| 1 | /*
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| 2 | Unix SMB/CIFS implementation.
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| 3 |
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| 4 | gain/lose root privileges
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| 5 |
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| 6 | Copyright (C) Andrew Tridgell 2004
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| 7 |
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| 8 | This program is free software; you can redistribute it and/or modify
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| 9 | it under the terms of the GNU General Public License as published by
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| 10 | the Free Software Foundation; either version 3 of the License, or
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| 11 | (at your option) any later version.
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| 12 |
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| 13 | This program is distributed in the hope that it will be useful,
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| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 16 | GNU General Public License for more details.
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| 17 |
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| 18 | You should have received a copy of the GNU General Public License
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| 19 | along with this program. If not, see <http://www.gnu.org/licenses/>.
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| 20 | */
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| 21 |
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| 22 | #include "includes.h"
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| 23 | #include "system/passwd.h"
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| 24 |
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| 25 | #ifdef HAVE_UNISTD_H
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| 26 | #include <unistd.h>
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| 27 | #endif
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| 28 |
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| 29 | #include "../lib/util/unix_privs.h"
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| 30 | #include "../lib/util/setid.h"
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| 31 |
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| 32 | /**
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| 33 | * @file
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| 34 | * @brief Gaining/losing root privileges
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| 35 | */
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| 36 |
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| 37 | /*
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| 38 | there are times when smbd needs to temporarily gain root privileges
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| 39 | to do some operation. To do this you call root_privileges(), which
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| 40 | returns a talloc handle. To restore your previous privileges
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| 41 | talloc_free() this pointer.
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| 42 |
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| 43 | Note that this call is considered successful even if it does not
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| 44 | manage to gain root privileges, but it will call smb_abort() if it
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| 45 | fails to restore the privileges afterwards. The logic is that
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| 46 | failing to gain root access can be caught by whatever operation
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| 47 | needs to be run as root failing, but failing to lose the root
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| 48 | privileges is dangerous.
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| 49 |
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| 50 | This also means that this code is safe to be called from completely
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| 51 | unprivileged processes.
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| 52 | */
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| 53 |
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| 54 | struct saved_state {
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| 55 | uid_t uid;
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| 56 | };
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| 57 |
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| 58 | static int privileges_destructor(struct saved_state *s)
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| 59 | {
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| 60 | if (geteuid() != s->uid &&
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| 61 | samba_seteuid(s->uid) != 0) {
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| 62 | smb_panic("Failed to restore privileges");
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| 63 | }
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| 64 | return 0;
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| 65 | }
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| 66 |
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| 67 | /**
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| 68 | * Obtain root privileges for the current process.
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| 69 | *
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| 70 | * The privileges can be dropped by talloc_free()-ing the
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| 71 | * token returned by this function
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| 72 | */
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| 73 | void *root_privileges(void)
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| 74 | {
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| 75 | struct saved_state *s;
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| 76 | s = talloc(NULL, struct saved_state);
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| 77 | if (!s) return NULL;
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| 78 | s->uid = geteuid();
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| 79 | if (s->uid != 0) {
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| 80 | samba_seteuid(0);
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| 81 | }
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| 82 | talloc_set_destructor(s, privileges_destructor);
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| 83 | return s;
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| 84 | }
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| 85 |
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| 86 | uid_t root_privileges_original_uid(void *s)
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| 87 | {
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| 88 | struct saved_state *saved = talloc_get_type_abort(s, struct saved_state);
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| 89 | return saved->uid;
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| 90 | }
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