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-rw-r--r--fs/exec.c149
1 files changed, 86 insertions, 63 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 9bd3559ddece..32f13e299417 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -55,6 +55,7 @@
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/tlb.h>
+#include "internal.h"
#ifdef __alpha__
/* for /sbin/loader handling in search_binary_handler() */
@@ -1007,15 +1008,17 @@ int flush_old_exec(struct linux_binprm * bprm)
*/
current->mm->task_size = TASK_SIZE;
- if (bprm->e_uid != current_euid() ||
- bprm->e_gid != current_egid()) {
- set_dumpable(current->mm, suid_dumpable);
+ /* install the new credentials */
+ if (bprm->cred->uid != current_euid() ||
+ bprm->cred->gid != current_egid()) {
current->pdeath_signal = 0;
} else if (file_permission(bprm->file, MAY_READ) ||
- (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
+ bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
set_dumpable(current->mm, suid_dumpable);
}
+ current->personality &= ~bprm->per_clear;
+
/* An exec changes our domain. We are no longer part of the thread
group */
@@ -1032,13 +1035,50 @@ out:
EXPORT_SYMBOL(flush_old_exec);
+/*
+ * install the new credentials for this executable
+ */
+void install_exec_creds(struct linux_binprm *bprm)
+{
+ security_bprm_committing_creds(bprm);
+
+ commit_creds(bprm->cred);
+ bprm->cred = NULL;
+
+ /* cred_exec_mutex must be held at least to this point to prevent
+ * ptrace_attach() from altering our determination of the task's
+ * credentials; any time after this it may be unlocked */
+
+ security_bprm_committed_creds(bprm);
+}
+EXPORT_SYMBOL(install_exec_creds);
+
+/*
+ * determine how safe it is to execute the proposed program
+ * - the caller must hold current->cred_exec_mutex to protect against
+ * PTRACE_ATTACH
+ */
+void check_unsafe_exec(struct linux_binprm *bprm)
+{
+ struct task_struct *p = current;
+
+ bprm->unsafe = tracehook_unsafe_exec(p);
+
+ if (atomic_read(&p->fs->count) > 1 ||
+ atomic_read(&p->files->count) > 1 ||
+ atomic_read(&p->sighand->count) > 1)
+ bprm->unsafe |= LSM_UNSAFE_SHARE;
+}
+
/*
* Fill the binprm structure from the inode.
* Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
+ *
+ * This may be called multiple times for binary chains (scripts for example).
*/
int prepare_binprm(struct linux_binprm *bprm)
{
- int mode;
+ umode_t mode;
struct inode * inode = bprm->file->f_path.dentry->d_inode;
int retval;
@@ -1046,14 +1086,15 @@ int prepare_binprm(struct linux_binprm *bprm)
if (bprm->file->f_op == NULL)
return -EACCES;
- bprm->e_uid = current_euid();
- bprm->e_gid = current_egid();
+ /* clear any previous set[ug]id data from a previous binary */
+ bprm->cred->euid = current_euid();
+ bprm->cred->egid = current_egid();
- if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
+ if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
/* Set-uid? */
if (mode & S_ISUID) {
- current->personality &= ~PER_CLEAR_ON_SETID;
- bprm->e_uid = inode->i_uid;
+ bprm->per_clear |= PER_CLEAR_ON_SETID;
+ bprm->cred->euid = inode->i_uid;
}
/* Set-gid? */
@@ -1063,50 +1104,23 @@ int prepare_binprm(struct linux_binprm *bprm)
* executable.
*/
if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
- current->personality &= ~PER_CLEAR_ON_SETID;
- bprm->e_gid = inode->i_gid;
+ bprm->per_clear |= PER_CLEAR_ON_SETID;
+ bprm->cred->egid = inode->i_gid;
}
}
/* fill in binprm security blob */
- retval = security_bprm_set(bprm);
+ retval = security_bprm_set_creds(bprm);
if (retval)
return retval;
+ bprm->cred_prepared = 1;
- memset(bprm->buf,0,BINPRM_BUF_SIZE);
- return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
+ memset(bprm->buf, 0, BINPRM_BUF_SIZE);
+ return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
}
EXPORT_SYMBOL(prepare_binprm);
-static int unsafe_exec(struct task_struct *p)
-{
- int unsafe = tracehook_unsafe_exec(p);
-
- if (atomic_read(&p->fs->count) > 1 ||
- atomic_read(&p->files->count) > 1 ||
- atomic_read(&p->sighand->count) > 1)
- unsafe |= LSM_UNSAFE_SHARE;
-
- return unsafe;
-}
-
-void compute_creds(struct linux_binprm *bprm)
-{
- int unsafe;
-
- if (bprm->e_uid != current_uid())
- current->pdeath_signal = 0;
- exec_keys(current);
-
- task_lock(current);
- unsafe = unsafe_exec(current);
- security_bprm_apply_creds(bprm, unsafe);
- task_unlock(current);
- security_bprm_post_apply_creds(bprm);
-}
-EXPORT_SYMBOL(compute_creds);
-
/*
* Arguments are '\0' separated strings found at the location bprm->p
* points to; chop off the first by relocating brpm->p to right after
@@ -1259,6 +1273,8 @@ EXPORT_SYMBOL(search_binary_handler);
void free_bprm(struct linux_binprm *bprm)
{
free_arg_pages(bprm);
+ if (bprm->cred)
+ abort_creds(bprm->cred);
kfree(bprm);
}
@@ -1284,10 +1300,20 @@ int do_execve(char * filename,
if (!bprm)
goto out_files;
+ retval = mutex_lock_interruptible(&current->cred_exec_mutex);
+ if (retval < 0)
+ goto out_free;
+
+ retval = -ENOMEM;
+ bprm->cred = prepare_exec_creds();
+ if (!bprm->cred)
+ goto out_unlock;
+ check_unsafe_exec(bprm);
+
file = open_exec(filename);
retval = PTR_ERR(file);
if (IS_ERR(file))
- goto out_kfree;
+ goto out_unlock;
sched_exec();
@@ -1301,14 +1327,10 @@ int do_execve(char * filename,
bprm->argc = count(argv, MAX_ARG_STRINGS);
if ((retval = bprm->argc) < 0)
- goto out_mm;
+ goto out;
bprm->envc = count(envp, MAX_ARG_STRINGS);
if ((retval = bprm->envc) < 0)
- goto out_mm;
-
- retval = security_bprm_alloc(bprm);
- if (retval)
goto out;
retval = prepare_binprm(bprm);
@@ -1330,21 +1352,18 @@ int do_execve(char * filename,
current->flags &= ~PF_KTHREAD;
retval = search_binary_handler(bprm,regs);
- if (retval >= 0) {
- /* execve success */
- security_bprm_free(bprm);
- acct_update_integrals(current);
- free_bprm(bprm);
- if (displaced)
- put_files_struct(displaced);
- return retval;
- }
+ if (retval < 0)
+ goto out;
-out:
- if (bprm->security)
- security_bprm_free(bprm);
+ /* execve succeeded */
+ mutex_unlock(&current->cred_exec_mutex);
+ acct_update_integrals(current);
+ free_bprm(bprm);
+ if (displaced)
+ put_files_struct(displaced);
+ return retval;
-out_mm:
+out:
if (bprm->mm)
mmput (bprm->mm);
@@ -1353,7 +1372,11 @@ out_file:
allow_write_access(bprm->file);
fput(bprm->file);
}
-out_kfree:
+
+out_unlock:
+ mutex_unlock(&current->cred_exec_mutex);
+
+out_free:
free_bprm(bprm);
out_files:
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-18 10:19:44 +0000