diff options
| -rw-r--r-- | include/linux/binfmts.h | 2 | ||||
| -rw-r--r-- | security/commoncap.c | 108 |
2 files changed, 60 insertions, 50 deletions
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index ee0ed48..826f623 100644 --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -38,7 +38,7 @@ struct linux_binprm{ misc_bang:1; struct file * file; int e_uid, e_gid; - kernel_cap_t cap_inheritable, cap_permitted; + kernel_cap_t cap_post_exec_permitted; bool cap_effective; void *security; int argc, envc; diff --git a/security/commoncap.c b/security/commoncap.c index 0b6537a..4afbece 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -162,8 +162,7 @@ void cap_capset_set (struct task_struct *target, kernel_cap_t *effective, static inline void bprm_clear_caps(struct linux_binprm *bprm) { - cap_clear(bprm->cap_inheritable); - cap_clear(bprm->cap_permitted); + cap_clear(bprm->cap_post_exec_permitted); bprm->cap_effective = false; } @@ -198,6 +197,7 @@ static inline int cap_from_disk(struct vfs_cap_data *caps, { __u32 magic_etc; unsigned tocopy, i; + int ret; if (size < sizeof(magic_etc)) return -EINVAL; @@ -225,19 +225,40 @@ static inline int cap_from_disk(struct vfs_cap_data *caps, bprm->cap_effective = false; } - for (i = 0; i < tocopy; ++i) { - bprm->cap_permitted.cap[i] = - le32_to_cpu(caps->data[i].permitted); - bprm->cap_inheritable.cap[i] = - le32_to_cpu(caps->data[i].inheritable); - } - while (i < VFS_CAP_U32) { - bprm->cap_permitted.cap[i] = 0; - bprm->cap_inheritable.cap[i] = 0; - i++; + ret = 0; + + CAP_FOR_EACH_U32(i) { + __u32 value_cpu; + + if (i >= tocopy) { + /* + * Legacy capability sets have no upper bits + */ + bprm->cap_post_exec_permitted.cap[i] = 0; + continue; + } + /* + * pP' = (X & fP) | (pI & fI) + */ + value_cpu = le32_to_cpu(caps->data[i].permitted); + bprm->cap_post_exec_permitted.cap[i] = + (current->cap_bset.cap[i] & value_cpu) | + (current->cap_inheritable.cap[i] & + le32_to_cpu(caps->data[i].inheritable)); + if (value_cpu & ~bprm->cap_post_exec_permitted.cap[i]) { + /* + * insufficient to execute correctly + */ + ret = -EPERM; + } } - return 0; + /* + * For legacy apps, with no internal support for recognizing they + * do not have enough capabilities, we return an error if they are + * missing some "forced" (aka file-permitted) capabilities. + */ + return bprm->cap_effective ? ret : 0; } /* Locate any VFS capabilities: */ @@ -269,9 +290,9 @@ static int get_file_caps(struct linux_binprm *bprm) goto out; rc = cap_from_disk(&vcaps, bprm, rc); - if (rc) + if (rc == -EINVAL) printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", - __func__, rc, bprm->filename); + __func__, rc, bprm->filename); out: dput(dentry); @@ -304,25 +325,24 @@ int cap_bprm_set_security (struct linux_binprm *bprm) int ret; ret = get_file_caps(bprm); - if (ret) - printk(KERN_NOTICE "%s: get_file_caps returned %d for %s\n", - __func__, ret, bprm->filename); - - /* To support inheritance of root-permissions and suid-root - * executables under compatibility mode, we raise all three - * capability sets for the file. - * - * If only the real uid is 0, we only raise the inheritable - * and permitted sets of the executable file. - */ - if (!issecure (SECURE_NOROOT)) { + if (!issecure(SECURE_NOROOT)) { + /* + * To support inheritance of root-permissions and suid-root + * executables under compatibility mode, we override the + * capability sets for the file. + * + * If only the real uid is 0, we do not set the effective + * bit. + */ if (bprm->e_uid == 0 || current->uid == 0) { - cap_set_full (bprm->cap_inheritable); - cap_set_full (bprm->cap_permitted); + /* pP' = (cap_bset & ~0) | (pI & ~0) */ + bprm->cap_post_exec_permitted = cap_combine( + current->cap_bset, current->cap_inheritable + ); + bprm->cap_effective = (bprm->e_uid == 0); + ret = 0; } - if (bprm->e_uid == 0) - bprm->cap_effective = true; } return ret; @@ -330,17 +350,9 @@ int cap_bprm_set_security (struct linux_binprm *bprm) void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) { - /* Derived from fs/exec.c:compute_creds. */ - kernel_cap_t new_permitted, working; - - new_permitted = cap_intersect(bprm->cap_permitted, - current->cap_bset); - working = cap_intersect(bprm->cap_inheritable, - current->cap_inheritable); - new_permitted = cap_combine(new_permitted, working); - if (bprm->e_uid != current->uid || bprm->e_gid != current->gid || - !cap_issubset (new_permitted, current->cap_permitted)) { + !cap_issubset(bprm->cap_post_exec_permitted, + current->cap_permitted)) { set_dumpable(current->mm, suid_dumpable); current->pdeath_signal = 0; @@ -350,9 +362,9 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) bprm->e_gid = current->gid; } if (cap_limit_ptraced_target()) { - new_permitted = - cap_intersect(new_permitted, - current->cap_permitted); + bprm->cap_post_exec_permitted = cap_intersect( + bprm->cap_post_exec_permitted, + current->cap_permitted); } } } @@ -364,9 +376,9 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) * in the init_task struct. Thus we skip the usual * capability rules */ if (!is_global_init(current)) { - current->cap_permitted = new_permitted; + current->cap_permitted = bprm->cap_post_exec_permitted; if (bprm->cap_effective) - current->cap_effective = new_permitted; + current->cap_effective = bprm->cap_post_exec_permitted; else cap_clear(current->cap_effective); } @@ -381,9 +393,7 @@ int cap_bprm_secureexec (struct linux_binprm *bprm) if (current->uid != 0) { if (bprm->cap_effective) return 1; - if (!cap_isclear(bprm->cap_permitted)) - return 1; - if (!cap_isclear(bprm->cap_inheritable)) + if (!cap_isclear(bprm->cap_post_exec_permitted)) return 1; } |
