From 32927393dc1ccd60fb2bdc05b9e8e88753761469 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 24 Apr 2020 08:43:38 +0200 Subject: sysctl: pass kernel pointers to ->proc_handler Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by: Christoph Hellwig Acked-by: Andrey Ignatov Signed-off-by: Al Viro --- include/linux/security.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/security.h') diff --git a/include/linux/security.h b/include/linux/security.h index a8d9310472df..6aa229b252ce 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -211,7 +211,7 @@ struct request_sock; #ifdef CONFIG_MMU extern int mmap_min_addr_handler(struct ctl_table *table, int write, - void __user *buffer, size_t *lenp, loff_t *ppos); + void *buffer, size_t *lenp, loff_t *ppos); #endif /* security_inode_init_security callback function to write xattrs */ -- cgit v1.2.3 From b8bff599261c930630385ee21d3f98e7ce7d4843 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sun, 22 Mar 2020 15:46:24 -0500 Subject: exec: Factor security_bprm_creds_for_exec out of security_bprm_set_creds Today security_bprm_set_creds has several implementations: apparmor_bprm_set_creds, cap_bprm_set_creds, selinux_bprm_set_creds, smack_bprm_set_creds, and tomoyo_bprm_set_creds. Except for cap_bprm_set_creds they all test bprm->called_set_creds and return immediately if it is true. The function cap_bprm_set_creds ignores bprm->calld_sed_creds entirely. Create a new LSM hook security_bprm_creds_for_exec that is called just before prepare_binprm in __do_execve_file, resulting in a LSM hook that is called exactly once for the entire of exec. Modify the bits of security_bprm_set_creds that only want to be called once per exec into security_bprm_creds_for_exec, leaving only cap_bprm_set_creds behind. Remove bprm->called_set_creds all of it's former users have been moved to security_bprm_creds_for_exec. Add or upate comments a appropriate to bring them up to date and to reflect this change. Link: https://lkml.kernel.org/r/87v9kszrzh.fsf_-_@x220.int.ebiederm.org Acked-by: Linus Torvalds Acked-by: Casey Schaufler # For the LSM and Smack bits Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman" --- include/linux/security.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/security.h') diff --git a/include/linux/security.h b/include/linux/security.h index a8d9310472df..1bd7a6582775 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -276,6 +276,7 @@ int security_quota_on(struct dentry *dentry); int security_syslog(int type); int security_settime64(const struct timespec64 *ts, const struct timezone *tz); int security_vm_enough_memory_mm(struct mm_struct *mm, long pages); +int security_bprm_creds_for_exec(struct linux_binprm *bprm); int security_bprm_set_creds(struct linux_binprm *bprm); int security_bprm_check(struct linux_binprm *bprm); void security_bprm_committing_creds(struct linux_binprm *bprm); @@ -569,6 +570,11 @@ static inline int security_vm_enough_memory_mm(struct mm_struct *mm, long pages) return __vm_enough_memory(mm, pages, cap_vm_enough_memory(mm, pages)); } +static inline int security_bprm_creds_for_exec(struct linux_binprm *bprm) +{ + return 0; +} + static inline int security_bprm_set_creds(struct linux_binprm *bprm) { return cap_bprm_set_creds(bprm); -- cgit v1.2.3 From 112b7147592e8f46bd1da4f961773e6d974f38a8 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 14 May 2020 12:53:44 -0500 Subject: exec: Convert security_bprm_set_creds into security_bprm_repopulate_creds Rename bprm->cap_elevated to bprm->active_secureexec and initialize it in prepare_binprm instead of in cap_bprm_set_creds. Initializing bprm->active_secureexec in prepare_binprm allows multiple implementations of security_bprm_repopulate_creds to play nicely with each other. Rename security_bprm_set_creds to security_bprm_reopulate_creds to emphasize that this path recomputes part of bprm->cred. This recomputation avoids the time of check vs time of use problems that are inherent in unix #! interpreters. In short two renames and a move in the location of initializing bprm->active_secureexec. Link: https://lkml.kernel.org/r/87o8qkzrxp.fsf_-_@x220.int.ebiederm.org Acked-by: Linus Torvalds Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman" --- include/linux/security.