces a wrong error if the operation didn't + actually need write permissions, but we don't know + it here.. */ + if (errno == EACCES) + missing_mode = 4; + } else { + str_append(errmsg, " UNIX perms appear ok " + "(ACL/MAC wrong?)"); + } + } + if (ret < 0) + ; + else if (st.st_uid != geteuid()) { + if (pw_name != NULL && i_getpwuid(st.st_uid, &pw) > 0 && + strcmp(pw.pw_name, pw_name) == 0) { + str_printfa(errmsg, ", conflicting dir uid=%s(%s)", + dec2str(st.st_uid), pw_name); + } else { + str_printfa(errmsg, ", dir owned by %s:%s mode=0%o", + dec2str(st.st_uid), dec2str(st.st_gid), + (unsigned int)(st.st_mode & 0777)); + } + } else if (missing_mode != 0 && + (((st.st_mode & 0700) >> 6) & missing_mode) == 0) { + str_append(errmsg, ", dir owner missing perms"); + } + if (ret == 0 && gr_name != NULL && st.st_gid != getegid()) { + if (i_getgrgid(st.st_gid, &group) > 0 && + strcmp(group.gr_name, gr_name) == 0) { + str_printfa(errmsg, ", conflicting dir gid=%s(%s)", + dec2str(st.st_gid), gr_name); + } + } + str_append_c(errmsg, ')'); + errno = orig_errno; + return str_c(errmsg); +} + +const char *eacces_error_get(const char *func, const char *path) +{ + return eacces_error_get_full(func, path, FALSE); +} + +const char *eacces_error_get_creating(const char *func, const char *path) +{ + return eacces_error_get_full(func, path, TRUE); +} + +const char *eperm_error_get_chgrp(const char *func, const char *path, + gid_t gid, const char *gid_origin) +{ + string_t *errmsg; + const struct group *group; + int orig_errno = errno; + + errmsg = t_str_new(256); + + str_printfa(errmsg, "%s(%s, group=%s", func, path, dec2str(gid)); + group = getgrgid(gid); + if (group != NULL) + str_printfa(errmsg, "(%s)", group->gr_name); + + str_printfa(errmsg, ") failed: Operation not permitted (egid=%s", + dec2str(getegid())); + group = getgrgid(getegid()); + if (group != NULL) + str_printfa(errmsg, "(%s)", group->gr_name); + if (gid_origin != NULL) + str_printfa(errmsg, ", group based on %s", gid_origin); + str_append(errmsg, " - see http://wiki2.dovecot.org/Errors/ChgrpNoPerm)"); + errno = orig_errno; + return str_c(errmsg); +} |