diff options
Diffstat (limited to 'security/apparmor/policy_compat.c')
| -rw-r--r-- | security/apparmor/policy_compat.c | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/security/apparmor/policy_compat.c b/security/apparmor/policy_compat.c new file mode 100644 index 000000000..0cb02da8a --- /dev/null +++ b/security/apparmor/policy_compat.c @@ -0,0 +1,326 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * AppArmor security module + * + * This file contains AppArmor functions for unpacking policy loaded + * from userspace. + * + * Copyright (C) 1998-2008 Novell/SUSE + * Copyright 2009-2022 Canonical Ltd. + * + * Code to provide backwards compatibility with older policy versions, + * by converting/mapping older policy formats into the newer internal + * formats. + */ + +#include <linux/ctype.h> +#include <linux/errno.h> + +#include "include/lib.h" +#include "include/policy_unpack.h" +#include "include/policy_compat.h" + +/* remap old accept table embedded permissions to separate permission table */ +static u32 dfa_map_xindex(u16 mask) +{ + u16 old_index = (mask >> 10) & 0xf; + u32 index = 0; + + if (mask & 0x100) + index |= AA_X_UNSAFE; + if (mask & 0x200) + index |= AA_X_INHERIT; + if (mask & 0x80) + index |= AA_X_UNCONFINED; + + if (old_index == 1) { + index |= AA_X_UNCONFINED; + } else if (old_index == 2) { + index |= AA_X_NAME; + } else if (old_index == 3) { + index |= AA_X_NAME | AA_X_CHILD; + } else if (old_index) { + index |= AA_X_TABLE; + index |= old_index - 4; + } + + return index; +} + +/* + * map old dfa inline permissions to new format + */ +#define dfa_user_allow(dfa, state) (((ACCEPT_TABLE(dfa)[state]) & 0x7f) | \ + ((ACCEPT_TABLE(dfa)[state]) & 0x80000000)) +#define dfa_user_xbits(dfa, state) (((ACCEPT_TABLE(dfa)[state]) >> 7) & 0x7f) +#define dfa_user_audit(dfa, state) ((ACCEPT_TABLE2(dfa)[state]) & 0x7f) +#define dfa_user_quiet(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 7) & 0x7f) +#define dfa_user_xindex(dfa, state) \ + (dfa_map_xindex(ACCEPT_TABLE(dfa)[state] & 0x3fff)) + +#define dfa_other_allow(dfa, state) ((((ACCEPT_TABLE(dfa)[state]) >> 14) & \ + 0x7f) | \ + ((ACCEPT_TABLE(dfa)[state]) & 0x80000000)) +#define dfa_other_xbits(dfa, state) \ + ((((ACCEPT_TABLE(dfa)[state]) >> 7) >> 14) & 0x7f) +#define dfa_other_audit(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 14) & 0x7f) +#define dfa_other_quiet(dfa, state) \ + ((((ACCEPT_TABLE2(dfa)[state]) >> 7) >> 14) & 0x7f) +#define dfa_other_xindex(dfa, state) \ + dfa_map_xindex((ACCEPT_TABLE(dfa)[state] >> 14) & 0x3fff) + +/** + * map_old_perms - map old file perms layout to the new layout + * @old: permission set in old mapping + * + * Returns: new permission mapping + */ +static u32 map_old_perms(u32 old) +{ + u32 new = old & 0xf; + + if (old & MAY_READ) + new |= AA_MAY_GETATTR | AA_MAY_OPEN; + if (old & MAY_WRITE) + new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE | + AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN; + if (old & 0x10) + new |= AA_MAY_LINK; + /* the old mapping lock and link_subset flags where overlaid + * and use was determined by part of a pair that they were in + */ + if (old & 0x20) + new |= AA_MAY_LOCK | AA_LINK_SUBSET; + if (old & 0x40) /* AA_EXEC_MMAP */ + new |= AA_EXEC_MMAP; + + return new; +} + +static void compute_fperms_allow(struct aa_perms *perms, struct aa_dfa *dfa, + aa_state_t state) +{ + perms->allow |= AA_MAY_GETATTR; + + /* change_profile wasn't determined by ownership in old mapping */ + if (ACCEPT_TABLE(dfa)[state] & 0x80000000) + perms->allow |= AA_MAY_CHANGE_PROFILE; + if (ACCEPT_TABLE(dfa)[state] & 0x40000000) + perms->allow |= AA_MAY_ONEXEC; +} + +static struct aa_perms compute_fperms_user(struct aa_dfa *dfa, + aa_state_t state) +{ + struct aa_perms perms = { }; + + perms.allow = map_old_perms(dfa_user_allow(dfa, state)); + perms.audit = map_old_perms(dfa_user_audit(dfa, state)); + perms.quiet = map_old_perms(dfa_user_quiet(dfa, state)); + perms.xindex = dfa_user_xindex(dfa, state); + + compute_fperms_allow(&perms, dfa, state); + + return perms; +} + +static struct aa_perms compute_fperms_other(struct aa_dfa *dfa, + aa_state_t state) +{ + struct aa_perms perms = { }; + + perms.allow = map_old_perms(dfa_other_allow(dfa, state)); + perms.audit = map_old_perms(dfa_other_audit(dfa, state)); + perms.quiet = map_old_perms(dfa_other_quiet(dfa, state)); + perms.xindex = dfa_other_xindex(dfa, state); + + compute_fperms_allow(&perms, dfa, state); + + return perms; +} + +/** + * compute_fperms - convert dfa compressed perms to internal perms and store + * them so they can be retrieved later. + * @dfa: a dfa using fperms to remap to internal permissions + * + * Returns: remapped perm table + */ +static struct aa_perms *compute_fperms(struct aa_dfa *dfa, + u32 *size) +{ + aa_state_t