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| author | Kees Cook <keescook@chromium.org> | 2017-07-19 00:25:28 +0200 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2017-08-01 21:03:09 +0200 |
| commit | ee67ae7ef6ff499137292ac8a9dfe86096796283 (patch) | |
| tree | 6a23c8212426db697546ead1019325504f53114c /security | |
| parent | commoncap: Refactor to remove bprm_secureexec hook (diff) | |
| download | linux-ee67ae7ef6ff499137292ac8a9dfe86096796283.tar.xz linux-ee67ae7ef6ff499137292ac8a9dfe86096796283.zip | |
commoncap: Move cap_elevated calculation into bprm_set_creds
Instead of a separate function, open-code the cap_elevated test, which
lets us entirely remove bprm->cap_effective (to use the local "effective"
variable instead), and more accurately examine euid/egid changes via the
existing local "is_setid".
The following LTP tests were run to validate the changes:
# ./runltp -f syscalls -s cap
# ./runltp -f securebits
# ./runltp -f cap_bounds
# ./runltp -f filecaps
All kernel selftests for capabilities and exec continue to pass as well.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Diffstat (limited to 'security')
| -rw-r--r-- | security/commoncap.c | 52 |
1 files changed, 10 insertions, 42 deletions
diff --git a/security/commoncap.c b/security/commoncap.c index abb6050c8083..d8e26fb9781d 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -285,15 +285,6 @@ int cap_capset(struct cred *new, return 0; } -/* - * Clear proposed capability sets for execve(). - */ -static inline void bprm_clear_caps(struct linux_binprm *bprm) -{ - cap_clear(bprm->cred->cap_permitted); - bprm->cap_effective = false; -} - /** * cap_inode_need_killpriv - Determine if inode change affects privileges * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV @@ -443,7 +434,7 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_c int rc = 0; struct cpu_vfs_cap_data vcaps; - bprm_clear_caps(bprm); + cap_clear(bprm->cred->cap_permitted); if (!file_caps_enabled) return 0; @@ -476,13 +467,11 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_c out: if (rc) - bprm_clear_caps(bprm); + cap_clear(bprm->cred->cap_permitted); return rc; } -static int is_secureexec(struct linux_binprm *bprm); - /** * cap_bprm_set_creds - Set up the proposed credentials for execve(). * @bprm: The execution parameters, including the proposed creds @@ -587,8 +576,6 @@ skip: if (WARN_ON(!cap_ambient_invariant_ok(new))) return -EPERM; - bprm->cap_effective = effective; - /* * Audit candidate if current->cap_effective is set * @@ -617,35 +604,16 @@ skip: return -EPERM; /* Check for privilege-elevated exec. */ - bprm->cap_elevated = is_secureexec(bprm); - - return 0; -} - -/** - * is_secureexec - Determine whether a secure execution is required - * @bprm: The execution parameters - * - * Determine whether a secure execution is required, return 1 if it is, and 0 - * if it is not. - * - * The credentials have been committed by this point, and so are no longer - * available through @bprm->cred. - */ -static int is_secureexec(struct linux_binprm *bprm) -{ - const struct cred *cred = bprm->cred; - kuid_t root_uid = make_kuid(cred->user_ns, 0); - - if (!uid_eq(cred->uid, root_uid)) { - if (bprm->cap_effective) - return 1; - if (!cap_issubset(cred->cap_permitted, cred->cap_ambient)) - return 1; + bprm->cap_elevated = 0; + if (is_setid) { + bprm->cap_elevated = 1; + } else if (!uid_eq(new->uid, root_uid)) { + if (effective || + !cap_issubset(new->cap_permitted, new->cap_ambient)) + bprm->cap_elevated = 1; } - return (!uid_eq(cred->euid, cred->uid) || - !gid_eq(cred->egid, cred->gid)); + return 0; } /** |