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/linux/security.h') diff --git a/include/linux/security.h b/include/linux/security.h index 1bd7a6582775..6dcec9375e8f 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -140,7 +140,7 @@ extern int cap_capset(struct cred *new, const struct cred *old, const kernel_cap_t *effective, const kernel_cap_t *inheritable, const kernel_cap_t *permitted); -extern int cap_bprm_set_creds(struct linux_binprm *bprm); +extern int cap_bprm_repopulate_creds(struct linux_binprm *bprm); extern int cap_inode_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags); extern int cap_inode_removexattr(struct dentry *dentry, const char *name); @@ -277,7 +277,7 @@ int security_syslog(int type); int security_settime64(const struct timespec64 *ts, const struct timezone *tz); int security_vm_enough_memory_mm(struct mm_struct *mm, long pages); int security_bprm_creds_for_exec(struct linux_binprm *bprm); -int security_bprm_set_creds(struct linux_binprm *bprm); +int security_bprm_repopulate_creds(struct linux_binprm *bprm); int security_bprm_check(struct linux_binprm *bprm); void security_bprm_committing_creds(struct linux_binprm *bprm); void security_bprm_committed_creds(struct linux_binprm *bprm); @@ -575,9 +575,9 @@ static inline int security_bprm_creds_for_exec(struct linux_binprm *bprm) return 0; } -static inline int security_bprm_set_creds(struct linux_binprm *bprm) +static inline int security_bprm_repopulate_creds(struct linux_binprm *bprm) { - return cap_bprm_set_creds(bprm); + return cap_bprm_repopulate_creds(bprm); } static inline int security_bprm_check(struct linux_binprm *bprm) -- cgit v1.2.3 From 56305aa9b6fab91a5555a45796b79c1b0a6353d1 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 29 May 2020 22:00:54 -0500 Subject: exec: Compute file based creds only once Move the computation of creds from prepare_binfmt into begin_new_exec so that the creds need only be computed once. This is just code reorganization no semantic changes of any kind are made. Moving the computation is safe. I have looked through the kernel and verified none of the binfmts look at bprm->cred directly, and that there are no helpers that look at bprm->cred indirectly. Which means that it is not a problem to compute the bprm->cred later in the execution flow as it is not used until it becomes current->cred. A new function bprm_creds_from_file is added to contain the work that needs to be done. bprm_creds_from_file first computes which file bprm->executable or most likely bprm->file that the bprm->creds will be computed from. The funciton bprm_fill_uid is updated to receive the file instead of accessing bprm->file. The now unnecessary work needed to reset the bprm->cred->euid, and bprm->cred->egid is removed from brpm_fill_uid. A small comment to document that bprm_fill_uid now only deals with the work to handle suid and sgid files. The default case is already heandled by prepare_exec_creds. The function security_bprm_repopulate_creds is renamed security_bprm_creds_from_file and now is explicitly passed the file from which to compute the creds. The documentation of the bprm_creds_from_file security hook is updated to explain when the hook is called and what it needs to do. The file is passed from cap_bprm_creds_from_file into get_file_caps so that the caps are computed for the appropriate file. The now unnecessary work in cap_bprm_creds_from_file to reset the ambient capabilites has been removed. A small comment to document that the work of cap_bprm_creds_from_file is to read capabilities from the files secureity attribute and derive capabilities from the fact the user had uid 0 has been added. Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman" --- include/linux/security.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'include/linux/security.h') diff --git a/include/linux/security.h b/include/linux/security.h index 6dcec9375e8f..8444fae7c5b9 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -140,7 +140,7 @@ extern int cap_capset(struct cred *new, const struct cred *old, const kernel_cap_t *effective, const kernel_cap_t *inheritable, const kernel_cap_t *permitted); -extern int cap_bprm_repopulate_creds(struct linux_binprm *bprm); +extern int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file); extern int cap_inode_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags); extern int cap_inode_removexattr(struct dentry *dentry, const char *name); @@ -277,7 +277,7 @@ int security_syslog(int type); int security_settime64(const struct timespec64 *ts, const struct timezone *tz); int security_vm_enough_memory_mm(struct mm_struct *mm, long pages); int security_bprm_creds_for_exec(struct linux_binprm *bprm); -int security_bprm_repopulate_creds(struct linux_binprm *bprm); +int security_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file); int security_bprm_check(struct linux_binprm *bprm); void security_bprm_committing_creds(struct linux_binprm *bprm); void security_bprm_committed_creds(struct linux_binprm *bprm); @@ -575,9 +575,10 @@ static inline int security_bprm_creds_for_exec(struct linux_binprm *bprm) return 0; } -static inline int security_bprm_repopulate_creds(struct linux_binprm *bprm) +static inline int security_bprm_creds_from_file(struct linux_binprm *bprm, + struct file *file) { - return cap_bprm_repopulate_creds(bprm); + return cap_bprm_creds_from_file(bprm, file); } static inline int security_bprm_check(struct linux_binprm *bprm) -- cgit v1.2.3