state; + unsigned int state_count; + struct aa_perms *table; + + AA_BUG(!dfa); + + state_count = dfa->tables[YYTD_ID_BASE]->td_lolen; + /* DFAs are restricted from having a state_count of less than 2 */ + table = kvcalloc(state_count * 2, sizeof(struct aa_perms), GFP_KERNEL); + if (!table) + return NULL; + *size = state_count * 2; + + for (state = 0; state < state_count; state++) { + table[state * 2] = compute_fperms_user(dfa, state); + table[state * 2 + 1] = compute_fperms_other(dfa, state); + } + + return table; +} + +static struct aa_perms *compute_xmatch_perms(struct aa_dfa *xmatch, + u32 *size) +{ + struct aa_perms *perms; + int state; + int state_count; + + AA_BUG(!xmatch); + + state_count = xmatch->tables[YYTD_ID_BASE]->td_lolen; + /* DFAs are restricted from having a state_count of less than 2 */ + perms = kvcalloc(state_count, sizeof(struct aa_perms), GFP_KERNEL); + if (!perms) + return NULL; + *size = state_count; + + /* zero init so skip the trap state (state == 0) */ + for (state = 1; state < state_count; state++) + perms[state].allow = dfa_user_allow(xmatch, state); + + return perms; +} + +static u32 map_other(u32 x) +{ + return ((x & 0x3) << 8) | /* SETATTR/GETATTR */ + ((x & 0x1c) << 18) | /* ACCEPT/BIND/LISTEN */ + ((x & 0x60) << 19); /* SETOPT/GETOPT */ +} + +static u32 map_xbits(u32 x) +{ + return ((x & 0x1) << 7) | + ((x & 0x7e) << 9); +} + +static struct aa_perms compute_perms_entry(struct aa_dfa *dfa, + aa_state_t state, + u32 version) +{ + struct aa_perms perms = { }; + + perms.allow = dfa_user_allow(dfa, state); + perms.audit = dfa_user_audit(dfa, state); + perms.quiet = dfa_user_quiet(dfa, state); + + /* + * This mapping is convulated due to history. + * v1-v4: only file perms, which are handled by compute_fperms + * v5: added policydb which dropped user conditional to gain new + * perm bits, but had to map around the xbits because the + * userspace compiler was still munging them. + * v9: adds using the xbits in policydb because the compiler now + * supports treating policydb permission bits different. + * Unfortunately there is no way to force auditing on the + * perms represented by the xbits + */ + perms.allow |= map_other(dfa_other_allow(dfa, state)); + if (VERSION_LE(version, v8)) + perms.allow |= AA_MAY_LOCK; + else + perms.allow |= map_xbits(dfa_user_xbits(dfa, state)); + + /* + * for v5-v9 perm mapping in the policydb, the other set is used + * to extend the general perm set + */ + perms.audit |= map_other(dfa_other_audit(dfa, state)); + perms.quiet |= map_other(dfa_other_quiet(dfa, state)); + if (VERSION_GT(version, v8)) + perms.quiet |= map_xbits(dfa_other_xbits(dfa, state)); + + return perms; +} + +static struct aa_perms *compute_perms(struct aa_dfa *dfa, u32 version, + u32 *size) +{ + unsigned int state; + unsigned int state_count; + struct aa_perms *table; + + AA_BUG(!dfa); + + state_count = dfa->tables[YYTD_ID_BASE]->td_lolen; + /* DFAs are restricted from having a state_count of less than 2 */ + table = kvcalloc(state_count, sizeof(struct aa_perms), GFP_KERNEL); + if (!table) + return NULL; + *size = state_count; + + /* zero init so skip the trap state (state == 0) */ + for (state = 1; state < state_count; state++) + table[state] = compute_perms_entry(dfa, state, version); + + return table; +} + +/** + * remap_dfa_accept - remap old dfa accept table to be an index + * @dfa: dfa to do the remapping on + * @factor: scaling factor for the index conversion. + * + * Used in conjunction with compute_Xperms, it converts old style perms + * that are encoded in the dfa accept tables to the new style where + * there is a permission table and the accept table is an index into + * the permission table. + */ +static void remap_dfa_accept(struct aa_dfa *dfa, unsigned int factor) +{ + unsigned int state; + unsigned int state_count = dfa->tables[YYTD_ID_BASE]->td_lolen; + + AA_BUG(!dfa); + + for (state = 0; state < state_count; state++) + ACCEPT_TABLE(dfa)[state] = state * factor; + kvfree(dfa->tables[YYTD_ID_ACCEPT2]); + dfa->tables[YYTD_ID_ACCEPT2] = NULL; +} + +/* TODO: merge different dfa mappings into single map_policy fn */ +int aa_compat_map_xmatch(struct aa_policydb *policy) +{ + policy->perms = compute_xmatch_perms(policy->dfa, &policy->size); + if (!policy->perms) + return -ENOMEM; + + remap_dfa_accept(policy->dfa, 1); + + return 0; +} + +int aa_compat_map_policy(struct aa_policydb *policy, u32 version) +{ + policy->perms = compute_perms(policy->dfa, version, &policy->size); + if (!policy->perms) + return -ENOMEM; + + remap_dfa_accept(policy->dfa, 1); + + return 0; +} + +int aa_compat_map_file(struct aa_policydb *policy) +{ + policy->perms = compute_fperms(policy->dfa, &policy->size); + if (!policy->perms) + return -ENOMEM; + + remap_dfa_accept(policy->dfa, 2); + + return 0; +} |