From 086f7316f0d400806d76323beefae996bb3849b1 Mon Sep 17 00:00:00 2001 From: "Andrew G. Morgan" Date: Fri, 4 Jul 2008 09:59:58 -0700 Subject: security: filesystem capabilities: fix fragile setuid fixup code This commit includes a bugfix for the fragile setuid fixup code in the case that filesystem capabilities are supported (in access()). The effect of this fix is gated on filesystem capability support because changing securebits is only supported when filesystem capabilities support is configured.) [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Andrew G. Morgan Acked-by: Serge Hallyn Acked-by: David Howells Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/open.c | 37 ++++++++++++++++++++++--------------- 1 file changed, 22 insertions(+), 15 deletions(-) (limited to 'fs') diff --git a/fs/open.c b/fs/open.c index a1450086e92..a99ad09c319 100644 --- a/fs/open.c +++ b/fs/open.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -425,7 +426,7 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode) { struct nameidata nd; int old_fsuid, old_fsgid; - kernel_cap_t old_cap; + kernel_cap_t uninitialized_var(old_cap); /* !SECURE_NO_SETUID_FIXUP */ int res; if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ @@ -433,23 +434,27 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode) old_fsuid = current->fsuid; old_fsgid = current->fsgid; - old_cap = current->cap_effective; current->fsuid = current->uid; current->fsgid = current->gid; - /* - * Clear the capabilities if we switch to a non-root user - * - * FIXME: There is a race here against sys_capset. The - * capabilities can change yet we will restore the old - * value below. We should hold task_capabilities_lock, - * but we cannot because user_path_walk can sleep. - */ - if (current->uid) - cap_clear(current->cap_effective); - else - current->cap_effective = current->cap_permitted; + if (!issecure(SECURE_NO_SETUID_FIXUP)) { + /* + * Clear the capabilities if we switch to a non-root user + */ +#ifndef CONFIG_SECURITY_FILE_CAPABILITIES + /* + * FIXME: There is a race here against sys_capset. The + * capabilities can change yet we will restore the old + * value below. We should hold task_capabilities_lock, + * but we cannot because user_path_walk can sleep. + */ +#endif /* ndef CONFIG_SECURITY_FILE_CAPABILITIES */ + if (current->uid) + old_cap = cap_set_effective(__cap_empty_set); + else + old_cap = cap_set_effective(current->cap_permitted); + } res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd); if (res) @@ -478,7 +483,9 @@ out_path_release: out: current->fsuid = old_fsuid; current->fsgid = old_fsgid; - current->cap_effective = old_cap; + + if (!issecure(SECURE_NO_SETUID_FIXUP)) + cap_set_effective(old_cap); return res; } -- cgit v1.2.3-70-g09d2